Co-reporter:Bernd Kampe;Sandra Kloß;Thomas Bocklitz;Petra Rösch
Frontiers of Optoelectronics 2017 Volume 10( Issue 3) pp:273-279
Publication Date(Web):13 July 2017
DOI:10.1007/s12200-017-0726-4
The presence of irrelevant and correlated data points in a Raman spectrum can lead to a decline in classifier performance. We introduce support vector machine (SVM)-based recursive feature elimination into the field of Raman spectroscopy and demonstrate its performance on a data set of spectra of clinically relevant microorganisms in urine samples, along with patient samples. As the original technique is only suitable for two-class problems, we adapt it to the multi-class setting. It is shown that a large amount of spectral points can be removed without degrading the prediction accuracy of the resulting model notably.
Co-reporter:I. J. Jahn;O. Žukovskaja;X.-S. Zheng;K. Weber;T. W. Bocklitz;D. Cialla-May;J. Popp
Analyst (1876-Present) 2017 vol. 142(Issue 7) pp:1022-1047
Publication Date(Web):2017/03/27
DOI:10.1039/C7AN00118E
The exhaustive body of literature published in the last four years on the development and application of systems based on surface-enhanced Raman spectroscopy (SERS) combined with microfluidic devices demonstrates that this research field is a current hot topic. This synergy, also referred to as lab-on-a-chip SERS (LoC-SERS) or nano/micro-optofluidics SERS, has opened the door for new opportunities where both techniques can profit. On the one hand, SERS measurements are considerably improved because the processes previously performed on a large scale in the laboratory and prone to human error can now be carried out in nanoliter volumes in an automatic and reproducible manner; on the other hand, microfluidic platforms need detection methods able to sense in small volumes and therefore, SERS is ideal for this task. The present review not only aims to provide the reader an overview of the recent developments and advancements in this field, but it also addresses the key aspects of fundamental SERS theory that influence the interpretation of SERS spectra, as well as the challenges brought about by the experimental conditions and chemometric data analysis.
Co-reporter:Katharina Eberhardt, Claudia BeleitesShiva Marthandan, Christian Matthäus, Stephan Diekmann, Jürgen Popp
Analytical Chemistry 2017 Volume 89(Issue 5) pp:
Publication Date(Web):January 27, 2017
DOI:10.1021/acs.analchem.6b04264
Cellular senescence is a terminal cell cycle arrested state, assumed to be involved in tumor suppression. We studied four human fibroblast cell strains (BJ, MRC-5, IMR-90, and WI-38) from proliferation into senescence. Cells were investigated by label-free vibrational Raman and infrared spectroscopy, following their transition into replicative senescence. During the transition into senescence, we observed rather similar biomolecular abundances in all four cell strains and between proliferating and senescent cells; however, in the four aging cell strains, we found common molecular differences dominated by protein and lipid modifications. Hence, aging induces a change in the appearance of biomolecules (including degradation and storage of waste) rather than in their amount present in the cells. For all fibroblast strains combined, the partial least squares-linear discriminant analysis (PLS-LDA) model resulted in 75% and 81% accuracy for the Raman and infrared (IR) data, respectively. Within this validation, senescent cells were recognized with 93% sensitivity and 90% specificity for the Raman and 84% sensitivity and 97% specificity for the IR data. Thus, Raman and infrared spectroscopy can identify replicative senescence on the single cell level, suggesting that vibrational spectroscopy may be suitable for identifying and distinguishing different cellular states in vivo, e.g., in skin.
Co-reporter:D. Cialla-May;X.-S. Zheng;K. Weber;J. Popp
Chemical Society Reviews 2017 vol. 46(Issue 13) pp:3945-3961
Publication Date(Web):2017/07/03
DOI:10.1039/C7CS00172J
The application of surface-enhanced Raman spectroscopy (SERS) in biological and biomedical detection schemes is feasible due to its excellent molecular specificity and high sensitivity as well as the capability of SERS to be performed in complex biological compositions. SERS-based investigation of cells, which are the basic structure and functional unit of organisms, represents the starting point of this review. It is demonstrated that SERS provides a deep understanding of living cells as well as their microenvironment which is needed to assess the development of diseases. The clinical relevance of SERS is proved by its application for the detection of cancer cells and tumour margins under in vivo conditions and examples for theranostic approaches are discussed. This review article provides a comprehensive overview of the recent progress within the last 3 years.
Co-reporter:Vinay Kumar B. N., Shuxia Guo, Thomas Bocklitz, Petra Rösch, and Jürgen Popp
Analytical Chemistry 2016 Volume 88(Issue 15) pp:7574
Publication Date(Web):June 15, 2016
DOI:10.1021/acs.analchem.6b01046
Carbon catabolite repression (CCR) is a regulatory phenomenon occurring in both lower organisms like bacteria and higher organisms like yeast, which allows them to preferentially utilize a specific carbon source to achieve highest metabolic activity and cell growth. CCR has been intensely studied in the model organisms Escherichia coli and Bacillus subtilis by following diauxic growth curves, assays to estimate the utilization or depletion of carbon sources, enzyme assays, Western blotting and mass spectrometric analysis to monitor and quantify the involvement of specific enzymes and proteins involved in CCR. In this study, we have visualized this process in three species of naphthalene degrading soil bacteria at a single cell level via Raman spectroscopy based stable isotope probing (Raman-SIP) using a single and double labeling approach. This is achieved using a combination of 2H and 13C isotope labeled carbon sources like glucose, galactose, fructose, and naphthalene. Time dependent metabolic flux of 13C and 2H isotopes has been followed via semi quantification and 2D Raman correlation analysis. For this, the relative intensities of Raman marker bands corresponding to 2H and 13C incorporation in newly synthesized macromolecules like proteins and lipids have been utilized. The 2D correlation analysis of time dependent Raman spectra readily identified small sequential changes resulting from isotope incorporation. Overall, we show that Raman-SIP has the potential to be used to obtain information about regulatory processes like CCR in bacteria at a single cell level within a time span of 3 h in fast growing bacteria. We also demonstrate the potential of this approach in identifying the most efficient naphthalene degraders asserting its importance for use in bioremediation.
Co-reporter:Thomas W. Bocklitz, Shuxia Guo, Oleg Ryabchykov, Nadine Vogler, and Jürgen Popp
Analytical Chemistry 2016 Volume 88(Issue 1) pp:133
Publication Date(Web):December 10, 2015
DOI:10.1021/acs.analchem.5b04665
Co-reporter:R. Geitner, J. Kötteritzsch, M. Siegmann, R. Fritzsch, T. W. Bocklitz, M. D. Hager, U. S. Schubert, S. Gräfe, B. Dietzek, M. Schmitt and J. Popp
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 27) pp:17973-17982
Publication Date(Web):15 Jun 2016
DOI:10.1039/C6CP03464K
The self-healing polymer P(LMA-co-MeAMMA) crosslinked with C60-fullerene has been studied by FT-Raman spectroscopy in combination with two-dimensional (2D) correlation analysis and density functional theory calculations. To unveil the molecular changes during the self-healing process mediated by the Diels–Alder equilibrium between 10-methyl-9-anthracenyl groups and C60-fullerene different anthracene–C60-fullerene adducts have been synthesized and characterized by time-, concentration- and temperature-dependent FT-Raman measurements. The self-healing process could be monitored via the C60-fullerene vibrations at 270, 432 and 1469 cm−1. Furthermore, the detailed analysis of the concentration-dependent FT-Raman spectra point towards the formation of anthracene–C60-fullerene adducts with an unusual high amount of anthracene bound to C60-fullerene in the polymer film, while the 2D correlation analysis of the temperature-dependent Raman spectra suggests a stepwise dissociation of anthracene–C60-fullerene adducts, which are responsible for the self-healing of the polymer.
Co-reporter:Wilm Schumacher;Stephan Stöckel;Petra Rösch;Jürgen Popp
Journal of Chemometrics 2016 Volume 30( Issue 5) pp:268-283
Publication Date(Web):
DOI:10.1002/cem.2788
In this contribution, a technique is proposed to create a data-driven interpretation of a given chemometric analysis of a Raman dataset. In real-world applications, the chemometric analysis is fixed by some external measurement, for example, a legal standard, or a set of fixed goals. Thus, the exact chemometric work flow is fixed because of those goals. However, a further optimization, for example, of the measurement itself relies on an interpretation of the resulting chemometric analysis. For this purpose, a data-driven analysis of the chemometric analysis itself has to be carried out. This contribution tries to achieve that goal by combining two methods. The first proposed technique is the calculation of the so-called importance map, which allows the computation of the importance of every channel for a given model and a given dataset. This importance map is constructed after the complete result of an out-of-bag (OOB) validation and the decrease of accuracy by randomized channels. The second technique is the growing of the optimal decision tree based on the action of the model used for chemometric analysis. By this way, a clustering is achieved on which by binary classifiers, the optimal decision tree is grown. This tree can be interpreted as dividing the whole dataset into meta clusters. Combining these techniques, a new way of interpreting datasets based on the chosen model is proposed. This combination closes the gap between chemometric analysis and the need for interpretation. Copyright © 2016 John Wiley & Sons, Ltd.
Co-reporter:Yan Su, Liang Qu, Hongying Duan, Nicolae Tarcea, Aiguo Shen, Jürgen Popp, Jiming Hu
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2016 Volume 153() pp:165-170
Publication Date(Web):15 January 2016
DOI:10.1016/j.saa.2015.08.005
•A non-invasive and comprehensive analysis of Chinese enamels from the Imperial Palace of China.•The major ingredient of the cloisonné enamel and the painted enamel was discussed for the first time.•Elemental analysis-aided Raman spectroscopy is useful with regard to the restoration cultural relic.Two kinds of enamels, including Chinese cloisonné wares from Fuwang chamber and gourd-shaped painted enamels decorations from the Forbidden City, in the Imperial Palace of China, are investigated by micro-Raman spectroscopy in combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy-dispersive X-ray fluorescence (EDXRF) in order to examine and analyze the composition of the glaze layer in each case. In this study the excitation is employed with either a NIR laser (785 nm) or a red laser (632.8 nm) in order to effectively eliminate the interference of background fluorescence and resonance effect. We have identified that the major matrix ingredients of the cloisonné wares are lead-based potash-lime silicate glasses while lead-potash silicate glass matrix is the main constituent for the painted enamels. Eight different colored areas of glaze layer also have been discussed in detail due to the distinct colors including turquoise, deep blue, yellow, white, red, pink, deep green and pale green. Their identification based on Raman data will be useful with regard to rapid and on site analysis and the restoration of the enamel decorations.
Co-reporter:Sandra Kloß, Petra Rösch, Wolfgang Pfister, Michael Kiehntopf, and Jürgen Popp
Analytical Chemistry 2015 Volume 87(Issue 2) pp:937
Publication Date(Web):December 17, 2014
DOI:10.1021/ac503373r
The identification of pathogens in ascitic fluid is standardly performed by ascitic fluid culture, but this standard procedure often needs several days. Additionally, more than half of the ascitic fluid cultures are negative in case of suspected spontaneous bacterial peritonitis (SBP). It is therefore important to identify and characterize the causing pathogens since not all of them are covered by the empirical antimicrobial therapy. The aim of this study is to show that pathogen identification in ascitic fluid is possible by means of Raman microspectroscopy and chemometrical evaluation with the advantage of strongly increased speed. Therefore, a Raman database containing more than 10000 single-cell Raman spectra of 34 bacterial strains out of 13 different species was built up. The performance of the used statistical model was validated with independent bacterial strains, which were grown in ascitic fluid.
Co-reporter:Vinay Kumar B. N., Bernd Kampe, Petra Rösch and Jürgen Popp
Analyst 2015 vol. 140(Issue 13) pp:4584-4593
Publication Date(Web):12 May 2015
DOI:10.1039/C5AN00438A
A soil habitat consists of an enormous number of pigmented bacteria with the pigments mainly composed of diverse carotenoids. Most of the pigmented bacteria in the top layer of the soil are photoprotected from exposure to huge amounts of UVA radiation on a daily basis by these carotenoids. The photostability of these carotenoids depends heavily on the presence of specific features like a carbonyl group or an ionone ring system on its overall structure. Resonance Raman spectroscopy is one of the most sensitive and powerful techniques to detect and characterize these carotenoids and also monitor processes associated with them in their native system at a single cell resolution. However, most of the resonance Raman profiles of carotenoids have very minute differences, thereby making it extremely difficult to confirm if these differences are attributed to the presence of different carotenoids or if it is a consequence of their interaction with other cellular components. In this study, we devised a method to overcome this problem by monitoring also the photodegradation of the carotenoids in question by UVA radiation wherein a differential photodegradation response will confirm the presence of different carotenoids irrespective of the proximities in their resonance Raman profiles. Using this method, the detection and characterization of carotenoids in pure cultures of five species of pigmented coccoid soil bacteria is achieved. We also shed light on the influence of the structure of the carotenoid on its photodegradation which can be exploited for use in the characterization of carotenoids via resonance Raman spectroscopy.
Co-reporter:R. Geitner, J. Kötteritzsch, M. Siegmann, T. W. Bocklitz, M. D. Hager, U. S. Schubert, S. Gräfe, B. Dietzek, M. Schmitt and J. Popp
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 35) pp:22587-22595
Publication Date(Web):01 Jun 2015
DOI:10.1039/C5CP02151K
The thermally healable polymer P(LMA-co-FMA-co-MIMA) has been studied by temperature-dependent FT-Raman spectroscopy, two-dimensional Raman correlation analysis and density functional theory (DFT) calculations. To the best of our knowledge this study reports for the first time on the investigation of a self-healing polymer by means of two-dimensional correlation techniques. The synchronous correlation spectrum reveals that the spectrally overlapping CC stretching vibrations at 1501, 1575, 1585 and 1600 cm−1 are perfect marker bands to monitor the healing process which is based on a Diels–Alder reaction of furan and maleimide. The comparison between experimental and calculated Raman spectra as well as their correlation spectra showed a good agreement between experiment and theory. The data presented within this study nicely demonstrate that Raman correlation analysis combined with a band assignment based on DFT calculations presents a powerful tool to study the healing process of self-healing polymers.
Co-reporter:Vinay Kumar;Bernd Kampe;Petra Rösch
Environmental Science and Pollution Research 2015 Volume 22( Issue 24) pp:19317-19325
Publication Date(Web):2015 December
DOI:10.1007/s11356-015-4593-5
A soil habitat consists of a significant number of bacteria that cannot be cultivated by conventional means, thereby posing obvious difficulties in their classification and identification. This difficulty necessitates the need for advanced techniques wherein a well-compiled biomolecular database consisting of the already cultivable bacteria can be used as a reference in an attempt to link the noncultivable bacteria to their closest phylogenetic groups. Raman spectroscopy has been successfully applied to taxonomic studies of many systems like bacteria, fungi, and plants relying on spectral differences contributed by the variation in their overall biomolecular composition. However, these spectral differences can be obscured due to Raman signatures from photosensitive microbial pigments like carotenoids that show enormous variation in signal intensity hindering taxonomic investigations. In this study, we have applied laser-induced photobleaching to expel the carotenoid signatures from pigmented cocci bacteria. Using this method, we have investigated 12 species of pigmented bacteria abundant in soil habitats belonging to three genera mainly Micrococcus, Deinococcus, and Kocuria based on their Raman spectra with the assistance of a chemometric tool known as the radial kernel support vector machine (SVM). Our results demonstrate the potential of Raman spectroscopy as a minimally invasive taxonomic tool to identify pigmented cocci soil bacteria at a single-cell level.
Co-reporter:Ute Münchberg;Lysett Wagner;Carsten Rohrer
Analytical and Bioanalytical Chemistry 2015 Volume 407( Issue 12) pp:3303-3311
Publication Date(Web):2015 May
DOI:10.1007/s00216-015-8544-2
Fungi of the genus Mortierella can accumulate large amounts of unusual lipids depending on species, strain, and growth conditions. Fast and easy determination of key parameters of lipid quality for these samples is required. In this contribution, we apply Raman microspectroscopy to determine the degree of unsaturation for fungal lipids directly inside intact hyphae without elaborate sample handling. Six Mortierella species were grown under varying conditions, and Raman spectra of single lipid vesicles were acquired. From the spectra, we calculate a peak intensity ratio I(1270 cm−1)/I(1445 cm−1) from the signals of =CH and –CH2/–CH3 groups, respectively. This ratio is linked to the iodine value (IV) using spectra of reference compounds with known IV. IVs of fungal samples are compared to gas chromatography results. Values from both methods are in good accordance. Lipid composition is found to vary between the investigated species, with Mortierella alpina having the most unsaturated lipid (IV up to 280) and Mortierella exigua the least unsaturated (IV as low as 70). We find Raman microspectroscopy a suitable tool to determine the IV reliably, fast, and easily inside intact hyphae without extensive sample handling or treatment. The method can also be transferred to other microscopic samples.
Co-reporter:Evelyn Kämmer, Konstanze Olschewski, Thomas Bocklitz, Petra Rösch, Karina Weber, Dana Cialla and Jürgen Popp
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 19) pp:9056-9063
Publication Date(Web):17 Mar 2014
DOI:10.1039/C3CP55312D
This study demonstrates a new concept of calibrating surface enhanced Raman scattering (SERS) intensities without using additional substances as an internal standard and explores factors such as laser fluctuation and different Ag substrates, which affect the results of quantitative analyses based on SERS. To demonstrate the capabilities of the concept, the model analyte adenine has been chosen. A lab-on-a-chip device is applied for the measurements to guarantee consistent data recording. In order to simulate varied measuring conditions, two varying silver colloids (batch 1 and 2) are utilized as a SERS substrate and two different laser power levels (25 or 55 mW) are applied on the sample. A concentration gradient was generated which allows the use of the analyte itself for the correction of the resulting SERS spectra regarding intensity deviations caused by different ambient conditions. In doing so, a vast improvement in the quantification using SERS, especially in view of the comparability, reproducibility and repeatability, is demonstrated.
Co-reporter:T. Tolstik, C. Marquardt, C. Matthäus, N. Bergner, C. Bielecki, C. Krafft, A. Stallmach and J. Popp
Analyst 2014 vol. 139(Issue 22) pp:6036-6043
Publication Date(Web):22 Sep 2014
DOI:10.1039/C4AN00211C
Discrimination of nodular lesions in cirrhotic liver is a challenge in the histopathologic diagnostics. For this reason, there is an urgent need for new detection methods to improve the accuracy of the diagnosis of liver cancer. Raman imaging allows to determine the spatial distribution of a variety of molecules in cells or tissue label-free and to correlate this molecular information with the morphological structures at the same sample location. This study reports investigations of two liver cancer cell lines, – HepG2 and SK-Hep1, – as well as HepG2 cells in different cellular growth phases using Raman micro-spectroscopic imaging. Spectral data of all cells were recorded as a color-coded image and subsequentially analyzed by hierarchical cluster and principal component analysis. A support vector machine-based classification algorithm reliably predicts previously unknown cancer cells and cell cycle phases. By including selectively the Raman spectra of the cytoplasmic lipids in the classifier, the accuracy has been improved. The main spectral differences that were found in the comparative analysis can be attributed to a higher expression of unsaturated fatty acids in the hepatocellular carcinoma cells and during the proliferation phase. This corresponds to the already examined de novo lipogenesis in cells of liver cancer.
Co-reporter:Ute Münchberg;Petra Rösch;Michael Bauer
Analytical and Bioanalytical Chemistry 2014 Volume 406( Issue 13) pp:3041-3050
Publication Date(Web):2014 May
DOI:10.1007/s00216-014-7747-2
The identification of pathogenic bacteria is a frequently required task. Current identification procedures are usually either time-consuming due to necessary cultivation steps or expensive and demanding in their application. Furthermore, previous treatment of a patient with antibiotics often renders routine analysis by culturing difficult. Since Raman microspectroscopy allows for the identification of single bacterial cells, it can be used to identify such difficult to culture bacteria. Yet until now, there have been no investigations whether antibiotic treatment of the bacteria influences the Raman spectroscopic identification. This study aims to rapidly identify bacteria that have been subjected to antibiotic treatment on single cell level with Raman microspectroscopy. Two strains of Escherichia coli and two species of Pseudomonas have been treated with four antibiotics, all targeting different sites of the bacteria. With Raman spectra from untreated bacteria, a linear discriminant analysis (LDA) model is built, which successfully identifies the species of independent untreated bacteria. Upon treatment of the bacteria with subinhibitory concentrations of ampicillin, ciprofloxacin, gentamicin, and sulfamethoxazole, the LDA model achieves species identification accuracies of 85.4, 95.3, 89.9, and 97.3 %, respectively. Increasing the antibiotic concentrations has no effect on the identification performance. An ampicillin-resistant strain of E. coli and a sample of P. aeruginosa are successfully identified as well. General representation of antibiotic stress in the training data improves species identification performance, while representation of a specific antibiotic improves strain distinction capability. In conclusion, the identification of antibiotically treated bacteria is possible with Raman microspectroscopy for diverse antibiotics on single cell level.
Co-reporter:Katharina Bräutigam, Thomas Bocklitz, Anja Silge, Christian Dierker, Rainer Ossig, Jürgen Schnekenburger, Dana Cialla, Petra Rösch, Jürgen Popp
Journal of Molecular Structure 2014 1073() pp: 44-50
Publication Date(Web):5 September 2014
DOI:10.1016/j.molstruc.2014.05.013
•Raman imaging was used for intracellular detection of non-labeled TiO2 nanomaterial.•Different intracellular TiO2 storage of fibroblasts and macrophages were identified.•Fibroblasts formed relatively small TiO2 aggregations in the cytoplasm.•Macrophages showed typical large storage vesicles with huge TiO2 accumulations.•Additional information on the current status of material properties can be detected.The increasing production and application of engineered nanomaterials requires a detailed understanding of the potential toxicity of nanoparticles and their uptake in living cells and tissue. For that purpose, a highly sensitive and selective method for detecting single nonlabeled nanoparticles and nanoparticle agglomerations in cells and animal tissue is required. Here, we show that Raman microspectroscopy allows for the specific detection of TiO2 nanoparticles inside cultured NIH/3T3 fibroblasts and RAW 264.7 macrophages. The spatial position of TiO2 nanoparticles and in parallel the relative intracellular concentration and distribution of cellular constituents such as proteins or DNA residues were identified and displayed by construction of two- and three-dimensional Raman maps. The resulting Raman images reflected the significant differences in nanoparticle uptake and intracellular storage of fibroblasts and macrophages. Furthermore, TiO2 nanomaterials could be characterized and the presence of rutile- and anatase-phase TiO2 were determined inside cells. Together, the data shown here prove that Raman spectroscopic imaging is a promising technique for studying the interaction of nanomaterials with living cells and for differentiating intracellular nanoparticles from those localized on the cell membrane. The technology provides a label-free, non-destructive, material-specific analysis of whole cells with high spatial resolution, along with additional information on the current status of the material properties.Download full-size image
Co-reporter:Moritz Klein, Ute Neugebauer, Ali Gheisari, Astrid Malassa, Taghreed M. A. Jazzazi, Frank Froehlich, Matthias Westerhausen, Michael Schmitt, and Jürgen Popp
The Journal of Physical Chemistry A 2014 Volume 118(Issue 29) pp:5381-5390
Publication Date(Web):June 30, 2014
DOI:10.1021/jp503407u
Carbon monoxide (CO) is a toxic gas for mammals, and despite this fact, it is naturally produced in these organisms and has been proven to be beneficial in medical treatments, too. Therefore, CO-releasing molecules (CORMs) are intensively developed to administer and dose CO for physiological applications. Nearly all of these compounds are metal carbonyl complexes, which have been synthesized and investigated. However, for most of these CORMs, the exact reaction mechanisms of CO release is not completely elucidated, although it is of utmost importance. The widely used myoglobin assay for testing the CO release has several disadvantages, and therefore, different methods have to be applied to characterize CORMs. In this work, different setups of IR absorption spectroscopy are used to analyze and quantify the CO release during the decay of various CORMs: IR spectroscopy of the gas phase is applied to follow the CO liberation, and attenuated total reflection (ATR) IR spectroscopy is used to record the decay of the metal carbonyl. IR spectroscopy supported by DFT calculations yields valuable insights in the CO release reaction mechanism. The focus is set on two different CORMs: CORM-2 (Ru2(CO)6Cl4) and on the photoactive CORM-S1 (photoCORM [Fe(CO)2(SCH2CH2NH2)2]). Our results indicate that the CO liberation from CORM-2 strongly depends on sodium dithionite, which is required for the commonly applied myoglobin assay and that CORM-S1 loses all its bound CO molecules upon irradiation with blue light.
Co-reporter:Valerian Ciobotă, Walid Salama, Paul Vargas Jentzsch, Nicolae Tarcea, Petra Rösch, Ahmed El Kammar, Rania S. Morsy, Jürgen Popp
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 118() pp:42-47
Publication Date(Web):24 January 2014
DOI:10.1016/j.saa.2013.08.059
•The mineralogy of the Upper Cretaceous Duwi phosphorite deposits were investigated.•Carbonate apatite was the only P-containing mineral detected in the investigated samples.•Apatite is usually associated with CaSO4 and seldom with CaCO3 in the studied samples.•Calcium sulfate and goethite are products of diagenesis and weathering.•The formation of the phosphorite deposits took place in marine environment.The mineral composition of the Upper Cretaceous Duwi phosphorite deposits and underlying Quseir Variegated Shale from Safaga district, Red Sea Range, Egypt, was investigated by dispersive and Fourier transformed Raman spectroscopy. The only phosphorous containing mineral detected in the phosphorite deposits was carbonate fluorapatite. Often carbonate fluorapatite appears associated with calcium sulfate and seldom with calcium carbonate in the investigated samples. Iron is present in the form of goethite and pyrite in the phosphorite layer, while pyrite, marcasite and hematite were identified in the Quseir Shale samples. Also, a high amount of disordered carbon was detected in the black shale layers. The Raman results confirm the hypothesis that the formation of the phosphorites took place in a marine environment. During the formation of black shale, the redox conditions changed, with the pH reaching values of 4 or even lower. Diagenetic and weathering transformations had taken place in the phosphorite deposits, calcium sulfate and goethite being products of these types of processes.Graphical abstract
Co-reporter:Sandra Kloß, Bernd Kampe, Svea Sachse, Petra Rösch, Eberhard Straube, Wolfgang Pfister, Michael Kiehntopf, and Jürgen Popp
Analytical Chemistry 2013 Volume 85(Issue 20) pp:9610
Publication Date(Web):September 6, 2013
DOI:10.1021/ac401806f
Urinary tract infection (UTI) is a very common infection. Up to every second woman will experience at least one UTI episode during her lifetime. The gold standard for identifying the infectious microorganisms is the urine culture. However, culture methods are time-consuming and need at least 24 h until the results are available. Here, we report about a culture independent identification procedure by using Raman microspectroscopy in combination with innovative chemometrics. We investigated, for the first time directly, urine samples by Raman microspectroscopy on a single-cell level. In a first step, a database of eleven important UTI bacterial species, which were grown in sterile filtered urine, was built up. A support vector machine (SVM) was used to generate a statistical model, which allows a classification of this data set with an accuracy of 92% on a species level. This model was afterward used to identify infected urine samples of ten patients directly without a preceding culture step. Thereby, we were able to determine the predominant bacterial species (seven Escherichia coli and three Enterococcus faecalis) for all ten patient samples. These results demonstrate that Raman microspectroscopy in combination with support vector machines allow an identification of important UTI bacteria within two hours without the need of a culture step.
Co-reporter:Martha Schwarz, Susanne Pahlow, Thomas Bocklitz, Carolin Steinbrücker, Dana Cialla, Karina Weber and Jürgen Popp
Analyst 2013 vol. 138(Issue 20) pp:5866-5870
Publication Date(Web):12 Aug 2013
DOI:10.1039/C3AN01240A
An easy and inexpensive detection method for DNA hybridization assays combining magnetic beads and enzymatically generated silver nanoparticles is introduced. The main advantage of this approach is the possibility to distinguish between positive and negative test results with the naked eye. In the case of complementary DNA sequences the sample will turn black within a few minutes, allowing readout without any hardware. In order to illustrate the applicability of the assay genomic DNA isolated from E. coli contaminated Ringer's solution was used for testing the sensitivity as well as specificity.
Co-reporter:Tobias Meyer, Martin Baumgartl, Thomas Gottschall, Torbjörn Pascher, Andreas Wuttig, Christian Matthäus, Bernd F. M. Romeike, Bernhard R. Brehm, Jens Limpert, Andreas Tünnermann, Orlando Guntinas-Lichius, Benjamin Dietzek, Michael Schmitt and Jürgen Popp
Analyst 2013 vol. 138(Issue 14) pp:4048-4057
Publication Date(Web):03 Apr 2013
DOI:10.1039/C3AN00354J
The past years have seen increasing interest in nonlinear optical microscopic imaging approaches for the investigation of diseases due to the method's unique capabilities of deep tissue penetration, 3D sectioning and molecular contrast. Its application in clinical routine diagnostics, however, is hampered by large and costly equipment requiring trained staff and regular maintenance, hence it has not yet matured to a reliable tool for application in clinics. In this contribution implementing a novel compact fiber laser system into a tailored designed laser scanning microscope results in a small footprint easy to use multimodal imaging platform enabling simultaneously highly efficient generation and acquisition of second harmonic generation (SHG), two-photon excited fluorescence (TPEF) as well as coherent anti-Stokes Raman scattering (CARS) signals with optimized CARS contrast for lipid imaging for label-free investigation of tissue samples. The instrument combining a laser source and a microscope features a unique combination of the highest NIR transmission and a fourfold enlarged field of view suited for investigating large tissue specimens. Despite its small size and turnkey operation rendering daily alignment dispensable the system provides the highest flexibility, an imaging speed of 1 megapixel per second and diffraction limited spatial resolution. This is illustrated by imaging samples of squamous cell carcinoma of the head and neck (HNSCC) and an animal model of atherosclerosis allowing for a complete characterization of the tissue composition and morphology, i.e. the tissue's morphochemistry. Highly valuable information for clinical diagnostics, e.g. monitoring the disease progression at the cellular level with molecular specificity, can be retrieved. Future combination with microscopic probes for in vivo imaging or even implementation in endoscopes will allow for in vivo grading of HNSCC and characterization of plaque deposits towards the detection of high risk plaques.
Co-reporter:Valerian Ciobotă, Shipeng Lu, Nicolae Tarcea, Petra Rösch, Kirsten Küsel, Jürgen Popp
Vibrational Spectroscopy 2013 Volume 68() pp:212-219
Publication Date(Web):September 2013
DOI:10.1016/j.vibspec.2013.08.005
A semi-quantitative investigation of the inorganic phase of pelagic, iron-rich aggregates (iron snow, IS) formed in an iron polluted aquatic environment was performed by means of Raman spectroscopy. IS samples were collected from two basins of an acidic lignite mine lake and at two different water depths. Although the water chemistry differed at all four sites with respect to oxygen, pH, and, Fe(II) concentrations, the Raman analyses showed that the main mineral formed was schwertmannite (ideal formula: Fe8O8(OH)6SO4) with concentrations of more than 88% in all IS samples. To determine potential differences in the microbial communities of the IS samples we used denaturing gradient gel electrophoresis. Microbial communities differed between two basins, but showed similarities between redoxcline and deeper water layers of IS samples from the same basin. Surprisingly, these microbiological differences did not lead to strikingly qualitative similarities in the mineral composition, although the initial step in mineral formation, the oxidation of Fe(II) to Fe(III), is a pure microbial process at low pH. Thus, a semi-quantitative method was necessary to elucidate differences in the consecutive mineralization process which is apparently more controlled by water geochemical conditions.
Co-reporter:Paul Vargas Jentzsch, Bernd Kampe, Valerian Ciobotă, Petra Rösch, Jürgen Popp
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 115() pp:697-708
Publication Date(Web):November 2013
DOI:10.1016/j.saa.2013.06.085
•The Raman spectra of 45 atmospheric salts were recorded and the bands assigned.•The carbonate salts can play an important role in the atmosphere.•Structural similarities among salts can be expressed in the classification tree.•The 45 salts were classified into 3 groups.Atmospheric particulate matter is composed of inorganic and organic components of natural and anthropogenic origin. Wind-transport is probably the most important process responsible for the emission of solid particulate matter into the troposphere, but there are also important contributions from chemical reactions due to the interaction of different atmospheric components in presence of water and solar radiation. Sulfate, nitrate and carbonate salts can be both reactants and products in this complex dynamic system, and there is no doubt about their important impact on the climate. Both simple and mixed salts can be produced in atmosphere by dissolution–crystallization processes. The Raman spectra of 45 representative salts of the atmospheric environment were recorded and the bands assigned. The chemometric analysis of the spectroscopic data of these 45 salts demonstrates the suitability of Raman spectroscopy to classify and identify sulfate, nitrate and carbonate salts of atmospheric importance. Salts were classified into three groups: “sulfates”, “nitrates or carbonates” and “sulfate-nitrates or sulfate-carbonate”. This kind of information is relevant in atmospheric studies because specific characteristics of the salts can provide valuable information about the origin of the salts, the atmospheric chemistry and climate forcing, thus contributing to the evaluation of environmental impacts.
Co-reporter:Katharina Bräutigam;Dr. Thomas Bocklitz; Dr. Michael Schmitt;Dr. Petra Rösch; Dr. Jürgen Popp
ChemPhysChem 2013 Volume 14( Issue 3) pp:550-553
Publication Date(Web):
DOI:10.1002/cphc.201200800
Abstract
There is an urgent need for methods allowing for a fast, non-invasive, sensitive and selective monitoring of the effectiveness of anticancer drugs during the course of a chemotherapeutic treatment of cancer patients. The possibility of predicting and controlling the efficiency of chemotherapeutic agents for every patient individually enables a personalized therapy with largely improved success rates. The results presented herein demonstrate that Raman microspectroscopy is perfectly suited to monitor the impact of chemotherapeutic agents on living cells. The influence of the clinically well-established chemotherapeutic docetaxel on both the morphology and also biochemistry of living colon cancer cells (HT-29) has been studied by means of Raman spectroscopy in combination with modern chemometric approaches. The work presented paves the way for establishing Raman spectroscopy as a monitoring tool of the effectiveness of a chemotherapy treatment and can therefore be seen as a step towards personalized therapy.
Co-reporter:Dr. Gudrun Hermann; Dr. Michael Schmitt; Dr. Benjamin Dietzek; Dr. Jürgen Popp
ChemPhysChem 2013 Volume 14( Issue 11) pp:2598-2600
Publication Date(Web):
DOI:10.1002/cphc.201300374
No abstract is available for this article.
Co-reporter:Susanne Pahlow;Sra Kloß;Dr. Verena Blättel;Konstantin Kirsch;Dr. Uwe Hübner;Dr. Dana Cialla;Dr. Petra Rösch;Dr. Karina Weber; Dr. Jürgen Popp
ChemPhysChem 2013 Volume 14( Issue 15) pp:3600-3605
Publication Date(Web):
DOI:10.1002/cphc.201300543
Abstract
We developed a Raman-compatible chip for isolating microorganisms from complex media. The isolation of bacteria is achieved by using antibodies as capture molecules. Due to the very specific interaction with the targets, this approach is promising for isolation of bacteria even from complex matrices such as body fluids. Our choice of capture molecules also enabled the investigation of samples containing yet unidentified bacteria, as the antibodies can capture a large variety of bacteria based on their analogue cell wall surface structures. The capability of our system is demonstrated for a broad range of different Gram-positive and Gram-negative germs. Subsequent identification is done by recording Raman spectra of the bacteria. Further, it is shown that classification with chemometric methods is possible.
Co-reporter:Paul VargasJentzsch;Valerian Ciobot&x103;;Dr. Petra Rösch;Dr. Jürgen Popp
Angewandte Chemie 2013 Volume 125( Issue 5) pp:1450-1453
Publication Date(Web):
DOI:10.1002/ange.201208319
Co-reporter:Paul VargasJentzsch;Valerian Ciobot&x103;;Dr. Petra Rösch;Dr. Jürgen Popp
Angewandte Chemie International Edition 2013 Volume 52( Issue 5) pp:1410-1413
Publication Date(Web):
DOI:10.1002/anie.201208319
Co-reporter:Paul Vargas Jentzsch, Ralph Michael Bolanz, Valerian Ciobotă, Bernd Kampe, Petra Rösch, Juraj Majzlan, Jürgen Popp
Vibrational Spectroscopy 2012 Volume 61() pp:206-213
Publication Date(Web):July 2012
DOI:10.1016/j.vibspec.2012.03.007
The atmospheric particulate matter contains organic and inorganic components of both natural and anthropogenic origin. It is well-known that ions such as Na+, K+, Ca2+, Mg2+, NH4+, and SO42−, occur in atmosphere, therefore the formation of simple and mixed salts as a consequence of dissolution–precipitation processes within water droplets, e.g., in fog or haze, is also possible. Considering the known occurrence in atmosphere of mixed salts such as K2Ca(SO4)2·H2O (syngenite), (NH4)2Ca(SO4)2·H2O (koktaite), Na2Ca(SO4)2 (glauberite), and K2Ca2Mg(SO4)4·2H2O (polyhalite), more specific studies should elucidate their origin and environmental implications. This contribution presents the Raman spectroscopic study of the mentioned calcium-mixed salts. Based on experiments using single solution droplets, the atmospheric origin of syngenite and koktaite are postulated. The atmospheric origin of glauberite and polyhalite are discussed considering the characteristics of atmosphere as well as some principles usually used to explain the precipitation of minerals in evaporite deposits.
Co-reporter:S. Stöckel;S. Meisel;Dr. M. Elschner;Dr. P. Rösch;Dr. J. Popp
Angewandte Chemie International Edition 2012 Volume 51( Issue 22) pp:5339-5342
Publication Date(Web):
DOI:10.1002/anie.201201266
Co-reporter:S. Stöckel;S. Meisel;Dr. M. Elschner;Dr. P. Rösch;Dr. J. Popp
Angewandte Chemie 2012 Volume 124( Issue 22) pp:5433-5436
Publication Date(Web):
DOI:10.1002/ange.201201266
Co-reporter:Evelyn Kämmer, Thomas Dörfer, Andrea Csáki, Wilm Schumacher, Paulo Augusto Da Costa Filho, Nicolae Tarcea, Wolfgang Fritzsche, Petra Rösch, Michael Schmitt, and Jürgen Popp
The Journal of Physical Chemistry C 2012 Volume 116(Issue 10) pp:6083-6091
Publication Date(Web):February 14, 2012
DOI:10.1021/jp211863y
UV-SERS measurements offer a great potential for environmental or food (detection of food contaminats) analytics. Here, the UV-SERS enhancement potential of various kinds of metal colloids, such as Pd, Pt, Au, Ag, Au–Ag core–shell, and Ag–Au core–shell with different shapes and sizes, were studied using melamine as a test molecule. The influence of different activation (KF, KCl, KBr, K2SO4) agents onto the SERS activity of the nanomaterials was investigated, showing that the combination of a particular nanoparticle with a special activation agent is extremely crucial for the observed SERS enhancement. In particular, the size dependence of spherical nanoparticles of one particular metal on the activator has been exploited. By doing so, it could be shown that the SERS enhancement increases or decreases for increasing or decreasing size of a nanoparticle, respectively. Overall, the presented results demonstrate the necessity to adjust the nanoparticle size and the activation agent for different experiments in order to achieve the best possible UV-SERS results.
Co-reporter:Anne März;Sabine Trupp;Petra Rösch
Analytical and Bioanalytical Chemistry 2012 Volume 402( Issue 8) pp:2625-2631
Publication Date(Web):2012 March
DOI:10.1007/s00216-011-5273-z
Within this contribution, the proof-of-principle for a new concept for indirect surface-enhanced Raman spectroscopy (SERS) detection is presented. The fluorescence dye FR-530 is applied as a label molecule for the antibiotic erythromycin. The antibiotic binds directly to the label molecule. Changes within the SERS spectrum of the fluorescence dye appearing with the presence of the antibiotic are utilized for the detection and quantitative investigations of erythromycin. With the new concept of binding the label molecule directly to the analyte molecule, the application of linkage compounds like antibodies or any other recognition molecules becomes dispensable.
Co-reporter:Katharina Hartmann;Melanie Becker-Putsche
Analytical and Bioanalytical Chemistry 2012 Volume 403( Issue 3) pp:745-753
Publication Date(Web):2012 May
DOI:10.1007/s00216-012-5887-9
Chemotherapies feature a low success rate of about 25%, and therefore, the choice of the most effective cytostatic drug for the individual patient and monitoring the efficiency of an ongoing chemotherapy are important steps towards personalized therapy. Thereby, an objective method able to differentiate between treated and untreated cancer cells would be essential. In this study, we provide molecular insights into Docetaxel-induced effects in MCF-7 cells, as a model system for adenocarcinoma, by means of Raman microspectroscopy combined with powerful chemometric methods. The analysis of the Raman data is divided into two steps. In the first part, the morphology of cell organelles, e.g. the cell nucleus has been visualized by analysing the Raman spectra with k-means cluster analysis and artificial neural networks and compared to the histopathologic gold standard method hematoxylin and eosin staining. This comparison showed that Raman microscopy is capable of displaying the cell morphology; however, this is in contrast to hematoxylin and eosin staining label free and can therefore be applied potentially in vivo. Because Docetaxel is a drug acting within the cell nucleus, Raman spectra originating from the cell nucleus region were further investigated in a next step. Thereby we were able to differentiate treated from untreated MCF-7 cells and to quantify the cell–drug response by utilizing linear discriminant analysis models.
Co-reporter:Jürgen Popp
Analytical and Bioanalytical Chemistry 2012 Volume 404( Issue 9) pp:2523-2524
Publication Date(Web):2012 November
DOI:10.1007/s00216-012-6366-z
Co-reporter:Dana Cialla;Anne März;René Böhme;Frank Theil
Analytical and Bioanalytical Chemistry 2012 Volume 403( Issue 1) pp:27-54
Publication Date(Web):2012 April
DOI:10.1007/s00216-011-5631-x
Surface-enhanced Raman spectroscopy (SERS) combines molecular fingerprint specificity with potential single-molecule sensitivity. Therefore, the SERS technique is an attractive tool for sensing molecules in trace amounts within the field of chemical and biochemical analytics. Since SERS is an ongoing topic, which can be illustrated by the increased annual number of publications within the last few years, this review reflects the progress and trends in SERS research in approximately the last three years. The main reason why the SERS technique has not been established as a routine analytic technique, despite its high specificity and sensitivity, is due to the low reproducibility of the SERS signal. Thus, this review is dominated by the discussion of the various concepts for generating powerful, reproducible, SERS-active surfaces. Furthermore, the limit of sensitivity in SERS is introduced in the context of single-molecule spectroscopy and the calculation of the ‘real’ enhancement factor. In order to shed more light onto the underlying molecular processes of SERS, the theoretical description of SERS spectra is also a growing research field and will be summarized here. In addition, the recording of SERS spectra is affected by a number of parameters, such as laser power, integration time, and analyte concentration. To benefit from synergies, SERS is combined with other methods, such as scanning probe microscopy and microfluidics, which illustrates the broad applications of this powerful technique.
Co-reporter:Robert Hanf;Sonja Fey; Michael Schmitt;Dr. Gudrun Hermann; Benjamin Dietzek; Jürgen Popp
ChemPhysChem 2012 Volume 13( Issue 8) pp:2013-2015
Publication Date(Web):
DOI:10.1002/cphc.201200194
Co-reporter:Anne März, Thomas Bocklitz, and Jürgen Popp
Analytical Chemistry 2011 Volume 83(Issue 21) pp:8337
Publication Date(Web):September 14, 2011
DOI:10.1021/ac2015799
Concerning the usability of lab-on-a-chip surface enhanced Raman spectroscopy (LOC-SERS) for analytical tasks applying chemometric data evalutation, a secure, reproducible, and stable data output independent of inconsistent ambient conditions has to be accomplished. In this contribution, we present a new approach to achieve reliable and robust measurements based on segmented flow LOC-SERS via online-wavenumber calibration.
Co-reporter:Sebastian Dochow, Christoph Krafft, Ute Neugebauer, Thomas Bocklitz, Thomas Henkel, Günter Mayer, Jens Albert and Jürgen Popp
Lab on a Chip 2011 vol. 11(Issue 8) pp:1484-1490
Publication Date(Web):22 Feb 2011
DOI:10.1039/C0LC00612B
Raman spectroscopy has been recognized to be a powerful tool for label-free discrimination of cells. Sampling methods are under development to utilize the unique capabilities to identify cells in body fluids such as saliva, urine or blood. The current study applied optical traps in combination with Raman spectroscopy to acquire spectra of single cells in microfluidic glass channels. Optical traps were realized by two 1070 nm single mode fibre lasers. Microflows were controlled by a syringe pump system. A novel microfluidic glass chip was designed to inject single cells, modify the flow speed, accommodate the laser fibres and sort cells after Raman based identification. Whereas the integrated microchip setup used 514 nm for excitation of Raman spectra, a quartz capillary setup excited spectra with 785 nm laser wavelength. Classification models were trained using linear discriminant analysis to differentiate erythrocytes, leukocytes, acute myeloid leukaemia cells (OCI-AML3), and breast tumour cells BT-20 and MCF-7 with accuracies that are comparable with previous Raman experiments of dried cells and fixed cells in a Petri dish. Implementation into microfluidic environments enables a high degree of automation that is required to improve the throughput of the approach for Raman activated cell sorting.
Co-reporter:Anne März, Thomas Henkel, Dana Cialla, Michael Schmitt and Jürgen Popp
Lab on a Chip 2011 vol. 11(Issue 21) pp:3584-3592
Publication Date(Web):30 Sep 2011
DOI:10.1039/C1LC20638A
This review outlines concepts and applications of droplet formation via flow-through microdevices in Raman and surface enhanced Raman spectroscopy (SERS) as well as the advantages of the approach. Even though the droplet-based flow-through technique is utilized in various fields, the review focuses on implementing droplet-based fluidic systems in Raman and SERS as these highly specific detection methods are of major interest in the field of analytics. With the combination of Raman or SERS with droplet-based fluidics, it is expected to achieve novel opportunities for analytics. Besides the approach of using droplet-based microfluidic devices as a detection platform, the unique properties of flow-through systems for the formation of droplets are capitalized to produce SERS active substrates and to accomplish uniform sample preparation. Within this contribution, previous reported applications on droplet-based flow-through Raman and SERS approaches and the additional benefit with regard to the importance in the field of analytics are considered.
Co-reporter:Thomas Bocklitz, Angela Walter, Katharina Hartmann, Petra Rösch, Jürgen Popp
Analytica Chimica Acta 2011 Volume 704(1–2) pp:47-56
Publication Date(Web):17 October 2011
DOI:10.1016/j.aca.2011.06.043
Raman spectroscopy in combination with chemometrics is gaining more and more importance for answering biological questions. This results from the fact that Raman spectroscopy is non-invasive, marker-free and water is not corrupting Raman spectra significantly. However, Raman spectra contain despite Raman fingerprint information other contributions like fluorescence background, Gaussian noise, cosmic spikes and other effects dependent on experimental parameters, which have to be removed prior to the analysis, in order to ensure that the analysis is based on the Raman measurements and not on other effects.Here we present a comprehensive study of the influence of pre-processing procedures on statistical models. We will show that a large amount of possible and physically meaningful pre-processing procedures leads to bad results. Furthermore a method based on genetic algorithms (GAs) is introduced, which chooses the spectral pre-processing according to the carried out analysis task without trying all possible pre-processing approaches (grid-search). This was demonstrated for the two most common tasks, namely for a multivariate calibration model and for two classification models. However, the presented approach can be applied in general, if there is a computational measure, which can be optimized. The suggested GA procedure results in models, which have a higher precision and are more stable against corrupting effects.Highlights► The pre-processing was arranged in a hierarchical manner. ► A library of pre-processing methods for Raman spectra was set together. ► The influence of pre-processing was checked for calibration and classification task. ► A genetic optimization was introduced in order to enhance the pre-processing.
Co-reporter:Susann Meisel, Stephan Stöckel, Mandy Elschner, Petra Rösch and Jürgen Popp
Analyst 2011 vol. 136(Issue 23) pp:4997-5005
Publication Date(Web):13 Oct 2011
DOI:10.1039/C1AN15761B
The identification of single microorganism in food samples by conventional plating techniques or molecular genetic methods requires a time consuming enrichment step. Raman spectroscopy in combination with a suitable extraction method however offers the possibility to rapidly identify bacteria on a single cell level. Here we evaluate the two well-known bacteria extraction methods from milk: “buoyant density centrifugation” and “enzymatic milk clearing” towards their recovery efficiency and their compatibility with Raman spectroscopy for a rapid identification of microorganisms in milk. The achieved recovery yields are slightly better compared to those which are already applied for food investigations, where a loss of one order of magnitude is usually reached. For example, buoyant density centrifugation allows collecting up to 35% of the milk-spiked microorganisms. To prove the suitability of the isolation techniques for use in combination with the spectroscopic approach, a small Raman database has been created by recording Raman spectra of well-known contaminants in dairy products. Two subspecies of Escherichia coli and three different Pseudomonas species, which were inoculated to UHT (ultra-high-temperature processed) milk and afterwards extracted by the two techniques mentioned above, were analysed. At a first glance, grave spectral artefacts caused by the matrix itself or especially by the extraction techniques were not obvious. But via chemometric analysis, it could be shown that these factors noticeably influence the identification rates: while the samples prepared via milk clearing did not provide sufficient identification results, buoyant density centrifugation allows an identification of the investigated species with an overall accuracy of 91% in combination with linear discriminant analysis.
Co-reporter:Roberto Menzel;Alexer Breul;Christian Pietsch;Johann Schäfer;Christian Friebe;Eric Täuscher;Dieter Weiß;Benjamin Dietzek;Jürgen Popp;Rainer Beckert;Ulrich S. Schubert
Macromolecular Chemistry and Physics 2011 Volume 212( Issue 8) pp:840-848
Publication Date(Web):
DOI:10.1002/macp.201000752
Co-reporter:Roberto Menzel;Alexer Breul;Christian Pietsch;Johann Schäfer;Christian Friebe;Eric Täuscher;Dieter Weiß;Benjamin Dietzek;Jürgen Popp;Rainer Beckert;Ulrich S. Schubert
Macromolecular Chemistry and Physics 2011 Volume 212( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/macp.201190017
Co-reporter:Michael Schmitt; Dr. Jürgen Popp
Chemie in unserer Zeit 2011 Volume 45( Issue 1) pp:14-23
Publication Date(Web):
DOI:10.1002/ciuz.201100540
Abstract
Die Raman-Mikrospektroskopie hat sich in den letzten Jahren aufgrund ihrer Labelfreiheit und ihrer hohen molekularen Selektivität als extrem leistungsstarke Analysenmethode für die biomedizinische Diagnostik etabliert. So gelingt es mittels der Raman-Mikrospektroskopie Mikroorganismen wie bakterielle Krankheiterreger auf Einzelzellebene schnell zu identifizieren und charakterisieren. Lineare Raman-Spektroskopie und nichtlineare Raman-Techniken wie die CARS-Mikroskopie besitzen großes Potenzial zur objektiven Beurteilung von Zellen oder Gewebe zur Frühdiagnose von Krankheiten wie Krebs.
Raman microspectroscopy has established itself in the last years as an extremely capable analytical method for biomedical diagnosis because it is labelfree and provides high molecular selectivity. That way Raman microspectroscopy allows for a fast identification and characterization of microorganisms like e.g. pathogens on a single cell level. Linear Raman spectroscopy and non-linear Raman techniques like CARS microscopy have great potential for an objective evaluation of cells or tissue for an early diagnosis of diseases like e.g. cancer.
Co-reporter:Paul Vargas Jentzsch, Bernd Kampe, Petra Rösch, and Jürgen Popp
The Journal of Physical Chemistry A 2011 Volume 115(Issue 22) pp:5540-5546
Publication Date(Web):May 13, 2011
DOI:10.1021/jp200142n
Mg2+, Na+, and SO42– are common ions in natural systems, and they are usually found in water bodies. Precipitation processes have great importance in environmental studies because they may be part of complex natural cycles; natural formation of atmospheric particulate matter is just one case. In this work, Na2Mg(SO4)2·5H2O (konyaite), Na6Mg(SO4)4 (vanthoffite), and Na12Mg7(SO4)13·15H2O (loeweite) were synthesized and their Raman spectra reported. By slow vaporization (at 20 °C and relative humidity of 60–70%), crystallization experiments were performed within small droplets (diameter ≤ 1–2 mm) of solutions containing MgSO4 and Na2SO4, and crystal formations were studied by Raman spectroscopy. Crystallization of Na2Mg(SO4)2·4H2O (bloedite) was observed, and the formation of salt mixtures was confirmed by Raman spectra. Bloedite, konyaite, and loeweite, as well as Na2SO4 and MgSO4·6H2O, were the components found to occur in different proportions. No crystallization of Na6Mg(SO4)4 (vanthoffite) was observed under the crystallization condition used in this study.
Co-reporter:Robert Hanf, Sonja Fey, Benjamin Dietzek, Michael Schmitt, Christiane Reinbothe, Steffen Reinbothe, Gudrun Hermann, and Jürgen Popp
The Journal of Physical Chemistry A 2011 Volume 115(Issue 27) pp:7873-7881
Publication Date(Web):June 16, 2011
DOI:10.1021/jp2035899
The light-driven NADPH:protochlorophyllide oxidoreductase (POR) is a key enzyme of chlorophyll biosynthesis in angiosperms. POR’s unique requirement for light to become catalytically active makes the enzyme an attractive model to study the dynamics of enzymatic reactions in real time. Here, we use picosecond time-resolved fluorescence and femtosecond pump–probe spectroscopy to examine the influence of the protein environment on the excited-state dynamics of the substrate, protochlorophyllide (PChlide), in the enzyme/substrate (PChlide/POR) and pseudoternary complex including the nucleotide cofactor NADP+ (PChlide/NADP+/ POR). In comparison with the excited-state processes of unbound PChlide, the lifetime of the thermally equilibrated S1 excited state is lengthened from 3.4 to 4.4 and 5.4 ns in the PChlide/POR and PChlide/NADP+/POR complex, whereas the nonradiative rates are decreased by ∼30 and 40%, respectively. This effect is most likely due to the reduced probability of nonradiative decay into the triplet excited state, thus keeping the risk of photosensitized side reactions in the enzyme low. Further, the initial reaction path involves the formation of an intramolecular charge-transfer state (SICT) as an intermediate product. From a strong blue shift in the excited-state absorption, it is concluded that the SICT state is stabilized by local interactions with specific protein sites in the catalytic pocket. The possible relevance of this result for the catalytic reaction in the enzyme POR is discussed.
Co-reporter:Anne März;Bettina Mönch;Petra Rösch
Analytical and Bioanalytical Chemistry 2011 Volume 400( Issue 9) pp:2755-2761
Publication Date(Web):2011 July
DOI:10.1007/s00216-011-4811-z
In this contribution, the great potential of surface enhanced Raman spectroscopy (SERS) in a lab-on-a-chip (LOC) device for the detection of analyte molecules in a complex environment is demonstrated. Using LOC-SERS, the enzyme activity of thiopurine S-methyltransferase (TPMT) is analysed and identified in lysed red blood cells. The conversion of 6-mercaptopurine to 6-methylmercaptopurine catalysed by TPMT is observed as it gives evidence for the enzyme activity. Being able to determine the TPMT activity before starting a treatment using 6-mercaptopurine, an optimized dosage can be applied to each patient and serious toxicity appearing within thiopurine treatment will be prevented.
Co-reporter:Michael Karnahl, Stefanie Tschierlei, Christian Kuhnt, Benjamin Dietzek, Michael Schmitt, Jürgen Popp, Matthias Schwalbe, Sven Krieck, Helmar Görls, Frank W. Heinemann and Sven Rau
Dalton Transactions 2010 vol. 39(Issue 9) pp:2359-2370
Publication Date(Web):19 Jan 2010
DOI:10.1039/B917484B
A series of novel regioselective substituted tpphz ligands and two novel mononuclear ruthenium complexes of the type [(tbbpy)2Ru(tpphzRn)](PF6)2 (where tbbpy = 4,4′-di-tert.-butyl-2,2′-bipyridine, tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine, with n = 2 and R represents the bromine substituents at different positions) have been synthesized. All compounds were completely characterized by NMR and MS spectroscopy, absorption and steady-state emission spectroscopy as well as emission lifetime and electrochemical measurements. Additionally the solid-state structures of the two isomers [(tbbpy)2Ru(Br2tpphz)](PF6)26 and [(tbbpy)2Ru(tpphzBr2)](PF6)27 are presented and compared with the results of density-functional theory calculations (DFT). Furthermore calculated Raman spectra were obtained by means of DFT calculations and used to assign the vibrational modes of the measured off resonance Raman spectra. A clear influence caused by the electronic effects of the different type and position of the substituents of tpphz on the photophysical behavior was observed.
Co-reporter:Angela Walter, Susann Erdmann, Thomas Bocklitz, Elke-Martina Jung, Nadine Vogler, Denis Akimov, Benjamin Dietzek, Petra Rösch, Erika Kothe and Jürgen Popp
Analyst 2010 vol. 135(Issue 5) pp:908-917
Publication Date(Web):12 Mar 2010
DOI:10.1039/B921101B
The cytochrome distribution in hyphal tip cells of Schizophyllum commune was visualized using resonance Raman mapping and CARS microscopy. For comparison, resonance Raman mapping and CARS imaging of cytochrome was also performed during branch formation and in completely developed central hyphae. Cytochrome, as an essential component of the electron transport chain in mitochondria, plays an important role in providing energy to actively growing mycelia. It could be shown that mitochondria at the growing hyphal tips and at branching regions are more active, i.e. contain more cytochrome, as compared to those in older parts of the hyphae. This finding is compatible with the idea of high energy consumption for biosynthesis and intracellular transport at the growing tip, while older hyphae have lower needs for ATP generated via the respiratory chain in mitochondria. To the best of our knowledge this is the first study reporting about the localization and distribution of cytochrome, as an indirect mitochondria localization within S. commune or other basidiomycetous fungi, by means of resonance Raman microspectroscopy and CARS microscopy. These Raman methods bear the potential of label-free in vivo mitochondria localization and investigation.
Co-reporter:Benjamin Dietzek, Stefanie Tschierlei, Robert Hanf, Sonja Seidel, Arkady Yartsev, Michael Schmitt, Gudrun Hermann, Jürgen Popp
Chemical Physics Letters 2010 Volume 492(1–3) pp:157-163
Publication Date(Web):26 May 2010
DOI:10.1016/j.cplett.2010.04.027
Abstract
In this study the excited-state dynamics of protochlorophyllide a (PChlide), the substrate of the enzyme protochlorophyllide oxidoreductase, was examined by means of time-resolved absorption anisotropy and magic-angle measurements. The solvent polarity dependent anisotropy data provide strong evidence for the existence of an excited-state with charge-transfer character. A solvent dependency is also observed in the magic-angle kinetics. In a nonpolar environment wave packet oscillations are monitored while they are quenched in a polar solvent. These results show that the excited-state relaxations of PChlide are determined by the nature of the solvent environment. The implications of these findings are discussed with respect to the enzyme catalysed reaction.
Co-reporter:Katharina K. Strelau;Robert Kretschmer
Analytical and Bioanalytical Chemistry 2010 Volume 396( Issue 4) pp:1381-1384
Publication Date(Web):2010 February
DOI:10.1007/s00216-009-3374-8
A sequence-specific detection method of DNA is presented combining a solid chip surface for immobilisation of capture DNAs with a microfluidic platform and a readout of the chip based on SERS. The solid chip surface is used for immobilisation of different capture DNAs, where target strands can be hybridised and unbound surfactants can be washed away. For the detection via SERS, short-labelled oligonucleotides are hybridised to the target strands. This technique is combined with a microfluidic platform that enables a fast and automated preparation process. By applying a chip format, the problems of sequence-specific DNA detection in solution phase by means of SERS can be overcome. With this setup, we are able to distinguish between different complementary and non-complementary target sequences in one sample solution.
Co-reporter:Martin Presselt, Benjamin Dietzek, Michael Schmitt, Sven Rau, Andreas Winter, Michael Jäger, Ulrich S. Schubert, and Jürgen Popp
The Journal of Physical Chemistry A 2010 Volume 114(Issue 50) pp:13163-13174
Publication Date(Web):November 23, 2010
DOI:10.1021/jp107007a
To gain a deeper understanding of how structural modifications may influence photochemical properties of 4′-phenyl-2,2′:6′,2′′-terpyridines, the investigations presented here focus on electron delocalization in 4′-phenyl-2,2′:6′,2′′-terpyridine derivatives and their Ru(II) and Zn(II) complexes. In those systems of neighboring aromatic rings the considerable torsion between the rings is commonly regarded to be the limiting factor for a well pronounced π-conjugation between the rings. A common approach to improve the π-conjugation is to lower the steric hindrance, thus achieving a more planar geometry. Here, we present a fundamentally different approach towards enhanced π-conjugation by manipulation of the electronic properties of the pyridine−phenyl (py−ph) bond. This is accomplished by introducing various substituents at the phenylene moiety or coordinating the terpyridine moiety to transition metal ions. The electron delocalization was quantified via the DFT-calculated ellipticity in the bond-critical point (BCP) of the py−ph bond. This ellipticity can be modified due to substituents in the para position of phenylene and via the transition metals coordinated to the terpyridine moiety. Changes in electron density distribution induced by the substituents and the metal ions are further studied by means of intermolecular electron density difference plots. It was shown that a NH2 group in the para position of the phenyl ring as well as the coordination to Ru(II) or Zn(II) ions significantly enhances the π-character of the py−ph bond. Surprisingly, an even higher π-character of the py−ph bond is achieved by introducing additional NH2 groups in ortho position to the py−ph bond, despite the increased torsion between pyridine and phenylene. The introduction of other substituents (−NO2, −Br, −CN, −vinyl, −ethynyl) studied within the presented work enables an actuation of the electron delocalization between terpyridine and phenylene. In doing so, the ellipticity is a concise quantity to characterize electron delocalization in the studied systems. Furthermore, the ellipticity in the BCP of the py−ph bond is related to the corresponding geometrical properties (e.g., bond length and dihedral angle) and to the DFT-calculated HOMO and LUMO energies.
Co-reporter:Dana Cialla;Jörg Petschulat;Uwe Hübner Dr.;Henrik Schneidewind Dr.;Matthias Zeisberger Dr.;Rol Mattheis Dr.;Thomas Pertsch Dr.;Michael Schmitt Dr. habil.;Robert Möller Dr.;Jürgen Popp Dr.
ChemPhysChem 2010 Volume 11( Issue 9) pp:1918-1924
Publication Date(Web):
DOI:10.1002/cphc.200901009
Abstract
In general, the electromagnetic mechanism is understood as the strongest contribution to the overall surface-enhanced Raman spectroscopy (SERS) enhancement. Due to the excitation of surface plasmons, a strong electromagnetic field is induced at the interfaces of a metallic nanoparticle leading to a drastic enhancement of the Raman scattering cross-section. Furthermore, the Raman scattered light expierences an emission enhancement due to the plasmon resonances of the nanoantennas. Herein, this second part of the electromagnetic enhancement phenomenon is investigated for different Raman bands of crystal violet by utilizing the anisotropic plasmonic character of gold nanorhomb SERS arrays. We aim at evaluating the effects of localized and propagating surface plasmon polariton modes as well as their combination on the scattered SERS intensity. From that point of view, design and fabrication strategies towards the fabrication of SERS arrays for excitation wavelengths in the visible and near-infrared (NIR) spectral region can be given, also using a double-resonant electromagnetic enhancement.
Co-reporter:Stefanie Tschierlei;Michael Karnahl;Martin Presselt Dr.;Benjamin Dietzek Dr.;Julien Guthmuller Dr.;Leticia González Dr.;Michael Schmitt Dr.;Sven Rau Dr.;Jürgen Popp Dr.
Angewandte Chemie International Edition 2010 Volume 49( Issue 23) pp:3981-3984
Publication Date(Web):
DOI:10.1002/anie.200906595
Co-reporter:Benjamin Dietzek Dr.;Stefanie Tschierlei;Gudrun Hermann Dr.;Arkady Yartsev Dr.;Torbjörn Pascher Dr.;Villy Sundström Dr.;Michael Schmitt Dr.;Jürgen Popp Dr.
ChemPhysChem 2009 Volume 10( Issue 1) pp:144-150
Publication Date(Web):
DOI:10.1002/cphc.200800536
Abstract
The photochemistry of protochlorophyllide a, a precursor in the biosynthesis of chlorophyll and substrate of the light regulated enzyme protochlorophyllide oxidoreductase, is investigated by pump-probe spectroscopy. Upon excitation into the lowest lying Q-band the light induced changes are recorded over a wide range of probe wavelengths in the visible and near-IR region between 500 and 1000 nm. Following excitation, an initial ultrafast 450 fs process is observed related to the motion out of the Franck-Condon region on the excited state surface; thus directly unraveling previous suggestions based on time-resolved fluorescence measurements (ChemPhysChem2006, 7, 1727–1733). Furthermore, the data reveals a previously concealed photointermediate, whose formation on a nanosecond timescale matches the overall fluorescence decay and is assigned to a triplet state. The implications of this finding with respect to the photochemistry of NADPH:protochlorophyllide oxidoreductase (POR) are discussed.
Co-reporter:Andreas Winter Dr.;Christian Friebe;Manuela Chiper Dr.;Ulrich S. Schubert Dr.;Martin Presselt;Benjamin Dietzek Dr.;Michael Schmitt Dr.;Jürgen Popp Dr.
ChemPhysChem 2009 Volume 10( Issue 5) pp:787-798
Publication Date(Web):
DOI:10.1002/cphc.200800714
Co-reporter:Dana Cialla;Ronald Siebert;Uwe Hübner
Analytical and Bioanalytical Chemistry 2009 Volume 394( Issue 7) pp:1811-1818
Publication Date(Web):2009 August
DOI:10.1007/s00216-009-2749-1
Surface-enhanced Raman scattering (SERS) is a potent tool in bioanalytical science because the technique combines high sensitivity with molecular specificity. However, the widespread and routine use of SERS in quantitative biomedical diagnostics is limited by tight requirements on the reproducibility of the noble metal substrates used. To solve this problem, we recently introduced a novel approach to reproducible SERS substrates. In this contribution, we apply ultrafast time-resolved spectroscopy to investigate the photo-induced collective charge-carrier dynamics in such substrates, which represents the fundamental origin of the SERS mechanism. The ultrafast experiments are accompanied by scanning-near field optical microscopy and SERS experiments to correlate the appearance of plasmon dynamics with the resultant evanescent field distribution and the analytically relevant SERS enhancement.
Co-reporter:Mario Krause, Petra Rösch, Benno Radt and Jürgen Popp
Analytical Chemistry 2008 Volume 80(Issue 22) pp:8568
Publication Date(Web):October 11, 2008
DOI:10.1021/ac8014559
A fast, easy, and reliable identification of microorganisms is indispensable in many fields such as medicine, food production, or the pharmaceutical industry. However, in native samples, biotic particles often appear together with abiotic particles. Therefore, it is a prerequisite that biotic particles can be differentiated from abiotic particles appearing in the identification setup. In addition, for many applications, not all microorganisms are of interest but only the living ones. Therefore, in this contribution, different bacteria species were stained with a live/dead staining kit (SYTO 9 and propidium iodide) prior to Raman spectroscopic identification. Since only living and dead microorganisms are getting stained by SYTO 9 or PI, biotic particles can easily be spotted and localized in-between abiotic particles. By using a Raman laser excitation wavelength outside the absorption band of the dye, fluorescence-free Raman spectra were obtained. The living cells were identified by means of Raman spectroscopy in combination with a support vector machine. Furthermore, the localization of bacterial cells in a mix of abiotic particles is demonstrated.
Co-reporter:Michaela Harz, Michael Kiehntopf, Stephan Stöckel, Petra Rösch, Thomas Deufel and Jürgen Popp
Analyst 2008 vol. 133(Issue 10) pp:1416-1423
Publication Date(Web):28 May 2008
DOI:10.1039/B716132H
This contribution provides a new approach for single blood cell analysis in cerebrospinal fluid (CSF) with the possibility of utilizing simultaneously on the same sample the unique capabilities of the two methods fluorescence staining and Raman spectroscopy. By doing so this technique enables the potential of accurate and rapid cell identification in order to determine cell parameters immediately (e.g. the study of the level of activation or phagocytosis activity of single blood cells). Fluorescence labeling of blood cells offers the great possibility of differentiating easily between the subtypes of white blood cells, while Raman spectroscopy reveals molecular fingerprint information with a spatial resolution down to the diffraction limit. Compared to an unstained cell, the presented results nicely demonstrate that the selected fluorescence dye does not influence the Raman spectrum of a labeled blood cell notably. By the combined application of Raman spectroscopy and statistical data analysis a distinction between white blood cell substructures could be performed. Since several blood cell types also differ in the amount of their cell components, differentiation between several blood cell types is also possible when one blood cell is described in the database by several Raman spectra according their presented sub-microscopic structures. This capability with the possibility of accurate and rapid blood cell identification in cerebrospinal fluid is extremely promising for implementation in clinical diagnostics.
Co-reporter:Martin Presselt, Benjamin Dietzek, Michael Schmitt, Jürgen Popp, Andreas Winter, Manuela Chiper, Christian Friebe and Ulrich S. Schubert
The Journal of Physical Chemistry C 2008 Volume 112(Issue 47) pp:18651-18660
Publication Date(Web):2017-2-22
DOI:10.1021/jp807461j
The synthesis and photophysical properties of an ethynylphenyl-substituted terpyridine ligand L and its corresponding zinc(II) complex [Zn(L)2](PF6)2, serving as model compounds for self-assembling Zn(II)-based metallopolymers suited for photoluminscent and electroluminescent devices, are presented. The UV−vis spectra are characterized, and the photoluminescence quantum yields are determined. The ground-state structures are calculated by means of DFT, and the structural key features are approved by experimental as well as by DFT-calculated Raman spectra. Special attention is paid to the π-electron delocalization between phenylene (ph) and pyridine (py) and, in particular, to changes in the ph−py bond due to complexation. The DFT-calculated ph−py bond shortening in [Zn(L)2](PF6)2 compared to L correlates well with the higher wavenumber of the v(ph−py(trig)) vibration, which involves strong ph−py bond stretching. The higher ellipticity in the ph−py bond due to complexation, calculated according to Bader’s QTAIM indicating the π-character of a bond, is confirmed by the higher Raman intensity of the v(ph−py(trig)) vibration. The electron density distributions in the ph−py bond between [Zn(L)2](PF6)2 and L are compared in an inter−Δρ plot, which highlights the changes in the bonding situation of the ph−py bond induced by complex forming.
Co-reporter:Katharina Konstanze Hering;Robert Möller Dr.;Wolfgang Fritzsche Dr.;Jürgen Popp Dr.
ChemPhysChem 2008 Volume 9( Issue 6) pp:867-872
Publication Date(Web):
DOI:10.1002/cphc.200700591
Abstract
The growing interest in DNA diagnostics is addressed today by microarrays with fluoresence detection. In our approach, we utilize spatially defined arrays of short oligonucleotides on a modified glass surface. Surface enhanced resonance Raman scattering (SERRS) is used to obtain molecularly specific spectra of the Raman-active dye-labeled DNA. Nanoparticles produced by enzymatic silver deposition are used as SERS-active substrate. They grow directly on the modified oligonucleotides and only in the spatially defined areas on the chip. Furthermore, they potentially offer several advantages for SERS detection. The nanoparticles are characterized and their ability for use as SERS- and SERRS-active substrate is estimated. Three different Raman-active dyes are investigated for their potential for involvement in sequence specific DNA analysis.
Co-reporter:Katharina Hering;Dana Cialla;Katrin Ackermann
Analytical and Bioanalytical Chemistry 2008 Volume 390( Issue 1) pp:113-124
Publication Date(Web):2008 January
DOI:10.1007/s00216-007-1667-3
Raman spectroscopy is a valuable tool in various research fields. The technique yields structural information from all kind of samples often without the need for extensive sample preparation. Since the Raman signals are inherently weak and therefore do not allow one to investigate substances in low concentrations, one possible approach is surface-enhanced (resonance) Raman spectroscopy. Here, rough coin metal surfaces enhance the Raman signal by a factor of 104–1015, depending on the applied method. In this review we discuss recent developments in SERS spectroscopy and their impact on different research fields.
Co-reporter:Dana Cialla;Uwe Hübner Dr.;Henrik Schneidewind Dr.;Robert Möller Dr.;Jürgen Popp Dr.
ChemPhysChem 2008 Volume 9( Issue 5) pp:758-762
Publication Date(Web):
DOI:10.1002/cphc.200700705
Abstract
New types of microfabricated surface-enhanced Raman spectroscopy (SERS) active substrates produced by electron beam lithography and ion beam etching are introduced. In order to achieve large enhancement factors by using the lightning rod effect, we prepare arrays consisting of sharp-edged nanostructures instead of the commonly used dots. Two experimental methods are used for fabrication: a one-stage process, leading to gold nanostar arrays and a two-stage process, leading to gold nanodiamond arrays. Our preparation process guarantees high reproducibility. The substrates contain a number of arrays for practical applications, each 200×200 μm2 in size. To test the SERS activity of these nanostar and nanodiamond arrays, a monolayer of the dye crystal violet is used. Enhancement factors are estimated to be at least 130 for the nanodiamond and 310 for the nanostar arrays.
Co-reporter:Nicolae Tarcea, Michaela Harz, Petra Rösch, Torsten Frosch, Michael Schmitt, Hans Thiele, R. Hochleitner, Jürgen Popp
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2007 Volume 68(Issue 4) pp:1029-1035
Publication Date(Web):15 December 2007
DOI:10.1016/j.saa.2007.06.051
We report on the great advantages of using deep UV Raman system for in situ planetary applications. Among them are to be mentioned: (I) higher scattering efficiency compared to VIS–IR Raman excitation wavelengths, (II) electronic resonance effects which increase the intrinsically weak Raman signal thus improving the S/N ratio of the detected Raman signals and (III) spectral separation of Raman and fluorescence signals.All these advantages are making UV Raman a valuable technique for in situ planetary applications. Mineral as well as biological samples were analyzed using Raman deep UV excitation and the results are presented. For the mineral samples a comparison with excitation in the NIR–VIS spectral regions is made. The impact of fluorescence on Raman data acquisition at different laser excitation wavelengths is assessed. Making use of the resonance effects, spectra of microorganisms were recorded with a high S/N ratio, allowing afterwards a very precise identification and classification (to the strain level) of the measured samples.
Co-reporter:Katrin R. Ackermann;Thomas Henkel Dr.;Jürgen Popp Dr.
ChemPhysChem 2007 Volume 8(Issue 18) pp:2665-2670
Publication Date(Web):5 DEC 2007
DOI:10.1002/cphc.200700554
Herein, quantitative online monitoring of concentration fluctuations of different interesting drugs, namely, the phenothiazine promethazine as well as the anti-cancer agent mitoxantrone via surface enhanced Raman scattering assay based on a microfluidic device is demonstrated. With the applied liquid/liquid two-phase-segmented flow system we succeed in preventing the adhesion of nanoparticle aggregates to the channel walls which is necessary for a quantitative analysis. Even after repeated cycles no carry-over due to sedimentation of colloid particles is observed. To the best of our knowledge these are the first measurements applying a combination of a microfluidic device with SERS detection for quantitative online monitoring of fluctuations in drug concentrations over hours without use of aggressive chemicals for rinsing the chip surfaces prior to each measurement.
Co-reporter:Ute Neugebauer;Knut Baumann Priv.-Doz. Dr.;Wilma Ziebuhr Priv.-Doz. Dr.;Ulrike Schmid;Svetlana Kozitskaya Dr.;Volker Deckert Priv.-Doz. Dr.;Michael Schmitt Priv.-Doz. Dr.;Jürgen Popp Dr.
ChemPhysChem 2007 Volume 8(Issue 1) pp:124-137
Publication Date(Web):5 DEC 2006
DOI:10.1002/cphc.200600507
Bacteria are a major cause of infection. To fight disease and growing resistance, research interest is focused on understanding bacterial metabolism. For a detailed evaluation of the involved mechanisms, a precise knowledge of the molecular composition of the bacteria is required. In this article, various vibrational spectroscopic techniques are applied to comprehensively characterize, on a molecular level, bacteria of the strain Staphylococcus epidermidis, an opportunistic pathogen which has evolved to become a major cause of nosocomial infections. IR absorption spectroscopy reflects the overall chemical composition of the cells, with major focus on the protein vibrations. Smaller sample volumes—down to a single cell—are sufficient to probe the overall chemical composition by means of micro-Raman spectroscopy. The nucleic-acid and aromatic amino-acid moieties are almost exclusively explored by UV resonance Raman spectroscopy. In combination with statistical evaluation methods [hierarchical cluster analysis (HCA), principal component analysis (PCA), linear discriminant analysis (LDA)], the protein and nucleic-acid components that change during the different bacterial growth phases can be identified from the in vivo vibrational spectra. Furthermore, tip-enhanced Raman spectroscopy (TERS) provides insight into the surface structures and follows the dynamics of the polysaccharide and peptide components on the bacterial cells with a spatial resolution below the diffraction limit. This might open new ways for the elucidation of host–bacteria and drug–bacteria interactions.
Co-reporter:Remigius Mastalerz;Renate Petry Dr.;Günther Völksch Dr.;Thomas G. Mayerhöfer Dr.;Stefan Zahn;Lothar Viereck-Götte Dr.;Lothar Holz Dr.;Birgit Kreher-Hartmann Dr.;Markus Lankers Dr.;Jürgen Popp Dr.
ChemPhysChem 2006 Volume 7(Issue 2) pp:414-420
Publication Date(Web):3 JAN 2006
DOI:10.1002/cphc.200500303
The applicability of a UV micro-Raman setup was assessed for the rapid identification of fibrous asbestos minerals using 257 and 244 nm laser light for excitation. Raman spectra were obtained from six asbestos reference standards belonging to two basic structural groups: the serpentines (chrysotile) and the amphiboles (crocidolite, tremolite, amosite, anthophyllite, and actinolite). The UV Raman spectra reported here for the first time are free from fluorescence, which is especially helpful in assessing the hydroxyl-stretching vibrations. The spectra exhibit sharp bands characteristic of each asbestos species, which can be used for the unambiguous identification of known and unknown asbestos fibres. Evident changes of the relative band intensities sensitively reflect the chemical substitutions that typically occur in asbestos minerals. The elemental composition of the asbestos reference samples was analysed by using a scanning electron microscope equipped with an energy-dispersive X-ray (EDX) spectrometer. The discussion of the experimental results in terms of EDX analysis sheds new light on the structural and vibrational consequences of cation distribution in asbestos minerals.
Co-reporter:Ute Neugebauer;Petra Rösch Dr.;Jürgen Popp Dr.;Carine Julien Dr.;Michael Schmitt Dr.;Christian Budich;Akiko Rasmussen Dr.;Volker Deckert Dr.
ChemPhysChem 2006 Volume 7(Issue 7) pp:1428-1430
Publication Date(Web):21 JUN 2006
DOI:10.1002/cphc.200600173
A straight tip: With tip-enhanced Raman spectroscopy (TERS), chemical and topographical information with nanometric resolution below the diffraction limit of soft biological samples such as bacteria can be gained simultaneously at short measuring times. This noninvasive technique opens new ways for the investigation of many problems in biology and biomedicine.
Co-reporter:Benjamin Dietzek Dr.;Wolfgang Kiefer Dr.;Jörg Blumhoff Dipl.-Chem.;Lars Böttcher Dipl.-Chem.;Sven Rau Dr.;Dirk Walther Dr.;Ute Uhlemann Dipl.-Chem.;Michael Schmitt Priv.-Doz. Dr.;Jürgen Popp Dr.
Chemistry - A European Journal 2006 Volume 12(Issue 19) pp:
Publication Date(Web):21 APR 2006
DOI:10.1002/chem.200501093
A detailed study on the excited-state-excitation migration taking place within the tetranuclear complex [{(tbbpy)2Ru(tmbi)}2{Pd(allyl)}2](PF6)2 (tbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine and tmbi = 5,6,5′,6′-tetramethyl-2,2′-bibenzimidazolate) is presented. The charge transfer is initiated by the photoexcitation into the lowest metal-to-ligand charge-transfer (MLCT) band of one of the peripheral ruthenium(II) chromophores and terminates on the central structurally complex Pd2II(allyl)2 subunit. Thus, the system under investigation can be thought of as a functional model for the photosynthesis reaction center in plants. The kinetic steps involved in the overall process are inferred from femtosecond time-resolved transient-grating kinetics recorded at spectral positions within the regions of ground-state bleach and transient absorption. The kinetics features a complex non-exponential time behavior and can be fitted to a bi-exponential rise (τ1≥200 fs, τ2≈1.5 ps) and a mono- or bi-exponential decay, depending on the experimental situation. The data leads to the formulation of a model for the intramolecular excitation-hopping ascribing intersystem crossing and subsequent cooling as the two fastest observed processes. Following these initial steps, charge transfer from the ruthenium to the central complex Pd2(allyl)2 moiety is observed with a characteristic time constant of 50 ps. A 220-ps component that is observed in the ground-state recovery only is attributed to excitation equilibration between the two identical Pd(allyl) chromophores.
Co-reporter:K. Gaus;P. Rösch;R. Petry;K.-D. Peschke;O. Ronneberger;H. Burkhardt;K. Baumann;J. Popp
Biopolymers 2006 Volume 82(Issue 4) pp:
Publication Date(Web):18 JAN 2006
DOI:10.1002/bip.20448
UV-resonance Raman spectroscopy is applied as a method for the identification of lactic acid bacteria from yogurt. Eight different strains of bacteria from Lactobacillus acidophilus, L. delbrueckii ssp. bulgaricus, and Streptococcus thermophilus were investigated. At an excitation wavelength of 244 nm signals from nucleic acids and proteins are selectively enhanced. Classification was accomplished using different chemometric methods. In a first attempt, the unsupervised methods hierarchical cluster analysis and principal component analysis were applied to investigate natural grouping in the data. In a second step the spectra were analyzed using several supervised methods: K-nearest neighbor classifier, nearest mean classifier, linear discriminant analysis, and support vector machines. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 286–290, 2006
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Co-reporter:P. Rösch;M. Harz;K.-D. Peschke;O. Ronneberger;H. Burkhardt;J. Popp
Biopolymers 2006 Volume 82(Issue 4) pp:
Publication Date(Web):18 JAN 2006
DOI:10.1002/bip.20449
For a fast identification of eukaryotic cells such as yeast species without a cultivation step it should be possible to perform the investigation on only one single cell. Since yeasts as eukaryotes are heterogeneous and their Raman spectra are therefore dependent on the measuring position, one Raman spectra is not representative of the whole cell. In this contribution we demonstrate the application of average Raman spectra of a line scan over single yeast cells. These average spectra are used for classification with the help of a support vector machine. © 2006 Wiley Periodicals, Inc. Biopolymers 82:312–316, 2006
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Co-reporter:U. Neugebauer;U. Schmid;K. Baumann;U. Holzgrabe;W. Ziebuhr;S. Kozitskaya;W. Kiefer;M. Schmitt;J. Popp
Biopolymers 2006 Volume 82(Issue 4) pp:
Publication Date(Web):18 JAN 2006
DOI:10.1002/bip.20447
In this work we monitor the bacterial growth of a Bacillus pumilus batch culture by means of UV resonance Raman spectroscopy. Excitation with a wavelength of 244 nm especially enhances the Raman scattering of the aromatic amino acids and the nucleic acid bases and therefore is a good method to track the metabolic changes that occur during bacterial growth. Furthermore, a drug from the fluoroquinolone group is added to the bacterial suspension at the beginning of the exponential growth phase. With the help of chemometrical methods such as hierarchical cluster analysis (HCA) and principal component analysis (PCA) it is possible to visualize the small changes that occur in the UV resonance Raman spectra due to the interaction of the drug with its biological targets DNA and the enzyme gyrase within the bacterial cell. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 306–311, 2006
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Co-reporter:Torsten Frosch;Michael Schmitt;Karla Schenzel;Johan H. Faber;Gerhard Bringmann;Wolfgang Kiefer;Jürgen Popp
Biopolymers 2006 Volume 82(Issue 4) pp:
Publication Date(Web):1 FEB 2006
DOI:10.1002/bip.20459
Near infrared Fourier transform (NIR FT) micro Raman spectroscopy in combination with density functional theory (DFT) calculations has been applied for an in vivo localization of the antiplasmodial naphthylisoquinoline alkaloid dioncophylline A (1) in the tropical liana Triphyophyllum peltatum. Fluorescence microscopy images suggest finding this active agent in 10 μm big inclusions located in the cortex of the stem or the beginning of the leaves. By means of spatially resolved FT Raman micro spectroscopy, we could detect dioncophylline A (1) in these inclusions. FT Raman spectroscopy is an extremely selective tool capable of differentiating between various structurally similar naphthylisoquinoline alkaloids. With the help of DFT calculations, we succeeded in assigning the differences found in the FT Raman spectra of the various naphthylisoquinolines to νCC vibrations of the naphthyl ring. The presented results are of relevance for the investigation and extraction of new antimalarial active agents. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 295–300, 2006
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Co-reporter:M. Harz;R. A. Claus;C. L. Bockmeyer;M. Baum;P. Rösch;K. Kentouche;H.-P. Deigner;J. Popp
Biopolymers 2006 Volume 82(Issue 4) pp:
Publication Date(Web):27 FEB 2006
DOI:10.1002/bip.20489
Various diseases shift the composition of human plasma; hence, the relative quantification of plasma constituents offers the opportunity to use the dynamic and complex composition of plasma to gain information on novel diagnostic and prognostic factors. Since plasma contains, besides water, mostly proteins, UV-resonance Raman spectroscopy (UVRR) seems to be a suitable method for investigating plasma. With this method the signals of aromatic amino acids and proteins are selectively enhanced. In this study an UV-resonance Raman approach was used for the investigation of human plasma of healthy volunteers and patients with thrombotic microangiopathy. For comparison, selected plasma components were analyzed for a more detailed characterization of cryoprecipitates from human plasma. © 2006 Wiley Periodicals, Inc. Biopolymers 82:317–324, 2006
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Co-reporter:M. Harz, P. Rösch, K.-D. Peschke, O. Ronneberger, H. Burkhardt and J. Popp
Analyst 2005 vol. 130(Issue 11) pp:1543-1550
Publication Date(Web):30 Sep 2005
DOI:10.1039/B507715J
Microbial contamination is not only a medical problem, but also plays a large role in pharmaceutical clean room production and food processing technology. Therefore many techniques were developed to achieve differentiation and identification of microorganisms. Among these methods vibrational spectroscopic techniques (IR, Raman and SERS) are useful tools because of their rapidity and sensitivity. Recently we have shown that micro-Raman spectroscopy in combination with a support vector machine is an extremely capable approach for a fast and reliable, non-destructive online identification of single bacteria belonging to different genera. In order to simulate different environmental conditions we analyzed in this contribution different Staphylococcus strains with varying cultivation conditions in order to evaluate our method with a reliable dataset. First, micro-Raman spectra of the bulk material and single bacterial cells that were grown under the same conditions were recorded and used separately for a distinct chemotaxonomic classification of the strains. Furthermore Raman spectra were recorded from single bacterial cells that were cultured under various conditions to study the influence of cultivation on the discrimination ability. This dataset was analyzed both with a hierarchical cluster analysis (HCA) and a support vector machine (SVM).
Co-reporter:M. Baranska;H. Schulz;S. Reitzenstein;U. Uhlemann;M. A. Strehle;H. Krüger;R. Quilitzsch;W. Foley;J. Popp
Biopolymers 2005 Volume 78(Issue 5) pp:
Publication Date(Web):26 APR 2005
DOI:10.1002/bip.20284
This article presents a novel and original approach to analyze in situ the main components of Eucalyptus oil by means of Raman spectroscopy. The obtained two-dimensional Raman maps demonstrate a unique possibility to study the essential oil distribution in the intact plant tissue. Additionally, Fourier Transform (FT)-Raman and attenuated total reflection (ATR)-IR spectra of essential oils isolated from several Eucalyptus species by hydrodistillation are presented. Density Functional Theory (DFT) calculations were performed in order to interpret the spectra of the essential oils of the Eucalyptus species. It is shown that the main components of the essential oils can be recognized by both vibrational spectroscopic techniques using the spectral information of the pure terpenoids. Spectroscopic analysis is based on the key bands of the individual volatile substances and therefore allows one to discriminate different essential oil profiles of several Eucalyptus species. It has been found that the presented spectroscopic data correlate very well with those obtained by gas chromatography (GC) analysis. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with vibrational spectroscopic techniques in combination with DFT calculations. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 237–248, 2005
Co-reporter:M. A. Strehle;P. Rösch;M. Baranska;H. Schulz;J. Popp
Biopolymers 2005 Volume 77(Issue 1) pp:
Publication Date(Web):1 DEC 2004
DOI:10.1002/bip.20178
Essential oils are one of the most valuable natural products. The price of special essential oils that can be purchased on the market strongly depends on the quality of the product. The quality, which depends on the quantitative and qualitative variation of different monoterpenes, varies with respect of the origin and the harvesting period. This contribution reports on a Raman spectroscopic study on the essential oil occurring in fennel. Cross-sections of fennel seed were investigated by use of Raman spectroscopy and Raman mapping to localize the essential oil and to analyze its chemical composition directly in the plant. Furthermore the practicability of a home-built mobile transportable Raman spectrometer to perform on-site measurements was successfully tested. © 2004 Wiley Periodicals, Inc. Biopolymers, 2005
Co-reporter:U. Neugebauer, A. Szeghalmi, M. Schmitt, W. Kiefer, J. Popp, U. Holzgrabe
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2005 Volume 61(Issue 7) pp:1505-1517
Publication Date(Web):May 2005
DOI:10.1016/j.saa.2004.11.014
Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug–target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.
Co-reporter:M. A. Strehle, P. Rösch, R. Petry, A. Hauck, R. Thull, W. Kiefer and J. Popp
Physical Chemistry Chemical Physics 2004 vol. 6(Issue 22) pp:5232-5236
Publication Date(Web):11 Oct 2004
DOI:10.1039/B406524G
The adsorption of proteins that contain the amino acid sequence Arg-Gly-Asp (RGD) plays a crucial role for the biocompatibility of implant materials. Detailed knowledge of the adsorption process is of great interest because it is a dominant factor that decides on the integration or rejection of an implant by the organism. We have studied the adsorption process on titanium dioxide nanoparticles via two proteins, namely fibrinogen and fibronectin. Bulk protein spectra are compared to spectra of proteins that were adsorbed on TiO2 nanoparticles (as an enlarged model surface for TiO2 implants). In the Raman spectra of the adsorbed proteins a characteristic band occurs that can be assigned to an interaction between TiO2 nanoparticles and the carboxylate groups of the protein. A moderate shift of the amide I band towards higher wavenumbers observed in the adsorbed fibrinogen spectrum in comparison to the bulk protein spectrum is due to conformational changes during the adsorption process. In the spectra of adsorbed fibrinogen the peak area of the multiplet of CH3 and CH2 deformation modes in relation to the amide I Raman peak area is decreased as compared to the spectra of bulk fibrinogen. These spectral features indicate an increasing content of β-sheet and a decrease of α-helical structure content for fibrinogen while for fibronectin an increase of β-sheet structure and a decreasing content of random coil structure was found. The adsorption takes place via the protein side-chains.
Co-reporter:R. Geßner, P. Rösch, R. Petry, M. Schmitt, M. A. Strehle, W. Kiefer and J. Popp
Analyst 2004 vol. 129(Issue 12) pp:1193-1199
Publication Date(Web):10 Nov 2004
DOI:10.1039/B411690A
The applicability of an etched and silver or gold coated SERS fiber probe in combination with a commercially available laboratory micro-Raman setup or a home built mobile micro-Raman setup to perform on-site field measurements was evaluated and successfully tested on different biological samples. The SERS fiber probe allows one to perform measurements with high spatial resolution. Simultaneously, the laser power used for Raman spectroscopy on biological samples as compared with conventional Raman experiments can be reduced by more than two orders of magnitude. This experimental arrangement was tested to investigate sensitive biological samples like mint plants (Bergamot mint, spear mint) and citrus fruits (kumquat). Furthermore, traces of fungicides on wine leaves were detected by means of such a SERS fiber probe setup.
Co-reporter:R. Geßner Dr.;C. Winter;P. Rösch Dr.;M. Schmitt Dr.;R. Petry Dr.;W. Kiefer Dr. Dr. h. c.;M. Lankers Dr.;J. Popp Dr.
ChemPhysChem 2004 Volume 5(Issue 8) pp:
Publication Date(Web):10 AUG 2004
DOI:10.1002/cphc.200400026
A highly versatile setup, which introduces an optical gradient trap into a Raman spectrometer, is presented. The particular configuration, which consists of two lasers, makes trapping independent from the Raman excitation laser and allows a separate adjustment of the trapping and excitation wavelengths. Thus, the excitation wavelength can be chosen according to the needs of the application. We describe the successful application of an optical gradient trap on transparent as well as on reflective, metal-coated microparticles. Raman spectra were recorded from optically trapped polystyrene beads and from single biological cells (e.g., erythrocytes, yeast cells). Also, metal-coated microparticles were trapped and used as surface enhanced Raman spectroscopy (SERS) substrates for tests on yeast cells. Furthermore, the optical gradient trap was combined with a SERS fiber probe. Raman spectra were recorded from trapped red blood cells using the SERS fiber probe for excitation.
Co-reporter:M. A. Strehle;F. Jenke;B. Fröhlich;J. Tautz;M. Riederer;W. Kiefer;J. Popp
Biopolymers 2003 Volume 72(Issue 4) pp:
Publication Date(Web):29 MAY 2003
DOI:10.1002/bip.10379
Micro-Raman spectroscopy and Raman mapping are applied to investigate the spatial distribution and chemical composition of wax and propolis in the comb of Apis mellifera carnica (Pollm). A thick layer of propolis at the rim of some cells is identified by Raman spectroscopy. Raman mapping is applied to resolve the distribution of propolis and wax on a micron scale. Both components are connected at the rim of the cell with a mixture of wax and propolis. A layer of almost pure propolis is found on top of the mixture. It appears that even in the mixture, where both components come into close contact, the propolis and the wax remain separated and keep their chemical identity. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 000–000, 2003
Co-reporter:Ute Neugebauer, Petra Rösch, Jürgen Popp
International Journal of Antimicrobial Agents (December 2015) Volume 46(Supplement 1) pp:S35-S39
Publication Date(Web):1 December 2015
DOI:10.1016/j.ijantimicag.2015.10.014
Raman spectroscopy is a label-free method that measures quickly and contactlessly, providing detailed information from the sample, and has proved to be an ideal tool for medical and life science research. In this review, recent advances of the technique towards drug monitoring and pathogen identification by the Jena Research Groups are reviewed. Surface-enhanced Raman spectroscopy (SERS) and ultraviolet resonance Raman spectroscopy in hollow-core optical fibres enable the detection of drugs at low concentrations as shown for the metabolites of the immunosuppressive drug 6-mercaptopurine as well as antimalarial agents. Furthermore, Raman spectroscopy can be used to characterise pathogenic bacteria in infectious diseases directly from body fluids, making time-consuming cultivation processes dispensable. Using the example of urinary tract infection, it is shown how bacteria can be identified from patients’ urine samples within <1 h. The methods cover both single-cell analysis and dielectrophoretic capturing of bacteria in suspension. The latter method could also be used for fast (<3.5 h) identification of antibiotic resistance as shown exemplarily for vancomycin-resistant enterococci.
Co-reporter:Ute Neugebauer, Petra Rösch, Jürgen Popp
International Journal of Antimicrobial Agents (December 2015) Volume 46(Supplement 1) pp:S35-S39
Publication Date(Web):1 December 2015
DOI:10.1016/j.ijantimicag.2015.10.014
Raman spectroscopy is a label-free method that measures quickly and contactlessly, providing detailed information from the sample, and has proved to be an ideal tool for medical and life science research. In this review, recent advances of the technique towards drug monitoring and pathogen identification by the Jena Research Groups are reviewed. Surface-enhanced Raman spectroscopy (SERS) and ultraviolet resonance Raman spectroscopy in hollow-core optical fibres enable the detection of drugs at low concentrations as shown for the metabolites of the immunosuppressive drug 6-mercaptopurine as well as antimalarial agents. Furthermore, Raman spectroscopy can be used to characterise pathogenic bacteria in infectious diseases directly from body fluids, making time-consuming cultivation processes dispensable. Using the example of urinary tract infection, it is shown how bacteria can be identified from patients’ urine samples within <1 h. The methods cover both single-cell analysis and dielectrophoretic capturing of bacteria in suspension. The latter method could also be used for fast (<3.5 h) identification of antibiotic resistance as shown exemplarily for vancomycin-resistant enterococci.
Co-reporter:Evelyn Kämmer, Konstanze Olschewski, Thomas Bocklitz, Petra Rösch, Karina Weber, Dana Cialla and Jürgen Popp
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 19) pp:NaN9063-9063
Publication Date(Web):2014/03/17
DOI:10.1039/C3CP55312D
This study demonstrates a new concept of calibrating surface enhanced Raman scattering (SERS) intensities without using additional substances as an internal standard and explores factors such as laser fluctuation and different Ag substrates, which affect the results of quantitative analyses based on SERS. To demonstrate the capabilities of the concept, the model analyte adenine has been chosen. A lab-on-a-chip device is applied for the measurements to guarantee consistent data recording. In order to simulate varied measuring conditions, two varying silver colloids (batch 1 and 2) are utilized as a SERS substrate and two different laser power levels (25 or 55 mW) are applied on the sample. A concentration gradient was generated which allows the use of the analyte itself for the correction of the resulting SERS spectra regarding intensity deviations caused by different ambient conditions. In doing so, a vast improvement in the quantification using SERS, especially in view of the comparability, reproducibility and repeatability, is demonstrated.
Co-reporter:D. Cialla-May, X.-S. Zheng, K. Weber and J. Popp
Chemical Society Reviews 2017 - vol. 46(Issue 13) pp:NaN3961-3961
Publication Date(Web):2017/06/22
DOI:10.1039/C7CS00172J
The application of surface-enhanced Raman spectroscopy (SERS) in biological and biomedical detection schemes is feasible due to its excellent molecular specificity and high sensitivity as well as the capability of SERS to be performed in complex biological compositions. SERS-based investigation of cells, which are the basic structure and functional unit of organisms, represents the starting point of this review. It is demonstrated that SERS provides a deep understanding of living cells as well as their microenvironment which is needed to assess the development of diseases. The clinical relevance of SERS is proved by its application for the detection of cancer cells and tumour margins under in vivo conditions and examples for theranostic approaches are discussed. This review article provides a comprehensive overview of the recent progress within the last 3 years.
Co-reporter:Michael Karnahl, Stefanie Tschierlei, Christian Kuhnt, Benjamin Dietzek, Michael Schmitt, Jürgen Popp, Matthias Schwalbe, Sven Krieck, Helmar Görls, Frank W. Heinemann and Sven Rau
Dalton Transactions 2010 - vol. 39(Issue 9) pp:NaN2370-2370
Publication Date(Web):2010/01/19
DOI:10.1039/B917484B
A series of novel regioselective substituted tpphz ligands and two novel mononuclear ruthenium complexes of the type [(tbbpy)2Ru(tpphzRn)](PF6)2 (where tbbpy = 4,4′-di-tert.-butyl-2,2′-bipyridine, tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine, with n = 2 and R represents the bromine substituents at different positions) have been synthesized. All compounds were completely characterized by NMR and MS spectroscopy, absorption and steady-state emission spectroscopy as well as emission lifetime and electrochemical measurements. Additionally the solid-state structures of the two isomers [(tbbpy)2Ru(Br2tpphz)](PF6)26 and [(tbbpy)2Ru(tpphzBr2)](PF6)27 are presented and compared with the results of density-functional theory calculations (DFT). Furthermore calculated Raman spectra were obtained by means of DFT calculations and used to assign the vibrational modes of the measured off resonance Raman spectra. A clear influence caused by the electronic effects of the different type and position of the substituents of tpphz on the photophysical behavior was observed.
Co-reporter:R. Geitner, J. Kötteritzsch, M. Siegmann, R. Fritzsch, T. W. Bocklitz, M. D. Hager, U. S. Schubert, S. Gräfe, B. Dietzek, M. Schmitt and J. Popp
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 27) pp:NaN17982-17982
Publication Date(Web):2016/06/15
DOI:10.1039/C6CP03464K
The self-healing polymer P(LMA-co-MeAMMA) crosslinked with C60-fullerene has been studied by FT-Raman spectroscopy in combination with two-dimensional (2D) correlation analysis and density functional theory calculations. To unveil the molecular changes during the self-healing process mediated by the Diels–Alder equilibrium between 10-methyl-9-anthracenyl groups and C60-fullerene different anthracene–C60-fullerene adducts have been synthesized and characterized by time-, concentration- and temperature-dependent FT-Raman measurements. The self-healing process could be monitored via the C60-fullerene vibrations at 270, 432 and 1469 cm−1. Furthermore, the detailed analysis of the concentration-dependent FT-Raman spectra point towards the formation of anthracene–C60-fullerene adducts with an unusual high amount of anthracene bound to C60-fullerene in the polymer film, while the 2D correlation analysis of the temperature-dependent Raman spectra suggests a stepwise dissociation of anthracene–C60-fullerene adducts, which are responsible for the self-healing of the polymer.
Co-reporter:R. Geitner, J. Kötteritzsch, M. Siegmann, T. W. Bocklitz, M. D. Hager, U. S. Schubert, S. Gräfe, B. Dietzek, M. Schmitt and J. Popp
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 35) pp:NaN22595-22595
Publication Date(Web):2015/06/01
DOI:10.1039/C5CP02151K
The thermally healable polymer P(LMA-co-FMA-co-MIMA) has been studied by temperature-dependent FT-Raman spectroscopy, two-dimensional Raman correlation analysis and density functional theory (DFT) calculations. To the best of our knowledge this study reports for the first time on the investigation of a self-healing polymer by means of two-dimensional correlation techniques. The synchronous correlation spectrum reveals that the spectrally overlapping CC stretching vibrations at 1501, 1575, 1585 and 1600 cm−1 are perfect marker bands to monitor the healing process which is based on a Diels–Alder reaction of furan and maleimide. The comparison between experimental and calculated Raman spectra as well as their correlation spectra showed a good agreement between experiment and theory. The data presented within this study nicely demonstrate that Raman correlation analysis combined with a band assignment based on DFT calculations presents a powerful tool to study the healing process of self-healing polymers.
![1,5-Dimethyl-2,4-bis[2-(trimethylsilyl)ethynyl]benzene](http://img.cochemist.com/ccimg/1379900/1379822-08-8.png)
![1,5-Dimethyl-2,4-bis[2-(trimethylsilyl)ethynyl]benzene](http://img.cochemist.com/ccimg/1379900/1379822-08-8_b.png)
![1,10-Phenanthroline, 3,8-bis[3,5-bis(trifluoromethyl)phenyl]-](/data/chemimg/3726600/1228032-35-6.png)
![1,10-Phenanthroline, 3,8-bis[3,5-bis(trifluoromethyl)phenyl]-](/data/chemimg/3726600/1228032-35-6_b.png)
![Propanoic acid, 2-[[(butylthio)thioxomethyl]thio]-](/data/chemimg/68400/480436-46-2.png)
![Propanoic acid, 2-[[(butylthio)thioxomethyl]thio]-](/data/chemimg/68400/480436-46-2_b.png)
![D-[UL-13C6]MANNITOL](http://img.cochemist.com/ccimg/350900/350818-69-8.png)
![D-[UL-13C6]MANNITOL](http://img.cochemist.com/ccimg/350900/350818-69-8_b.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8_b.png)
![Ethanol, 2-(4-[2,2':6',2''-terpyridin]-4'-ylphenoxy)-](http://img.cochemist.com/ccimg/127200/127192-72-7.png)
![Ethanol, 2-(4-[2,2':6',2''-terpyridin]-4'-ylphenoxy)-](http://img.cochemist.com/ccimg/127200/127192-72-7_b.png)
![Benzaldehyde, 4-[(2-ethylhexyl)oxy]-](http://img.cochemist.com/ccimg/119700/119630-71-6.png)
![Benzaldehyde, 4-[(2-ethylhexyl)oxy]-](http://img.cochemist.com/ccimg/119700/119630-71-6_b.png)
![(1R,3R)-7-[5-hydroxy-2-(hydroxymethyl)-4-methoxynaphthalen-1-yl]-1,3-dimethyl-1,2,3,4-tetrahydroisoquinolin-8-ol](http://img.cochemist.com/ccimg/60200/60158-81-8.png)
![(1R,3R)-7-[5-hydroxy-2-(hydroxymethyl)-4-methoxynaphthalen-1-yl]-1,3-dimethyl-1,2,3,4-tetrahydroisoquinolin-8-ol](http://img.cochemist.com/ccimg/60200/60158-81-8_b.png)
![[(1s,3r)-3-hydroxy-4-[(3e,5e,7e,9e,11z)-11-[4-[(e)-2-[(1r,3s,6s)-3-hydroxy-1,5,5-trimethyl-7-oxabicyclo[4.1.0]heptan-6-yl]ethenyl]-5-oxofuran-2-ylidene]-3,10-dimethylundeca-1,3,5,7,9-pentaenylidene]-3,5,5-trimethylcyclohexyl] Acetate](http://img.cochemist.com/ccimg/33300/33281-81-1.png)
![[(1s,3r)-3-hydroxy-4-[(3e,5e,7e,9e,11z)-11-[4-[(e)-2-[(1r,3s,6s)-3-hydroxy-1,5,5-trimethyl-7-oxabicyclo[4.1.0]heptan-6-yl]ethenyl]-5-oxofuran-2-ylidene]-3,10-dimethylundeca-1,3,5,7,9-pentaenylidene]-3,5,5-trimethylcyclohexyl] Acetate](http://img.cochemist.com/ccimg/33300/33281-81-1_b.png)
![Poly[oxy[(1R)-1-methyl-3-oxo-1,3-propanediyl]]](http://img.cochemist.com/ccimg/31800/31759-58-7.png)
![Poly[oxy[(1R)-1-methyl-3-oxo-1,3-propanediyl]]](http://img.cochemist.com/ccimg/31800/31759-58-7_b.png)
![2-CYANO-N-[6-[(2-CYANOACETYL)AMINO]HEXYL]ACETAMIDE](/data/chemimg/490000/26889-89-4.png)
![2-CYANO-N-[6-[(2-CYANOACETYL)AMINO]HEXYL]ACETAMIDE](/data/chemimg/490000/26889-89-4_b.png)
![1H-Cycloprop[e]azulene,decahydro-1,1,7-trimethyl-4-methylene-, (1aR,4aS,7R,7aR,7bS)-](http://img.cochemist.com/ccimg/25300/25246-27-9.png)
![1H-Cycloprop[e]azulene,decahydro-1,1,7-trimethyl-4-methylene-, (1aR,4aS,7R,7aR,7bS)-](http://img.cochemist.com/ccimg/25300/25246-27-9_b.png)
![Magnesium, [2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato(2-)-κN21,κN22,κN23,κN24]-, (SP-4-1)-](/data/chemimg/20400/20910-35-4.png)
![Magnesium, [2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato(2-)-κN21,κN22,κN23,κN24]-, (SP-4-1)-](/data/chemimg/20400/20910-35-4_b.png)
![Dipyrido[3,2-a:2',3'-c]phenazine](/data/chemimg/1778900/19535-47-8.png)
![Dipyrido[3,2-a:2',3'-c]phenazine](/data/chemimg/1778900/19535-47-8_b.png)
![Ethanesulfonic acid,2-[[(3a,5b)-24-oxo-3-(sulfooxy)cholan-24-yl]amino]-](http://img.cochemist.com/ccimg/15400/15324-65-9.png)
![Ethanesulfonic acid,2-[[(3a,5b)-24-oxo-3-(sulfooxy)cholan-24-yl]amino]-](http://img.cochemist.com/ccimg/15400/15324-65-9_b.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8_b.png)
![Bicyclo[2.2.1]heptan-2-one,1,3,3-trimethyl-](http://img.cochemist.com/ccimg/1200/1195-79-5.png)
![Bicyclo[2.2.1]heptan-2-one,1,3,3-trimethyl-](http://img.cochemist.com/ccimg/1200/1195-79-5_b.png)
![Glycine, N-[(3a,5b,7a)-3,7-dihydroxy-24-oxocholan-24-yl]-](http://img.cochemist.com/ccimg/700/640-79-9.png)
![Glycine, N-[(3a,5b,7a)-3,7-dihydroxy-24-oxocholan-24-yl]-](http://img.cochemist.com/ccimg/700/640-79-9_b.png)
![Ethanesulfonic acid,2-[[(3a,5b)-3-hydroxy-24-oxocholan-24-yl]amino]-](http://img.cochemist.com/ccimg/600/516-90-5.png)
![Ethanesulfonic acid,2-[[(3a,5b)-3-hydroxy-24-oxocholan-24-yl]amino]-](http://img.cochemist.com/ccimg/600/516-90-5_b.png)
![Ethanesulfonic acid,2-[[(3a,5b,12a)-3,12-dihydroxy-24-oxocholan-24-yl]amino]-](http://img.cochemist.com/ccimg/600/516-50-7.png)
![Ethanesulfonic acid,2-[[(3a,5b,12a)-3,12-dihydroxy-24-oxocholan-24-yl]amino]-](http://img.cochemist.com/ccimg/600/516-50-7_b.png)
![[2,3'-Biindolinylidene]-2',3-dione](http://img.cochemist.com/ccimg/500/479-41-4.png)
![[2,3'-Biindolinylidene]-2',3-dione](http://img.cochemist.com/ccimg/500/479-41-4_b.png)
![Glycine, N-[(3a,5b)-3-hydroxy-24-oxocholan-24-yl]-](http://img.cochemist.com/ccimg/500/474-74-8.png)
![Glycine, N-[(3a,5b)-3-hydroxy-24-oxocholan-24-yl]-](http://img.cochemist.com/ccimg/500/474-74-8_b.png)
![4H-Imidazol-5-amine,N-(4-methylphenyl)-4-[(4-methylphenyl)imino]-2-phenyl-](http://img.cochemist.com/ccimg/200600/200510-95-8.png)
![4H-Imidazol-5-amine,N-(4-methylphenyl)-4-[(4-methylphenyl)imino]-2-phenyl-](http://img.cochemist.com/ccimg/200600/200510-95-8_b.png)
![Jarosite(K[Fe3(OH)6(SO4)2])](http://img.cochemist.com/ccimg/12300/12207-14-6.png)
![Jarosite(K[Fe3(OH)6(SO4)2])](http://img.cochemist.com/ccimg/12300/12207-14-6_b.png)
![Magnesate(1-), [3,4-didehydro-9-ethenyl-14-ethyl-21-(methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoato(3-)-κN23,κN24,κN25,κN26]-](/data/chemimg/442400/20369-67-9.png)
![Magnesate(1-), [3,4-didehydro-9-ethenyl-14-ethyl-21-(methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoato(3-)-κN23,κN24,κN25,κN26]-](/data/chemimg/442400/20369-67-9_b.png)
