Low-abundance metabolites or proteins in single-cell samples are usually undetectable by mass spectrometry (MS) due to the limited amount of substances in single cells. This limitation inspired us to further enhance the sensitivity of commercial mass spectrometers. Herein, we developed a technique named repeated ion accumulation by ion trap MS, which is capable of enhancing the sensitivity by selectively and repeatedly accumulating ions in a linear ion trap for up to 25 cycles. The increase in MS sensitivity was positively correlated with the number of repeated cycles. When ions were repeatedly accumulated for 25 cycles, the sensitivity of adenosine triphosphate detection was increased by 22-fold within 1.8 s. Our technique could stably detect low-abundance ions, especially MSn ions, at the single-cell level, such as 5-methylcytosine hydrolyzed from sample equivalent to ∼0.2 MCF7 cell. The strategy presented in this study offers the possibility to aid single-cell analysis by enhancing MS detection sensitivity.

•A catalysts screening platform for azide–alkyne cycloaddition was realized by ICP-MS/MS.•The yields of Co+ and Sc+ ions as catalysts were found even higher than the Cu+ ions.•The ICP-MS/MS platform can be used to discover new single atom/ion catalysts in reactions.We developed a rapid high-throughput screening platform using a modified ICP-MS/MS system for monovalence metal ions catalysts discovery in azide–alkyne cycloaddition. Among the ten monovalence metal ions in the first row of periodic table containing Sc+, Ti+, V+, Cr+, Mn+, Fe+, Co+, Ni+, Cu+, and Zn+, five monovalence metal ions of Sc+, Co+, Ni+, Cu+ and Zn+ ions show relatively stronger catalytic activities than others. The catalytic mechanism of Sc+, Co+ and Ni+ ions is similar to the Cu+ ions, but Zn+ ions take a different catalytic route. A yields range of 77–98% for azide-alkyne cycloaddition was achieved with Sc+, Co+, Ni+, Cu+ and Zn+ ions as catalyst, respectively by using a UV laser ablation reactor in 20 min, notable that the yields of Co+ and Sc+ ions were even higher than the common catalyst of Cu+ ions. The proposed platform would be used not only for catalyst discovery in azide-alkyne cycloaddition, but also for the discovery of single atom/ion catalysts in other organic reactions.

AbstractDesigning probes for real-time imaging of dynamic processes in living cells is a continuous challenge. Herein, a novel near-infrared (NIR) photoluminescence probe having a long lifetime was exploited for photoluminescence lifetime imaging (PLIM) using an iridium-alkyne complex. This probe offers the benefits of deep-red to NIR emission, a long Stokes shift, excellent cell penetration, low cytotoxicity, and good resistance to photobleaching. This example is the first PLIM probe applicable to the click reaction of copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) with remarkable lifetime shifts of 414 ns, before and after click reaction. The approach fully eliminates the background interference and distinguishes the reacted probes from the unreacted probes, thus enabling the wash-free imaging of the newly synthesized proteins within single living cells. Based on the unique properties of the iridium complexes, it is anticipated to have applications for imaging other processes within living cells.

AbstractDesigning probes for real-time imaging of dynamic processes in living cells is a continuous challenge. Herein, a novel near-infrared (NIR) photoluminescence probe having a long lifetime was exploited for photoluminescence lifetime imaging (PLIM) using an iridium-alkyne complex. This probe offers the benefits of deep-red to NIR emission, a long Stokes shift, excellent cell penetration, low cytotoxicity, and good resistance to photobleaching. This example is the first PLIM probe applicable to the click reaction of copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) with remarkable lifetime shifts of 414 ns, before and after click reaction. The approach fully eliminates the background interference and distinguishes the reacted probes from the unreacted probes, thus enabling the wash-free imaging of the newly synthesized proteins within single living cells. Based on the unique properties of the iridium complexes, it is anticipated to have applications for imaging other processes within living cells.

Plasma-based ambient mass spectrometry (AMS) exhibits great potential in the direct analysis of raw samples with minimum pretreatment. A variety of plasma-based ionization sources have emerged and presented favorable advantages of their high sensitivity, fast analysis speed, and promising qualitative and quantitative abilities for a wide range of applications. Successive efforts have been made to further improve the plasma-based sources for reliable practical applications. Herein, the instrumentation, mechanisms, novel configurations, and applications of versatile plasma-based AMS techniques have been overviewed, and further perspectives have been discussed in the end.

Metabolic azide amino acid labelling followed by the use of bioorthogonal chemistry is an efficient technique for imaging newly synthesized proteins. Recently, AHA-labelling together with the proximity-ligation assay was used to identify newly synthesized proteins of interest (POI) (Tom Dieck et al., Nat. Meth. 2015, 12, 411). Here we build on this study replacing the proximity-ligation assay with FRET to improve the spatial resolution. Herein, we develop a FRET-based strategy for imaging the newly synthesized endogenous POI within cells: a FRET acceptor is installed onto the newly synthesized proteins via click chemistry, and a FRET donor onto the POI via immunocytochemistry. We found that a photobleaching based FRET efficiency imaging mode and a fluorescence lifetime imaging mode showed the distribution of newly synthesized proteins more accurately compared to the direct observation of FRET signals. We demonstrated the capability of this FRET-based imaging method by visualizing several newly synthesized proteins including TDP-43, tubulin and CaMKIIα in different cell lines. This novel analytical imaging method could be used to visualize other specific endogenous proteins of interest in situ.

The present work indicated that ligand-exchanged metal–organic frameworks could behave as superlenses in air to resolve 100 nm under a conventional white-light microscope, obtaining a super-resolution of λ/6. This discovery greatly expands the types of materials for preparing superlens used for the observation of biological samples and fabrication of new superlenses.

The unambiguous quantification of biomolecules is of great significance in fundamental biological research as well as practical clinical diagnosis. Due to the lack of a detectable moiety, the direct and highly sensitive quantification of biomolecules is often a “mission impossible”. Consequently, tagging strategies to introduce detectable moieties for labeling target biomolecules were invented, which had a long and significant impact on studies of biomolecules in the past decades. For instance, immunoassays have been developed with radioisotope tagging by Yalow and Berson in the late 1950s. The later languishment of this technology can be almost exclusively ascribed to the use of radioactive isotopes, which led to the development of nonradioactive tagging strategy-based assays such as enzyme-linked immunosorbent assay, fluorescent immunoassay, and chemiluminescent and electrochemiluminescent immunoassay. Despite great success, these strategies suffered from drawbacks such as limited spectral window capacity for multiplex detection and inability to provide absolute quantification of biomolecules. After recalling the sequences of tagging strategies, an apparent question is why not use stable isotopes from the start?A reasonable explanation is the lack of reliable means for accurate and precise quantification of stable isotopes at that time. The situation has changed greatly at present, since several atomic mass spectrometric measures for metal stable isotopes have been developed. Among the newly developed techniques, inductively coupled plasma mass spectrometry is an ideal technique to determine metal stable isotope-tagged biomolecules, for its high sensitivity, wide dynamic linear range, and more importantly multiplex and absolute quantification ability. Since the first published report by our group, metal stable isotope tagging has become a revolutionary technique and gained great success in biomolecule quantification. An exciting research highlight in this area is the development and application of the mass cytometer, which fully exploited the multiplexing potential of metal stable isotope tagging. It realized the simultaneous detection of dozens of parameters in single cells, accurate immunophenotyping in cell populations, through modeling of intracellular signaling network and undoubted discrimination of function and connection of cell subsets. Metal stable isotope tagging has great potential applications in hematopoiesis, immunology, stem cells, cancer, and drug screening related research and opened a post-fluorescence era of cytometry.Herein, we review the development of biomolecule quantification using metal stable isotope tagging. Particularly, the power of multiplex and absolute quantification is demonstrated. We address the advantages, applicable situations, and limitations of metal stable isotope tagging strategies and propose suggestions for future developments. The transfer of enzymatic or fluorescent tagging to metal stable isotope tagging may occur in many aspects of biological and clinical practices in the near future, just as the revolution from radioactive isotope tagging to fluorescent tagging happened in the past.

Rapid screening of Cu+-intermediates by using 63Cu+ or 65Cu+ ions as catalysts with or without ligand protection in Cu(I)-catalyzed azide–alkyne cycloaddition was realized using an on-line modified ICP-MS/MS platform in this work, while the Cu+-intermediates without ligand protection are very active, which are extremely difficult to be observed using other existing techniques. This universal platform was suitable to study the mechanism of organic reactions catalyzed by unstable metal(I) ions as well as to discover new candidates for metal(I) catalysts.

Current detection methods for paper-based analytical devices (PADs) rely on spectroscopic and electrochemical properties, which place special requirements on the analyte or need analyte labeling. Here, ion-transmission mass spectrometry (MS) was proposed for coupling with PADs to enable rapid in situ MS analysis of the sample on paper. The sample was analyzed directly on paper via analyte ionization by ions transmitted through the paper, generated by a low-temperature plasma probe. Prior to MS analysis, the sample can be separated by paper electrophoresis or by paper chromatography, among a variety of other features offered by PADs. The versatility of this technique was demonstrated by MS analysis of a paper microarray, a mixture of amino acids, and whole blood doped with drugs on PADs.

Sensitive detection of biomolecules in small-volume samples by mass spectrometry is, in many cases, challenging because of the use of buffers to maintain the biological activities of proteins and cells. Here, we report a highly effective desalting method for picoliter samples. It was based on the spontaneous separation of biomolecules from salts during crystallization of the salts. After desalting, the biomolecules were deposited in the tip of the quartz pipet because of the evaporation of the solvent. Subsequent detection of the separated biomolecules was achieved using solvent assisted electric field induced desorption/ionization (SAEFIDI) coupled with mass spectrometry. It allowed for direct desorption/ionization of the biomolecules in situ from the tip of the pipet. The organic component in the assistant solvent inhibited the desorption/ionization of salts, thus assured successful detection of biomolecules. Proteins and peptides down to 50 amol were successfully detected using our method even if there were 3 × 105 folds more amount of salts in the sample. The concentration and ion species of the salts had little influence on the detection results.

We had developed pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) for systematically profiling and determining components in small volume sample. Pulsed-dc-ESI utilized constant high voltage to induce the generation of single polarity pulsed electrospray remotely. This method had significantly boosted the sample economy, so as to obtain several minutes MS signal duration from merely picoliter volume sample. The elongated MS signal duration enable us to collect abundant MS2 information on interested components in a small volume sample for systematical analysis. This method had been successfully applied for single cell metabolomics analysis. We had obtained 2-D profile of metabolites (including exact mass and MS2 data) from single plant and mammalian cell, concerning 1034 components and 656 components for Allium cepa and HeLa cells, respectively. Further identification had found 162 compounds and 28 different modification groups of 141 saccharides in a single Allium cepa cell, indicating pulsed-dc-ESI a powerful tool for small volume sample systematical analysis.

In this study, we developed a probe-electrospray ionization method by coupling a SPME probe modified with nanosized TiO2 directly to nanoESI-MS for the phosphoproteome analysis, which demonstrated excellent selectivity and sensitivity for enrichment of phosphopeptides in complex biological samples.

Methylmercury (CH3Hg) is one of the most widespread toxic contaminants. Although the formation of CH3Hg in aqueous environments has been widely investigated, little information is available on direct anthropogenic or natural emissions of CH3Hg to the atmosphere. In this work, ICP-MS/MS was chosen as a tool to study abiotic methylation of inorganic mercury reacting with VOCs in a gas environment for the first time. We found that the gaseous Hg+ ions were transformed to the more toxic CH3Hg+ ions instantaneously when colliding with some VOCs. Several VOCs, e.g., methyl iodide (CH3I), methylbenzene, acetic acid and ethyl acetate, exhibited good methylation of Hg+ ions with productivities of 1.77%, 1.28%, 1.35% and 1.18%, respectively. Four isotope peaks of CH3199Hg (M = 214), CH3200Hg (M = 215), CH3201Hg (M = 216) and CH3202Hg (M = 217) were identified when Hg+ ions collided with CH3I, and the methyl group in CH3Hg+ was validated by the source of CD3I, indicating that CH3Hg+ ions were formed. This study reveals that the abiotic methylation of Hg+ ions could occur when in contact with the VOCs in the atmosphere, leading to secondary environmental pollution.

Molecular analysis at cellular and subcellular levels, whether on selected molecules or at the metabolomics scale, is still a challenge now. Here we propose a method based on probe ESI mass spectrometry (PESI-MS) for single cell analysis. Detection of metabolites at cellular and subcellular levels was successfully achieved. In our work, tungsten probes with a tip diameter of about 1 μm were directly inserted into live cells to enrich metabolites. Then the enriched metabolites were directly desorbed/ionized from the tip of the probe for mass spectrometry (MS) detection. The direct desorption/ionization of the enriched metabolites from the tip of the probe greatly improved the sensitivity by a factor of about 30 fold compared to those methods that eluted the enriched analytes into a liquid phase for subsequent MS detection. We applied the PESI-MS to the detection of metabolites in single Allium cepa cells. Different kinds of metabolites, including 6 fructans, 4 lipids, and 8 flavone derivatives in single cells, have been successfully detected. Significant metabolite diversity was observed among different cells types of A. cepa bulb and different subcellular compartments of the same cell. We found that the inner epidermal cells had about 20 fold more fructans than the outer epidermal cells, while the outer epidermal cells had more lipids. We expected that PESI-MS might be a candidate in the future studies of single cell “omics”.

With the inspiration of an ancient Chinese poison test approach, we report a rapid hydrogen sulfide detection strategy in specific areas of live cells using silver needles with good spatial resolution of 2 × 2 μm2. Besides the accurate-localization ability, this reflection-based strategy also has attractive merits of convenience and robust response when free pretreatment and short detection time are concerned. The success of endogenous H2S level evaluation in cellular cytoplasm and nuclear of human A549 cells promises the application potential of our strategy in scientific research and medical diagnosis.

The fluorescence, catalytic activity and assembly behavior of GO could be simultaneously changed after interaction with proteins, leading to distinct response patterns related to each specific protein. Based on the phenomenon, a triple-channel optical sensor has been proposed in the present communication for protein discrimination with GO as a single sensing element.

Fluorescent gold nanoparticle (GNP) is an easily synthesized and biocompatible optical platform for sensing and imaging with tunable near-infrared (NIR) emission. However, the relatively low fluorescence (FL) quantum yield limits the further improvement of sensitivity and application. Here, we find that, on plasmonic substrates, the FL intensity of protein-directed synthesized GNPs can be enhanced significantly (∼20-fold). Moreover, protein analytes can interact with GNPs and influence the enhanced fluorescence process so that we can obtain distinct FL image patterns. Then, using the array-based sensing strategy, protein discrimination can be achieved. In our present experiment, five GNPs were used as sensing elements and 10 kinds of proteins at three concentrations (0.2, 0.5, and 1 μM) were successfully identified. This array-based sensing strategy using enhanced-fluorescence from GNPs is highly sensitive and differentiable, expanding the application field of GNPs.

Here we report a cataluminescence-based method in the combinatorial discovery of active catalysts for NO reduction by C3H6. This method is based on the fact that NO reduction generates cataluminescence emission on the surface of various metal catalysts supported on BaO/Al2O3, whose intensity is correlated to the activity of the catalyst. The catalytic activities of the catalysts were evaluated in parallel by both the cataluminescence method and a micro-reactor evaluation system. The correlation coefficients are in the range of 0.676–0.9236 for the two methods and all above 0.632 at the confidence level 95% in the temperature region of 250–500 °C, indicating that the cataluminescence method can be applied to the evaluation of the catalytic activity of de-NOx catalysts.

In this paper, superhydrophobic Zinc-CPPs (coordination polymer particles) with controllable shapes were synthesized by an in situ ligand generating reaction in combination with monofunctional ligands as capping reagents. The as-synthesized samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersion X-ray (EDX) spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. The Zn–CPPs exhibit superhydrophobicity. Crystalline ZnO particles were formed from the calcination of Zn–CPPs, exhibiting superhydrophobicity and good photocatalytic activity.

The fluorescence of metal nanoclusters provides an amusing optic feature to be applied in various fields. However, rational design of dual functional fluorescent metal nanoclusters directed by active enzyme with targeted application remains little explored. In this work, we report a new strategy to construct enzyme functionalized fluorescent gold nanoclusters via a biomineralization process for the detection of hydrogen peroxide. Horseradish peroxidase (HRP) was used as a model functional template to direct the synthesis of fluorescent gold nanoclusters (Au NCs) at physiological conditions to form HRP−Au NCs bioconjugates. We found that the fluorescence of HRP−Au NCs can be quenched quantitatively by adding H2O2, indicating that HRP enzyme remains active and enables catalytic reaction of HRP−Au NCs and H2O2. Upon the addition of H2O2 under optimal conditions, the fluorescence intensity quenched linearly over the range of 100 nM to 100 μM with high sensitivity (LOD = 30 nM, S/N = 3). This study would be potentially extended to other functional proteins to generate dual functional nanoclusters and applied to real time monitoring of biologically important targets in living cells.

Cross-reactive sensor arrays, known as “chemical noses”, offer an alternative to time-consuming analytical methods. Here, we report a sensor array based on nanomaterial-assisted chemiluminescence (CL) for protein sensing and cell discrimination. We have found that the CL efficiencies are improved to varied degrees for a given protein or cell line on catalytic nanomaterials. Distinct CL response patterns as “fingerprints” can be obtained on the array and then identified through linear discriminant analysis (LDA). The sensing of 12 kinds of proteins at three concentrations, as well as 12 types of human cell lines among normal, cancerous, and metastatic, has been performed. Compared with most fluorescent or colorimetric approaches which rely on the strong interaction between analytes and sensing elements, our array offers the advantage of both sensitivity and reversibility.

A novel ionization device for controlling the charge states of peptides based on an inductive elecrospray ionization technique was developed. This ion source keeps the major capabilities of electrospray ionization (ESI) which is compatible with liquid separation techniques (such as liquid chromatography (LC) and capillary electrophoresis (CE)) and can be potentially used to control the charge states of peptides accurately by simply varying the AC voltage applied. In comparison with conventional ESI, inductive ESI successfully simplifies the mass spectrum by reducing the charge states of peptide to a singly charged one, as well as eliminating the adduct ions.

Thermochemiluminescence (TCL) of organic compounds or biological substances is an interesting phenomenon and has been applied to polymer analysis and medical diagnostics. We improve traditional TCL assays using the assistance of catalytic nanomaterials and construct a nanomaterials array for the discrimination of three subtypes of proteins (albumin from human serum, bovine serum and porcine serum). With the assistance of catalytic nanomaterials, TCL signals of different protein samples are distinct due to the diverse catalytic activities of the nanomaterials and characteristics of proteins. Using this array-based technology, we obtained unique TCL patterns as ‘fingerprints’, and then accurately classified these 3 subtypes of serum albumins and the denatured albumins under different heat conditions. In the blind test, 24 unknown samples randomly chosen from these albumins were all assigned to the accurate groups. Moreover, on several nanomaterials, the intensity of TCL could be greatly amplified. For example, on MgO and BaO, albumins in aqueous solutions at 2 μg mL−1 (∼30 nM) offered robust responses. This improved TCL assay with reversible response and simple instrumentation can offer high differentiability and sensitivity.

A simple-structure, low-power, and low-cost low temperature plasma (LTP) ionization source, coupled with mass spectrometry, for the online detection of indoor volatile organic compounds (VOCs) has been constructed in this work. Air, instead of noble gases, was employed as the discharging and carrier gas. And a custom-built AC high-voltage power supply with a total power consumption of 5 W, frequency of 2–4 kHz, and amplitude around 1–5 kVp–p was used. This LTP source is a soft ionization source. The initial performance of the ionization source has been evaluated by ionizing samples including alcohols, ketones, aldehydes and aromatics. These compounds cover most of the common air pollutants concerning people's health. It is well known that those plasmas generated by dielectric barrier discharge (DBD) produce significant amount of metastable species and electrons with mean energies greater than several electronvolt, but minimal fragmentation was observed in our work. Protonated ions are the dominant product for the VOCs detected after the ionization process. Further work has been conducted to confirm the detection feature of this source. The results are promising enough to ensure the novel LTP ionization source as an effective tool for the online detection of indoor VOCs.

Simultaneous determination of As and Sb by hydride generation atomic fluorescence spectrometry was developed with the dielectric barrier discharge plasma as the hydride atomizer. The low-temperature and atmospheric-pressure micro-plasma was generated in a quartz cylindrical configuration device, which was constructed by an axial internal electrode and an outer electrode surrounding outside of the tube. The optimization of the atomizer construction and parameters for hydride generation and fluorescence detection systems were carried out. Under the optimized conditions, the detection limits for As and Sb were 0.04 and 0.05 μg L−1, respectively. In addition, the applicability of the present method was confirmed by the detection of As and Sb in reference materials of quartz sandstone (GBW07106) and argillaceous limestone (GBW07108). The present work provided a new approach to exploit the miniaturized hydride generation dielectric barrier discharge atomic fluorescence spectrometry system for simultaneous multi-element determination.

An atmospheric pressure dielectric barrier discharge (DBD) atomizer was investigated for bismuth (Bi) determination with hydride generation (HG) atomic fluorescence spectrometry (AFS). The characteristics of the atomizer and the effects of experimental parameters, including observation height, discharge power, flow rate of discharge gas and AFS carrier gas were optimized. The linear range of present method for Bi determination is 0.5–300.0 μg L−1 with a detection limit of 0.07 μg L−1 (3σ). The method was validated by the analysis of reference materials (GBW08517 and GSB-14) and the results agreed well with the reference values. The established method was applied to the determination of Bi in ore, soil and ash samples.

An l-cysteine-assisted self-assembly process for constructing complex PbS from cubes to star and dendritic structures via hydrothermal routes is reported. In this process, l-cysteine (Cys) was used as both a sulfur source and a chelating reagent. The effects of the molar ratios of Cys/Pb2+, the concentrations, reaction time and temperature on the self-assembly of PbS microcrystals were investigated. The X-ray diffraction (XRD) patterns confirmed the crystalline structure of PbS crystals. Raman spectroscopy helped to further demonstrate the purity of the products. Transmission electron microscopy (TEM) helped to determine the size and shape of the products. On the basis of systemic studies about the influence of experimental parameters on the products, possible evolution processes were proposed. The shape of PbS crystals was closely related to the relative growth rate of the {100} and {111} faces. The Cys/Pb2+ molar ratios, the concentrations, and the reaction temperatures influenced the growth rate of the {100} and {111} faces, which determined the final morphology of PbS microcrystals.

Here we report a cataluminescence-based method in the combinatorial discovery of active catalysts for NO reduction by C3H6. This method is based on the fact that NO reduction generates cataluminescence emission on the surface of various metal catalysts supported on BaO/Al2O3, whose intensity is correlated to the activity of the catalyst. The catalytic activities of the catalysts were evaluated in parallel by both the cataluminescence method and a micro-reactor evaluation system. The correlation coefficients are in the range of 0.676–0.9236 for the two methods and all above 0.632 at the confidence level 95% in the temperature region of 250–500 °C, indicating that the cataluminescence method can be applied to the evaluation of the catalytic activity of de-NOx catalysts.

Rapid screening of Cu+-intermediates by using 63Cu+ or 65Cu+ ions as catalysts with or without ligand protection in Cu(I)-catalyzed azide–alkyne cycloaddition was realized using an on-line modified ICP-MS/MS platform in this work, while the Cu+-intermediates without ligand protection are very active, which are extremely difficult to be observed using other existing techniques. This universal platform was suitable to study the mechanism of organic reactions catalyzed by unstable metal(I) ions as well as to discover new candidates for metal(I) catalysts.

The fluorescence, catalytic activity and assembly behavior of GO could be simultaneously changed after interaction with proteins, leading to distinct response patterns related to each specific protein. Based on the phenomenon, a triple-channel optical sensor has been proposed in the present communication for protein discrimination with GO as a single sensing element.

Methylmercury (CH3Hg) is one of the most widespread toxic contaminants. Although the formation of CH3Hg in aqueous environments has been widely investigated, little information is available on direct anthropogenic or natural emissions of CH3Hg to the atmosphere. In this work, ICP-MS/MS was chosen as a tool to study abiotic methylation of inorganic mercury reacting with VOCs in a gas environment for the first time. We found that the gaseous Hg+ ions were transformed to the more toxic CH3Hg+ ions instantaneously when colliding with some VOCs. Several VOCs, e.g., methyl iodide (CH3I), methylbenzene, acetic acid and ethyl acetate, exhibited good methylation of Hg+ ions with productivities of 1.77%, 1.28%, 1.35% and 1.18%, respectively. Four isotope peaks of CH3199Hg (M = 214), CH3200Hg (M = 215), CH3201Hg (M = 216) and CH3202Hg (M = 217) were identified when Hg+ ions collided with CH3I, and the methyl group in CH3Hg+ was validated by the source of CD3I, indicating that CH3Hg+ ions were formed. This study reveals that the abiotic methylation of Hg+ ions could occur when in contact with the VOCs in the atmosphere, leading to secondary environmental pollution.

In this paper, superhydrophobic Zinc-CPPs (coordination polymer particles) with controllable shapes were synthesized by an in situ ligand generating reaction in combination with monofunctional ligands as capping reagents. The as-synthesized samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersion X-ray (EDX) spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. The Zn–CPPs exhibit superhydrophobicity. Crystalline ZnO particles were formed from the calcination of Zn–CPPs, exhibiting superhydrophobicity and good photocatalytic activity.

Metabolic azide amino acid labelling followed by the use of bioorthogonal chemistry is an efficient technique for imaging newly synthesized proteins. Recently, AHA-labelling together with the proximity-ligation assay was used to identify newly synthesized proteins of interest (POI) (Tom Dieck et al., Nat. Meth. 2015, 12, 411). Here we build on this study replacing the proximity-ligation assay with FRET to improve the spatial resolution. Herein, we develop a FRET-based strategy for imaging the newly synthesized endogenous POI within cells: a FRET acceptor is installed onto the newly synthesized proteins via click chemistry, and a FRET donor onto the POI via immunocytochemistry. We found that a photobleaching based FRET efficiency imaging mode and a fluorescence lifetime imaging mode showed the distribution of newly synthesized proteins more accurately compared to the direct observation of FRET signals. We demonstrated the capability of this FRET-based imaging method by visualizing several newly synthesized proteins including TDP-43, tubulin and CaMKIIα in different cell lines. This novel analytical imaging method could be used to visualize other specific endogenous proteins of interest in situ.