Peng Liu

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Organization: Wuhan University of Technology

Department: Department of Chemistry, School of Sciences

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TOPICS

Polymer

Stimuli Responsive Polymers PH Responsive Polymers Stimuli Responsive Polymers PH Responsive Polymers Temperature Responsive Polymers

Chemicals
References

Effects of nano-TiO2 on Chlamydomonas reinhardtii cell surface under UV, natural light conditions

Co-reporter:Xiaojuan Chen 陈小娟;Ruirui Lu 刘鹏

Journal of Wuhan University of Technology-Mater. Sci. Ed. 2017 Volume 32( Issue 1) pp:217-222

Publication Date(Web):12 February 2017

DOI:10.1007/s11595-017-1583-0

Cell surface of aquatic organisms constitutes a primary site for the interaction and a barrier for the nano-TiO2 biological effects. In the present study, the biological effects of nano-TiO2 on a unicellular green algae Chlamydomonas reinhardtii were studied by observing the changes of the cell surface morphology and functional groups under UV or natural light. By SEM, the cell surface morphology of C. reinhardtii was changed under UV light, nano-TiO2 with UV light or natural light, which indicated that photocatalysis damaged cell surface. It was also observed that cell surface was surrounded by TiO2 nanoparticles. The ATR-FTIR spectra showed that the peaks of functional groups such as C-N, -C=O, -C-O-C and P=O, which were the important components of cell wall and membrane, were all depressed by the photocatalysis of nano-TiO2 under UV light or natural light. The photocatalysis of nano-TiO2 promoted peroxidation of functional groups on the surface of C. reinhardtii cells, which led to the damages of cell wall and membrane.

Studies on the interaction of CdTe QDs with bovine serum albumin

Co-reporter:Peng Liu;Yisi Liu ;Qisui Wang

Journal of Chemical Technology and Biotechnology 2012 Volume 87( Issue 12) pp:1670-1675

Publication Date(Web):

DOI:10.1002/jctb.3815

Abstract

BACKGROUND: Quantum dots (QDs) have attracted much attention in biological and medical applications. In particular, the interaction of QDs with bovine serum albumin (BSA) is crucial, and has been systematically investigated by various spectroscopic techniques under the physiological conditions.

RESULTS: The effects of ionic strength and pH on the interaction of CdTe QDs with BSA were studied by changing NaCl concentration and pH in mixed solution and making fluorescence spectroscopic measurements. The Stern-Volmer quenching constant (K_a) of different ionic strength and pH were calculated, and information on the structural features of BSA were discussed by means of circular dichroism (CD) spectrum.

CONCLUSION: Both fluorescence (FL) and circular dichroism (CD) results indicated that hydrophobic and electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs-BSA complexes. Copyright © 2012 Society of Chemical Industry

Study on the effect of surface modifier on self-aggregation behavior of Ag nano-particle

Co-reporter:Song Li, Peng Liu, Qisui Wang

Applied Surface Science 2012 Volume 263() pp:613-618

Publication Date(Web):15 December 2012

DOI:10.1016/j.apsusc.2012.09.117

Abstract

In this study, four kinds of Ag nano-particles were synthesized with poly (vinylpyrrolidone) (PVP), polyaniline (PAN), l-cysteine (l-cys), and oleic acid (OA) as modified groups. The properties of these Ag nano-particles were characterized by several techniques. Transmission electron microscopy (TEM) observation show four samples were close to monodisperse spherical with diameters about 7, 3, 10, and 5 nm, respectively. The interplanar spacing was calculated and the crystal was discussed with X-ray diffraction (XRD) results. Both Fourier transform infrared spectra (FTIR) and thermogravimetry (TG)-differential scanning calorimetry (DSC) has revealed the binding group of four molecules on Ag nano-particle's surface. After the Ag nanoparticles (NPs) deposited onto the substrate, surface modifier would collapse on the particle surface. Ag nanoparticles are easier to self-aggregate for the weaker binding of surface modifier. As a result, the conductive film is formed. The effect of modified group and temperature were discussed on the conductivity of the silver films.

Interaction of different thiol-capped CdTe quantum dots with bovine serum albumin

Co-reporter:Qisui Wang, Xiaolei Zhang, Xiaolan Zhou, Tingting Fang, Pengfei Liu, Peng Liu, Xinmin Min, Xi Li

Journal of Luminescence 2012 Volume 132(Issue 7) pp:1695-1700

Publication Date(Web):July 2012

DOI:10.1016/j.jlumin.2012.02.016

Due to their unique optical properties, quantum dots (QDs) are rapidly revolutionizing many areas of medicine and biology. Despite the remarkable speed of development of nanoscience, relatively little is known about the interaction of nanoscale objects with organism. In this work, interaction of CdTe QDs coated with mercaptopropanoic acid (MPA), L-cysteine (L-cys), and glutathione (GSH) with bovine serum albumin (BSA) was investigated. Fluorescence (FL), UV–vis absorption, and circular dichroism (CD) spectra methods were used. The Stern-Volmer quenching constant (Ksv) at different temperatures, corresponding thermodynamic parameters (ΔH, ΔG and ΔS), and information of the structural features of BSA were gained. We found that QDs can effectively quench the FL of BSA in a ligand-dependent manner, electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs-BSA complexes. The CD spectra showed that the secondary and tertiary structure of BSA was changed. This study contributes to a better understanding of the ligand effects on QDs-proteins interactions, which is a critical issue for the applications in vivo.Highlights► The interaction between three thiol-capped QDs and BSA by UV–vis, FL, and CD spectra. ► The bio-effect of CdTe QDs on BSA was a ligand-dependent manner. ► The thermodynamic parameters and the structural features of BSA were gained.

Thermodynamic and conformational investigation of the influence of CdTe QDs size on the toxic interaction with BSA

Co-reporter:Qisui Wang, Pengfei Liu, Xiaolan Zhou, Xiaolei Zhang, Tingting Fang, Peng Liu, Xinmin Min, Xi Li

Journal of Photochemistry and Photobiology A: Chemistry 2012 230(1) pp: 23-30

Publication Date(Web):15 February 2012

DOI:10.1016/j.jphotochem.2011.12.014

Water-soluble fluorescent colloidal quantum dots (QDs) have been widely used in some biological and biomedical fields, so the interaction of QDs with biomolecules recently attracts increasing attention. In this study, the fluorescence (FL) quenching method, circular dichroism (CD) technique, attenuated total reflection-Fourier transform infrared (ATR-FTIR) and UV–vis absorption spectra were used to investigate systematically the influence of CdTe QDs size on the toxic interaction with bovine serum albumin (BSA). Three size CdTe QDs with maximum emission of 543 nm (green-emitting QDs, GQDs), 579 nm (yellow-emitting QDs, YQDs) and 647 nm (red-emitting QDs, RQDs) were tested. The Stern–Volmer quenching constant (Ksv) at different temperatures, corresponding thermodynamic parameters (ΔH, ΔG and ΔS), and information of the structural features of BSA were gained. The FL results indicated that QDs can effectively quench the FL of BSA in a size-dependent manner, electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs–BSA complexes. The CD and ATR-FTIR spectra showed that the secondary structure of BSA was changed by QDs, indicating the toxic on protein.Graphical abstractHighlights► The interaction between three size QDs and BSA by UV–vis, FL, and CD spectra. ► The bio-effect of CdTe QDs on BSA was a size-dependent manner. ► The thermodynamic parameters and the structural features of BSA were gained.

Bovine serum albumin-directed synthesis of biocompatible CdSe quantum dots and bacteria labeling

Co-reporter:Qisui Wang, Fangyun Ye, Tingting Fang, Wenhan Niu, Peng Liu, Xinmin Min, Xi Li

Journal of Colloid and Interface Science 2011 Volume 355(Issue 1) pp:9-14

Publication Date(Web):1 March 2011

DOI:10.1016/j.jcis.2010.11.035

A simple method was developed for preparing CdSe quantum dots (QDs) using a common protein (bovine serum albumin (BSA)) to sequester QD precursors (Cd2+) in situ. Fluorescence (FL) and absorption spectra showed that the chelating time between BSA and Cd2+, the molar ratio of BSA/Cd2+, temperature, and pH are the crucial factors for the quality of QDs. The average QD particle size was estimated to be about 5 nm, determined by high-resolution transmission electron microscopy. With FL spectra, Fourier transform infrared spectra, and thermogravimetric analysis, an interesting mechanism was discussed for the formation of the BSA–CdSe QDs. The results indicate that there might be conjugated bonds between CdSe QDs and –OH, –NH, and –SH groups in BSA. In addition, fluorescence imaging suggests that the QDs we designed can successfully label Escherichia coli cells, which gives us a great opportunity to develop biocompatible tools to label bacteria cells.Graphical abstractPreparation of BSA-Conjugated CdSe QDs through (a) our simple, one-pot, and “green” synthetic route and (b) the conventional and complex step method.Research highlights► CdSe QDs were prepared by using a common protein (bovine serum albumin). ► An interesting mechanism was discussed for the formation of the BSA-CdSe QDs. ► There might be conjugated bonds between QDs and -OH, -NH and -SH groups in BSA. ► FL imaging suggests that the QDs we designed can successfully label E. coli cells.

Study of the bioeffects of CdTe quantum dots on Escherichia coli cells

Co-reporter:Qisui Wang, Tingting Fang, Peng Liu, Xinmin Min, Xi Li

Journal of Colloid and Interface Science 2011 Volume 363(Issue 2) pp:476-480

Publication Date(Web):15 November 2011

DOI:10.1016/j.jcis.2011.08.016

Quantum dots (QDs) hold great potential for applications in nanomedicine, however, only a few studies investigate their toxic- and bio-effects. Using Escherichia coli (E. coli) cells as model, we found that CdTe QDs exhibited a dose-dependent inhibitory effect on cell growth by microcalorimetric technique and optical density (OD600). The growth rate constants (k) were determined, which showed that they were related to the concentration of QDs. The mechanism of cytotoxicity of QDs was also studied through the attenuated total reflection–fourier transform infrared (ATR–FTIR) spectra, fluorescence (FL) polarization, and scanning electron microscopy (SEM). It was clear that the cell out membrane was changed or damaged by the addition of QDs. Taken together, the results indicated that CdTe QDs have cytotoxic effects on E. coli cells, and this effects might attribute to the damaged structure of the cell out membrane, thus QDs and by-products (free radicals, reactive oxygen species (ROS), and free Cd2+) which might enter the cells.Graphical abstractCdTe quantum dots exhibit a dose-dependent inhibitory effect Escherichia coli cells growth using microcalorimetric technique.Highlights► CdTe QDs have toxic effect on E. coli cells using microcalorimetric technique. ► The cytotoxicity of QDs was studied by ATR–FTIR spectra, FL polarization, and SEM. ► This effect might attribute to the damaged structure of the cell out membrane.

Interactions between CdSe/CdS quantum dots and DNA through spectroscopic and electrochemical methods

Co-reporter:Qisui Wang, Lu Yang, Tingting Fang, Shuang Wu, Peng Liu, Xinmin Min, Xi Li

Applied Surface Science 2011 Volume 257(Issue 23) pp:9747-9751

Publication Date(Web):15 September 2011

DOI:10.1016/j.apsusc.2011.05.123

Abstract

The interaction of CdSe/CdS quantum dots (QDs) with Herring sperm-DNA (hs-DNA) has been studied by UV–vis spectroscopy and electrochemical method. Cu(phen)₂^2+/1+ (phen = 1, 10-phenanthroline) was used as an indicator for electroactive dsDNA or ssDNA. The apparent association constant has been deduced (4.94 × 10³ M⁻¹ and 2.39 × 10² M⁻¹) from the absorption spectral changes of the dsDNA–QDs and ssDNA–QDs. The results of dissociation method suggest that Cu(phen)₂^2+/1+ is more easily dissociated from dsDNA or ssDNA modified gold electrode (dsDNA/Au or dsDNA/Au) in presence of QDs. The dissociation rate constant (k) of Cu(phen)₂^2+/1+ on dsDNA/Au is 4.48 times higher than that in absence of QDs, while k is 2.34 times higher than that in absence of QDs on ssDNA/Au in Tris buffer with low ionic strength (pH 7.0, 0.5 mM NaCl). The results illuminate that hs-DNA has high affinity for QDs due to electrostatic force, hydrogen bonds, and van der Waals interactions, and the binding force of QDs with dsDNA is stronger than ssDNA.

Studies on the interactions of fluorescent-magnetic nanocomposites with biomolecules and cells labeling

Co-reporter:Qisui Wang, Tingting Fang, Peng Liu, Xinmin Min, Xi Li

Applied Surface Science 2010 Volume 257(Issue 3) pp:872-877

Publication Date(Web):15 November 2010

DOI:10.1016/j.apsusc.2010.07.084

Abstract

In this study, the fluorescent-magnetic nanocomposites were synthesized. The interactions between nanocomposites and bovine serum albumin (BSA) were studied by absorption and FL titration experiments. The experiments show that binding of nanocomposites and BSA may be caused by the formation of QDs–BSA complex. A magnetic separation method was designed to directly demonstrate the interactions between the surface of bifunctional nanocomposites with CdSe/CdS quantum dots (QDs) and biomolecules (BSA and DNA). The fluorescence (FL) labeling on the Escherchia coli (E. coli) cells was also successfully developed for studying the biolabeling of the bifunctional nanocomposites. The results directly reveal that the bifunctional nanocomposites can separate biomolecules and label cells. The studies we have performed showed that the fluorescent-magnetic nanocomposites are proved to be a kind of novel biofuctional materials, which can be used in bioseparation and biolabeling applications.

Zeta-potentials and enthalpy changes in the process of electrostatic self-assembly of cations on silica surface

Co-reporter:Liu Peng, Wang Qisui, Li Xi, Zhang Chaocan

Powder Technology 2009 Volume 193(Issue 1) pp:46-49

Publication Date(Web):10 July 2009

DOI:10.1016/j.powtec.2009.02.006

Zeta potentials of silica were measured at different pH. With the increment of pH values, zeta potentials increased accordingly, resulting from the increase of the concentration of the negative charges on the silica surface. With further increment of pH values, however, zeta potentials decreased when pH value reached beyond 10.55. When HCl was added into the system to increase pH, negative charges on the silica surface reduced and so the zeta potential decreased. The isoelectric point of silica colloid appeared at pH 2.99. The density of negative charges was also measured in the process of electrostatic self-assembly of nine kinds of cations (LiCl, NaCl, KCl, MgCl2, CaCl2, SrCl2, BaCl2, AlCl3, NH4Cl). The increased ionity and number of charges of cations were favorable for coagulation of silica colloids. Only Al3+ can make the negative charges positive without causing colloid to coagulate. The changes of enthalpy and Gibbs free energy in the process of electrostatic self-assembly were determined by calorimetry and calculation, respectively. With the decreased disorder and exothermal change, the electrostatic self-assembly of cations on silica surface is regarded as an “enthalpy-driven” reaction.The density of negative charges was measured in the process of electrostatic self-assembly of nine kinds of cations. The increased ionity and number of charges of cations were favorable for coagulation of silica colloids. According to the changes of enthalpy and Gibbs free energy, the electrostatic self-assembly of cations on silica surface is regarded as an “enthalpy-driven” reaction with the decreased disorder and exothermal change.

Thermodynamic Studies of Electrostatic Self-assembly of Poly Diallyldimethylammonium Chloride on Proton Exchange Membrane

Co-reporter:Peng LIU;Xi LI;Mu PAN

Chinese Journal of Chemistry 2008 Volume 26( Issue 7) pp:1215-1218

Publication Date(Web):

DOI:10.1002/cjoc.200890221

Abstract

The electrostatic self-assembly of polymer on proton exchange membrane was studied by calorimetric technique. The titration of poly diallyldimethylammonium chloride (PDDA) into Nafion membrane was designed and performed to determine the thermodynamic parameters. The enthalpy change Δ_rH^⊖_m and binding constant K in the process of self-assembly were obtained from data analysis with the help of Origin. According to the calculated thermodynamic parameters, the electrostatic self-assembly of PDDA on the proton exchange membrane is an "enthalpy-driven" reaction. The released heat indicates decrease of energy, which is helpful for the occurrence of the self-assembly process, and the degree of disorder is reduced, which went against the adsorption process. As to every ion bond, the value of Δ_rH^⊖_m of DDA is beyond PDDA because a small molecule can bind itself to the membrane without steric hindrance.