Co-reporter:Shi Jin, Dong-Dong Zheng, Bo Sun, Xianghui Yu, Xiao Zha, Yongjiang Liu, Shuming Wu, and Yuqing Wu
ACS Applied Materials & Interfaces December 21, 2016 Volume 8(Issue 50) pp:
Publication Date(Web):November 25, 2016
DOI:10.1021/acsami.6b12456
Based on the helix4-exchanged HPV16 L1 and HPV18 L1, HPV16 L1 Bi and HPV18 L1 Bi, we have successfully realized the controlled hybrid-assembly of HPV16/18 L1 Bi VLPs (bihybrid-VLPs) in vitro. The bihybrid-VLPs were further confirmed by fluorescence resonance energy transfer (FRET) and complex-immunoprecipitation (Co-IP) assays. The ratio of 16 L1 Bi and 18 L1 Bi in bihybrid-VLPs was verified to be 3:5 based on a modified magnetic Co-IP procedure, when mixing 1 equiv pentamer in assembly buffer solution, but it changed with conditions. In addition, the bihybrid-VLPs showed identical thermal stability as that of normal VLPs, suggesting high potential in practical applications. The present study is significant because it modified one of the vital steps of virus life cycle at the stage of virus assembly, supplying a new approach not only to deepen structural insights but also a possibility to prepare stable, low-cost, bivalent antivirus vaccine. Furthermore, the controlled hybrid-assembly of bihybrid-VLPs in vitro provides suggestions for the design of effective multivalent hybrid-VLPs, being a potential to develop broad-spectrum vaccines for the prevention of infection with multiple types of HPV.Keywords: bihybrid-VLPs; capsid protein L1; controlled hybrid-assembly; human papillomavirus (HPV); in vitro; virus like particles (VLPs);
Co-reporter:Wei-Xian Wang;Yee-Wai Cheung;Roderick M. Dirkzwager;Wai-Chung Wong;Julian A. Tanner;Hong-Wei Li
Analyst (1876-Present) 2017 vol. 142(Issue 5) pp:800-807
Publication Date(Web):2017/02/27
DOI:10.1039/C6AN02417C
Innovative nanomaterials offer significant potential for diagnosis of severe diseases of the developing world such as malaria. Small sized silver nanoclusters have shown promise for diagnostics due to their intense fluorescence emission and photo-stabilities. Here, double-stranded DNA-scaffolded silver nanoclusters (AgNCs-dsDNA) were prepared to detect the established malaria biomarker, Plasmodium falciparum lactate dehydrogenase (PfLDH). Significant luminescence enhancement over a wide concentration range of PfLDH was demonstrated. In addition, a low limit of detection at 0.20 nM (7.4 pg μL−1) was achieved for PfLDH in buffer solution, sensitive enough for practical use correlating with the clinical level of PfLDH in plasma from malaria-infected patients. Unique specificity was observed towards Plasmodium falciparum over Plasmodium vivax and human lactate dehydrogenase, as well as other non-specific proteins, by combining the use of AgNCs-dsDNA with a DNA aptamer against PfLDH. Moreover, the intrinsic mechanism was revealed in detail for the two-step luminescence response. The combination of DNA-scaffolded silver nanoclusters coupled to a selective single-stranded DNA aptamer allows for a highly specific and sensitive detection of PfLDH with significant promise for malaria diagnosis in future.
Co-reporter:Jiao Liu;Hong-Wei Li;Wei-Xian Wang
Journal of Materials Chemistry B 2017 vol. 5(Issue 19) pp:3550-3556
Publication Date(Web):2017/05/17
DOI:10.1039/C7TB00438A
Gold nanoclusters (AuNCs) have been widely applied in fluorescence sensing, bioimaging and phototherapy. Although great progress has been made, the relatively low quantum yield (QY, <10%) in most currently reported AuNCs limits their application greatly. In the present study, adenosine monophosphate (AMP) capped gold nanoclusters (AuNC@AMP) are prepared by using a newly developed heating method in a short time (within 60 min), and are found to show a strong and stable luminescence emission in a relative high QY (14.52%). In addition, an in-depth investigation by employing infrared, 1H and 31P NMR spectroscopy has attributed the origin of such a high luminescence to both the binding of the purine ring and/or the phosphate moiety of AMP as well as their orientations at the gold core surface. In addition, electron-rich atoms such as nitrogen and oxygen, or group moieties such as –NH2 in the ligands can largely promote the luminescence emission of AuNCs. The present study reveals the intriguing generation of ultrabright luminescence from metal nanoclusters, and it will stimulate more research both on the fabrication and practical applications of luminescent metal NCs. With regard to the high QY of these AuNCs, they have great potential for biological applications as adenine is crucially important in life sciences.
Co-reporter:Xin-Xin Yuan;Xiang-Yu Jia;Hong-Wei Li;Xu Yu
RSC Advances (2011-Present) 2017 vol. 7(Issue 54) pp:34276-34282
Publication Date(Web):2017/07/04
DOI:10.1039/C7RA05630C
The tumor suppressor protein p53 has been a famous biomarker for many years both in biological and medical science. The core domain of it (residues 94–292) plays an important role for specific DNA binding. The involved 9 tyrosine and 9 cysteine residues provide the possibility to reduce and combine with gold to get metal nanoclusters such as BSA–AuNCs. In the present study, we develop a new method to synthesize red-emitting nanoclusters, p53–AuNCs, by using p53 core as both reductant and template. The synthetic procedure is one-step, straightforward and ecofriendly. In addition, the p53–AuNCs are found to be a sensitive fluorescence probe to detect and screen myricetin from Chinese medicine, providing a bridge between the kind of tumor-related protein and metallic nanoclusters. Particularly, these AuNCs are highly biocompatible as shown by cytotoxicity experiments and can be readily internalized by Hela cells, illustrating dual functions as a red-emitting material in bioimaging and a potential nanocarrier in drug delivery.
Co-reporter:Jiao Liu;Hong-Wei Li
RSC Advances (2011-Present) 2017 vol. 7(Issue 22) pp:13438-13443
Publication Date(Web):2017/02/24
DOI:10.1039/C7RA00158D
Ultrabright adenosine monophosphate (AMP) capped gold nanoclusters (AuNCs@AMP) were used as a novel fluorescent probe to detect lactate dehydrogenase (LDH), an important biomarker of common injuries and diseases. The fluorescence emission of AuNCs@AMP is quenched linearly in the presence of a wide concentration range of LDH (50–1000 nM), covering the range for clinical diagnosis. Particularly, the detection is very sensitive with an extremely low detection limit of 0.2 nM (26 pg μL−1, 0.8 U L−1), being more sensitive than the previously reported ones. However, the proposed probe does not response to other commercially available proteins with different isoelectric points, which shows a high selectivity toward LDH. In addition, the response mechanism is also investigated in detail, where the quenching response is attributed to the binding of AuNCs to the free thiol groups at the LDH surface. Therefore, the present study supplies a cost-effective, fast and easily performed approach to detect LDH with high selectivity and sensitivity, which has potential use in clinical diagnosis in future.
Co-reporter:Teng Zhang, Ding-Yi Fu, Yuqing Wu, Yizhan Wang and Lixin Wu
RSC Advances 2016 vol. 6(Issue 34) pp:28612-28618
Publication Date(Web):08 Mar 2016
DOI:10.1039/C6RA00105J
Cervical cancer is the second-largest killer of women worldwide. Development of biomarkers that can be used to efficiently screen cervical cancer would be extremely useful for clinical management. The presence of human papillomavirus (HPV) capsid proteins, L1 and L2, is extremely important clinically and warrants further examination of cervical cancer. The present study supplied an easy, cost-effective and efficient fluorescence-enhanced method to detect the cationic peptides of HPV capsid proteins by using an Eu-containing polyoxometalate. The binding-induced luminescence enhancement of EuW10 was further successfully used to detect HPV L1 pentamers expressed from Escherichia coli, which could be extended to detect other proteins involving a large amount of polybasic segments. The present study showed an excellent application of a type of inorganic material, polyoxometalate, to viral and biological science.
Co-reporter:Zhongyuan Ren, Liping Zhang, Yuqing Wu, Saida Mebarek, René Buchet
Vibrational Spectroscopy 2016 Volume 86() pp:206-211
Publication Date(Web):September 2016
DOI:10.1016/j.vibspec.2016.07.009
Phosphatase activity in osteoblasts like Saos-2 cells was previously determined by measuring infrared spectra of substrates (pyrophosphate, 4-nitrophenyl phosphate, α-glucose-1-phosphate or β-Glycerophosphate), in the presence of Saos-2 cells under physiological conditions, at 37 °C and pH = 8. In this work, 2D correlation analysis served to resolve component bands in infrared spectra to obtain accurate values of enzymatic activity. We critically analyzed the advantages and pitfalls of 2D correlation analysis and compared their results with those obtained from infrared difference spectra. In the case of PPi substrate, 2D correlation analysis resolved well the overlapping bands associated to PPi and Pi. We obtained an average specific activity of hydrolysis of PPi by Saos-2 cells of around 133 ± 16 nmol mg−1 min−1 by using peak positions determined from 2D correlation analysis as compared with the value of around 118 ± 10 nmol mg−1 min−1 obtained from peak positions determined by IR difference spectra. However, in the case of 4-nitrophenyl phosphate, 2D correlation analysis, as well as infrared difference spectra, failed to resolve Pi band located at 990 cm−1 from the strongly overlapped 4-nitrophenyl phosphate band located at around 980 cm−1. This is explained by the fact that the 990 cm−1-band increased during hydrolysis, while the 980 cm−1-band decreased, cancelling each other. In the case of β-glycerophosphate, 2D IR correlation analysis confirmed the peak position of Pi within 2 cm−1 as determined by infrared spectroscopy. The specific activity of hydrolysis of β-glycerophosphate as determined by both methods was identical within experimental errors. Taken together our findings indicated that each method yielded specific activity values of TNAP in osteoblast cells within 20% from each other. The combination of 2D-correlation analysis and IR spectroscopy confirmed and reinforced the interpretation of IR spectra. Both approaches are complementary and provided a solid rationale to select peak positions for accurate determination of enzymatic activity in cells.
Co-reporter:Xueling Cao, Hongwei Li, Lili Lian, Na Xu, Dawei Lou, Yuqing Wu
Analytica Chimica Acta 2015 Volume 871() pp:43-50
Publication Date(Web):29 April 2015
DOI:10.1016/j.aca.2015.02.031
•A new method for the detection of trace amount of clenbuterol in real sample is proposed.•This paper provides a dual-responsive fluorescence way to detect clenbuterol.•This method has a wide concentration range and with low detection limit.•Protein-protected gold nanoclusters is used as fluorescence probe.The illegal feeding of clenbuterol (CLB) to domestic animals and the potential harm of it to human health lead an urgent requirement for the efficient detection of CLB, especially in the edible meat. In this paper we reported a new fluorescence method for the detection of trace amount of CLB by using the BSA-protected gold nanoclusters (AuNCs@BSA). Under the excitation of either 280 or 500 nm the emission of AuNCs@BSA was quenched obviously by diazotized CLB, supplying a dual-responsive fluorescence method to detect CLB in aqueous solution. In addition, the linear response of the fluorescence intensity of AuNCs@BSA to diazotized CLB allowed the quantitative detection of CLB in a range of 4.0 nM–300 μM upon excitation at two wavelength, and the limit of detection for CLB was 3.0 nM upon 280 nm excitation and 1.6 nM upon 500 nm excitation, respectively. In addition, the dual-responsive mechanism of AuNCs@BSA to CLB was investigated in detail by using several CLB analogues and reference compounds. Particularly, the proposed method was successfully applied to detect CLB in pork mince and the results were validated well by HPLC, illustrating it could be used as a reliable, rapid, and cost-effective technique for the determination of CLB residues in real samples.
Co-reporter:Ding-Yi Fu, Shi Jin, Dong-Dong Zheng, Xiao Zha, and Yuqing Wu
ACS Medicinal Chemistry Letters 2015 Volume 6(Issue 4) pp:381
Publication Date(Web):February 25, 2015
DOI:10.1021/ml500392y
A new 14 peptide, originating essentially from the helix 5 of HPV 16L1, illustrates an IC50 of 19.38 nM for the inhibition of HPV 16 L1 pentamer formation, which is highly efficient for targeting a specific protein segment. In addition, mechanism studies reveal that the length, sequence, and the folding of the peptide are critical factors for its inhibition. Particularly, the peptide shows similar inhibition against the pentamer formation of HPV 58L1, although it is designed specially for HPV 16 L1. This study opens a way for the development of high-efficiency, broad-spectrum inhibitors as a new class of anti-HPV agents, which could be extended to the treatment of other virus types.Keywords: human papillomavirus; inhibitor; pentamer formation; Peptide
Co-reporter:Teng Zhang;Dr. Hong-Wei Li;Dr. Yuqing Wu;Dr. Yizhan Wang ;Dr. Lixin Wu
Chemistry - A European Journal 2015 Volume 21( Issue 25) pp:9028-9033
Publication Date(Web):
DOI:10.1002/chem.201501243
Abstract
Two-step assembly of a peptide from HPV16 L1 with a highly charged europium-substituted polyoxometalate (POM) cluster, accompanying a great luminescence enhancement of the inorganic polyanions, is reported. The mechanism is discussed in detail by analyzing the thermodynamic parameters from isothermal titration calorimetry (ITC), time-resolved fluorescent and NMR spectra. By comparing the actions of the peptide analogues, a binding process and model are proposed accordingly. The driving forces in each binding step are clarified, and the initial POM aggregation, basic-sequence and hydrophobic C termini of peptide are revealed to contribute essentially to the two-step assembly. The present study demonstrates both a meaningful preparation for bioinorganic materials and a strategy using POMs to modulate the assembly of peptides and even proteins, which could be extended to other proteins and/or viruses by using peptides and POMs with similar properties.
Co-reporter:Teng Zhang
The Journal of Physical Chemistry C 2015 Volume 119(Issue 15) pp:8321-8328
Publication Date(Web):March 26, 2015
DOI:10.1021/acs.jpcc.5b00032
Through a self-assembly of arginine/lysine-rich peptide from human papillomavirus (HPV) capsid protein and an Eu-containing polyoxometalate (POM), Na9[EuW10O36]·32H2O (EuW10), the formation of well-defined hybrid nanospheres in aqueous solution is presented, showing large luminescence enhancement of POM and use as a potential “turn-on” fluorescence probe in biology. The binding mechanisms between them have been explored at the molecular level by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), fluorescence spectra, isothermal titration calorimetry (ITC), ζ-potential, and nuclear magnetic resonance (1H NMR) titration spectra. ITC study confirmed the assembly was completely enthalpy driven, and ζ-potential proved that the driving force was governed mainly by the electrostatic interaction. 1H NMR spectroscopy indicated changes in hydrogen bond of EuW10 and the peptide segment, and the binding model was clarified. Our design constructed the self-assembly fabrication of well-defined nanoparticles by using inorganic POM and bioapplicable peptide combined with strong fluorescence characterization together. The enhanced luminescence and specific targeted-HPV peptide ability would be important and useful in the detection of HPV capsid protein and/or HPV genotypes, and such a protocol could be extended to another virus once using the corresponding peptides. Therefore, the present report will be helpful to promote the development of antivirus agents in the future.
Co-reporter:Dong-Dong Zheng, Ding-Yi Fu, Yuqing Wu, Yu-Long Sun, Li-Li Tan, Ting Zhou, Shi-Qi Ma, Xiao Zha and Ying-Wei Yang
Chemical Communications 2014 vol. 50(Issue 24) pp:3201-3203
Publication Date(Web):29 Jan 2014
DOI:10.1039/C3CC49789E
Pillarenes and calixarenes showed obvious inhibition of HPV16 L1 pentamer formation via their selective binding to Arg and Lys residues at the monomer interface, which was reversible after the release of cyclic arenes. Pillarenes are more effective than calixarenes in terms of the inhibition efficiency, attributing to the different kinetics and binding affinity.
Co-reporter:Lili Lian, Xueling Cao, Yuqing Wu, Dazhi Sun, Dawei Lou
Applied Surface Science 2014 Volume 289() pp:245-251
Publication Date(Web):15 January 2014
DOI:10.1016/j.apsusc.2013.10.144
Highlights
- •
Magnetic bentonite was prepared by hydrothermal synthesis.
- •
Fe3O4@Al-B had advantages both in adsorption and separation.
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Adsorption capacity evaluated by using Langmuir model was 161.29 mg/g.
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Fe3O4@Al-B was also developed to remove MC-LR from river water sample.
Co-reporter:Yuan Yue, Hong-Wei Li, Tian-Ying Liu, Yuqing Wu
Vibrational Spectroscopy 2014 Volume 74() pp:137-141
Publication Date(Web):September 2014
DOI:10.1016/j.vibspec.2014.04.005
Previously, we have explored the mechanism of the response of BSA-protected small gold nanoclusters (Au16NCs@BSA) to silver (I) ions (Ag+) by using XPS, but the role of the ligand BSA in this response was not clear. Therefore, we used FT-IR and circular dichroism (CD) spectra to monitor the changes of the secondary structure of ligand BSA. After adding Ag+ to the AuNCs@BSA, compare with the native BSA, the ligand-BSA showed little differences in the position of main peaks but more differences in the profile of this peak in FT-IR spectra. While in CD spectra it is not only peak shape changed but also peak position. All the results showed silver ions can bind to ligand BSA, and induced their secondary structure changes. But the changes of ligand BSA are not enough to influence the fluorescence emission of AuNCs@BSA, especially for the emission of AuNCs. And BSA-protected different size gold nanoclusters have the similar changes in spatial structure of ligand BSA, but only the Au16NCs@BSA could response to Ag+, which indicated that the ligand BSA was not the key role for the special fluorescent response.
Co-reporter:Liping Zhang, Min Zhang, Yuqing Wu
Journal of Molecular Structure 2014 1069() pp: 245-250
Publication Date(Web):8 July 2014
DOI:10.1016/j.molstruc.2014.02.060
In the present study, we apply fluorescence spectroscopy and Fourier transform infrared (FT IR) spectroscopy to investigate the temperature-induced optical property and conformational changes of BSA-protected gold nanoclusters (AuNCs@BSA). By the plot of single-band-shift, combined with VV-2D correlation analysis including hetero-spectral correlation and moving window correlation, the dynamics changes of the ligand BSA induced by temperature have been investigated in detail and compared with that induced by the perturbation of pressure. The study may be helpful to stimulate more experimental and theoretical research on the atomic level design of luminescent metal nanoclusters for promising optoelectronic and other applications.
Co-reporter:Dr. Hong-Wei Li;Dr. Yizhan Wang;Teng Zhang;Dr. Yuqing Wu;Dr. Lixin Wu
ChemPlusChem 2014 Volume 79( Issue 8) pp:1208-1213
Publication Date(Web):
DOI:10.1002/cplu.201402091
Abstract
A europium-substituted polyoxometalate (K13[Eu(SiW10MoO39)2]⋅28 H2O, EuSiWMo) can selectively bind to basic amino acids, namely, lysine, arginine, and histidine, and induce the emission enhancement of Eu3+ significantly. The mechanism is attributed to electrostatic interactions and hydrogen bonds between basic residues of the amino acids and negative charges of EuSiWMo based on the 1H NMR titration spectra of amino acids and time-resolved fluorescence decay curves of EuSiWMo.
Co-reporter:Dong-Dong Zheng, Dong Pan, Xiao Zha, Yuqing Wu, Chunlai Jiang and Xianghui Yu
Chemical Communications 2013 vol. 49(Issue 76) pp:8546-8548
Publication Date(Web):24 Jul 2013
DOI:10.1039/C3CC44986F
The recombinant GST fusion protein HPV 16 L1 from E. coli was proved to exist as a monomer rather than a pentamer, providing the possibility of real-time monitoring of the pentamer formation in vitro. Time-dependent kinetic studies of the process were performed for the first time by using static light scattering and western blot analysis, where the essential factors were revealed, offering a new biotechnical approach for virus control and/or the development of anti-viral agents.
Co-reporter:Xing-Feng Ren, Hong-Wei Li, Xuexun Fang, Yuqing Wu, Lincong Wang and Shuxue Zou
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 7) pp:1143-1148
Publication Date(Web):12 Dec 2012
DOI:10.1039/C2OB26624E
We have developed a series of azadipeptide nitriles with different P3 groups. A triaryl meta-phenyl derivative, compound 13, was not only a potent inhibitor for cathepsin K (Ki = 0.0031 nM), but also highly selective over both cathepsins B and S (∼1000-fold). A protein–ligand docking study performed on the series provided a possible explanation why compound 13 could be significantly more potent than the others, especially compound 12 in the same series.
Co-reporter:Xiao-Yu Yuan, Ding-Yi Fu, Xing-Feng Ren, Xuexun Fang, Lincong Wang, Shuxue Zou and Yuqing Wu
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 35) pp:5847-5852
Publication Date(Web):16 Jul 2013
DOI:10.1039/C3OB41165F
As a new type of cathepsin K inhibitor, azadipeptide nitriles have the characteristics of proteolytic stability and excellent inhibitory activity, but they exhibit barely any satisfactory selectivity. Great efforts have focused on improving their selectivity toward cathepsin K. In this sequential study, we report the further structural optimization, synthesis, molecular modeling, and in vitro enzymatic assays of a new series of potent and selective inhibitors of cathepsin K without the P2–P3 amide linker. Significant selective improvements were achieved for cathepsin K over L, S and B, and a triaryl meta-product 13′ possessed the favorable balance between potency (Ki = 0.29 nM) and selectivity of cathepsin K over cathepsin L (320-fold), S (1784-fold) and B (8566-fold). We undertook a covalent protein–ligand docking study to explain the improved selectivity of several representative compounds. Such a selectivity improvement would be useful to avoid harmful side effects in practical applications of these compounds.
Co-reporter:Xue-Ling Cao, Hong-Wei Li, Yuan Yue, Yuqing Wu
Vibrational Spectroscopy 2013 Volume 65() pp:186-192
Publication Date(Web):March 2013
DOI:10.1016/j.vibspec.2013.01.004
We investigated the pH-induced fluorescence changes of BSA-protected gold nanoclusters, Au16NCs@BSA, and the corresponding conformational changes of ligand protein by fluorescence, circular dichrosim (CD) and IR spectral measurements. The studies presented here demonstrated that BSA in AuNCs@BSA underwent identifiable conformational changes on both the secondary and the tertiary structure levels. The results of CD and IR interpreted the significant change of second structures at extreme acidity and alkaline, where more unordered structures were gained. Of note was that the extreme alkaline (pH = 11.43) induced the changes from exposed to buried α-helices, which was different from the pH-induced structural changes of BSA. In addition, the large fluorescence intensity gap of tryptophan between AuNCs@BSA and native BSA indicated efficient energy transfer took place between BSA and AuNCs, implying that the gold core resided near tryptophan in BSA.
Co-reporter:Hong-Wei Li, Yuan Yue, Tian-Ying Liu, Dongmei Li, and Yuqing Wu
The Journal of Physical Chemistry C 2013 Volume 117(Issue 31) pp:16159-16165
Publication Date(Web):July 10, 2013
DOI:10.1021/jp403466b
We report the clarification of responsive mechanism of the BSA-protected small gold nanoclusters (Au16NCs@BSA) to silver(I) ions (Ag+). The titration of Au16NCs@BSA solutions with Ag+ produces a blue-shift and enhancement of the fluorescence spectra, but no similar effects can be observed for other metal ions. Meanwhile, an isosbestic point in UV–vis absorbance spectra of Au16NCs@BSA induced by Ag+ is observed, which indicates a stoichiometric conversion of one substance to another. Through X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and MALDI-TOF mass spectrum measurements, the reduction of Ag+ to Ag0 by Au16NCs@BSA have been ascertained, where the Au16NCs act as reductant toward Ag+ in forming hybrid Au@AgNCs adducts. The mechanism revealed provided a facile and mild method to build high luminescent alloy nanoclusters.
Co-reporter:Min Zhang, Yong-Qiang Dang, Tian-Ying Liu, Hong-Wei Li, Yuqing Wu, Qian Li, Kai Wang, and Bo Zou
The Journal of Physical Chemistry C 2013 Volume 117(Issue 1) pp:639-647
Publication Date(Web):December 17, 2012
DOI:10.1021/jp309175k
We investigated the pressure-induced fluorescence enhancement of BSA-protected gold nanoclusters, AuNCs@BSA, and the corresponding conformational changes of ligand protein by in situ fluorescence and IR spectral measurements. It is documented that the fluorescence enhancement of AuNCs@BSA is essentially attributed to the conformational changes of the ligand, which undergoes substantial secondary and tertiary structural changes. Under compression BSA loses more buried α-helical structure, while it changes oppositely in the AuNCs@BSA as the protein adopts a more flexible conformational state at the boundary surface of gold nanoclusters. The present work will be helpful to understand the fundamental mechanism and to reveal the important factors of ligands in nanoclusters, which are hope to improve the luminescence efficiency of gold nanoclusters in final.
Co-reporter:Yong-Qiang Dang, Hong-Wei Li, and Yuqing Wu
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 3) pp:1267
Publication Date(Web):February 22, 2012
DOI:10.1021/am3000984
Due to possessing unique optical properties, semiconductor quantum dots (QDs) have been applied to construct bioconjugates. Using QDs as donors, the Förster resonance energy transfer (FRET) system can be developed and applied to biological imaging and sensing, and various construction strategies have been reported. To provide a new practicable method, we introduce a protocol with two routes to construct a supramolecular FRET system based on the high-affinity interaction between melittin and phosphocholine. Melittin exists with a random coil structure in aqueous environments but will adopt a bent helix when inserted into natural or artificial membranes. Such specific and high affinity protein–membrane interaction makes it possible to construct a QDs-based FRET system. The strategy applying protein–membrane interaction to construct a QDs-based FRET system can be applied to the investigation on the protein–membrane interaction through distance-depended FRET and further proteolysis of trypsin. Because of the existence of various protein–membrane interactions in real life, the system has the potential to be expanded to other related systems.Keywords: Förster resonance energy transfer; melittin; phosphocholine; protease; protein−membrane interaction; quantum dots; trypsin;
Co-reporter:Li-Jun Ma, Yuhua Yan, Liping Chen, Weiguang Cao, Hongwei Li, Liting Yang, Yuqing Wu
Analytica Chimica Acta 2012 Volume 751() pp:135-139
Publication Date(Web):2 November 2012
DOI:10.1016/j.aca.2012.09.003
A new fluorescence reagent, N,N-bi[4(1-pyrene)-butyroyl]-lysine (1) was synthesized. The new fluorescence sensor showed high sensitivity (detection limit up to 20.7 μg L−1) and specific selectivity for Pb2+ over other metal ions examined in aqueous solutions. It could also be used to remove Pb2+ from aqueous solutions by filtering the insoluble 1–Pb2+ complex with sufficient reversibility.Graphical abstractA new fluorescence reagent, N,N-bi[4(1-pyrene)-butyroyl]-lysine (1) was synthesized. The new fluorescence sensor showed high sensitivity (detection limit up to 20.7 μg L−1) and specific selectivity for Pb2+ over other metal ions examined in aqueous solutions. It could also be used to remove Pb2+ from aqueous solutions by filtering the insoluble 1–Pb2+ complex with sufficient reversibility.Highlights► A new fluorescence reagent (1) for Pb2+ was synthesized. ► The fluorescence sensor shows a low detection limit (20.7 μg L−1) for Pb2+. ► The sensor exhibits a specific selectivity for Pb2+ in aqueous solution. ► The reagent can remove Pb2+ with a good reversibility from aqueous solution.
Co-reporter:Yong-Qiang Dang, Qian Li, Kai Wang, Yuqing Wu, Lili Lian, and Bo Zou
The Journal of Physical Chemistry B 2012 Volume 116(Issue 36) pp:11010-11016
Publication Date(Web):August 23, 2012
DOI:10.1021/jp306466j
FRET has been used as a powerful tool in biological fields as biosensors, bioimaging, protein folding/unfolding monitoring, biomolecular interactions, and so on. It is also important to applying FRET to high hydrostatic pressure studies on biosystems or biorelated systems. Herein, we construct a FRET system by labeling Cy3 on C-phycocyanin (C-PC) to investigate the effect of hydrostatic pressure on the fluorescence and FRET behavior between them. The fluorescence spectra of individual Cy3, C-PC, and integrated Cy3/C-PC system are measured separately under compression. An enhanced FRET efficiency under compression is concluded based on fluorescence behavior differences between them. To further reveal the origination of the enhanced FRET efficiency with pressure, the overlap integral between Cy3 emission and C-PC absorption is also calculated, and several possible explanations are proposed.
Co-reporter:Jian Sun, Ji-Sheng Yu, Zhiwu Yu, Xiao Zha, Yuqing Wu
The Journal of Chemical Thermodynamics 2012 Volume 47() pp:130-137
Publication Date(Web):April 2012
DOI:10.1016/j.jct.2011.10.003
The high-risk types of human papillomaviruses (HPV) HPV-16 and -18 are the predominant types associated with cervical cancer. HPV-16 and -18 account for about 50% and 20%, respectively, of cervical cancers worldwide. While the reason and molecular mechanism of the distinct prevalence and distributions between them remain poorly understood, the binding affinity of cell surface receptor with capsid proteins, especially L1, may be involved. We examined heparin binding with two synthetic peptides corresponding to the 14 amino acid C-terminal peptides of HPV-16 and -18 L1 with the goal of comparing the equivalent residues in different HPV types. Using isothermal titration calorimetry (ITC) and static right-angle light scattering (SLS), we determined the binding constant K, reaction enthalpy ΔH, and other thermodynamic parameters in the interaction. Especially, we assessed the role of specific residues in binding with heparin by comparing the NMR spectra of free and heparin-bound peptides.Graphial abstractThe differences in heparin binding for the C-terminal basic-sequence-rich peptides of HPV-16 and HPV-18 capsid protein L1.Highlights► Several driving forces contribute to the interaction between heparin and peptides. ► C-terminal of HPV L1 is a potential candidate for the attachment to host cells. ► The C-terminal peptides of HPV-16 and -18 L1 have different heparin-binding. ► The different heparin-binding provides an explanation for the distinct prevalences.
Co-reporter:Yingyi Ma;Jing Liang;Dr. Hang Sun; Lixin Wu;Yongqiang Dang; Yuqing Wu
Chemistry - A European Journal 2012 Volume 18( Issue 2) pp:526-531
Publication Date(Web):
DOI:10.1002/chem.201102337
Abstract
Here we report the rapid and convenient patterning of proteins on porous polymer film using the inverse microemulsion approach. Following this method, proteins, which were dissolved in water, were transferred into dichloromethane solution of polymers through the formation of inverse microemulsion by mixing the two solutions. The protein-containing microemulsion droplets accumulated automatically into large and stable ones on the surface of organic solution casting on solid substrates, and formed tightly packed microemulsion droplet arrays driven by surface tension. With the evaporation of organic solvent and water, the microemulsion droplet arrays, which act as the template, turn to honeycomb patterned pores bearing proteins in them. The formed protein patterns can be locally applied for the detection of other proteins through specific recognition. The generality and reproducibility for the formation of BSA/PS microporous film and protein patterning by using different polymers and solvents were demonstrated by investigating surfactant addition, polymer and solvent types, and casting volume on the morphology of the microporous films. A preliminary mechanism for the protein patterning is discussed based on the analysis of the experimental results.
Co-reporter:Hong-Wei Li, Kelong Ai and Yuqing Wu
Chemical Communications 2011 vol. 47(Issue 35) pp:9852-9854
Publication Date(Web):21 Jul 2011
DOI:10.1039/C1CC12588E
An efficient, rapid, and fluorescence visual method for column separation of BSA-protected gold-nanoclusters was proposed based on the dansylation of BSA. After optimization, this procedure can be extended to the separation of any other macromolecule-protected noble metal bioconjugates.
Co-reporter:Bin Wang, Yang Gao, Hong-Wei Li, Zhi-Peng Hu and Yuqing Wu
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 11) pp:4032-4034
Publication Date(Web):12 Apr 2011
DOI:10.1039/C1OB05372H
A new probe/Cu2+ complex for the detection of his-tagged protein has been developed, based on an improved probe, Dansyl-Gly-Py (1), by closely mimicing the structure of a peptide, ATCUN. In aqueous solution, 1/Cu2+ has good selectivity to histidine and cysteine, and further can detect histidine-rich protein by releasing the quenched fluorescence of 1.
Co-reporter:Min Zhang, Liping Zhang, Yuqing Wu
Vibrational Spectroscopy 2011 Volume 57(Issue 2) pp:319-325
Publication Date(Web):November 2011
DOI:10.1016/j.vibspec.2011.09.007
Poly-l-lysine can form either of three different conformers as α-helix, anti-parallel β-sheet and random coil stably under appropriate conditions. In buffer solution poly-l-lysine exists in a random coil at about pH 4, an α-helix above pH 12, and transforms from α-helix to β-sheet when the sample is heated to 46 °C for 30 min. The effects of elevated hydrostatic pressure on three different initial conformers of poly-l-lysine are investigated with Fourier transform infrared spectroscopy and two-dimensional correlation analysis. Changes observed in the amide I′ band indicate that the α-helix conformer undergo hydration enhancement at low pressure (<400 MPa), then gradually transition into an α′-helix. Two initial conformers, the β-sheet and random coiled polypeptide, undergo conformational changes to an α-helix at low pressure and to an α′-helix at high pressure. Moreover, the conversion occurred at a lower pressure for the β-sheet (∼250 MPa) than for the α-helix (∼300 MPa) and the random coil (∼850 MPa).
Co-reporter:Bin Wang;Hong-Wei Li;Yang Gao;Houyu Zhang
Journal of Fluorescence 2011 Volume 21( Issue 5) pp:1921-1931
Publication Date(Web):2011 September
DOI:10.1007/s10895-011-0891-6
We synthesized a tetra-functional fluorescence probe based on dansyl and peptide motif, dansyl-Gly-Trp (DGT, 1), that efficiently bound several metal ions and showed distinguishing optical properties. The probe 1 could respond to Hg2+ with enhanced and blue-shifted fluorescence emission but to Cu2+ with obvious fluorescence quenching. In addition, 1 was sensitive to pH ranging from 2.0 to 5.0 and precipitated in the presence of Pb2+ at neutral conditions. The combination of these intrinsic properties with the selective responses to different chemical inputs allows this system to be implemented as an ionic switch. Furthermore, 1 could penetrate the cell membrane and accumulated well in intracellular region. The underlying mechanisms of the probe to different kind of metal ion were explored successfully by using either 1H NMR, NOESY, electron paramagnetic resonance (EPR) or FT-IR spectra. In addition, to investigate the binding model of 1/Hg2+ and 1/Cu2+, simulations were also performed by using density functional theory (DFT) and reasonable binding configurations were achieved for these two complexes.
Co-reporter:Yang Gao, Min Zhang, Huafei Zhang, Xianghui Yu, Wei Kong, Xiao Zha, and Yuqing Wu
The Journal of Physical Chemistry B 2011 Volume 115(Issue 21) pp:7038-7044
Publication Date(Web):May 4, 2011
DOI:10.1021/jp200060q
Survivin exists as a homodimeric conformation to act as a suppressor of apoptosis in organisms. Previously, we found that the deletants with truncations of N-terminal residues up to Arg18 lost the binding ability to Smac/DIABLO but not the binding force of homodimers. In order to establish the relationship between function and structural stability, thermal unfolding of SurF and its deletants in buffer have been studied in the present paper. The fluorescent results indicated that with the removal of the N-terminus, the thermal stability of the tertiary structure dropped vigorously, especially for SurΔN18. However, using circular dichroism (CD) spectroscopy, we observed that the main unfolding of the secondary structures was not affected very much with N-terminus deletion. Fourier transform infrared (FT-IR) spectroscopy and two-dimensional (2D) correlation analysis were further used to provide structural information that occurred in the main transitions, which were associated with conformational changes of several β-components and α-helix, followed by the gain of some aggregations and random coils at high temperature. In addition, more aggregates were found to form for the longer N-terminal deletants during the main unfolding.
Co-reporter:Yue Li, Hong-Wei Li, Li-Jun Ma, Yong-Qiang Dang and Yuqing Wu
Chemical Communications 2010 vol. 46(Issue 21) pp:3768-3770
Publication Date(Web):22 Apr 2010
DOI:10.1039/B925401C
We report a unique protein labeling system based on melittin and a pyrene derivative (1). The specific region of the C-terminal in melittin efficiently induced the formation of the pyrene eximer, which can be used as a tag to target proteins and for further detection.
Co-reporter:Lina Li, René Buchet, Yuqing Wu
Journal of Inorganic Biochemistry 2010 Volume 104(Issue 4) pp:446-454
Publication Date(Web):April 2010
DOI:10.1016/j.jinorgbio.2009.12.018
The effects of sinomenine (SIN, an alkaloid extracted from the Chinese medicinal plant Sinomenium acutum used for centuries to treat rheumatic disease, including rheumatoid arthritis) on apatitic nucleation and matrix vesicle (MV)-induced mineral formation were compared with those of cysteine, levamisole, and theophylline. We found that SIN was not an inhibitor of tissue non-specific alkaline phosphatase (TNAP), a marker of biological mineralization, but confirmed that cysteine, levamisole, and theophylline were. Further, none of these four molecules directly affected the nucleation of hydroxyapatite (HA) formation, in contrast to pyrophosphate (PPi) which did. Incubation of 0.25–1.0 mM cysteine, theophylline, or levamisole with MVs in synthetic cartilage lymph (SCL) containing AMP and Ca2+, but not inorganic phosphate (Pi), prolonged the induction time of mineral formation, apparently by inhibiting TNAP activity. SIN at the same levels neither inhibited TNAP activity nor affected the induction time of MV mineral formation. However, SIN did markedly delay MV-induced mineral formation in SCL containing Pi (instead of AMP) in a manner similar to theophylline, but to a lesser extent than levamisole. Cysteine did not delay, in fact it slightly accelerated MV-induced mineral formation in Pi-containing SCL. These findings suggest that levamisole, SIN and theophylline may directly affect Ca2+ and/or Pi accretion during mineral formation; however, TNAP was not directly involved. The possible roles of annexins and other ion transporters, such as proteins of the solute carrier family implicated in Ca2+ and Pi influx are discussed.The effects of sinomenine (SIN, an alkaloid extracted from the Chinese medicinal plant Sinomenium acutum used for centuries to treat rheumatic disease, including rheumatoid arthritis) on apatitic nucleation and matrix vesicle (MV)-induced mineral formation were studied and compared with those of cysteine, levamisole and theophylline. The possible roles of annexins and other ion transporters, such as proteins of the solute carrier family implicated in Ca2+ and Pi influx are discussed.
Co-reporter:Lei Li, Yong-Qiang Dang, Hong-Wei Li, Bin Wang, Yuqing Wu
Tetrahedron Letters 2010 Volume 51(Issue 4) pp:618-621
Publication Date(Web):27 January 2010
DOI:10.1016/j.tetlet.2009.11.070
A chemosensor 1, based on the Schiff base, is easily prepared by reacting tryptophan and 2-hydroxy-1-naphthaldehyde in methanol. The optical properties of 1 are investigated in buffered aqueous solution, which displays specific recognition to Zn2+, and especially avoids the interference of Cd2+ when 1 is tested against a range of physiological and environmentally relevant metal ions. Such a novel fluorescent probe can also be used to detect Zn2+ in live cells.Chemosensor 1 shows specific selectivity to Zn2+ from other metal ions, especially Cd2+, with an enhanced fluorescence emission in aqueous solution.
Co-reporter:Li Ping Zhang, Isao Noda, Yuqing Wu
Journal of Molecular Structure 2010 Volume 974(1–3) pp:80-87
Publication Date(Web):16 June 2010
DOI:10.1016/j.molstruc.2009.11.045
We have demonstrated an application of “concatenated” 2D correlation analysis in quantitative or semi-quantitative examination of the reversibility of the temperature-induced hydration variation of PNiPMA in water solution. Hydration reversibility of hydrophilic amide group and hydrophobic CH group are compared in different temperature ranges. The appearance of significant cross-peaks in the asynchronous spectrum calculated from the roundtrip data matrix indicates the existence of certain inter-asynchronicity between heating and cooling cycle. The contribution of different factors to the 2D asynchronous spectrum could be separated by selecting the range of the spectral dataset for concatenation. The irreversibility of the temperature-induced hydration variation in PNiPMA is not constant during the whole round trip: it is most obvious in the phase separation process, while in the range far away from that period it is nearly neglectable. The hydration variation of PNiPMA manifests significant irreversibility in the phase separation stage. The asynchronous peaks of hydrophobic CH groups are much weaker than that of hydrophilic amide group during any temperature range in the temperature round trip. The irreversibility of CH groups is not as strong as that of amide group during the round trip. It further supports the conclusion that the hydration variation of hydrophilic amide group is dominated in the temperature-induced phase separation of the polymer in water solution.
Co-reporter:Jian Sun, Ji-Sheng Yu, Shi Jin, Xiao Zha, Yuqing Wu and Zhiwu Yu
The Journal of Physical Chemistry B 2010 Volume 114(Issue 30) pp:9854-9861
Publication Date(Web):July 15, 2010
DOI:10.1021/jp1009719
Capsid proteins binding cell surface proteoglycans is a key early event in human papillomavirus (HPV) infection. The positively charged sequences at the C-terminus of the L1 protein and the N- and C-termini of the L2 protein of HPV-16 can efficiently bind to heparin receptors, which were characterized in the present study by quantitative isothermal titration calorimetry experiments primarily, fluorescence spectroscopy, and static right-angle light scattering. The binding constant, K, was at an order of magnitude of 107 M−1 for the two peptides at the N- and C-termini of HPV-16 L2 and segment b at the C-terminus of HPV-16 L1, while that for other L1 analogues were of a smaller order, illustrating that the heparin binding is a typical sequence-specific and -dependent phenomenon. These results suggest that, in addition to L1, the L2 protein may participate in cell surface attachment during HPV infection. Furthermore, the calorimetry results demonstrated that hydrophobic interactions and hydrogen bonding are involved in peptide binding to heparin in addition to the essential electrostatic interactions. Meanwhile, circular dichroism spectroscopy revealed that binding to heparin does not induce obvious secondary structural changes in the peptides.
Co-reporter:Hong-Wei Li, Bin Wang, Yong-Qiang Dang, Lei Li, Yuqing Wu
Sensors and Actuators B: Chemical 2010 Volume 148(Issue 1) pp:49-53
Publication Date(Web):30 June 2010
DOI:10.1016/j.snb.2010.03.060
Co-reporter:Yang Gao, Huafei Zhang, Min Zhang, Haihong Zhang, Xianghui Yu, Wei Kong, Xiao Zha, and Yuqing Wu
The Journal of Physical Chemistry B 2010 Volume 114(Issue 47) pp:15656-15662
Publication Date(Web):November 9, 2010
DOI:10.1021/jp1036603
Survivin, as an apoptosis suppressor, exists as a homodimer interfacing at the N-terminal portion (residues 6−13) of its baculovirus IAP repeat (BIR) domain and a linker segment (residues 89−102). Here we expressed full-length human Survivin (SurF) and a series of its mutants, SurΔN7, SurΔN13, and SurΔN18 with significant truncations of the N-terminus, all of which could still dimerize in solution. Single-molecule force spectroscopy (SMFS) was used to quantitate the unbinding forces of full-length and the mutant homodimers and revealed that the N-terminal residues up to Arg18 were not essential for dimerization. Meanwhile, the binding of SurΔN7 to Smac/DIABLO determined by ELISA was as efficient as the wild-type, but that of SurΔN13 was significantly reduced, and that of SurΔN18 was completely lost. Together, these findings provide direct evidence that the N-terminal sequence of Survivin is not critical for dimer formation but may contribute to correct folding and function of BIR.
Co-reporter:Hong-Wei Li, Yue Li, Yong-Qiang Dang, Li-Jun Ma, Yuqing Wu, Guangfeng Hou and Lixin Wu
Chemical Communications 2009 (Issue 29) pp:4453-4455
Publication Date(Web):12 Jun 2009
DOI:10.1039/B907386H
A hypersensitive water-soluble fluorescent probe, dansyl-L-tryptophan methyl ester (1), was easily prepared for the detection of Hg2+ with a significantly improved detection limit (5 nM vs. 500 nM) in buffered aqueous solution.
Co-reporter:Yong-Qiang Dang, Hong-Wei Li, Bin Wang, Lei Li and Yuqing Wu
ACS Applied Materials & Interfaces 2009 Volume 1(Issue 7) pp:1533
Publication Date(Web):June 9, 2009
DOI:10.1021/am9001953
A simply prepared gold nanoparticle-based sensor, 5,5′-dithiobis (2-nitrobenzoic acid) (DTNBA)-modified gold nanoparticles, was prepared to explore the sensitive and selective detection of metal ions using a colorimetric technique. The selective detection of trace levels (93.6 ppb) Cr3+ in aqueous solution was achieved over 15 other metal ions. The functionalized gold nanoparticles became aggregated in solution in the presence of Cr3+ by an ion-templated chelation process, which caused an easily measurable change in the extinction spectrum of the particles and provided an inherently sensitive method for Cr3+ detection in aqueous solution.Keywords: chromium; colorimetric; DTNBA; gold nanoparticles; ion detection
Co-reporter:Lijun Ma, Yue Li, Lei Li, Yuqing Wu, Rene Buchet, Yihong Ding
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 72(Issue 2) pp:306-311
Publication Date(Web):March 2009
DOI:10.1016/j.saa.2008.09.014
The detection of lead ion is very important both in environment and in biological systems because of its toxicity. A fluoroionophore sensor, N-[4(1-pyrene)-butyroyl]-l-tryptophan (PLT), distinguishing Pb2+ from other 12 metal ions and exhibiting a very high sensitivity (0.15 μM) in aqueous solution, has been reported. The present study describes the spectroscopic clarification of the intrinsic differences of the binding model between PLT with Pb2+ and with other ions. The fluorescent property of solid metal carboxylates reflects a character of the metal complex in solution, which results in a facility to solve problems by using solid sample of complex and vibrational spectroscopy. Both FT-infrared and Raman spectroscopy are employed to clarify the binding model between lead ion and its high sensitive and selective fluoroionophore sensor PLT, and essentially to explain why the metal ions other than Pb2+ cannot response to PLT. The IR spectral data clearly show that a bridging bidentate coordination occurs when PLT is coordinated with Cu2+ and Zn2+; while a chelating bidentate coordination between the carboxyl anion and Pb2+ exists in PLT–Pb, which is a new information beyond the NMR results in previous report. Meanwhile, the present study also indicates a characteristic interaction of lead ion and indole ring as well as the hydrogen bonding between amide groups. Furthermore, the quantum chemical calculations at the DFT level confirm the spectral and structural information of PLT–Pb2+ proposed by experiments. Thus, the type of coordination, the interaction of the indole ring with the metal ion, and the hydrogen bonding between amide groups in PLT–Pb are likely responsible for the high selectivity of PLT to the lead(II) ion.
Co-reporter:Lijun Ma, Hongwei Li, Yuqing Wu
Sensors and Actuators B: Chemical 2009 Volume 143(Issue 1) pp:25-29
Publication Date(Web):4 December 2009
DOI:10.1016/j.snb.2009.09.010
We report herein a fluorescent sensor derived from 1-pyrene-butyric acid and bicarboxyl-containing glutamic acid. The chemosensor shows high sensitivity (detection limit up to 1.5 μM) and dual illustration of specific selectivity for lead ion (Pb2+) over Na+, Mg2+, K+, Ca2+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+ and Hg2+ in aqueous solution.
Co-reporter:Li-Jun Ma, Yue Li, Lei Li, Jian Sun, Chunjuan Tian and Yuqing Wu
Chemical Communications 2008 (Issue 47) pp:6345-6347
Publication Date(Web):30 Oct 2008
DOI:10.1039/B815281K
A fluorescent sensor, dansyl-L-aspartic acid (1), coupled with BSA was used to specifically detect Hg2+ in a neutral aqueous solution as well as in live cells; the fluorescence emission spectrum underwent an obvious blue shift with an enhancement in fluorescence intensity, and these effects were evident as color changes in fluorescence imaging pictures.
Co-reporter:Yuqing Wu, Isao Noda
Journal of Molecular Structure 2008 Volumes 883–884() pp:149-154
Publication Date(Web):30 July 2008
DOI:10.1016/j.molstruc.2007.11.039
The basic idea of orthogonal signal correction (OSC) is to remove a certain portion of the systematic variations of data not directly affected by the pertinent controlling variables. We have explored the combination of such OSC filtering and two-dimensional (2D) correlation analysis together to improve the quality of 2D correlation spectra. In particular, we proposed the quadrature OSC (QOSC) filtering method to deal with the problem of losing the portion of information, which is perpendicular to the external controlling variable but being quite significant to the 2D asynchronous correlation analysis. The present study will describe the concept of either PCA- or PLS-based QOSC 2D analysis, and their application to a simulated spectral dataset with one strong contaminating peak on temperature-dependent IR spectra of poly(N-isopropylacrylamide) (PNiPa). The comparison of the different QOSC techniques, e.g., directly external variable based, PCA-based, and PLS-based QOSC, on the new spectral dataset is also performed.
Co-reporter:Li-Xu Wang, Filip Meersman, Yuqing Wu
Journal of Molecular Structure 2008 Volumes 883–884() pp:79-84
Publication Date(Web):30 July 2008
DOI:10.1016/j.molstruc.2007.11.053
The analysis of protein unfolding pathways and the identification of specific conformational changes under perturbation are of fundamental importance for protein folding. In this study, thermally induced early unfolding events of bovine pancreatic ribonuclease A (RNase A) in the presence of 2-mercaptoethanol are evidenced successfully by principal component analysis and two-dimensional correlation infrared spectroscopy. The analyses of secondary structural changes in different stages have clearly distinguished the early events from the main unfolding in the temperature course of RNase A. It is revealed that in the early stage of the thermal unfolding subtle structural changes of the more temperature-sensitive β-sheet in RNase A dominates this process; while the main unfolding of RNase A is initiated with the structural changes of the more temperature-sensitive β-sheet, random coils and β-turns, followed by the less temperature-sensitive β-sheet component and the formation of a β-sheet-rich aggregate. The quantitative analysis of the power spectra reveals that the intensity variations from early stages are almost same in the scale, and each accounts for less than 1% that of the main unfolding. These findings demonstrate that the utilization of 2D IR spectrum and its power spectrum is powerful in exploring the minor early events and closely related structural changes of protein.
Co-reporter:Li-Jun Ma, Yi-Fu Liu and Yuqing Wu
Chemical Communications 2006 (Issue 25) pp:2702-2704
Publication Date(Web):23 May 2006
DOI:10.1039/B604623A
We report herein a fluoroionophore sensor derivated from tryptophan that shows high sensitivity (detection limit up to 0.15 µM) and specific selectivity for lead ion (Pb2+) over Ca2+, Cd2+, Co2+, Cr3+, Cu2+, K+, Mg2+, Na+, Fe2+, Mn2+, Ni2+ and Zn2+ in aqueous solution.
Co-reporter:Yuqing Wu, Isao Noda, Filip Meersman, Yukihiro Ozaki
Journal of Molecular Structure 2006 Volume 799(1–3) pp:121-127
Publication Date(Web):6 November 2006
DOI:10.1016/j.molstruc.2006.03.030
Orthogonal signal correction (OSC) is a chemometrical data processing technique used for removing the information unrelated to the target variables based on the constrained principal component analysis (PCA). The combined use of OSC filtering and two-dimensional (2D) correlation analysis, which is called orthogonal signal corrected 2D (OSC 2D) correlation spectroscopy, is proposed in the present study to enable one to develop high quality of 2D correlation spectra by eliminating any information unrelated to the external variables. A set of temperature-dependent infrared spectra of poly(N-isopropylacrylamide) (PNiPa) in aqueous solutions, as well as the simulated spectra developed by adding different random noise spectra or a systematic noise spectrum of contaminating water after multiplied with a random weight factor to the experimental spectra, were used as examples. The results provided by OSC 2D were compared to those obtained by 2D without OSC filtering, and OSC 2D spectrum has demonstrated its substantial power in eliminating signals that are unrelated to the external variable and the great improvement in the synchronous spectrum.
Co-reporter:Yuqing Wu, Filip Meersman, Karel Heremans, Yukihiro Ozaki
Journal of Molecular Structure 2006 Volume 799(1–3) pp:134-140
Publication Date(Web):6 November 2006
DOI:10.1016/j.molstruc.2006.03.048
The changes in hydration of poly(N-isopropylacrylamide) in aqueous solution have been monitored by FTIR spectroscopy as a function of temperature and pressure. Heating the sample above the LCST induces a phase separation that reflects a dehydration of the polymer chain on the molecular level, whereas above the LCSP the phase separation is associated with increased chain hydration. Using these data, we demonstrate the principle of hybrid 2D correlation analysis for the case of two independent data sets obtained under two different physical perturbations. For comparison we also have examined the individual processes by sample–sample (SS) two-dimensional (2D) correlation spectroscopy (COS). SS hybrid 2D correlation analysis enables one to explore the correlation between the concentration dynamics of PNiPA species induced by pressure and temperature, whereas homo SS 2D COS investigates the concentration dynamics of the PNiPA species induced by either one of these physical perturbations. The synchronous SS hybrid-2D correlation spectrum shows a strong negative correlation in the high pressure–temperature region, indicating the pressure- and temperature-induced species are different. Variable–variable (VV) hybrid-2D spectrum is applied to obtain information pertaining to the correlation of conformational variations of PNiPA during the transitions. A critical examination of the method and its applicability is given.
Co-reporter:Li-Xu Wang, Yuqing Wu, Filip Meersman
Journal of Molecular Structure 2006 Volume 799(1–3) pp:85-90
Publication Date(Web):6 November 2006
DOI:10.1016/j.molstruc.2006.03.031
Thermal unfolding of ribonuclease A (RNase A) in deuterated Tris buffer is studied by Fourier transform infrared (FT-IR) spectroscopy. Two kinds of two-dimensional (2D) correlation spectroscopy, variable–variable (VV) 2D and sample–sample (SS) 2D spectroscopy, have been employed to analyze the observed thermally induced spectral variations of RNase A. Using SS 2D spectroscopy one can observe a pretransition at 45 °C prior to the main transition at 66 °C. This pretransition cannot be detected by a single-frequency analysis or the SS 2D correlation analysis of the original infrared spectra of RNase A. The VV 2D correlation spectroscopy study provides information about the structural changes that occur during these transitions: in the pretransition, the observed structural variations are associated with local conformational changes of an α-helical segment and the modification of a certain amount of β-sheet structure; in the main unfolding, changes in irregular and α-helical structures are followed by those in the β-sheet structure, including the antiparallel β-sheet components, resulting in the loss of secondary structure. This work demonstrates that 2D correlation spectroscopy can be used as an alternative to principal component analysis.
Co-reporter:Li-Xu Wang, Yuqing Wu, Filip Meersman
Vibrational Spectroscopy 2006 Volume 42(Issue 2) pp:201-205
Publication Date(Web):24 November 2006
DOI:10.1016/j.vibspec.2006.05.010
Thermal denaturation of ribonuclease A (RNase A) in D2O solution is studied by Fourier transform infrared (FT-IR) spectroscopy. Sample–sample two-dimensional correlation (SS 2D) spectroscopy and principal component analysis (PCA) are applied to these spectral data to reveal the thermal kinetics of RNase A. The second scores plot of PCA constructed from temperature-dependent original IR spectra illustrates a pretransition at 46 °C as well as a clear main transition at 66 °C. The latter is revealed by the SS 2D correlation spectra and the first score of PCA because of their illustration of the main denaturation event of RNase A, while the former cannot. Therefore, the present study demonstrates the great potential of PCA in revealing subtle phase transition of proteins in aqueous solutions.
Co-reporter:Hai-Hao Zhang, Yuqing Wu, Bing-Lian Bai, Min Li
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2006 Volume 63(Issue 1) pp:117-125
Publication Date(Web):January 2006
DOI:10.1016/j.saa.2005.04.052
Classification of hydrogen-bonding species in a series of novel hydrazide modified p-methoxyazobenzene derivatives, 4-{n-[4-(4-methoxy-phenylazo)-phenoxy]-alkoxy}-benzoic acid hydrazide (Dn, n = 3, 6, 10) are performed in the present study. Temperature-dependent infrared (IR) spectra of Dn have been measured to investigate the thermal stability of the weak intermolecular interactions, such as hydrogen bonding among hydrazide moieties, π–π stacking among aromatic groups, and hydrophobic interaction between alkyl chains. In order to reveal the hydrogen bonding formed between NH, NH2, and CONH groups efficiently, two-dimensional (2D) correlation spectra have been constructed in the thermal sensitive spectral regions of (a) 3500–3100 cm−1 and (b) 1700–1450 cm−1, separately, and it have also been constructed between these two spectral regions. Based on the experimental data, the ab initio computational models have been developed to the proposed patterns of hydrogen bonding related to intermolecular interactions in Dn. The intermolecular hydrogen bondings and molecular alignments patterns result from both the experimental data and the computational models are performed for D3, D6, and D10, respectively, in the present study.
Co-reporter:Ya-Qiong Hao, Yuqing Wu, Lixin Wu, Junqiu Liu, Guimin Luo
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2005 Volumes 257–258() pp:111-115
Publication Date(Web):5 May 2005
DOI:10.1016/j.colsurfa.2004.10.035
Surface-enhanced Raman scattering (SERS) spectroscopy has been used to explore the recognition mechanism between a selenium-containing glutathione peroxidase (GPX) mimic, 2,2′-diseleno-bis-β-cyclodextrin (2-SeCD) and two glutathione (GSH) alternatives, S-dinitrophenyl-glutathione (GSH-S-DNP) and 4,4′-bis(carboxymethyleneoxy)azobenzene (BCMAB). SERS spectra have been employed to investigate how these alternatives bind with β-CD and 2-SeCD. SERS signals of the spectra of GSH-S-DNP and BCMAB are much intense in comparison with those of theirs complexes, GSH-S-DNP/CDs and BCMAB/CDs in silver colloid solutions, which suggest that GSH-S-DNP and BCMAB are included into the CD cavity when they bind with β-CD or 2-SeCD. Weak Raman signals in the SERS spectra of the GSH-S-DNP/CDs in silver colloid solution make it difficult to investigate the recognition mechanism between CDs and GSH-S-DNP by using SERS efficiently. The bands at 1388 and 1379 cm−1 in the SERS spectra of BCMAB/CDs strongly suggest that BCMAB does not bind with β-CD or 2-SeCD via its COOH group.
Co-reporter:Lijun Ma, Hongwei Li, Yuqing Wu
Sensors and Actuators B: Chemical (4 December 2009) Volume 143(Issue 1) pp:25-29
Publication Date(Web):4 December 2009
DOI:10.1016/j.snb.2009.09.010
We report herein a fluorescent sensor derived from 1-pyrene-butyric acid and bicarboxyl-containing glutamic acid. The chemosensor shows high sensitivity (detection limit up to 1.5 μM) and dual illustration of specific selectivity for lead ion (Pb2+) over Na+, Mg2+, K+, Ca2+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+ and Hg2+ in aqueous solution.
Co-reporter:Na Xu, Hong-Wei Li, Yuqing Wu
Analytica Chimica Acta (15 March 2017) Volume 958() pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.aca.2016.12.033
•This paper provides the first hydrothermal synthesis of platinum nanoclusters.•The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%.•A new method to detect trace amount of metronidazole in urine is proposed.A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body.
Co-reporter:Dong-Dong Zheng, Dong Pan, Xiao Zha, Yuqing Wu, Chunlai Jiang and Xianghui Yu
Chemical Communications 2013 - vol. 49(Issue 76) pp:NaN8548-8548
Publication Date(Web):2013/07/24
DOI:10.1039/C3CC44986F
The recombinant GST fusion protein HPV 16 L1 from E. coli was proved to exist as a monomer rather than a pentamer, providing the possibility of real-time monitoring of the pentamer formation in vitro. Time-dependent kinetic studies of the process were performed for the first time by using static light scattering and western blot analysis, where the essential factors were revealed, offering a new biotechnical approach for virus control and/or the development of anti-viral agents.
Co-reporter:Yue Li, Hong-Wei Li, Li-Jun Ma, Yong-Qiang Dang and Yuqing Wu
Chemical Communications 2010 - vol. 46(Issue 21) pp:NaN3770-3770
Publication Date(Web):2010/04/22
DOI:10.1039/B925401C
We report a unique protein labeling system based on melittin and a pyrene derivative (1). The specific region of the C-terminal in melittin efficiently induced the formation of the pyrene eximer, which can be used as a tag to target proteins and for further detection.
Co-reporter:Hong-Wei Li, Kelong Ai and Yuqing Wu
Chemical Communications 2011 - vol. 47(Issue 35) pp:NaN9854-9854
Publication Date(Web):2011/07/21
DOI:10.1039/C1CC12588E
An efficient, rapid, and fluorescence visual method for column separation of BSA-protected gold-nanoclusters was proposed based on the dansylation of BSA. After optimization, this procedure can be extended to the separation of any other macromolecule-protected noble metal bioconjugates.
Co-reporter:Li-Jun Ma, Yue Li, Lei Li, Jian Sun, Chunjuan Tian and Yuqing Wu
Chemical Communications 2008(Issue 47) pp:NaN6347-6347
Publication Date(Web):2008/10/30
DOI:10.1039/B815281K
A fluorescent sensor, dansyl-L-aspartic acid (1), coupled with BSA was used to specifically detect Hg2+ in a neutral aqueous solution as well as in live cells; the fluorescence emission spectrum underwent an obvious blue shift with an enhancement in fluorescence intensity, and these effects were evident as color changes in fluorescence imaging pictures.
Co-reporter:Hong-Wei Li, Yue Li, Yong-Qiang Dang, Li-Jun Ma, Yuqing Wu, Guangfeng Hou and Lixin Wu
Chemical Communications 2009(Issue 29) pp:NaN4455-4455
Publication Date(Web):2009/06/12
DOI:10.1039/B907386H
A hypersensitive water-soluble fluorescent probe, dansyl-L-tryptophan methyl ester (1), was easily prepared for the detection of Hg2+ with a significantly improved detection limit (5 nM vs. 500 nM) in buffered aqueous solution.
Co-reporter:Xiao-Yu Yuan, Ding-Yi Fu, Xing-Feng Ren, Xuexun Fang, Lincong Wang, Shuxue Zou and Yuqing Wu
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 35) pp:NaN5852-5852
Publication Date(Web):2013/07/16
DOI:10.1039/C3OB41165F
As a new type of cathepsin K inhibitor, azadipeptide nitriles have the characteristics of proteolytic stability and excellent inhibitory activity, but they exhibit barely any satisfactory selectivity. Great efforts have focused on improving their selectivity toward cathepsin K. In this sequential study, we report the further structural optimization, synthesis, molecular modeling, and in vitro enzymatic assays of a new series of potent and selective inhibitors of cathepsin K without the P2–P3 amide linker. Significant selective improvements were achieved for cathepsin K over L, S and B, and a triaryl meta-product 13′ possessed the favorable balance between potency (Ki = 0.29 nM) and selectivity of cathepsin K over cathepsin L (320-fold), S (1784-fold) and B (8566-fold). We undertook a covalent protein–ligand docking study to explain the improved selectivity of several representative compounds. Such a selectivity improvement would be useful to avoid harmful side effects in practical applications of these compounds.
Co-reporter:Xing-Feng Ren, Hong-Wei Li, Xuexun Fang, Yuqing Wu, Lincong Wang and Shuxue Zou
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 7) pp:NaN1148-1148
Publication Date(Web):2012/12/12
DOI:10.1039/C2OB26624E
We have developed a series of azadipeptide nitriles with different P3 groups. A triaryl meta-phenyl derivative, compound 13, was not only a potent inhibitor for cathepsin K (Ki = 0.0031 nM), but also highly selective over both cathepsins B and S (∼1000-fold). A protein–ligand docking study performed on the series provided a possible explanation why compound 13 could be significantly more potent than the others, especially compound 12 in the same series.
Co-reporter:Bin Wang, Yang Gao, Hong-Wei Li, Zhi-Peng Hu and Yuqing Wu
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 11) pp:NaN4034-4034
Publication Date(Web):2011/04/12
DOI:10.1039/C1OB05372H
A new probe/Cu2+ complex for the detection of his-tagged protein has been developed, based on an improved probe, Dansyl-Gly-Py (1), by closely mimicing the structure of a peptide, ATCUN. In aqueous solution, 1/Cu2+ has good selectivity to histidine and cysteine, and further can detect histidine-rich protein by releasing the quenched fluorescence of 1.
Co-reporter:Jiao Liu, Hong-Wei Li, Wei-Xian Wang and Yuqing Wu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 19) pp:NaN3556-3556
Publication Date(Web):2017/04/04
DOI:10.1039/C7TB00438A
Gold nanoclusters (AuNCs) have been widely applied in fluorescence sensing, bioimaging and phototherapy. Although great progress has been made, the relatively low quantum yield (QY, <10%) in most currently reported AuNCs limits their application greatly. In the present study, adenosine monophosphate (AMP) capped gold nanoclusters (AuNC@AMP) are prepared by using a newly developed heating method in a short time (within 60 min), and are found to show a strong and stable luminescence emission in a relative high QY (14.52%). In addition, an in-depth investigation by employing infrared, 1H and 31P NMR spectroscopy has attributed the origin of such a high luminescence to both the binding of the purine ring and/or the phosphate moiety of AMP as well as their orientations at the gold core surface. In addition, electron-rich atoms such as nitrogen and oxygen, or group moieties such as –NH2 in the ligands can largely promote the luminescence emission of AuNCs. The present study reveals the intriguing generation of ultrabright luminescence from metal nanoclusters, and it will stimulate more research both on the fabrication and practical applications of luminescent metal NCs. With regard to the high QY of these AuNCs, they have great potential for biological applications as adenine is crucially important in life sciences.
Co-reporter:Dong-Dong Zheng, Ding-Yi Fu, Yuqing Wu, Yu-Long Sun, Li-Li Tan, Ting Zhou, Shi-Qi Ma, Xiao Zha and Ying-Wei Yang
Chemical Communications 2014 - vol. 50(Issue 24) pp:NaN3203-3203
Publication Date(Web):2014/01/29
DOI:10.1039/C3CC49789E
Pillarenes and calixarenes showed obvious inhibition of HPV16 L1 pentamer formation via their selective binding to Arg and Lys residues at the monomer interface, which was reversible after the release of cyclic arenes. Pillarenes are more effective than calixarenes in terms of the inhibition efficiency, attributing to the different kinetics and binding affinity.
![Benzenemethanol, 4-amino-3,5-dichloro-α-[[(1,1-dimethylethyl)amino]methyl]-](/data/chemimg/568900/37148-27-9.png)
![Benzenemethanol, 4-amino-3,5-dichloro-α-[[(1,1-dimethylethyl)amino]methyl]-](/data/chemimg/568900/37148-27-9_b.png)