BIOELECTROCHEMISTRY
·
2011
·
IF 3.52
Xiao Liu,Liqiang Luo,Yaping Ding,Daixin Ye
A novel poly-glutamic acid (PGA) film modified carbon paste electrode (CPE) incorporating carbon nanotubes (CNTs) was first prepared for the determination of l -tryptophan ( l -Trp). Scanning electron microscopy and Fourier transform infrared spectroscopy were applied for characterization of the surface morphology of the modified electrodes and cyclic voltammetry was used to investigate the electrochemical properties of the proposed electrode towards the oxidation of l -Trp. Optimization of the experimental parameters was performed with regard to pH, ratio of CNTs, concentration of glutamic acid , electro-polymerization cycles, accumulation time and concentration of sodium dodecylbenzene sulfonate . The linearity between the oxidation peak current and the l -Trp concentration was obtained in the range of 5.0 × 10 − 8 to 1.0 × 10 − 4 M with a detection limit of 1.0 × 10 − 8 M ( S / N = 3) and the sensitivity was calculated to be 1143.79 μA∙mM − 1 ∙ cm − 2 . In addition, the PGA modified CPE incorporating CNTs displayed high selectivity, good stability and reproducibility, making it suitable for the routine analysis of l -Trp in clinical use.
研究领域:
生物医学工程
·
分析化学
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高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 30
·18055-18066
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IF 3.945
Haoyang Li,Guanyu Jiang,Menghui Jia,Simin Cao,Sanjun Zhang,Jinquan Chen,Haitao Sun,Jianhua Xu,Jay R. Knutson
Ultrafast Förster Resonance Energy Transfer (FRET) between Tyrosine (Tyr, Y) and Tryptophan (Trp, W) in the model peptides Trp-(Pro)n-Tyr (WPnY) has been investigated using a femtosecond up-conversion spectrophotofluorometer. The ultrafast energy transfer process (<100 ps) in short peptides (WY, WPY and WP2Y) has been resolved. In fact, this FRET rate is found to be mixed with the rates of solvent relaxation (SR), ultrafast population decay (QSSQ) and other lifetime components. To further dissect and analyze the FRET, a spectral working model is constructed, and the contribution of a FRET lifetime is separated by reconciling the shapes of decay associated spectra (DAS). Surprisingly, FRET efficiency did not decrease monotonically with the growth of the peptide chain (as expected) but increased first and then decreased. The highest FRET efficiency occurred in peptide WPY. The kinetic results have been accompanied with molecular dynamics simulations that reconcile and explain this strange phenomenon: due to the strong interaction between amino acids, the distance between the donor and receptor in peptide WPY is actually closest, resulting in the fastest FRET. In addition, the FRET lifetimes (τcal) were estimated within the molecular dynamics simulations, and they were consistent with the lifetimes (τexp) separated out by the experimental measurements and the DAS working model. This benchmark study has implications for both previous and future studies of protein ultrafast dynamics. The approach taken can be generalized for the study of proximate tyrosine and tryptophan in proteins and it suggests spectral strategies for extracting mixed rates in other complex FRET problems.
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高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2021
·
IF 2.991
Qin Zhang,Bingyao Wang,Yifei Zhang,Jie Yang,Bodan Deng,Bei Ding,Dongping Zhong
Transient amyloid intermediates are likely to be cytotoxic and play an essential role in amyloid-associated neurodegenerative diseases. Characterization of their structural and dynamic evolution is the key to elucidating the molecular mechanism of amyloid formation. Here, combining circular dichroism (CD), exciton couplet theory, and Fourier transform infrared spectroscopy with site-specific tryptophan (Trp) and its noncanonical derivative 5-cyano-tryptochan (Trp5CN), we developed a method to monitor strand-to-strand tertiary and sheet-to-sheet quaternary interactions in the aggregation cascades of an amyloidogenic fragment from protein SOD128–38 (with the sequence KVKVWGSIKGL). We found that the exciton couplet generated from the Bb band of Trp can be used as a probe for side chain interactions. Its sensitivity can be further improved by four times with the incorporation of Trp5CN. We further observed a red-shift of ∼2 cm–1 and a broadening of ∼2 cm–1 in the IR band generated from the CN stretch during the aggregation, which we attributed to the transition from a corkscrew-like structure to a cross-linked intermediate phase. We show here that the integration of optical methods with unique aromatic side chain-related probes is able to elucidate amyloid intermolecular interactions and even capture elusive transient intermediates on and off the amyloid assembling pathway.
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2015
·Vol. 39
·期 9
·6919-6924
·
IF 3.086
Ya Chen,Juanjuan Xu,Cui Chen,Dongmei Guo,Yingzi Fu
A new nanocomposite of L-tryptophan functionalized graphene-supported platinum nanoparticles (L-Trp-rGO@PtNPs) was synthesized utilizing a facile ultrasonic method via π–π conjugate action between graphene-supported platinum nanoparticles and L-tryptophan (L-Trp) molecules. The prepared nanomaterial, which dispersed well in water and presented excellent conductivity, was modified on a glassy carbon electrode (L-Trp-rGO@PtNPs/GCE) for the chiral sensing of DOPA enantiomers. The immobilization process of L-Trp-rGO@PtNPs/GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, ultraviolet-visible (UV-vis) spectrometry and Raman spectroscopy. The electrochemical reactions of DOPA enantiomers were investigated via differential pulse voltammetry. The proposed electrochemical method showed excellent enantiospecificity for DOPA enantiomers and exhibited a stronger enantiospecificity for D-DOPA. In addition, the experimental parameters such as the concentration, the amount of L-Trp-rGO@PtNPs and the pH values were optimized. Under optimum conditions, the linear response ranges for the discrimination of DOPA were from 5.0 × 10−8 to 5.0 × 10−3 mol L−1 with a detection limit of 1.7 × 10−8 mol L−1 (S/N = 3).
研究领域:
材料科学
·
分析化学
·
生物化学
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高影响因子
FOOD CHEMISTRY
·
2023
·
IF 8.8
Kam-Chun Chan,Wei-Hao Zhang,Yui-Man Chan,Hiu-Lam Li,Jing Fang,Han-Yan Luo,Jun Xu
Sulfur treatment for the pesticidal and antibacterial processing of food products has been criticized since it impairs the quality of treated products. The inspection of sulfur-treated products is thus required to achieve the regulation of sulfur treatment. Sulfite assay is currently available for the inspection, but it bears the disadvantages of inaccurate results and complex experimental procedures. Here we report a new chemical marker, namely tryptophan sulfonate, that can be used for the accurate and efficient inspection of sulfur-treated foods. First, the marker was discovered in sulfur-fumigated ginger, yam, and ginseng by untargeted metabolomics. The marker identity was then elucidated using chromatographic separation, nuclear magnetic resonance analysis and chemical synthesis. Finally, to demonstrate its applicability in the inspection, a tryptophan sulfonate assay was developed to test 50 commercial food samples, and the results indicated that it performed better than the sulfite assay in terms of both accuracy and efficiency.
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高影响因子
CHROMATOGRAPHIA
·
2019
·Vol. 83
·期 2
·205-217
·
IF 1.552
Li Li,Chen Naijiang,Gu Puzhong,Li Honglei,Li Mengqing,Zhang Ziyue,Chen Ruiling,Zhang Ming
Abstract Compound amino acid injection-18 AA (CAAI-18 AA) is widely applied in medical care as a part of total parenteral nutrition systems. Thus, suitable quality control of CAAI-18 AA is of crucial importance for safety of the patients. Tryptophan (TRP) is one of the main components in CAAI-18 AA and may be degraded to 5-hydroxy-tryptophan (5-HTP), 5-hydroxytryptamine (5-HT), kynurenine (KYN) and indole (IN) under certain conditions, such as oxidation environments, ultraviolet light radiation and nonsterile conditions. The existence of these harmful impurities seriously affects the quality of CAAI-18 AA. Here, a simple HPLC approach with a PDA detector was developed and validated for simultaneous determination of the concentrations of 5-HTP, 5-HT, KYN and IN impurities in CAAI-18 AA. Separation of these four impurities in CAAI-18 AA was achieved under a gradient condition using acetonitrile and 10 mM phosphate buffer (containing 10 mM sodium 1-octanesulfonate, pH adjusted to 1.8 with phosphoric acid). To detect the four analytes with high sensitivity, multi-wavelength detection at 257, 270 and 276 nm was carried out during the separation. The method was validated in accordance with ICH guidelines and the results were compared to that obtained by UHPLC–MS/MS, showing that the two approaches did not provide significantly different results. Our results reveal that the simple and less expensive HPLC method holds great potential for quantitation of the four impurities in CAAI-18 AA. Graphic Abstract
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高影响因子
MICROCHEMICAL JOURNAL
·
2019
·
IF 3.206
Wenshuai Li,Saipeng Huang,Huiyun Wen,Yane Luo,Jiewei Cheng,Zhao Jia,Pu Han,Weiming Xue
Tryptophan (Trp) serves as an essential amino acid in protein and peptide metabolism of human body. Sensitive detection and quantification of Trp is imperative for the early diagnosis and prevention of Trp-associated disease. Herein, a highly sensitive and selective carbon quantum dot (Py-CDs) was fabricated and synthesized by a high-efficiency, one-pot hydrothermal route utilizing pyridine (Py) derivative 3-aminoisonicotinic acid. The biosensor with superior optical and biological characteristics exhibited excellent water solubility, good photostability, high biocompatibility and great cellular imaging capability. The Py-CDs exhibited high sensitivity and selectivity toward Trp with low detection limits of 5.7 nM. The mechanism research of high selectivity revealed the surface pyridine ring of Py-CDs served as an active site and formed the table nonfluorescence composite with tryptophan within just 15 s. Meanwhile, the biosensor has realized tryptophan detection in human serum samples with satisfactory accuracy and recovery. Furthermore, the biosensor was also extended to efficient detection of intracellular Trp, which illustrated its bright prospect and great potential in practical application of tryptophan associated disease prevention and early clinical diagnosis.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Datong Wu,Yin Yu,Jie Zhang,Lili Guo,Yong Kong
Here, a novel fluorescent chiral poly(ionic liquid) (S)-PCIL-4 with nonconjugated backbone is designed and synthesized in the control of micelle through free-radical polymerization, whose fluorescence emission maximum is at λem,max = 430 nm. It is observed that polymers with spatially proximate units (phenyl group and pyridinium cation) have photoluminescence through spatial π–π and ion−π interaction. Then, (S)-PCIL-4 can be served as a fluorescent turn off/on sensor for chiral recognition of phenylalaninol and tryptophan in the presence of Cu(II). For example, when (S)-PCIL-4–Cu(II) is treated with (R/S)-phenylalaninol, it will exhibit different fluorescence responses. Values of the enantiomeric fluorescence difference ratio for phenylalaninol and tryptophan are 1.10 and 1.08, respectively. In brief, we believe that the approach opens up a possible pathway to prepare a variety of fluorescent polymers with nonconjugated backbone and proves to be desirable in further application.
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高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2018
·Vol. 22
·期 8
·2405-2412
·
IF 2.509
Mo Zunli,Niu Xiaohui,Gao Huhu,Li Zhenliang,Meng Shujuan,Guo Ruibin
A novel and simple chiral sensing platform had been successfully fabricated by means of amidation reaction between 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA) and chitosan (CS) to form 3, 4, 9, 10-perylenetetracarboxylic acid–chitosan (PTCA–CS) composite film. Since CS has chiral center and PTCA has excellent electrical conductivity, the PTCA–CS composite modified glassy carbon electrode (PTCA–CS/GCE) could be treated as an effective electrochemical chiral sensor and applied for chiral discrimination of tryptophan (Trp) enantiomers theoretically. PTCA–CS composite was characterized by Fourier transform infrared (FTIR) spectroscopy and cyclic voltammetry (CV). When the prepared chiral sensing interface interacted with tryptophan isomers, a higher selectivity was received from D-Trp by differential pulse voltammetry (DPV). It indicated that the PTCA–CS/GCE can be treated as an electrochemical chiral sensor for the discrimination of Trp enantiomers. Further study demonstrated that the peak currents were linearly increased with the increasing percentage of L-Trp of Trp racemic mixture. Furthermore, the enantioselective interaction of the PTCA–CS/GCE was systematically studied by other experimental factors, such as the incubation time and acidity.
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高影响因子
ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Xiaohui Niu,Xing Yang,Zunli Mo,Ruibin Guo,Nijuan Liu,Pan Zhao,Zhenyu Liu,Meixuan Ouyang
Two types of ferrocene-functionalized multiwalled carbon nanotubes (MWCNTs) are described. The first was obtained by adsorption of ferrocene (Fc) on MWCNTs via π-π stacking and is referred to as Fc/MWCNTs. The second was prepared via a conjugation reaction between ferrocenecarboxylic acid and aminated MWCNTs to result on covalently modified MWCNTs referred to as MWCNT-Fc. MWCNT/Fc has a better conductivity than MWCNT-Fc. But electrochemical recognition results clearly showed the MWCNTs-Fc/β-CD/GCE can exhibit better chiral recognition ability to tryptophan enantiomers than β-CD/Fc/MWCNTs/GCE. By combining the merits of β-cyclodextrin (β-CD) and MWCNTs-Fc, an electrochemical sensor for l -tryptophan was obtained. Its characterizations by SEM, TEM , TGA , Raman spectroscopy and XPS showed that the Fc/MWCNTs and MWCNTs-Fc have successfully been synthesized. Enantioselective recognition was accomplished by differential pulse voltammetry . Tryptophan enantiomers can be differentiated with an enantioselectivity coefficient (I D-Trp /I L-Trp ) of 5.78. Moreover, the chiral recognition mechanism of β-CD recognition tryptophan enantiomers was proposed.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Danfeng Sun,Hongji Li,Mingji Li,Cuiping Li,Hongli Dai,Dazhi Sun,Baohe Yang
A novel NiO/carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite with a coaxial tubular nanostructure was successfully deposited on a glassy carbon electrode (GCE) through electrochemical processes. The outer PEDOT matrix has a high affinity for biomolecules, while the CNT inner layer has a strong electron-transport capacity. Hence, the NiO/CNT/PEDOT/GCE was used for the simultaneous determination of dopamine (DA), serotonin (5-HT), and tryptophan (Trp). Electrochemical responses of the NiO/CNT/PEDOT/GCE sensor were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. Three well-separated oxidation peaks were observed in a mixed system containing DA, 5-HT, and Trp; the 5-HT–DA and Trp–5-HT potential separations were 160 and 324 mV, respectively, owing to the synergistic effect of NiO, CNT, and PEDOT. Linear responses were obtained for DA, 5-HT, and Trp in the 0.03–20, 0.3–35, and 1–41 μM concentration ranges, with detection limits of 0.026, 0.063, and 0.210 μM, respectively. In addition, it was possible to simultaneously determine the three analytes using the NiO/CNT/PEDOT composite, which suggests that the sensor has promising applicability.
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Analytical Methods
·
2017
·Vol. 9
·期 35
·5149-5155
·
IF 1.9
Zhenliang Li,Zunli Mo,Ruibin Guo,Shujuan Meng,Ruijuan Wang,Huhu Gao,Xiaohui Niu
A novel chiral electrochemical sensor based on hydroxyethyl chitosan (HECS) covalently binding with the carboxylic multi-walled carbon nanotubes (MWCNT–COOH) was fabricated for discrimination of tryptophan (Trp) enantiomers. HECS preferably combined with L-Trp than with D-Trp because of the favorability of host–guest interactions between HECS and Trp enantiomers. Thus, the recognition efficiency was remarkably improved after hydroxyethyl groups were grafted onto chitosan (CS); this might be attributed to the formation of hydrogen bonds between Trp enantiomers and HECS. In addition, the small stereo-hindrance effect could play an important role in enantioselective discrimination.
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