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排序方式: 共有171条查询结果,搜索用时 62 毫秒
81.
Chen-I Wang Chih-Ching Huang Yang-Wei Lin Wen-Tsen Chen Huan-Tsung Chang 《Analytica chimica acta》2012
In this study, we developed a fluorescence assay for the highly sensitive and selective detection of Hg2+ and Pb2+ ions using a gold nanoparticle (Au NP)-based probe. The Hg–Au and Pb–Au alloys that formed on the Au NP surfaces allowed the Au NPs to exhibit peroxidase-mimicking catalytic activity in the H2O2-mediated oxidation of Amplex UltraRed (AUR). The fluorescence of the AUR oxidation product increased upon increasing the concentration of either Hg2+ or Pb2+ ions. By controlling the pH values of 5 mM tris–acetate buffers at 7.0 and 9.0, this H2O2–AUR–Au NP probe detected Hg2+ and Pb2+ ions, respectively, both with limits of detection (signal-to-noise ratio: 3) of 4.0 nM. The fluorescence intensity of the AUR oxidation product was proportional to the concentrations of Hg2+ and Pb2+ ions over ranges 0.05–1 μM (R2 = 0.993) and 0.05–5 μM (R2 = 0.996), respectively. The H2O2–AUR–Au NP probe was highly selective for Hg2+ (>100-fold) and Pb2+ (>300-fold) ions in the presence of other tested metal ions. We validated the practicality of this simple, selective, and sensitive H2O2–AUR–Au NP probe through determination of the concentrations of Hg2+ and Pb2+ ions in a lake water sample and of Pb2+ ions in a blood sample. To the best of our knowledge, this system is the first example of Au NPs being used as enzyme-mimics for the fluorescence detection of Hg2+ and Pb2+ ions. 相似文献
82.
Stefan Benndorf Dr. Sihem Groni Leanne M. Stafast Dr. Helmar Görls Dr. Claire Fave Prof. Dr. Bernd Schöllhorn Prof. Dr. Wolfgang Weigand 《欧洲无机化学杂志》2023,26(10):e202200684
[FeFe] hydrogenase (H2ase) mimicking complexes containing lipoic and selenolipoic acid moieties connected to 2-hydroxy-1,3-dithiopropane and 2-hydroxy-1,3-diselenopropane bridging ligands were synthesized and characterized using different spectroscopic methods. X-ray diffraction analysis was utilized to determine the molecular structure of a triphenylphosphane substituted analogue. Cyclic voltammetry (CV) investigations on the redox chemistry in presence and absence of acetic acid (AcOH) revealed differing behaviours among the mimics. IR spectroelectrochemistry (IR SEC) enabled deeper insights of structural changes during electrochemical measurements. The elaboration of surface confined systems was studied in preliminary experiments. CV experiments showed that the lipoic acid derivatives of the [FeFe] H2ase mimics formed well-organized self-assembled monolayers (SAMs) on Pt electrodes, a promising result for future work. 相似文献
83.
Metal–Organic Framework‐Derived Copper Nanoparticle@Carbon Nanocomposites as Peroxidase Mimics for Colorimetric Sensing of Ascorbic Acid 下载免费PDF全文
Dr. Hongliang Tan Chanjiao Ma Li Gao Qian Li Prof. Yonghai Song Dr. Fugang Xu Prof. Tao Wang Prof. Li Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16377-16383
Metal–organic frameworks (MOFs) have emerged as very fascinating functional materials due to their diversity nature. A nanocomposite consisting of copper nanoparticles dispersed within a carbon matrix (Cu NPs@C) is prepared through a one‐pot thermolysis of copper‐based metal–organic framework precursors. Cu NPs@C can catalyze the oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) to form a colored product in the presence of H2O2. As a peroxidase mimic, Cu NPs@C not only has the advantages of low cost, high stability, and easy preparation, but also follows Michaelis–Menten behaviors and shows strong affinity to H2O2. As the Cu NPs’ surfaces are free from stabilizing agent, Cu NPs@C exhibited a higher affinity to H2O2 than horseradish peroxidase. On the basis of the inhibitory effect of ascorbic acid (AA) on oxidation of TMB, this system serves as a colorimetric method for the detection of AA, suggesting that the present work would expand the potential applications of MOF‐derived nanocomposites in biomedical fields. 相似文献
84.
Dr. Anirban Bhattacharjee Dr. Murielle Chavarot‐Kerlidou Prof. Jillian L. Dempsey Prof. Harry B. Gray Dr. Etsuko Fujita Dr. James T. Muckerman Prof. Marc Fontecave Dr. Vincent Artero Prof. Guilherme M. Arantes Dr. Martin J. Field 《Chemphyschem》2014,15(14):2951-2958
The reduced CoI states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen‐evolving catalytic activity of these species. In this work we analyze the low‐energy electronic absorption bands of two cobaloxime systems experimentally and use a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task. 相似文献
85.
Liqiang Luo Yuting Zhang Fang LiXiaojing Si Yaping DingDongmei Deng Tianlin Wang 《Analytica chimica acta》2013
A series of spinel-type CoxNi1−xFe2O4 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) magnetic nanomaterials were solvothermally synthesized as enzyme mimics for the eletroctrocatalytic oxidation of H2O2. X-ray diffraction and scanning electron microscope were employed to characterize the composition, structure and morphology of the material. The electrochemical properties of spinel-type CoxNi1−xFe2O4 with different (Co/Ni) molar ratio toward H2O2 oxidation were investigated, and the results demonstrated that Co0.5Ni0.5Fe2O4 modified carbon paste electrode (Co0.5Ni0.5Fe2O4/CPE) possessed the best electrocatalytic activity for H2O2 oxidation. Under optimum conditions, the calibration curve for H2O2 determination on Co0.5Ni0.5Fe2O4/CPE was linear in a wide range of 1.0 × 10−8–1.0 × 10−3 M with low detection limit of 3.0 × 10−9 M (S/N = 3). The proposed Co0.5Ni0.5Fe2O4/CPE was also applied to the determination of H2O2 in commercial toothpastes with satisfactory results, indicating that CoxNi1−xFe2O4 is a promising hydrogen peroxidase mimics for the detection of H2O2. 相似文献
86.
Enzyme-linked immunosorbent assay (ELISA) methods based on natural enzyme-labeled probes have been applied in the immunoassays, but most have some inevitable limitations (e.g. harsh preparation, purification and storage) and are unsuitable for routine use. Herein we synthesized a new class of irregular-shaped platinum nanoparticles (ISPtNP) with a mean length of 7.0 nm and a narrowing width from 2.0 to 5.0 nm along the longitudinal axes, which were utilized as peroxidase-like mimics for the development of colorimetric immunoassays. Compared with bioactive horseradish peroxidase (HRP), the synthesized ISPtNP exhibited a low Km value (~0.12 mM) and a high Kcat value (~2.27 × 104 s−1) for 3,3′,5,5′-tetramethylbenzidine (TMB) with strong thermal stability and pH tolerance. The catalytic mechanism of the ISPtNP toward TMB/H2O2 was for the first time discussed and deliberated in this work. Based on a sandwich-type assay format, two types of colorimetric immunoassay protocols were designed and developed for the detection of rabbit IgG (RIgG, as a model) by using the synthesized ISPtNP and conventional HRP as the labeling of detection antibodies, respectively. Similar detection limits (LODs) of 2.5 ng mL−1 vs. 1.0 ng mL−1 were obtained toward RIgG with the ISPtNP labeling compared to HRP format. Intra- and inter-assay coefficients of variation were less than 13%. Importantly, the ISPtNP-based assay system could be suitable for use in a mass production of miniaturized lab-on-a-chip devices and open new opportunities for protein diagnostics and biosecurity. 相似文献
87.
Sascha Janssen 《Journal of carbohydrate chemistry》2013,32(4-6):611-647
Glycosylation of 3‐O‐unprotected 2‐azido‐2‐deoxy‐galactopyranoside (compound 5) with O‐(2,3‐di‐O‐acyl‐4,6‐O‐benzylidene‐D‐galactopyranosyl) trichloroacetimidates (compounds 4A, B) as glycosyl donors afforded β (1–3)‐linked disaccharides (9A, B) in high yield. Removal of the 2,3‐O‐acyl groups and selective 3‐O‐alkylation with α‐benzyloxycarbonyl‐alkyl triflates furnished the protected target molecules, which could be readily transformed into the desired ganglioside mimics. 相似文献
88.
Zeyuan Dong Yongguo Wang Yanzhen Yin Junqiu Liu 《Current Opinion in Colloid & Interface Science》2011,(6):451-458
The development of supramolecular chemistry has led to a shift in the research focus from the structural design of supramolecules to developing functional systems, such as supramolecular enzyme models. The supramolecular enzyme mimics can be readily constructed by self-assembly which is an efficient strategy for generating highly-ordered structures with complex and hierarchical architectures to mimic the biopolymers. The study of supramolecular enzyme mimics has implications for understanding both the structure–function relationships of natural enzymes and the thermodynamic mechanism during catalysis. Additionally, they are potentially useful in many important applications, e.g., medicinal application and industrial biocatalysts and so on. This review is aimed at giving a brief overview of the synthesis of supramolecular enzyme mimics and their functions. 相似文献
89.
Fangfang Cao Lu Zhang Yawen You Lirong Zheng Jinsong Ren Xiaogang Qu 《Angewandte Chemie (International ed. in English)》2020,59(13):5108-5115
Sepsis, characterized by immoderate production of multiple reactive oxygen and nitrogen species (RONS), causes high morbidity and mortality. Despite progress made with nanozymes, efficient antioxidant therapy to eliminate these RONS remains challenging, owing largely to the specificity and low activity of exploited nanozymes. Herein, an enzyme‐mimicking single‐atom catalyst, Co/PMCS, features atomically dispersed coordinatively unsaturated active Co‐porphyrin centers, which can rapidly obliterate multiple RONS to alleviate sepsis. Co/PMCS can eliminate O2.? and H2O2 by mimicking superoxide dismutase, catalase, and glutathione peroxidase, while removing .OH via the oxidative‐reduction cycle, with markedly higher activity than nanozymes. It can also scavenge .NO through formation of a nitrosyl–metal complex. Eventually, it can reduce proinflammatory cytokine levels, protect organs from damage, and confer a distinct survival advantage to the infected sepsis mice. 相似文献
90.
超氧化物歧化酶化学模拟的新进展 总被引:1,自引:0,他引:1
超氧化物歧化酶在生物体内特异性地催化超氧离子自由基(O2˙ˉ)的歧化反应, 具有抗氧化、抗癌症、抗炎症等重要生理学作用。近年来,超氧化物歧化酶的化学模拟倍受关注并引发人们极广泛的研究兴趣。本文系统综述了超氧化物歧化酶模拟物在设计合成及应用上的新近研究进展。 相似文献