JOURNAL OF MATERIALS SCIENCE
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2015
·Vol. 50
·期 19
·6339-6348
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IF 2.371
He Beibei,Zhao Qingguo,Zeng Zhigang,Wang Xiaohong,Han Sheng
Au@CeO 2 core–shell nanostructure catalysts were synthesized by hydrothermal reaction method. The effect of hydrothermal reaction time and calcination temperature on the textural and morphological characteristics of the catalyst was investigated by TEM, SEM, XRD, XPS, ICP, UV–Vis, and N 2 adsorption–desorption techniques. The results proved that gold core and CeO 2 shell formed simultaneously at the beginning of the reaction. By extending the hydrothermal reaction time, both the grain size of Au core and CeO 2 shell increased. The crystallization degree of CeO 2 and the interaction between Au and CeO 2 were also enhanced. The 90 % CO conversion temperature (T 90 % ) of Au@CeO 2 declined from 187 to 142 °C with the hydrothermal reaction time extended from 6 to 20 h. After 70-h reaction, the catalytic activity was still maintained without any loss. The effect of the calcination temperature on the catalytic performance was also investigated and it turned out that high calcination temperature has a positive influence on the catalytic activity. The likely active sites are the interface between Au core and CeO 2 shell. Gold content, metal–support interaction (MSI), and oxygen vacancy are all related to the activity. The excellent performance of 20 h-600 °C-Au@CeO 2 in catalytic activity and stability results from the joint effects of these triple factors.
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ANALYTICAL SCIENCES
·
2015
·Vol. 31
·期 5
·429-436
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IF 1.394
Xinfei ZHOU,Kunyun HE,Yu WANG,Haitao ZHENG,Shin-ichiro SUYE
A new composite film-modified electrode was prepared by the electropolymerisation of poly(3,4-ethylenedioxythiophene) (PEDOT) and superconductive carbon black (SCB) on a gold electrode. The PEDOT-SCB/Au electrode exhibited excellent ability towards the electrocatalytic oxidation of ascorbic acid, in terms of a 480 mV shift of the oxidation potential in the negative direction, and a dramatically enhanced oxidation current. Under the optimum conditions, the amperometric detection of ascorbic acid provided a wide linear detection range from 1.0 × 10−7 to 8.0 × 10−4 M, and a detection limit of 5.0 × 10−8 M (S/N = 2) as well as good reproducibility and stability.
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JOURNAL OF RAMAN SPECTROSCOPY
·
2013
·Vol. 44
·期 8
·1120-1125
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IF 2.679
Bi-Qi Zhang,Song-Bo Li,Qing Xiao,Ju Li,Jian-Jun Sun
The recently reported shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is considered as the next generation of advanced spectroscopy for its surface and molecular generality. With the aim to utilize the virtues of shell-isolated strategy and advance the SHINERS technique, we introduce a silane-based rapid synthesis method of silica-coating Au nanorods (Au@SiO 2 NRs) with manoeuvrable ultra-thin shell and tunable SPR. The results demonstrate that the SPR of Au NRs could be optimized to obtain large Raman enhancement using either 633 nm or 785 nm laser. Differing from previously reported Au@SiO 2 NRs synthesis method, we can tune the silica shell thickness within several nanometers to maximize the Raman signal while effectively eliminating the exterior interference. And this advanced synthesis method has also significantly reduced the silica-coating time from one day to ca. 1 h. This method as a new development of SHINERS technique has successfully got enhanced signal in solution Raman tests of malachite green, giving a great potential to be extended to in-situ measurement for daily life detection. Copyright © 2013 John Wiley & Sons, Ltd.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2015
·
IF 7.435
Zhi Liang Zhao,Lian Ying Zhang,Shu Juan Bao,Chang Ming Li
Metal core–shell nanostructures have been extensively studied as one of the most promising electrocatalysts to significantly reduce the loading of the expensive Pt catalyst for fuel cells but it is very challenging to fabricate such a structure to possess proper metal components while making small and uniformly distributed nanoparticles for high catalytic performance. In this work, small and uniformly distributed Au-core/PtCu alloy–shell structured nanoparticles (Au@PtCu NPs) were fabricated by a novel one-pot facile method. The as-prepared Au@PtCu/C has a much larger electrochemical active surface area (ECSA) (64.8 m 2 g −1 Pt ) than that of AuPtCu/C(38.5 m 2 g −1 Pt ), PtCu/C (31.02 m 2 g −1 Pt ) and commercial Pt/C (25.4 m 2 g −1 Pt ) catalyst. This new catalyst not only greatly reduces Pt loading but also significantly increases the catalytic activity and stability toward methanol oxidation reaction in comparison to the commercial electrocatalyst. This is mainly attributed to a synergistic effect from the small and uniform core–shell nanostructure and the unique chemical compositions of Au and PtCu alloy, thus offering a great potential for a less expensive but highly active catalyst toward direct methanol fuel cells (DMFCs).
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RSC Advances
·
2015
·Vol. 5
·期 40
·31262-31269
·
IF 3.84
Yulan Wang,Yueyun Li,Hongmin Ma,Xiang Ren,Wei Cao,Tao Yan,Qin Wei
A simple and novel label-free electrochemical immunosensor based on a bimetallic alloy was fabricated in this work. Three-dimensional (3D) pine-like Au–Cu nanodendrites (NDs) electrodeposited on the bare glassy carbon electrode (GCE) were employed as transducing materials to achieve the production and amplification of the electrochemical signal. The electrochemical detection was based on the fact that the immunocomplex can hinder the direct electron transfer in the redox process of Cu. Cu, instead of the traditional redox electron mediators, was exploited as a new signal producer. Au with good electron transfer ability could act as signal amplifier and capture antibodies. In addition, the 3D pine-like morphology of Au–Cu NDs with large specific surface area was beneficial to the immobilization of antibodies and the electron transfer between protein and metal. Under the optimal conditions, by using carbohydrate antigen 724 (CA724) as the target analyte, the label-free electrochemical immunosensor exhibited a wide linear range from 0.5 pg mL−1 to 500 ng mL−1 and a low detection limit of 0.25 pg mL−1. The proposed immunosensor also displayed a satisfying electrochemical performance with good reproducibility, selectivity and stability. In this sense, this novel method will provide a new promising application for the clinical immunoassay of other biomarkers.
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BIOSENSORS & BIOELECTRONICS
·
2016
·
IF 7.476
Weiwei Hu,Quansheng Chen,Huanhuan Li,Qin Ouyang,Jiewen Zhao
Rare earth-doped upconversion nanoparticles have promising potential in the field of pesticide detection because of their unique frequency upconverting capability and high detection sensitivity. This paper reports a novel aptamer-based nanosensor for acetamiprid detection using fluorescence resonance energy transfer (FRET) between NH 2 -NaYF 4 : Yb, [email protected] 2 (UCNPs) and gold nanoparticles (GNPs). Herein, GNPs as acceptors efficiently quench the fluorescence of UCNPs and acetamiprid specifically interacts with acetamiprid binding aptamer (ABA), causing the conformation changes of ABA from random coil to hairpin structure. Accordingly, ABA no longer stabilizes the GNPs in salt solution, leading to the varying aggregation extent of GNPs. Thus, the fluorescence of UCNPs are proportionally recovered. Under the optimized conditions, the enhancement efficiency was observed to increase linearly with the concentration of acetamiprid from 50 nM to 1000 nM, resulting in a relatively low limit of 3.2 nM. Additionally, the aptasensor demonstrated high selectivity to similar structure pesticides such as imidacloprid and chlorpyrifos , and further confirmed its application capacity in adulterated tea samples.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 37
·5565-5575
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IF 3.474
Hui-Ze Wang,Bo Chen,Deng-Yuan Hao,Xin-Peng Miao,Dan Zhao,Ning Zhang
Pursuing a general and feasible method to construct precious metal (PM) nanostructures bounded by high-index facets (HIFs) is highly desirable for both academic and industrial interests in promising metal materials. Herein, attempts to employ modified galvanic replacement processes between MClxy− (M = Pt, Pd or Au) PM precursors and sacrificed templates of Ag nanocubic particles with deliberately introduced high [Cl−] (concentration of Cl−) were investigated to gain more acceptable HIF PM nanostructures. Typically, the Pt–Ag system was chosen as a representative system and monitored by the comprehensive characterizations of UV-vis, XRD, XPS and TEM to illuminate the evolution of the corresponding particles. It was demonstrated that the deliberately introduced Cl− at a certain concentration ([Cl−] was not lower than 1.5 M) could play dual roles in the kinetic evolution of the particles: one was dramatically lowering the etching speed to confine the reaction to the surface layers of the Ag substrates, and the other was facilitating the anisotropic etching process along the PVP-protected Ag surface through the Nernst–Einstein diffusion influence on PtCl42−, which in turn led to the formation of concave nanocubic particles with Pt-highly-dispersed [hk0] high-index surfaces (combined by the [210], [410] and [510] atomic terraces) on the Ag templates. The efficiencies of the method were further confirmed by constructing similar Pd- or Au-highly-dispersed high-index surfaces on Ag templates, suggesting that the method is a novel and general strategy to directly construct PM-based high-index surfaces with high PM dispersion in bimetallic nanostructures, which could be referenced as a solution to obtain superior precious metal materials possessing both unique HIF surface configuration and cost-saving competitiveness for advanced applications.
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RSC Advances
·
2016
·Vol. 6
·期 58
·53080-53088
·
IF 3.289
Jie Liu,Zhiwei Zhao,Zhaoxia Ding,Zhendong Fang,Fuyi Cui
Magnetic Au–Fe3O4 nanocomposites with various Au weight loading were synthesized through a one step strategy. The morphology and physicochemical properties of the as-synthesized solids were characterized through various methods. After that, the catalysts were applied to activate H2O2 for the degradation of 4-chlorophenol (4-CP). The results showed that Au–Fe3O4 can catalyze oxidation of 4-CP efficiently in the presence of H2O2 at pH 5, which may be attributed to the synergistic catalysis in the nanocomposites for hydroxyl radical generation. And then, the influence of reaction parameters on the oxidation of 4-CP, including the Au weight loading of the nanocomposites, pH, catalyst dosage, H2O2 dosage and temperature, were assessed. The stabilization and reusability of the Au–Fe3O4 nanocomposites was shown to be excellent, with no leakage of Au. The hydroxyl radicals (˙OH) were the main reactive radicals released in the Au–Fe3O4/H2O2 system according to the addition of tert-butanol and the spin-trapping electron paramagnetic resonance (EPR) by means of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), while the ˙OH in the bulk solution acted in the main role for 4-CP degradation. Finally, the mechanism of H2O2 activated with Au–Fe3O4 for 4-CP degradation was proposed.
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RSC Advances
·
2016
·Vol. 6
·期 114
·113058-113065
·
IF 3.289
Xudong Sun,Jing Dong,Jinan Li,Mingliang Ye,Junjie Ou,Lingyi Zhang,Weibing Zhang
The development of hydrophilic stationary phase for highly efficient and selective enrichment and identification of low-abundance glycopeptides from a complex biological sample is an important prerequisite in glycoproteomics research. Herein, a hydrophilic cysteine functionalized macroporous adsorption resin/gold nanoparticle (MAR/Au–Cys) was synthesized and applied to the highly selective enrichment and identification of N-linked glycopeptides. The unique porous structure and high specific surface area of MAR provide abundant bonding sites for the immobilization of Au nanoparticles, and subsequently for the loading of cysteine via robust Au–S bonds. The structure and chemical composition of MAR/Au–Cys were confirmed by scanning electron microscopy, nitrogen adsorption–desorption analysis, mercury intrusion porosimetry and Fourier-transform infrared spectroscopy. Besides, the MAR/Au–Cys exhibited good performance in glycopeptide enrichment of tryptic digests from human immunoglobulin G and horseradish peroxidase by operation of a HILIC-SPE tip, revealing good universality, high enrichment selectivity, low detection limit (2.5 fmol) and satisfactory enrichment recovery (above 79%). Furthermore, the proposed material was successfully utilized in the N-glycoproteomics analysis of a complex biological sample. 1305 unique glycopeptides with 883 N-glycosylation sites from 476 different N-linked glycoproteins were identified from the proteins extracted from mouse liver. These results show that the proposed Au–cysteine modified macroporous adsorption resin is a promising affinity material for glycoproteomics research of real complex biological samples.
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TALANTA
·
2024
·
IF 5.6
Kaida Kuang,Yao Lu,Yang Chen,Pei Zhang,Nengqin Jia
The traditional luminol electrochemiluminescence (ECL) sensing suffers from low signal response and instability issues. Here, an Au/ZnCuS double-enhanced g -C 3 N 4 -supported luminol ECL aptasensor is constructed for the sensitive detection of human mucin 1 (MUC1). In this platform, g -C 3 N 4 of a large specific surface area is beneficial to load more luminol illuminants. Au nanoparticles promote the decomposition of H 2 O 2 coreactants to generate more reactive oxygen (•OH and O 2 • − ) intermediates, while ZnCuS can immobilize the aptamer and simultaneously catalyze H 2 O 2 decomposition, realizing the double-wing signal amplification. Under optimal conditions, this sensor shows a good detection capability within 1.0 × 10 −4 –1.0 × 10 3 ng mL −1 and a low detection limit of 5.0 × 10 −5 ng mL −1 , as well as ideal stability, selectivity, and reproducibility. This double-enhanced aptasensor highlights a new signal-enhancement approach for early biomarker detection.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
·
IF 4.9
Qingjie Yu,Chenxi Ke,Yu Wu,Zichen Song,Mengjiao Li,Hongda Zhu,Huiling Guo,Hongmei Sun,Mingxing Liu
Ochratoxin A (OTA) is a kind of mycotoxin , and developing a sensitive and simple method to detect OTA is of great significance for ensuring food safety and human health. In this study, a competitive fluorescent immunosensor based on fluorescence resonance energy transfer (FRET) was designed for the ultra-sensitive detection of OTA. Here, Ag@SiO 2 @N, S-GQDs nanocomposites were successfully designed, fabricated, and characterized by heteroatom co-doping and metal enhanced fluorescence (MEF) techniques, which can improve the fluorescence intensity and quantum yield . This study indicated that FRET between OTA antigen-modified Ag@SiO 2 @N, S-GQDs (Ag@SiO 2 @N, S-GQDs-OTA-Antigen) and OTA antibody-modified AuNPs can effectively quench the strong fluorescence of Ag@SiO 2 @N, S-GQDs-OTA-Antigen. The competitive fluorescent immunosensor based on FRET can detect OTA with a linear range of 0.5–1000 pg/mL and a limit of detection (LOD) of 0.094 pg/mL under optimal conditions. The recoveries ranged from 94% to 110% for the red wine sample, suggesting that the developed FRET-based competitive fluorescent immunosensor can be an effective tool for the ultra-sensitive detection of OTA, meanwhile, it might provide a better method for the detection of other toxic small molecules in food and the environment.
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Biomaterials Advances
·
2024
·
IF 5.5
Wuming Wu,Xiaolian Jiang,Qin Zeng,Huiyu Zou,Chunyan Deng
In this study, epigallocatechin-3-gallate nanospheres (EGCG NSs) are employed as an innovative alternative to traditional reducing agents for the in-situ growth of AuNPs on the EGCG NS surface to produce the Au nanoparticles decorated EGCG nanospheres (EGCG NS@AuNPs). This eco-friendly approach avoids toxic chemicals and simplifies the synthesis process, enhancing biocompatibility and functional properties of the resulting EGCG NS@AuNPs nanocomposite. The nanocomposite exhibits remarkable stability, photothermal properties, and peroxidase-like enzymatic activity. Taking advantage of the enhanced photothermal properties, the application of EGCG NS@AuNPs in the antibacterial field was investigated, and the antibacterial activity was greatly improved against both Gram-negative and Gram-positive bacteria comparing to bare AuNPs or EGCG Ns. Additionally, based on the excellent enzymatic activity, the sensing application of EGCG NS@AuNPs was explored by developing a colorimetric method for detecting ascorbic acid (AA). A remarkably low detection limit of 0.076 μM was achieved. This method has been successfully applied to measure the AA content in vitamin C tablets, demonstrating the practicality and accuracy of this approach. Therefore, the synthesis for EGCG NS@AuNPs is not only rapid, and cost-effective, but also eco-friendly and not harmful to biological systems, which is potential in biosensing, clinical diagnosis, and therapeutics. Future research could explore further applications of EGCG NS@AuNPs in biomedicine field, revealing even more of its remarkable potential.
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