ELECTROCHIMICA ACTA
·
2016
·
IF 4.803
Han Song,Lu Zhang,Feng Yu,Bang-Ce Ye,Yingchun Li
We describe here an ultrasensitive electrochemical detection of metronidazole (MNZ) by using a freestanding Au-Ag alloy microrod (AMR) as working electrode. Nanoporous Au-Ag AMR (NPAMR) was facilely prepared by dealloying of smooth AMR and further modified with electropolymerized molecularly imprinted polymer (MIP), which affords simultaneous identification and quantification of the target molecules by cyclic voltammetry (CV) with Fe(CN) 6 3−/4− as probe to indicate the current intensity. The MIP-decorated NPAMR showed a remarkably low detection limit of 2.7 × 10 −14 M (S/N = 3) and a wide determination range from 8.0 × 10 −14 to 1.0 × 10 −6 M for MNZ. The developed sensor has been successfully applied in detection of MNZ in real samples (fish tissues and drug tablet), and admirable specificity and anti-interference capability were achieved. This protocol offers great promise for cost-effective and precisely quantitative analysis of trace biological and chemical substances without assistance of any extra working electrode.
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ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Jian Huang,Dayan Ma,Feng Chen,Dongzhen Chen,Min Bai,Kewei Xu,Yongxi Zhao
Surface-enhanced Raman scattering (SERS) has proven to be an effective technique for identifying and providing fingerprint structural information on various analytes in low concentration. However, this analytical technique has been plagued by the ubiquitous presence of organic contaminants on roughened SERS substrate surfaces, which not only often result in poorer detection sensitivity but also significantly affect the reproducibility and accuracy of SERS analysis. Herein, we developed a clean, stable, and recyclable three-dimensional (3D) chestnutlike Ag/WO3–x (0 < x < 0.28) SERS substrate by simple hydrothermal reaction and subsequent green in situ decoration of silver nanoparticles. None of the organic additives were used in synthesis, which ensures the substrate surfaces are completely clean and free of interferences from impurities. The innovative design combines the SERS enhancement effect and self-cleaning property, making it a multifunctional and reusable SERS platform for highly sensitive SERS detection. Using malachite green as a model target, the as-prepared SERS substrates exhibited good reproducibility (relative standard deviation of 7.5%) and pushed the detection limit down to 0.29 pM. The enhancement factor was found to be as high as 1.4 × 107 based on the analysis of 4-aminothiophenol. The excellent regeneration performance indicated that the 3D biomimetic SERS substrates can be reused many times. In addition, the fabricated substrate was successfully employed for detecting thiram in water with a detection limit of 0.32 nM, and a good linear relationship was obtained between the logarithmic intensities and the logarithmic concentrations of thiram ranging from 1 nM to 1 μM. More importantly, the resultant SERS-active colloid can be used for accurate and reliable determination of thiram in real fruit peels. These results predict that the proposed SERS system have great potential toward rapid, reliable, and on-site analysis, especially for food safety and environmental supervision.
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CRYSTAL GROWTH & DESIGN
·
2017
·
IF 4.055
Kaisheng Yao,Zhiyong Li,Xinying Li,Weiwei Lu,Airong Xu,Hucheng Zhang,Jianji Wang
The design of green and ingenious strategies for the fabrication of anisotropic nanoparticles and their assembly is particularly important in the advancement of nanoscience and nanotechnology but still remains an enormous challenge. In this work, the Ag films, with variously shaped particles as building blocks, were successfully prepared at the interface of different ionic liquids and water (ILs–H2O) under ambient conditions only by using ILs with different cationic structures. The as-prepared Ag films with different morphologies were characterized and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray powder diffraction. The possible growth mechanisms were also suggested for the formation of differently morphological Ag films at the ILs–H2O interface. The as-obtained Ag films could be directly applied to perform surface-enhanced Raman scattering (SERS) studies. It was found that the nanobelt-contructed Ag films prepared at the interface of methyltrioctylammonium bis(trifluoromethylsulfonyl)imide ([N8881][Tf2N]) and water exhibited striking SERS sensitivities and good reproducibility.
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Analytical Methods
·
2016
·Vol. 8
·期 9
·2097-2105
·
IF 1.915
Junrong Li,Liang Lv,Guannan Zhang,Xiaodong Zhou,Aiguo Shen,Jiming Hu
We herein present a simple and surfactant-free synthetic strategy for the preparation of core–shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles (FBNPs) via a combination of galvanic replacement and reagent reduction, in which a chitosan (CS)-mediated epitaxial growth of Pt multi-branches occurs on cresyl violet labeled Au core–Ag shell nanoparticles (NPs) at room temperature. The as-prepared novel nanostructures exhibit an enzyme mimetic activity due to the formation of a Fructus Broussonetia-shaped Pt shell, the absence of surfactants and the positively charged CS molecules intertwined within the outermost Pt NPs. Relying on the high sensitivity of resonance-enhanced Raman scattering and the highly efficient intrinsic peroxidase-like activity of FBNPs, H2O2 was detected with a wide detection window from 10 pM to 100 μM when utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate. Based on the H2O2–TMB catalytic oxidation system a simple, sensitive, selective and universal platform has been extended for the detection of all peroxidase-related analytes. For example, glucose at a concentration range of 1 nM to 200 μM was detected in the presence of glucose oxidase with a limit of detection of 1 nM.
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PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
·
2016
·Vol. 33
·期 4
·212-220
·
IF 4.367
Mei Lei,Wei Wu,Shuanglei Yang,Xingang Zhang,Zhuo Xing,Feng Ren,Xiangheng Xiao,Changzhong Jiang
The reduction of 4-nitrophenol (Nip) into 4-aminophenol (Amp) by NaBH 4 , which is catalyzed by both binary and ternary yolk–shell noble-metal/SnO 2 heterostructures, is reported. The binary heterostructures contain individual Au or Ag nanoparticles (NPs) and the ternary heterostructures contain both Au and Ag NPs. The Au@SnO 2 yolk–shell NPs are synthesized via a silica seeds-mediated hydrothermal method. Subsequently, the Au@SnO 2 @Ag and Au@SnO 2 @Au yolk–shell–shell (YSS) NPs are synthesized, whereby SnO 2 is located between the Au and Ag NPs. The morphology, composition, and optical properties of the as-prepared samples are analyzed. For the binary heterostructures, the rate of the reduction reaction increases with decreasing particle size. The catalytic results demonstrate the synergistic effect of Au and Ag in the ternary metal–semiconductor heterostructures, which is beneficial to the catalytic reduction of Nip into Amp. Both the binary and ternary heterostructures exhibit significantly better catalytic performances than the corresponding bare Au and Ag NPs. It is envisaged that the current synthesized strategy will promote further interest in the field of bimetal NP-based catalysis.
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Nanoscale
·
2017
·Vol. 9
·期 7
·2640-2645
·
IF 7.367
Lin Yang,Ming Xuan Gao,Lei Zhan,Min Gong,Shu Jun Zhen,Cheng Zhi Huang
Early detection of cancer is helpful for the control and prevention of diseases. Due to the low content of cancer biomarkers in the early disease phases, however, an ultrasensitive and selective method is critical. In this contribution, an ultrasensitive surface-enhanced Raman scattering (SERS) immunoassay is newly developed with the principle of introducing a common enzyme-induced deposition (EID) reaction to coat a silver layer on the surface of gold nanoparticles and to form a core–shell nanostructure of Au@Ag. By using alkaline phosphatase (ALP) to dephosphorylate its substrate, 2-phospho-L-ascorbic acid trisodium salt (AAP), to form vitamin C, silver ions could be reduced into silver atoms and coated on the surface of the AuNPs; a greatly enhanced SERS signal was then obtained. As a proof of concept, α-fetoprotein (AFP) was detected as a target, which is a biomarker of liver cancer. Excellent analytical performance of the SERS immunoassay could be achieved in the range from 0.5 to 100 pg mL−1 with a limit of detection of 0.081 pg mL−1 (3σ). Identical results could be obtained by using the newly proposed SERS immunoassay for the clinical detection of AFP in serum samples of patients to those clinically obtained by chemiluminescence immunoassays, demonstrating the potential applications of the developed method in clinical diagnosis.
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JOURNAL OF MATERIALS SCIENCE
·
2016
·Vol. 51
·期 23
·10574-10584
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IF 2.302
Zhao Jie,Xie Yu,Fang Jing,Ling Yun,Gao Yunhua,Liu Xiaoming,Zhang Qiugen,Xu Qiuhua,Xiong Hui
A novel electromagnetic material has been synthesized through P -phenylenediamine-benzoquinone (PB) Schiff base Ag(I) complexes chemically bonded to few-layered graphene (FLG). The structure of the samples was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The shape and size were observed by scanning electron microscopy and transmission electron microscopy. The conductive properties were tested by a four-probe conductivity tester at room temperature, and the magnetic properties of the samples were tested with the vibrating sample magnetometer. These results show that the PB Schiff base Ag(I) complexes are chemically bonded onto the FLG layers. The conductivity, magnetic saturation, residual magnetization, and coercive force of the composite achieve 5.86 S cm −1 , 1.47 emu g −1 , 0.26 emu g −1 , and 208.3 Oe, respectively. Finally, based on the experimental results, the probable formation, electronic transmission, and magnetic mechanism have also been investigated.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Tao Zheng,Zhenxiang Xu,Yong Zhao,Hongqi Li,Rong Jian,Congcong Lu
A spiropyran-appended polysiloxane ( SP-Si ) was synthesized and characterized. The photochromic SP-Si has good thermal stability and exhibits high fatigue resistance to light. SP-Si acts as a dual colorimetric and spectroscopic probe for determining multi-scale pH over a wide range of 1∼14, and for detection of Ag + and Fe 3+ ions. Based on the transformation from colorless SP-Si solution without absorption at 440 nm to brown SP-Si /Ag + showing extremely strong absorption at 440 nm by addition of Ag + ions and subsequent transformation from brown to colorless SP-Si /Ag + /Hg 2+ with very weak absorption at 440 nm after addition of 1 equivalent of Hg 2+ ions, SP-Si /Ag + system serves as a dual colorimetric and spectroscopic probe for highly selective and sensitive detection of Hg 2+ ions. The detection is not interfered by common competitive metal ions such as Na + , K + , Li + , Ni 2+ , Fe 2+ , Zn 2+ , Co 2+ , Sr 2+ , Cu 2+ , Al 3+ , Ce 3+ and Cr 3+ . Applicability of SP-Si for real water sample analysis has been proved.
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BIOSENSORS & BIOELECTRONICS
·
2017
·
IF 7.78
Fenglei Gao,Taotao Fan,Shanshan Ou,Jing Wu,Xing Zhang,Jianjun Luo,Na Li,Yao Yao,Yingfeng Mou,Xianjiu Liao,Deqin Geng
In this paper, we reported a sensitive and selective electrochemical method for quantify DNA methylation , analyzing DNA MTase activity and screening of MTase inhibitor based on silver nanoparticles (Ag NPs) decorated carbon nanocubes (CNCs) as signal tag. The Ag NPs/CNCs was prepared by in situ growth of nanosilver on carboxylated CNCs and used as a tracing tag to label antibody. The sensor was prepared by immobilizing the double DNA helix structure on the surface of gold electrode. When DNA MTase was introduced, the probe was methylated. Successively, anti-5-methylcytosine antibody labeled Ag NPs/CNCs was specifically conjugated on the CpG methylation site. The electrochemical stripping signal of the Ag NPs was used to monitor the activity of MTase. The electrochemical signal has a linear relationship with M.SssI activities ranging from 0.05 to 120 U/mL with a detection limit of 0.03 U/mL. In addition, we also demonstrated the method could be used for rapid evaluation and screening of the inhibitors of MTase. The newly designed strategy avoid the requirement of deoxygenation for electrochemical assay, and thus provide a promising potential in clinical application.
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NEW JOURNAL OF CHEMISTRY
·
2016
·Vol. 41
·期 4
·1582-1590
·
IF 3.277
Qinye He,Aiwu Zhao,Lei Li,Henghui Sun,Dapeng Wang,Hongyan Guo,Mei Sun,Ping Chen
Fe3O4@SiO2@Ag magnetic–plasmonic nanospindles with efficient SERS performance and magnetic responsiveness have been successfully fabricated. Uniform and monodispersed Fe3O4@SiO2 nanospindles were prepared by a robust strategy through annealing the obtained β-FeOOH@SiO2 nanospindles in hydrogen atmospheres at 350 °C; the SiO2 shell could be regarded as an interlayer to maintain the morphology and offer a solid support for the further growth of Ag nanoparticles. Ag nanoparticles were introduced via in situ reduction of AgNO3, and the coverage rate of Ag nanoparticles anchored on Fe3O4@SiO2 was adjusted through regulating the AgNO3 concentration. Fe3O4@SiO2@Ag magnetic–plasmonic nanospindles can serve as highly efficient SERS active substrates with controllable magnetic aggregation due to steady enrichment of mass molecules in close proximity to abundant hot spots. Moreover, these nanospindles are used for label-free detection of thiram, and the detection limit is as low as 1 × 10−7 M (about 0.024 ppm), which is lower than the maximal residue limit of 7 ppm in fruits prescribed by the U.S. Environmental Protection Agency. Therefore, such magnetic–plasmonic nanospindles in the magnetic aggregation state may be potentially applied in rapid trace detection of residual pesticides or other specific analytes.
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Journal of the Taiwan Institute of Chemical Engineers
·
2016
·
IF 2.848
Huan Chen,Shihai Cao,Jinhua Yao,Fang Jiang
A novel Ag nanowires–CdS–Au (Ag NWs–CdS–Au) photocatalyst was synthesized by a two-step solvothermal method. As a metal core, thioglycolic acid (TGA) functionalized Ag NWs provided abundant active sites, facilitating the attachment of CdS ; and the excessive S 2− on the surface of CdS favored the loading of Au, leading to the well-developed combined interface of Ag NWs–CdS and CdS–Au. The combination and interaction between Ag NWs–CdS and CdS–Au was beneficial to the electron transfer in the photocatalysis. Multiple electron transfer processes happened in the Ag NWs–CdS–Au photocatalyst, enhancing charge carrier separation efficiency. Therefore, Ag NWs–CdS–Au possessed much higher photocatalytic degradation efficiency (89%) of MB than that of Ag NWs–CdS (45%) under visible light irradiation. Additionally, the Ag NWs–CdS–Au photocatalyst could absorb more visible light, favoring the generation of leuco-methylene blue (LMB) molecules, and further promoting the formation of ·OH. The finding provides a novel method to obtain bimetallic photocatalyst with separated bimetals to achieve high visible light photocatalytic activity and stability.
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ACS Applied Materials & Interfaces
·
2015
·
IF 6.723
Jian Sun,Fan Yang,Dan Zhao,Chuanxia Chen,Xiurong Yang
By means of employing 11-mercaptoundecanoic acid (11-MUA) as a reducing agent and protecting ligand, we present straightforward one-pot preparation of fluorescent Ag/Au bimetallic nanoclusters (namely AgAuNCs@11-MUA) from AgNO3 and HAuCl4 in alkaline aqueous solution at room temperature. It is found that the fluorescence of AgAuNCs@11-MUA has been selectively quenched by Cu2+ ions, and the nonfluorescence off-state of the as-prepared AgAuNCs@11-MUA–Cu2+ ensemble can be effectively switched on upon the addition of histidine and cysteine. By incorporating Ni2+ ions and N-ethylmaleimide, this phenomenon is further exploited as an integrated logic gate and a specific fluorescence turn-on assay for selectively and sensitively sensing histidine and cysteine has been designed and established based on the original noncovalent AgAuNCs@11-MUA–Cu2+ ensemble. Under the optimal conditions, histidine and cysteine can be detected in the concentration ranges of 0.25–9 and 0.25–7 μM; besides, the detection limits are found to be 87 and 111 nM (S/N = 3), respectively. Furthermore, we demonstrate that the proposed AgAuNCs@11-MUA-based fluorescent assay can be successfully utilized for biological fluids sample analysis.
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