APPLIED CATALYSIS B-ENVIRONMENTAL
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2015
·
IF 7.435
Wei Zhu,Peijue Liu,Shuning Xiao,Wenchao Wang,Dieqing Zhang,Hexing Li
A novel Ag-doped MOF-like organotitanium polymer (Ag@NH 2 -MOP(Ti)) was synthesized via a microwave-assisted coordination and polymerization reaction with 2-aminoterephthalic acid (H 2 ATA) and tetra- n -butyl titanate (Ti(OC 4 H 9 ) 4 ), followed by the crystal growth and assembly onto Ag nanoparticles (NPs). This Ag@NH 2 -MOP(Ti) exhibited excellent activity in visible-light driven photocatalytic NO oxidization, much higher than N -doped TiO 2 by two times. The NH 2 -MOP(Ti) absorbed visible lights to generate photoelectrons and holes, accompanied by producing HO and O 2 − active sites for the subsequent NO oxidation into NO 3 − . The Ag NPs allowed assembly of NH 2 -MOP(Ti) polymer favoring light absorbance via multiple reflections and also facilitated photoelectrons transfer to reduce photoelectron–hole recombination, leading to the enhanced photocatalytic activity for NO oxidation and inactivating bacteria. Moreover, it could be used repetitively owing to the high stability.
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JOURNAL OF HAZARDOUS MATERIALS
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2015
·
IF 4.529
Yunfang Chen,Jianzhang Fang,Shaoyou Lu,Yan Wu,Dazhi Chen,Liyan Huang,Cong Cheng,Lu Ren,Ximiao Zhu,Zhanqiang Fang
This study aims at photocatalytic degradation of 2,4-DCP with the assistance of H 2 O 2 in aqueous solution by a composite catalyst of Ag-rectorite. The catalysts were prepared via a novel thermal decomposition method followed after the cation-exchange process. The synthesized nano-materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface analyzer, Ultraviolet–visible light (UV–vis) absorption spectra, field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The different mechanisms of degradation process with or without visible light irradiation were discussed, respectively. Moreover, the degradation efficiency of 2,4-DCP wastewater under Ag-rectorite/H 2 O 2 /visible light system was investigated by series of experiments, concerning on effects of major operation factors, such as H 2 O 2 dosage and the initial pH value. The highest degradation rate was observed when adding 0.18 mL H 2 O 2 into 50 mL 2,4-DCP solution, and the optimal pH value was 4 for the reaction. Afterwards, total organic carbon (TOC) experiments were carried out to evaluate the mineralization ratio of 2,4-DCP.
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Scientific Reports
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2015
·Vol. 5
·期 1
·1-8
·
IF 5.578
Shen Mo-Hai,Zhou Xiao-Xia,Yang Xiao-Ya,Chao Jing-Bo,Liu Rui,Liu Jing-Fu
It is still not very clear what roles the various Ag species play in the toxicity of silver nanoparticles (AgNPs). In this study, we found that traditional exposure media result in uncontrollable but consistent physicochemical transformation of AgNPs, causing artifacts in determination of median lethal concentration (LC50) and hindering the identification of Ag species responsible for the acute toxicity of AgNPs to Daphnia magna . This obstacle was overcome by using 8 h exposure in 0.1 mmol L −1 NaNO 3 medium, in which we measured the 8-h LC50 of seven AgNPs with different sizes and coatings and determined the concentrations of various Ag species. The LC50 as free Ag + of the seven AgNPs (0.37–0.44 μg L −1 ) agreed very well with that of AgNO 3 (0.40 μg L −1 ) and showed the lowest value compared to that as total Ag, total Ag + and dissolved Ag, demonstrating free Ag + is exclusively responsible for the acute toxicity of AgNPs to D. magna , while other Ag species in AgNPs have no contribution to the acute toxicity. Our results demonstrated the great importance of developing appropriate exposure media for evaluating risk of nanomaterials.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2015
·
IF 4.097
Ziying Wang,Yong Zhang,Sen Liu,Tong Zhang
A novel NO 2 gas sensor has been constructed using Ag nanoparticles-SnO 2 nanoparticles-reduced graphene oxide (AgNPs-SnO 2 -rGO) hybrids as sensing materials. AgNPs-SnO 2 -rGO hybrids were prepared by a two-step wet-chemical method. Firstly, SnO 2 -rGO hybrids were synthesized by hydrothermal treatment of aqueous dispersion of GO in the presence of SnCl 4 . Then, AgNPs-SnO 2 -rGO hybrids were obtained by in situ reduction of AgNO 3 on the surface of SnO 2 -rGO hybrids. The combined characterizations of UV–vis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDX), elemental mapping, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and Raman spectra were used to investigate the structure of AgNPs-SnO 2 -rGO hybrids. Most importantly, the sensor based on AgNPs-SnO 2 -rGO hybrids exhibits good sensing performance for NO 2 sensing operating at room temperature . For example, the response time and recovery time of the sensor based on AgNPs-SnO 2 -rGO hybrids for 5 ppm NO 2 are 49 s and 339 s, which are much shorter than that of SnO 2 -rGO hybrids (415 s and 740 s), indicating that the sensing performances for NO 2 sensing at room temperature have been tremendously enhanced by introduction of AgNPs into SnO 2 -rGO hybrids.
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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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RSC Advances
·
2014
·Vol. 5
·期 8
·6043-6050
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IF 3.708
Jiang Xue Dong,Fei Qu,Nian Bing Li,Hong Qun Luo
This paper reports a dramatic cyclic regeneration of polyethyleneimine-templated silver nanoclusters (PEI-AgNCs) based on the pH-induced conformational changes of polyethyleneimine (PEI) in aqueous solution. The PEI-AgNCs have been synthesized and found to be highly sensitive to the pH of the solution in air. The studies show that small AgNCs would gather to form larger silver nanoparticles (AgNPs) by adjusting the pH to 1.5 with a nitric acid solution. The AgNPs in solution was then transformed gradually to Ag(I) ions with stirring in air. Subsequently, the above Ag(I) ions were reduced again to AgNCs by changing the pH to about 9 with a NaOH solution and adding a certain amount of formaldehyde as a reductant to solution. The fluorescence and UV-visible absorption spectra recorded this process in detail. The transmission electron microscopy images, X-ray powder diffraction patterns, and Fourier transform infrared spectra further demonstrated that the cyclic transformation existed among AgNCs, AgNPs, and Ag(I) ions. The amino-rich PEI plays a crucial role in the regeneration of PEI-AgNCs. A large number of amino groups on PEI could be reversibly protonated by adjusting the pH of solution, leading to a change of the interaction between Ag and PEI, which has laid foundation for this work.
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NEW JOURNAL OF CHEMISTRY
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2016
·Vol. 41
·期 4
·1582-1590
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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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ELECTROCHIMICA ACTA
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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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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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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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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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