FOOD CHEMISTRY
·
2022
·
IF 9.231
Bingxue Hu,Da-Wen Sun,Hongbin Pu,Zhibin Huang
Cellulose material holds considerable promise for effective surface-enhanced Raman scattering (SERS) substrate construction due to its extensive availability, chemically modifying capacity, ease of manufacture, high flexibility and low optical activity. A large-area, high-sensitivity, stable and uniform Au@Ag nanorods (NRs)-CMC substrate was successfully developed via electrostatic repulsion by using negatively-charged core–shell Au@Ag NRs as SERS active plasmonic nanomaterial, combined with negatively-charged carboxymethylcellulose (CMC) hydrogel for nanoparticles stabilization, homodisperse and protection. The obtained Au@Ag NRs-CMC substrate showed excellent sensitivity for the detection of thiram residues in fruits containing low and abundant pigment interferents, such as apples and blueberries, with detection limits of 58 and 78 ppb, respectively. Additionally, it retained more than 80% SERS performance after storage for 9 months under ambient conditions, demonstrating its great potential in facilitating the commercialization of cellulose-based SERS technology for cost-effective detection of food contaminants with advantages of facile preparation procedure, uniformity, reproducibility and long-term stability.
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Catalysis Science & Technology
·
2022
·Vol. 13
·期 4
·991-999
·
IF 6.177
Jie Gao,Zhenfu Wang,Ranran Guo,Yang Hu,Xiaoyan Dong,Qinghong Shi,Yan Sun
A chemoenzymatic cascade system (GA&GOx@Au–SiO2) was fabricated by immobilizing Au nanoparticles onto mesoporous silica nanoparticles (SiO2) followed by the co-immobilization of glucoamylase (GA) and glucose oxidase (GOx) for the efficient production of gluconic acid from starch. The proximity effect of Au nanoparticles, GOx, and GA allowed rapid transport of the reaction intermediates (glucose and H2O2) and timely removal of H2O2 that was harmful to the enzymes, thus improving the yield of gluconic acid as well as stability of the biocatalysts. The yield of gluconic acid with GA&GOx@Au–SiO2 reached 97.8% within 30 min, much higher than the control systems for comparison. Besides, GA&GOx@Au–SiO2 maintained 83.9% of initial activity after 10 cycles of usage, also higher than that without immobilized Au nanoparticles (57.5%). Such a chemoenzymatic cascade system provides a new strategy for improving the performance of enzymatic reactions with H2O2 generation.
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Nanoscale
·
2023
·Vol. 15
·期 8
·4063-4070
·
IF 6.7
Mengjiao Li,Qingjie Yu,Meie Zheng,Rongrong Jiang,Hongda Zhu,Huiling Guo,Hongmei Sun,Mingxing Liu
A label-free electrochemical immunosensor for high-sensitive detection of β-amyloid 1–42 (Aβ 1–42) was constructed based on Au-modified B, S, and N co-doped reduced graphene oxide (Au-BSN-rGO). The electronic structure of Au-BSN-rGO was investigated by first-principles calculations, which showed that the band gap of graphene was opened, thus improving its electrical conductivity. Moreover, Au-BSN-rGO was successfully prepared and characterized, and the obtained results discovered that it could be used as a signal amplifier for immunosensors due to the advantages of the good electrochemical characteristics and enormous surface area of BSN-rGO and the accelerated electron transfer ability of Au NPs. Furthermore, the label-free electrochemical immunosensor had a linear detection range of 0.1 pg mL−1–10 ng mL−1 and a detection limit of 0.072 pg mL−1, and it had good specificity, stability, and reproducibility. Also, this immunosensor showed recoveries of 89%–109% with an RSD of 2.61%–4.19% for detecting Aβ 1–42 in actual sample analysis. Therefore, the label-free electrochemical immunosensor based on Au-BSN-rGO should have a promising clinical application prospect for detecting Aβ 1–42.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Peng Yang,Heng Guo,Haoran Wu,Fengying Zhang,Jiaxin Liu,Mengyue Li,Yuantao Yang,Yuehan Cao,Guidong Yang,Ying Zhou
The electrocatalytic nitrogen reduction reaction (eNRR) to ammonia (NH 3 ) has been recognized as an effective, carbon–neutral, and great-potential strategy for ammonia production. However, the conversion efficiency and selectivity of eNRR still face significant challenges due to the slow transfer kinetics and lack of effective N 2 adsorption and activation sites in this process. Herein, we designed and fabricated defect-rich TiO 2 nanosheets furnished with oxygen vacancies (OVs) and Au nanoparticles (Au/TiO 2-x ) as the electrocatalyst for efficient N 2 -fixing. The experimental results demonstrate that OVs act as active sites, which enable efficient chemisorption and activation of N 2 molecules. The Au nanoparticles loaded on the OVs-rich TiO 2 nanosheets not only accelerate charge transfer but also change the local electronic structure, thus enhancing N 2 adsorption and activation. In this work, the optimal Au/TiO 2-x electrocatalyst displays a considerable NH 3 yield activity of 12.5 μg h −1 mg cat. -1 and a faradaic efficiency (FE) of 10.2 % at −0.40 V vs reversible hydrogen electrode (RHE). More importantly, the Au/TiO 2-x exhibits a stable N 2 -fixing activity in cycling and it persists even after 80 h of consecutive electrolysis. Density functional theory (DFT) calculations reveal that the OVs serve as the active sites in TiO 2 , while Au nanoparticles are crucial for improving N 2 chemisorption and lowering the reaction energy barrier by facilitating the charge transfer for eNRR with a distal hydrogenation pathway. This research offers a rational catalytic site design for modulating charge transfer of active sites on metal-supported defective catalysts to boost N 2 electroreduction to NH 3 .
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ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Baochao Fan,Jun Gu,Bin Deng,Weilu Guo,Shuaifeng Zhang,Li Li,Bin Li
The COVID-19 pandemic continues to spread worldwide. To protect and control the spread of SARS-CoV-2, varieties of subunit vaccines based on spike (S) proteins have been approved for human applications. Here, we report a new subunit vaccine design strategy that functions as both an antigen carrier and an adjuvant in immunization to elicit high-level immune responses. The complex of 2-hydroxypropyl-trimethylammonium chloride chitosan and amylose entangles Au nanoparticles (HTCC/amylose/AuNPs) forming 40 nm nanocarriers with a positive charge. The obtained positively charged nanoparticles reveal many merits, including the larger S protein loading capacity in PBS buffer, higher cellular uptake ability, and lower cell cytotoxicity, supporting their potential as safe vaccine nanocarriers. Two functionalized nanoparticle subunit vaccines are prepared via loading full-length S proteins derived from SARS-CoV-2 variants. In mice, both prepared vaccines elicit high specific IgG antibodies, neutralize antibodies, and immunoglobulin IgG1 and IgG2a. The prepared vaccines also elicit robust T- and B-cell immune responses and increase CD19+ B cells, CD11C+ dendritic cells, and CD11B+ macrophages at the alveoli and bronchi of the immunized mice. Furthermore, the results of skin safety tests and histological observation of organs indicated in vivo safety of HTCC/amylose/AuNP-based vaccines. Summarily, our prepared HTCC/amylose/AuNP have significant potential as general vaccine carriers for the delivery of different antigens with potent immune stimulation.
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FOOD CHEMISTRY
·
2023
·
IF 8.8
Huanhuan Li,Xiaofeng Luo,Suleiman A. Haruna,Muhammad Zareef,Quansheng Chen,Zhen Ding,Yiyong Yan
Pesticide residue detection in food has become increasingly important. Herein, surface-enhanced Raman scattering (SERS) coupled with an intelligent algorithm was developed for the rapid and sensitive detection of pesticide residues in tea. By employing octahedral Cu 2 O templates, Au-Ag octahedral hollow cages (Au-Ag OHCs) were developed, which improved the surface plasma effect via rough edges and hollow inner structure, amplifying the Raman signals of pesticide molecules. Afterward, convolutional neural network (CNN), partial least squares (PLS), and extreme learning machine (ELM) algorithms were applied for the quantitative prediction of thiram and pymetrozine. CNN algorithms performed optimally for thiram and pymetrozine, with correlation values of 0.995 and 0.977 and detection limits (LOD) of 0.286 and 29 ppb, respectively. Accordingly, no significant difference ( P greater than 0.05) was observed between the developed approach and HPLC in detecting tea samples. Hence, the proposed Au-Ag OHCs-based SERS technique could be utilized for quantifying thiram and pymetrozine in tea.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Juan Li,Shuliang Chen,Yunlong Chen,Li Zhao,Xinrong Li,Haiwen Wang,Xianzhi Hu,Futing Zi
It is important to develop a facile and highly efficient synthetic strategy to fabricate an adsorbent exhibiting excellent adsorption performance and separation ability to recover Au from thiosulfate solutions. Herein, we report a magnetic silica composite (Fe 3 O 4 @SiO 2 -SH) that was successfully fabricated using an economical, one-pot synthesis method for efficient Au(I) adsorption. The results revealed that the performance of the adsorbent was pH dependent, and the single saturated adsorption capacity was 15.11 mg/g. The adsorption process could be well-explained by the Elovich kinetic model and Langmuir isotherm model, indicating that chemical adsorption dominated the monolayer adsorption process. Furthermore, the adsorption process was exothermic. The chemical structures and properties of the adsorbents were analyzed using various characterization and analysis methods. The chelating interaction between -SH and Au(I) promoted the adsorption of Au on Fe 3 O 4 @SiO 2 -SH. The gold-loaded, highly reusable adsorbent could be readily eluted using Na 2 S 2 O 3 (3 mol/L), and > 90% of the gold could be recovered from the adsorbent in a thiosulfate gold leaching solution with Cu 2+ -NH 3 -S 2 O 3 2- as the leaching system. Most of the adsorbent in the pulp could be collected using a magnet, and this reduced the separation cost. The adsorbent can recover more than 90% of gold in both simulated and actual thiosulfate-based gold leaching solutions, indicating that the results reported herein provide a cost-effective strategy for the fabrication of magnetic silica composites characterized by a satisfactory adsorption capacity.
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BIOSENSORS & BIOELECTRONICS
·
2022
·
IF 12.545
Hongjie Xiong,Jing Ye,Maonan Wang,Yihan Wang,Xiaohui Liu,Hui Jiang,Xuemei Wang
Mitochondrion has emerged as a promising drug target for photodynamic therapy (PDT), due to its significant role in supporting life activities and being reactive oxygen species (ROS)-sensitive. Herein, we establish a new strategy that in-situ bio-synthesized Au NCs combine with mitochondria-targeted aptamer-Pyro conjugates (ApPCs) for specific tumor imaging and PDT. The prepared ApPCs can serve as template for the in-situ bio-synthesis of Au NCs, thereby facilitating the generation of Au NCs-ApPCs assemblies in unique tumor microenvironment . Compared with highly negatively charged ApPCs, bio-synthesized nanoscale Au NCs-ApPCs assemblies are conducive to cell uptake, which consequently benefits the delivery of ApPCs. After dissociated from Au NCs-ApPCs, internalized ApPCs can selectively accumulate in mitochondria and generate excess ROS to disrupt the mitochondrial membrane upon irradiation, thus inducing efficient cell killing. In vitro assays demonstrated that the fluorescent Au NCs-ApPCs assemblies could be specifically produced in cancerous cells, indicating the specific tumor imaging ability, while intracellular ApPCs co-localized well with mitochondria. CCK-8 results revealed over 80% cell death after PDT. In vivo study showed that fluorescent Au NCs-ApPCs assemblies were exclusively generated in tumor and achieved long-term retention; tumor growth was significantly inhibited after 15-day PDT treatment. All these evidences suggest that in-situ bio-synthesized Au NCs-ApPCs assembly is a potent mitochondria-targeted nanoprobe to boost the PDT efficacy of cancers.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Bo Tang,Di Wang,Ang Li,Hui-Min Tang,En-Cui Yang,Weili Dai
Herein, core-shell structured Snβ@mesosilica (MS) composite was constructed by oriented assembly of mesoporous silica on microporous Snβ zeolite . The mesoporous channels in the shell were verified vertically aligned to the Snβ core, rendering sufficient mass transfer between the shell and core. The resultant Snβ@MS was thereafter employed as the scaffolds for anchoring Au nanoparticles to develop a bifunctional Au/Snβ@MS catalyst for one-pot base-free conversion of glycerol to methyl lactate (ML), which is regarded as a promising and sustainable route to ML production. Under optimum reaction conditions, a remarkable activity with 98.2% glycerol conversion and 91.9% ML selectivity was achieved. More importantly, the introduction of mesoporous silica shell can efficiently modify the Lewis/Brønsted acid ratio of Snβ@MS, thus inhibit the side reactions. While the confinement effects could protect the highly dispersed Au nanoparticles against sintering. Accordingly, a high stability and recyclability was achieved over the Au/Snβ@MS catalyst.
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JOURNAL OF CATALYSIS
·
2022
·
IF 8.047
Xiaowen Sun,Qing-Nan Wang,Shengyang Wang,Pengfei Zhang,Zhendong Feng,Xianwen Zhang,Zhaochi Feng,Can Li
Photocatalytic selective oxidation of p -xylene with O 2 offers a mild pathway to synthesize p -methyl benzaldehyde ( p -MBA), which is one of the primary precursors in the manufacture of fine chemicals. Here, we report that Au/WO x /TiO 2 photocatalyst selectively catalyzes the oxidation of p -xylene to p -MBA with 88.6% selectivity at 1.0% conversion, the formation of CO x is suppressed to 0.8%. Kinetic experiments indicate that p -methylbenzyl alcohol and p -MBA are initial products. p -Methylbenzyl alcohol is further oxidized to form p -MBA, p -methylbenzyl acid and CO x ; p -MBA is further oxidized to p -methylbenzyl acid and CO x . On TiO 2 surface, p -methylbenzyl alcohol is more prone to directly combust to CO x by O 2 – . Loading of WO x can weaken the adsorption ability of p -methylbenzyl alcohol on the catalyst surface to avoid the combustion. Meanwhile, WO x and Au can facilitate the separation of photo-generated carriers to attain high activity and suppress the O 2 – formation to obtain high selectivity.
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Environmental Science-Nano
·
2022
·Vol. 9
·期 11
·4162-4176
·
IF 9.473
Qiuxia Liu,Yuelong Wang,Meicheng Wen,Yunlong Guo,Yupeng Wei,Guiying Li,Taicheng An
Formaldehyde has strong carcinogenic and cancer-promoting effects, and its removal from indoor air is still challenging. Transition metal oxides such as cobalt(II,III) oxide (Co3O4) are potential catalysts to eliminate formaldehyde. However, the inherent low activity of Co3O4 at room temperature has greatly limited its utilization for indoor air purification. In this work, an extremely facile and mild method was designed to prepare a Au@Co3O4 core–shell nanocomposite catalyst, and its catalytic and photocatalytic activities for formaldehyde oxidation were determined both under dark conditions and visible-light irradiation. This material exhibited not only high catalytic formaldehyde oxidation efficiency in the absence of light but also significantly promoted photocatalytic formaldehyde oxidation activity under visible-light irradiation. Electron paramagnetic resonance and in situ diffuse reflectance infrared Fourier transform spectroscopy were applied to identify the reactive oxygen species and the produced degradation intermediates which adsorbed onto the surface of the catalyst during the oxidation process. It was found that the enhanced catalytic activity of the Au@Co3O4 nanocomposite catalyst under visible-light irradiation was mainly attributed to the promotion of oxygen and formaldehyde activation by the photogenerated carriers, facilitating the formation of dioxymethylene and thereby accelerating the key step of the generation of formic acid and carbonate species. This fundamental study provides evidence for a catalytic mechanism of the photocatalytic degradation of formaldehyde and a basis for the rational design of catalysts that efficiently eliminate indoor formaldehyde through full use of visible light.
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ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Lei Jin,Zhi-Hao Liang,Jia-Qiang Yang,An-Ni Zheng,Zhao-Yun Wang,Fang-Zu Yang,De-Yin Wu,Zhong-Qun Tian,Dongping Zhan
5,5-Dimethylhydantoin (DMH), as a heterocyclic compound with N and O atoms, is an excellent complexing agent for trivalent gold ions . In this work, the tautomeric structures of DMH at different pH values in the solution are determined via theoretical calculations and Raman spectra . Only the ketonic form of DMH exists in weakly acidic and neutral mediums, and only the enolic form of DMH exists in highly alkaline mediums. In the weakly alkaline medium of pH 9, a large number of ketonic forms and a small number of enolic forms coexist. The coordination behavior between DMH and Au(Ⅲ) is clarified in the weakly alkaline medium of pH 9. The DMH in ketonic form is fully coordinated with Au(Ⅲ) at pH 9 and the optimal coordination structure is N2-Au with an N-Au bond energy of 16.17 eV. The electrochemical study reveals that Au(DMH) 4 − coordination ions are in the two-step electro-reductions with the first Au(Ⅲ) to Au(Ⅰ) and the second Au(Ⅰ) to Au on the gold electrode surface. The EC-SERS experiments further verify the interfacial process of tautomeric structures and Au(DMH) 4 − coordination ions.
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