PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
·
2016
·Vol. 33
·期 7
·388-395
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IF 4.367
Wenbin Wang,Liqiang Liu,Liguang Xu,Hua Kuang,Jianping Zhu,Chuanlai Xu
Staphylococcal enterotoxins (SEs) in food samples can cause severe gastroenteritis even at low doses. Detection of SEs with a single assay would not only improve reliability and portability, but would also save time. In this paper, for the first time, a multiplexed gold-nanoparticle-based immunochromatographic (ICT) strip that allows the simultaneous detection of the five main SEs has been reported: SEA, SEB, SEC, SED, and SEE. Based on the sandwich immunoassay of each SE, a multiplexed ICT strip with five test lines is developed. Sensitive and specific paired monoclonal antibodies facilitate the detection, allowing for high sensitivity and good specificity. The portable biosensor platform can simultaneously detect SEA, SEB, SEC, SED, and SEE at concentrations as low as 2.5, 2.5, 2.5, 1, and 5 ng mL −1 , respectively. The entire test can be performed within 15 min and requires no sophisticated instruments except a portable strip reader. To evaluate the multiplexed strip, naturally SEA and SEC contaminated milk samples and pure milk samples spiked with the five SEs are analyzed.
研究领域:
食品安全检测
·
免疫学
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FOOD CONTROL
·
2016
·
IF 3.388
Na Guo,Yu-Ping Zang,Qi Cui,Qing-Yan Gai,Jiao Jiao,Wei Wang,Yuan-Gang Zu,Yu-Jie Fu
Amomum tsaoko is widely distributed in south-west China as a spice. In present study, the antibacterial activity of Amomum tsaoko essential oil (AEO) against foodborne pathogens was evaluated. The antibacterial activity was determined by measuring the zones of inhibition (ZOI), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the time-kill assay. Results showed the susceptibility of foodborne bacteria Escherichia coli ( E. coli ) was excellent with the lowest MIC and MBC values of 3.13 and 6.25 mg/mL, respectively. The probable antibacterial mechanism of AEO was the change in permeability and integrity of the cell membranes leading to leakage of nucleic acids and proteins. Detection of the kinetics of E. coli deactivation in situ showed that AEO has good preservative activities in foods. It is necessary to consider that AEO will become a promising antibacterial additive for food preservative.
研究领域:
食品科学
·
微生物学
·
植物化学
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FOOD CHEMISTRY
·
2026
·
IF 10.4
Fengyang Wang,Panpan Liu,Yin Chen,Mengjuan Li,Yunlong Liu,Yan Qi,Xiaohui Xiong,Yuanjian Liu
Firstly, through various analytical methods, the mechanism by which the electrocatalytic oxygen reduction capacity of E. coli O157:H7 was enhanced under 4% NaCl stress was revealed. The cyclic voltammetry (CV) results indicated that the oxygen reduction ability of E. coli O157: H7 was improved under NaCl stress. Microbiological analysis confirmed the intracellular ROS levels in E. coli O157: H7 under NaCl stress is related to the upregulation of SOD/CAT activity. Metabolomics identified key metabolic adaptations in E. coli O157:H7, including enhanced tricarboxylic acid (TCA) cycles and ubiquinone (Q) biosynthesis, which promoted effective respiratory electron transfer in the bacteria. Secondly, the BPE-ECL (Bipolar Electrochemiluminescence) sensor designed based on 4% NaCl stress showed 9.72 times increase in anode ECL intensity. The detection limit was extremely low at 10 CFU for E. coli O157:H7 in 1 mL sample volume. This research provides a new solution for the sensitive screening of electrochemically active bacteria.
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Science Bulletin
·
2021
·
IF 11.78
Yibing Bu,Taoyu Shen,Wenke Yang,Shiyin Yang,Ye Zhao,Hu Liu,Yanjun Zheng,Chuntai Liu,Changyu Shen
With the rapid development of wearable intelligent devices, low-cost wearable strain sensors with high sensitivity and low detection limit are urgently demanded. Meanwhile, sensing stability of sensor in wet or corrosive environments should also be considered in practical applications. Here, superhydrophobic microcracked conductive paper-based strain sensor was fabricated by coating conductive Ti 3 C 2 T x MXene on printing paper via dip-coating process and followed by depositing superhydrophobic candle soot layer on its surface. Owing to the ultrasensitive microcrack structure in the conductive coating layer induced by the mismatch of elastic modulus and thermal expansion coefficient between conductive coating layer and paper substrate during the drying process, the prepared paper-based strain sensor exhibited a high sensitivity (gauge factor, GF = 17.4) in the strain range of 0–0.6%, ultralow detection limit (0.1% strain) and good fatigue resistance over 1000 cycles towards bending deformation . Interestingly, it was also applicable for torsion deformation detection, showing excellent torsion angle dependent, repeatable and stable sensing performances. Meanwhile, it displayed brilliant waterproof, self-cleaning and corrosion-resistant properties due to the existence of micro/nano-structured and the low surface energy candle soot layer. As a result, the prepared paper-based strain sensor can effectively monitor a series of large-scale and small-scale human motions even under water environment , showing the great promising in practical harsh outdoor environments . Importantly, it also demonstrated good applicability for spatial strain distribution detection of skin upon body movement when assembled into electronic-skin (E-skin). This study will provide great guidance for the design of next generation wearable strain sensor.
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Acta Biomaterialia
·
2021
·
IF 8.947
Ri-Tong Lan,Yue Ren,Xin Wei,Li-Zhi Tang,Nouman Ali Shah,Lu Xu,Shi-Shu Huang,Rizwan M. Gul,Jia-Zhuang Xu,Zhong-Ming Li
Oxidative stability of radiation crosslinked ultrahigh molecular weight polyethylene (UHMWPE) artificial joints is significantly improved by vitamin E (VE), but there is a dilemma that VE hinders crosslinking and thus jeopardizes the wear of UHMWPE. In this effort, we proposed an efficient strategy to stabilize UHMWPE under limited antioxidant contents, where VE and D-sorbitol (DS) were used as the primary antioxidant and the secondary antioxidant respectively. For non-irradiated blends with fixed antioxidant contents, oxidative stability accessed by oxidation induction time (OIT) of VE/DS/UHMWPE blends was superior to that of VE/UHMWPE blends, while DS/UHMWPE blends showed no increase in OIT. The cooperation between DS and VE exhibited a synergistic effect on enhancing the oxidative stability of UHMWPE. Interestingly, the irradiated VE/DS/UHMWPE blends showed comparable OIT but a significantly higher crosslink density than the irradiated VE/UHMWPE blends. The crystallinity, melting point, and in vitro biocompatibility of the blends were not affected by VE and DS. The quantitative relationships of mechanical properties , oxidation stability, crystallinity and crosslink density were established to unveil the correlation of these key factors. The overall properties of VE/UHMWPE and VE/DS/UHMWPE blends were compared to elucidate the superiority of the antioxidant compounding strategy. These findings provide a paradigm to break the trade-off between oxidative stability, crosslink density and mechanical properties, which is constructive to develop UHMWPE bearings with upgraded performance for total joint replacements. Statement of significance VE-stabilized UHMWPE is the most commonly used material in total joint replacements at present. However, oxidation and wear resistance of VE/UHMWPE implants cannot be unified since VE reduces the efficiency of radiation crosslinking. It limits the use of VE. Herein, we proposed a compounding stabilization by the synergy between VE and DS. The antioxidation capability of VE was revived by DS, thus enhancing the oxidation stability of unirradiated UHMWPE. The irradiated VE/DS/UHMWPE exhibited similar oxidation stability but higher crosslink density than irradiated VE/UHMWPE, which is beneficial to combat wear of UHMWPE and to inhibit the occurrence of osteolysis . This synergistic antioxidation strategy endows the UHMWPE joint material with good overall performance, which is of clinical significance.
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ANALYTICAL CHEMISTRY
·
2020
·
IF 6.785
Yu Wang,Yu Xue,Shuang Wang,Jianshe Huang,Xiurong Yang
One of the pathogenesis hypotheses of Alzheimer’s disease (AD) is amyloid depositions and neurofibrillary tangles. Apolipoprotein E (Apo E) acts a vital part in the development of AD by affecting the aggregation and clearance of amyloid-β (Aβ). In this paper, a dual polarization interferometry (DPI) technique was employed for a real-time investigation toward the binding events of Apo E isoforms, for instance, Apo E2, Apo E3, and Apo E4, with Aβ1–40. By evaluation of detailed binding information provided by DPI, the affinities between Apo E isoforms and Aβ1–40 follow the order of E4 > E3 > E2, and the dissociation constants (KD) of Aβ1–40 with Apo E2, Apo E3, and Apo E4 were determined to be 251 ± 37, 40 ± 0.65, and 24.6 ± 2.42 nM, respectively. Our findings reveal the isoform-specific binding behaviors from a kinetics perspective, which can help us understand that Apo E4 has a higher risk of causing AD because of its promoting effect on Aβ aggregation and fibrillation and inefficient clearance of Aβ. Remarkably, this work provides a promising method for exploring the dynamics of interactions between biomolecules and expectantly contributes to the development of AD drugs and therapies targeting Apo E and Aβ.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2021
·
IF 5.279
Chen Yang,Jiajia You,Mengkai Hu,Ganfeng Yi,Rongzhen Zhang,Meijuan Xu,Minglong Shao,Taowei Yang,Xian Zhang,ZhiMing Rao
2,5-Dimethylpyrazine (2,5-DMP) is an important pharmaceutical intermediate and an important essence. Conventional chemical synthesis methods are often accompanied by toxic substances as by-products, and the biosynthesis efficiency of 2,5-DMP is insufficient for industrial applications. In this study, the tdh and soaao genes were overexpressed to enhance enzymatic and nonenzymatic reactions in metabolic pathways, and kbl was knocked out to block competitive branching carbon flow metabolic pathways. Finally, a genetically engineered Escherichia coli strain with the highest carbon recovery rate (30.18%) and the highest yield reported to date was successfully constructed, and 9.21 g·L–1 threonine was able to produce 1682 mg·L–1 2,5-DMP after 24 h. At the same time, an expression regulation strategy and whole-cell biocatalysis helped to eliminate the damage to cells caused by 2,5-DMP, aminoacetone, and reactive oxygen species generated by aminoacetone oxidase from S. oligofermentans, and the negative effect of 2-amino-3-ketobutyrate CoA ligase on the yield of 2,5-DMP in E. coli was also demonstrated.
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EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2020
·Vol. 123
·期 1
·2000224
·
IF 2.056
Gaofeng Yuan,Mengmeng Xu,Meijuan Tan,Jian Dong,Xiaoe Chen
The study aims to investigate the effect of combined supplementation with docosahexaenoic acid (C22:6 n-3, DHA) and vitamin E (VE) on the oxidative stress and liver triglycerides (TG) accumulation induced by high-fat diet (HFD) in mice. C57BL/6J mice are fed either a control diet or an HFD for 8 weeks. Animals are supplemented with DHA, VE, or DHA + VE, respectively. Supplementation with DHA alone shows significant improvement in oxidative stress and hepatic steatosis in mice. Supplementation with DHA significantly reduces the liver TG and total cholesterol contents, and the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, compared with the HFD. Supplementation with DHA also significantly decreases the mRNA expression level of sterol regulatory element-binding protein 1C. However, supplementation with VE alone does not show improvement in oxidative stress and hepatic steatosis. DHA + VE supply obtains a superior effect in alleviation of hepatic steatosis than DHA supplementation alone in mice fed by HFD. The efficacy of DHA potentiated by VE can be due to that VE enhances the effect of DHA in decrease of ALT and AST levels and increase of antioxidant enzyme activity and glutathione level in mice fed by HFD. Practical Applications : Supplementation with DHA significantly improves the oxidative stress and hepatic steatosis induced by HFD in mice. The efficacy of DHA in the alleviation of hepatic steatosis induced by HFD is potentiated by VE. These findings may provide a rational basis for the use of DHA and VE co-supplementation in patients with liver steatosis.
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MOLECULES
·
2020
·Vol. 25
·期 3
·654
·
IF 3.267
Dongmei Ke,Wenxue Chen,Weijun Chen,Yong-Huan Yun,Qiuping Zhong,Xiaotang Su,Haiming Chen
Vitamin E (VE) and β-cyclodextrin (β-CD) can form an inclusion complex; however, the inclusion rate is low because of the weak interaction between VE and β-CD. The results of a molecular docking study showed that the oxygen atom in the five-membered ring of octenyl succinic anhydride (OSA) formed a strong hydrogen bond interaction (1.89 Å) with the hydrogen atom in the hydroxyl group of C-6. Therefore, β-CD was modified using OSA to produce octenyl succinic-β-cyclodextrin (OCD). The inclusion complexes were then prepared using OCD with VE. The properties of the inclusion complex were investigated by Fourier-transform infrared spectroscopy (FT-IR),13C CP/MAS NMR, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results demonstrated that VE had been embedded into the cavity of OCD. Furthermore, the emulsifying properties (particle size distribution, ζ-potential, and creaming index) of the OCD/VE inclusion-complex-stabilized emulsion were compared with that stabilized by β-CD, OCD, and an OCD/VE physical mixture. The results showed that the introduction of the OS group and VE could improve the physical stability of the emulsion. In addition, the OCD/VE inclusion complex showed the strongest ability to protect the oil in the emulsion from oxidation. OCD/VE inclusion complex was able to improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry.Keywords:octenyl succinic β-cyclodextrin;vitamin E;inclusion complex;emulsifying property;oxidation stability
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SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Xiaoyan Zhang,Tingting Wu,Yuemeng Yang,Yongqiang Wen,Shutao Wang,Li-Ping Xu
Superwettable microchips exhibit excellent ability to anchor microdroplets and great potential in ultratrace sample detection. Herein, we present a superwettable electrochemical biosensor based on a dual-DNA walker strategy (dual-DW biosensor) for the attomolar detection of food-borne microorganisms ssDNA in microdroplets. In the presence of the target E. coli O157: H7 ssDNA, the blocked walking probe is activated as the first-step DNA walker. With the aid of the Nt.BsmAI nicking endonuclease, the partial sequence of the basal probe was released, thus achieving the first-step signal amplification. Then the hairpin probe 1(H1) was opened by the released basal probe and followed by the autonomous strand displacement of the ferrocene (Fc) labeled hairpin probe 2 (H2) and movement of the basal probe. Under optimized conditions, the dual-DNA walker strategy finally renders the dual-DW biosensor an ultrahigh sensitivity of 30 aM toward E. coli O157: H7 ssDNA and a broad detection linear range. The dual-DW biosensor also enables successful analysis of trace amount of E. coli O157: H7 ssDNA in real food samples. The superwettable electrochemical biosensor based on a dual-DNA walker strategy is expected to be a versatile tool for ultratrace DNA detection and be promising in food analysis.
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METABOLIC ENGINEERING
·
2020
·
IF 7.263
Xi Deng,Liuqing Chen,Mohan Hei,Tiangang Liu,Yan Feng,Guang-Yu Yang
Medium-chain fatty acids (C6–C10) have attracted much attention recently for their unique properties compared to their long-chain counterparts, including low melting points and relatively higher carbon conversion yield. Thioesterase enzymes , which can catalyze the hydrolysis of acyl-ACP (acyl carrier protein) to release free fatty acids (FAs), regulate both overall FA yields and acyl chain length distributions in bacterial and yeast fermentation cultures. These enzymes typically prefer longer chain substrates. Herein, seeking to increase bacterial production of MCFAs, we conducted structure-guided mutational screening of multiple residues in the substrate-binding pocket of the E. coli thioesterase enzyme ‘TesA. Confirming our hypothesis that enhancing substrate selectivity for medium-chain acyl substrates would promote overall MCFA production, we found that replacement of residues lining the bottom of the pocket with more hydrophobic residues strongly promoted the C8 substrate selectivity of ‘TesA. Specifically, two rounds of saturation mutagenesis led to the identification of the ‘TesA RD−2 variant that exhibited a 133-fold increase in selectivity for the C8-ACP substrate as compared to C16-ACP substrate. Moreover, the recombinant expression of this variant in an E. coli strain with a blocked β -oxidation pathway led to a 1030% increase in the in vivo octanoic acid (C8) production titer. When this strain was fermented in a 5-L fed-batch bioreactor , it produced 2.7 g/L of free C8 (45%, molar fraction) and 7.9 g/L of total free FAs, which is the highest-to-date free C8 titer to date reported using the E. coli type II fatty acid synthetic pathway. Thus, reshaping the substrate binding pocket of a bacterial thioesterase enzyme by manipulating the hydrophobicity of multiple residues altered the substrate selectivity and therefore fatty acid product distributions in cells. Our study demonstrates the relevance of this strategy for increasing titers of industrially attractive MCFAs as fermentation products.
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Xiaolan Zhou,Dong Xu,Yuancai Chen,Yongyou Hu
Mn/Fe@porous carbon (PC) was successfully fabricated through a simple carbonization of Mn-doped MIL-53(Fe) precursor and used as cathode modification in hydroxyl radical ( OH) based heterogeneous electro-Fenton (hetero-EF) process for triclosan (TCS) degradation. With co-doping of bimetal (Mn and Fe) in porous carbon, Mn/Fe@PC could markedly enhance the electrocatalysis with low oxygen reduction potential, high electrochemical active area and low resistance. Mn/Fe@PC modified cathode showed high electrocatalytic activity, great stability and low energy consumption (1.92 kWh m −1 and 0.63 kWh log −1 m −3 ) for TCS degradation over a wide pH range. The complete TCS degradation within 120 min and a 56.9 ± 2.0% TOC removal within 240 min were achieved under the condition of current 40 mA and initial pH 3. Based on the CV curves, the more negative reductive peak of Fe and Mn revealed the kinetically beneficial regeneration of Fe II /Mn II/III in Mn/Fe@PC. The electron transfer between Fe II/III and Mn II/III/IV , together with the direct regeneration of Fe II / Mn II/III on the cathode, could markedly promote the utilization of H 2 O 2, eventually leading to facilitating TCS degradation. According to the GC–MS intermediates, the possible TCS degradation pathway was deduced, including hydroxylation and dehalogenation attacked by OH. Furthermore, the TCS degradation experiments were also performed in different water matrix including river water, tap water and municipal sewage, indicating the feasibility of the TCS degradation in actual waters with Mn/Fe@PC-CP cathode in hetero-EF process. The toxicity analysis indicated that the hetero-EF process could achieve the TCS degradation and toxicity reducing.
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危险品化学品经营许可证（带存储）