Nature Communications
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2020
·Vol. 11
·期 1
·1-13
·
IF 12.121
Liu Yi,Zhang Jihua,Li Yapeng,Qian Qizhu,Li Ziyun,Zhu Yin,Zhang Genqiang
Replacing sluggish oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) to produce hydrogen has been considered as a more energy-efficient strategy than water splitting. However, the relatively high cell voltage in two-electrode system and the required external electric power hinder its scalable applications, especially in mobile devices. Herein, we report a bifunctional P, W co-doped Co 3 N nanowire array electrode with remarkable catalytic activity towards both HzOR (−55 mV at 10 mA cm −2 ) and hydrogen evolution reaction (HER, −41 mV at 10 mA cm −2 ). Inspiringly, a record low cell voltage of 28 mV is required to achieve 10 mA cm −2 in two-electrode system. DFT calculations decipher that the doping optimized H* adsorption/desorption and dehydrogenation kinetics could be the underlying mechanism. Importantly, a self-powered H 2 production system by integrating a direct hydrazine fuel cell with a hydrazine splitting electrolyzer can achieve a decent rate of 1.25 mmol h −1 at room temperature.
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Nano Research
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2020
·Vol. 13
·期 9
·2420-2426
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IF 8.183
Luo Ergui,Wang Chen,Li Yang,Wang Xian,Gong Liyuan,Zhao Tuo,Jin Zhao,Ge Junjie,Liu Changpeng,Xing Wei
Fe/N/C material is the most competitive alternative to precious-metal catalysts for oxygen reduction. In view of the present consensus on active centers, further effort is directed at maximizing the density of single Fe atoms. Here, the imperfections in commonly used doping strategy of Fe for the synthesis of zeolitic imidazolateframework (ZIF)-derived Fe/N/C catalysts are revealed. More importantly, a strikingly improved catalyst is obtained by a ‘second pyrolysis’ method and delivers a half-wave potential of 0.825 V (vs. RHE) in acidic media. The strong confinement effect of carbonaceous host accounts for the formation of dense single-atom sites and thus the high activity. Our findings will potentially facilitate future improvement of M/N/C catalysts.
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CELLULOSE
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2020
·Vol. 27
·期 13
·7791-7803
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IF 4.21
Tang Bin,Xu Chengna,Zou Fan,Zhou Ji,Zhang Jin,Li Jingliang,Wang Jinfeng,Wang Xungai
Abstract Palladium nanoparticle (PdNP) loaded cotton fabrics were successfully prepared through in situ synthesis of PdNPs via heating. The resulting PdNP-treated cotton fabrics showed color originated from the localized surface plasmon resonance (LSPR) effect of PdNPs, with satisfactory color fastness to washing and rubbing, and enhanced UV protection properties. The PdNP-treated cotton greatly accelerated the reduction reaction of 4-nitrophenol (4-NP) by sodium borohydride, exhibiting distinct catalytic activity. More importantly, the PdNP-treated cotton fabric displayed enzyme mimicking activity to catalyze the oxidation of a chromogenic enzymatic substrate (3,3′,5,5′-tetramethylbenzidine) in the presence of hydrogen peroxide, which provides a visual sensing platform for hydrogen peroxide. This work demonstrated a versatile approach to fabricate PdNP-treated cotton fabrics with multiple functions. This study on the surface modification of cotton fabrics with PdNPs could promote the practical applications of functional fibrous materials in catalysis and sensing fields. Graphic Abstract
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BIOTECHNOLOGY LETTERS
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2020
·Vol. 42
·期 11
·2211-2221
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IF 1.977
Zhang Xiaomin,Chen Feiyun,He Chao,Fang Wei,Fang Zemin,Zhang Xuecheng,Wang Xiaotang,Xiao Yazhong
This study was aimed at improving the thermostability of dextran glucosidase PspAG97A, a member of the glycoside hydrolase family 97, from Pseudoalteromonas sp. K8. A total of 9 lysine residues were chosen using the TKSA-MC program based on the optimization of surface charge-charge interactions and were mutated to glutamate for shifting the enzyme’s isoelectric point off its optimum pH value. Three mutants K75E, K363E and K420E showed enhanced thermostability. The triple mutant, K75E/K363E/K420E, was found to be the best with a 7.3-fold increase in half-life ( t 1/2 ) at 33 °C compared to that of the wild-type (WT). Most importantly, this mutant showed comparable enzymatic activity to that of the WT protein. Structural modelling demonstrated that increased surface charge-charge interactions and optimization of surface hydrophobic and electrostatic contacts contributed to the improved thermostability displayed by K75E/K363E/K420E.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2020
·Vol. 27
·期 25
·31289-31299
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IF 3.056
Zhu Mengyu,Lu Jun,Hu Yadong,Liu Ying,Hu Shuheng,Zhu Chengzhu
The superoxide anion radical (O 2 •− ) is one of the most predominant reactive oxygen species (ROS), which is also involved in diverse chemical and biological processes. In this study, O 2 •− was generated by irradiating riboflavin in an O 2 -saturated solution using an ultraviolet lamp ( λ em = 365 nm) as the light source. The photochemical reduction of 1,4-benzoquinone ( p -BQ) by O 2 •− was explored by 355-nm laser flash photolysis (LFP) and 365-nm UV light steady irradiation. The results showed that the photodecomposition efficiency of p -BQ was influenced by the riboflavin concentration, p -BQ initial concentration, and pH values. The superoxide anion radical originating from riboflavin photolysis served as a reductant to react with p -BQ, forming reduced BQ radicals (BQ •− ) with a second-order rate constant of 1.1 × 10 9 L mol −1 s −1 . The main product of the photochemical reaction between p -BQ and O 2 •− was hydroquinone (H 2 Q). The present work suggests that the reaction with O 2 •− is a potential transformation pathway of 1, 4-benzoquinone in atmospheric aqueous environments.
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Nanoscale Research Letters
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2020
·Vol. 15
·期 1
·1-13
·
IF 3.578
Cai Defu,Han Cuiyan,Liu Chang,Ma Xiaoxing,Qian Jiayi,Zhou Jianwen,Li Yue,Sun Yiming,Zhang Changting,Zhu Wenquan
An enzyme-responsive colon-specific delivery system was developed based on hollow mesoporous silica spheres (HMSS) to which biodegradable chitosan (CS) was attached via cleavable azo bonds (HMSS–N=N–CS). Doxorubicin (DOX) was encapsulated in a noncrystalline state in the hollow cavity and mesopores of HMSS with the high loading amount of 35.2%. In vitro drug release proved that HMSS–N=N–CS/DOX performed enzyme-responsive drug release. The grafted CS could increase the biocompatibility and stability and reduce the protein adsorption on HMSS. Gastrointestinal mucosa irritation and cell cytotoxicity results indicated the good biocompatibility of HMSS and HMSS–N=N–CS. Cellular uptake results indicated that the uptake of DOX was obviously increased after HMSS–N=N–CS/DOX was preincubated with a colonic enzyme mixture. HMSS–N=N–CS/DOX incubated with colon enzymes showed increased cytotoxicity, and its IC 50 value was three times lower than that of HMSS–N=N–CS/DOX group without colon enzymes. The present work lays the foundation for subsequent research on mesoporous carriers for oral colon-specific drug delivery.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2020
·Vol. 412
·期 18
·4375-4382
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IF 3.637
Zhang Wen Jie,Liu Shi Gang,Zhang Xing Yue,Luo Hong Qun,Li Nian Bing
Ratiometric assays, which can effectively surmount external interference, have attracted extensive research interests. Herein, a novel ratiometric sensing platform for Hg 2+ is designed based on nitrogen-doped carbon dots (N-CDs) with two different optical signals. Under a single excitation, N-CDs have two emission peaks around 668 nm and 412 nm, which are second-order scattering and fluorescence, respectively. Upon the addition of Hg 2+ , the weak scattering emission at 668 nm can be increased apparently, while the strong fluorescence intensity at 412 nm is weakened. Moreover, the ratio of scattering intensity to fluorescence intensity is linearly dependent on Hg 2+ concentration (0.1–10 μM and 10–30 μM, respectively), and the detection limit is 66 nM. In addition, the ratiometric sensing mechanism is investigated in detail, which is due to the combined effect of aggregation-induced fluorescence quenching and scattering enhancement. Furthermore, the developed sensing approach holds a promising application for Hg 2+ detection in actual samples.
Graphical abstract
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MICROCHIMICA ACTA
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2020
·Vol. 187
·期 5
·1-9
·
IF 6.232
Fang Dandan,Zeng Baoshan,Zhang Shupei,Dai Hong,Lin Yanyu
A self-enhanced electrochemiluminescent ratiometric immunoassay for zearalenone is described. A system composed of N-aminobutyl-N-ethylisoluminol (ABEI) and glutathione (GSH) produces a strong electrochemiluminescence (ECL) at an applied potential of 0.8 V, probably because of short electron transfer distance and reduced energy loss. The method also uses octahedral anatase mesocrystals (OAM) with a large specific surface facilitating immobilization of ABEI and GSH. Helical carbon nanotubes, possessing a large specific surface, superior mechanical stability, and excellent electrical conductivity which serve as a solid support, greatly enhanced the loading capacity for g-C 3 N 4 nanosheets and horseradish peroxidase-labeled anti-antibody. The peroxidase accelerates the decomposition of H 2 O 2 to produce reactive oxygen species (ROSs), amplifying the blue ECL of ABEI and the green ECL of g-C 3 N 4 . The ratiometric sandwich immunoassay (performed by the ratio of ECL intensity at − 1.3 V and 0.8 V) allows for sensitive and reliable determination of ZEN in a wide linear range from 1.0 × 10 −4 ng/mL to 10 ng/mL. The method was successfully applied to the analysis of corn hazelnut samples for ZEN.
Schematic presentation of a self-enhanced electrochemiluminescent ratiometric immunosensor based on octahedral anatase mesocrystals (OAM) supported ABEI-glutathione (GSH) and g-C 3 N 4 functionalized helical carbon nanotubes (HCNT) for zearalenone (ZEN) determination.
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Science China-Chemistry
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2020
·Vol. 63
·期 7
·1012-1018
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IF 6.356
Guo Xiaoxi,Wu Jinghua,Xia Lian,Xiang Meihao,Qu Fengli,Li Jinghong
Photoelectrochemical (PEC) biosensors have shown great promise in bioanalysis and diagnostic applications in recent years. In this work, the CuO/Cu 2 O nanowire array (CuO/Cu 2 O Nanowire) supported on copper foam was prepared as a photocathode for detection of tyrosinase though quinone-chitosan conjugation chemistry method. The in-situ generated quinones that were the catalytic product of tyrosinase acted as electron acceptors, which were captured by the chitosan deposited on the surface of the electrode. Direct immobilization of electron acceptor on the electrode surface improved the photocurrent conversion efficiency and thus sensitivity. The as-prepared biosensor can realize a rapid response in a wide linear range of 0.05 U/mL to 10 U/mL with the detection limit as low as 0.016 U/mL of tyrosinase. The current work provides a new perspective to design and develop highly sensitive and selective PEC biosensor.
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3 Biotech
·
2020
·Vol. 10
·期 4
·1-9
·
IF 1.798
Xie Xu-Ting,Zhang Xiao,Liu Yang,Chen Xian-Qiang,Cheong Kit-Leong
This study determined the composition of the monosaccharide, 3, 6-anhydrogalactose (AnGal), in red algae and explored the potential whitening activity of the extract. Using gas chromatography–mass spectrometry (GC–MS), the AnGal composition of six different species of red seaweed ( Porphyra haitanensis , Gracilaria chouae , Gracilaria blodgettii , Gracilaria lemaneiformis , Eucheuma galetinae , and Gelidium amansii ) was successfully analyzed, revealing molar ratios ranging from 1.0:1.0 to 1.0:3.1 of AnGal and galactose (Gal), respectively. Employing the tyrosinase inhibition assay, the skin-whitening effect of AnGal red seaweed polysaccharides was determined. Polysaccharides from P. haitanensis , G. chouae , and G. blodgettii as well as their degradation products showed higher tyrosinase inhibitory activity (inhibition rates 24.2–26.8%). These results suggest that the GC–MS approach could conveniently be used in quality control or for the quantitative determination of AnGal and Gal in red seaweed polysaccharides as well as exploring their potential application in cosmetic and functional food products. The findings here exhibited that red seaweed polysaccharides and their degradation products were potential ingredients for cosmeceutical industries.
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SN Applied Sciences
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2020
·Vol. 2
·期 4
·1-8
·
IF 0
Wijerathne H. M. C. Suboda,Yan Dong,Zeng Bin,Xie Yanping,Hu Hongchao,Wickramaratne M. Nirmali,Han Yingchao
Surface properties of biomaterials are significant as they are intended to interact with biological system interfaces. This study was aimed to reveal the effect of nano-hydroxyapatite (Nano-HAP) on the properties of poly(lactic acid) (PLA) microspheres. Nano-HAP particles of 10–30% content were successfully embedded in PLA microspheres by emulsion solvent evaporation method. The incorporation of Nano-HAP particles resulted in the increases of surface hydrophilicity and surface rough of microspheres that depended on the content of Nano-HAP. With the increase of Nano-HAP content, the adsorption capacity for protein of PLA/Nano-HAP composite microspheres was increased significantly. Moreover, the incorporation of Nano-HAP could promote the adhesion and proliferation of rat Mesenchymal Stem cells (rMSCs) on microspheres, which could be attributed to the component of Nano-HAP as well as the increases of surface hydrophilicity and rough. In addition, PLA/Nano-HAP composite microspheres showed significant promotion on osteogenic differentiation of rMSCs due to the facilitation of Nano-HAP. Accordingly, the incorporation of Nano-HAP could improve the physicochemical and biological properties of PLA microspheres, and the resulting PLA/Nano-HAP composite microspheres could be expected to achieve good application in tissue repair.
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Journal of Food Measurement and Characterization
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2020
·Vol. 14
·期 4
·2010-2020
·
IF 1.648
Huang Shuai,Wang Qiang,Wang Yaosong,Ying Ruifeng,Fan Gongjian,Huang Meigui,Agyemang Mary
This study characterized the quality, composition and antioxidant activities of olive oil from four olive varieties grown in Chongqing, southwest of China. With the fruit skin turned from green to semi black, the percentage of oleic acid decreased while the percentage of linoleic acid increased. The highest concentrations of total phenolic content, total flavonoid content and total antioxidant activity were found in the Coratina olive oils, in which the lowest content of oleuropein was also observed. Significant differences of fatty acid composition at sn-2 position were observed among the varieties, with the percentage of oleic acid at sn-2 position in Picual olive oils were significantly higher than that of other varieties ( p < 0.05). In addition, the different varieties of olive oil samples were divided into three categories by principal component analysis (PCA), and the quality of Coratina olive oils were greatly affected by fruit ripening stage. With the fruit ripening, the levels of hydroxytyrosol, rutin, total phenolics, total flavonoids and antioxidant activities in Coratina olive oil all declined. This work can provide guidance for the harvesting time and processing of olives in Chongqing.
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