APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2019
·Vol. 103
·期 21
·8839-8851
·
IF 3.67
Liu Yang,Zhu Lingfeng,Qi Wenpeng,Yu Bo
D- p -hydroxyphenylglycine (D-HPG) functions as an intermediate and has important value in antibiotic industries. The high pollution and costs from chemical processes make biotechnological route for D-HPG highly desirable. Here, a whole-cell transformation process by D-hydantoinase(Hase) and D-carbamoylase(Case) was developed to produce D-HPG from DL-hydroxyphenylhydantoin(DL-HPH) in Escherichia coli . The artificially designed ribosome binding site with strong intensity significantly facilitated the protein expression of limiting step enzyme Case. Next, the cell wall permeability was improved by disturbing the peptidoglycan structure by overproduction of D,D-carboxypeptidases without obviously affecting cell growth, to increase the bioavailability of low soluble hydantoin substrate. By fine-tuning regulation of expression level of D,D-carboxypeptidase DacB, the final production yield of D-HPG increased to 100% with 140 mM DL-HPH substrate under the optimized transformation conditions. This is the first example to enhance bio-productivity of chemicals by cell wall engineering and creates a new vision on biotransformation of sparingly soluble substrates. Additionally, the newly demonstrated ‘hydroxyl occupancy’ phenomenon when Case reacts with hydroxyl substrates provides a referential information for the enzyme engineering in future.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 7
·2913-2922
·
IF 3.442
Zhong Zeqin,Chen Lingzhen,Huang Shaozhen,Shang Weili,Kong Lingyong,Sun Ming,Chen Lei,Ren Wangbao
Single-crystalline LiNi 0.5 Co 0.2 Mn 0.3 O 2 (denoted as SC-523) with micron size had been successfully synthesized through a facile method. Electrochemical impedance spectroscopy and differential scanning calorimetry were carried out to identify the improved electrochemical performance and desired thermal stability. Even after 100 cycles, SC-523 still delivered a discharge capacity of 151.1 mA h g −1 (capacity retention with 90.3%) at 1 C in voltage range from 3.0 to 4.5 V (vs. Li/Li + ), while polycrystalline spherical LiNi 0.5 Co 0.2 Mn 0.3 O 2 (denoted as PC-523) only exhibited 141.7 mA h g −1 (capacity retention with 78.4%). Besides, SC-523 shows a higher decomposition temperature of 332.13 °C, 14.61 °C higher than that of PC-523 during the thermal decomposition. Consequently, single-crystalline particles with robust morphological integrity ensure the enhanced cycling stability and thermal stability.
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高影响因子
MICROCHIMICA ACTA
·
2019
·Vol. 187
·期 1
·1-11
·
IF 5.479
Wang Qian-Long,Huang Wei-Xue,Zhang Pu-Juan,Chen Li,Lio Chon-Kit,Zhou Hua,Qing Lin-Sen,Luo Pei
An ultra-sensitive method is described here for the determination of HIF-1α (an early biomarker for myocardial infarction) in circulating exosomes in serum. Gold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. The apt-AuNP-coated gold seeds were grown by seed-mediated growth, and this significantly increased the peroxidase-mimicking property the nanoparticles. A chromogenic system composed of 3,3′5,5′-tetramethylbenzidine and hydrogen peroxide was used. Absorbance at 652 nm increases linearly in the 0.3 to 200 ng L −1 HIF-1α concentration range, and the limit of detection is 0.2 ng L −1 . The method was tested by analyzing rat serum from isoproterenol (ISO)-induced myocardial infarction. It allows HIF-1α to be directly determined in a 25 μL sample without preconcentration. The assay is not interfered by the polydispersity of exosomes released under either health and disease conditions.
Gold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. Nanosized gold seed particles were then modified with the functionalized gold nanospheres, and this strongly increases the peroxidase-mimicking activity of the nanomaterial. By using the tetramethylbenzidine/H 2 O 2 chromogenic system, the absorbance at 652 nm increases linearly in the 0.3 to 200 ng L -1 HIF-1α concentration range.
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高影响因子
Journal of Food Measurement and Characterization
·
2019
·Vol. 14
·期 2
·694-707
·
IF 1.415
Yin Xing-shuo,Zhang Xue-qin,Li De-qiang
In this study, the ultrasound-assisted extraction (UAE) of flavonoids with maximal antioxidant and tyrosinase inhibitory activities and identification of the principal individual flavonoids compounds of Semen Oroxyli by UHPLC-DAD-QTOF-MS/MS was proposed. The method was optimized by a three-factor-three-level Box–Behnken design (BBD) and Derringer’s desirability function using methanol concentration, extraction time, and liquid/solid ratio as factors, while, the total flavonoids content (TFC), antioxidant activities (DPPH, ABTS, FRAP, superoxide anion and hydroxyl radicals) and tyrosinase inhibitory activity as responses. The experimental results showed that the optimal extraction conditions were as followed: a solvent of 69.90% methanol, an extraction time of 30.64 min and a liquid/solid ratio of 31.30 mL/g, which give individual response values of 19.79 mg RE/g, 78.66%, 99.92%, 19.05 mM FE/g, 20.49%, and 13.37% for TFC, DPPH, ABTS, FRAP, superoxide anion and hydroxyl radicals, respectively. In addition, the tyrosinase inhibition assay showed that the extract of Semen Oroxyli exhibited strong inhibitory activity against the tyrosinase. There were no significant differences between the results of the optimization experiments and those predicted by the models. By UHPLC-DAD-QTOF-MS/MS analysis, the main flavonoids identified in the optimized UAE extracts of Semen Oroxyli were oroxin B, oroxin A, chrysin-7- O -β- d -glucuronid, baicalein and chrysin.
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CELLULOSE
·
2019
·Vol. 27
·期 2
·657-676
·
IF 3.917
Wang Hong,Pudukudy Manoj,Ni Yonghao,Zhi Yunfei,Zhang Heng,Wang Zhenquan,Jia Qingming,Shan Shaoyun
Abstract A single-step ammonium persulfate (APS)-assisted swelling, followed by oxidation, can prepare nanocrystalline cellulose (NCC) from cotton linters. The APS-swelling is the critical step in the process, and the effects of swelling time, temperature and solid–liquid ratios were thoroughly investigated. The optimal conditions for NCC preparation were a swelling time of 3.0 h, a swelling temperature of 25 °C, and a solid–liquid ratio of 1:50. Upon heating at 60 °C, the persulfate enters the amorphous region of the cellulose and produces active SO
·− 4
and H 2 O 2 , which effectively attack the two-phase structure of cellulose and oxidize the –OH group at the C-6 position. The swelling temperature of 25 °C plays a crucial role in breaking the hydrogen bonds between the molecular chains of cellulose. It permits the preparation of NCC with a high yield and crystallinity index. The crystalline structure of cellulose I β did not change after APS swelling and oxidation. The atomic force microscopic analysis confirmed the formation of spindle-shaped particles with a helical structure. Upon natural evaporation of the NCC suspension, brittle films were obtained, which exhibited a left-hand layered structure and high iridescence with a fingerprint-texture. These materials can be applied as strength additives and chiral templates. Graphic abstract
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 6
·2471-2481
·
IF 3.442
Ji Lijun,Zhou Shu,Liu Xi,Gong Mindong,Xu Tong
PAN–COOH fibers were prepared with PAN fibers and used as templates, carbon source and nitrogen source for the first time to prepare carbon- and nitrogen-doped TiO 2 /carbon (C, N–TiO 2 ) composite fibers. The C, N–TiO 2 composite fibers were characterized by TEM, SEM, XPS, XRD, IR, Raman and UV–Vis spectrum. The composite fibers exhibited strong photocatalytic activity in photodegradation of Rh B solution under UV–Vis light. Doping C and N into TiO 2 materials could reduce the band gap width of TiO 2 and expand the light absorption range. The carbon fiber inside the composite fiber promoted the transfer of photoelectrons and inhibited the combination of photogenerated electrons and holes. The large specific surface area of C, N–TiO 2 composite fibers was also conducive to the photocatalytic activity. The macroscale C, N–TiO 2 composite fibers were easy for recycling. Therefore, the C, N–TiO 2 composite fibers had the potential for dealing with organic pollutants in water.
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Communications Biology
·
2019
·Vol. 2
·期 1
·1-11
·
IF 0
Lin Yanke,Wang Shuai,Zhou Ziyue,Guo Lianxia,Yu Fangjun,Wu Baojian
Metabolism is a major defense mechanism of the body against xenobiotic threats. Here we unravel a critical role of Bmal1 for circadian clock-controlled Cyp3a11 expression and xenobiotic metabolism. Bmal1 deficiency decreases the mRNA, protein and microsomal activity of Cyp3a11, and blunts their circadian rhythms in mice. A screen for Cyp3a11 regulators identifies two circadian genes Dbp and Hnf4α as potential regulatory mediators. Cell-based experiments confirm that Dbp and Hnf4α activate Cyp3a11 transcription by their binding to a D-box and a DR1 element in the Cyp3a11 promoter, respectively. Bmal1 binds to the P1 distal promoter to regulate Hnf4α transcriptionally. Cellular regulation of Cyp3a11 by Bmal1 is Dbp- and Hnf4α-dependent. Bmal1 deficiency sensitizes mice to toxicities of drugs such as aconitine and triptolide (and blunts circadian toxicity rhythmicities) due to elevated drug exposure. In summary, Bmal1 connects circadian clock and Cyp3a11 metabolism, thereby impacting drug detoxification as a function of daily time.
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CLAYS AND CLAY MINERALS
·
2019
·Vol. 67
·期 4
·275-282
·
IF 1.835
Liu Xiaonan,Zhang Youkui,Bian Liang,Li Jinshan
The adsorption of bovine serum albumin (BSA) protein is important for protein research but remains a great challenge. Here, the hydrothermal method and calcination in a hydrogen-argon mixed atmosphere were used to obtain ordered mono-crystalline magnetic Fe 3 O 4 nanorings with controllable size and uniform structure, which were applied to the adsorption of BSA protein. The results showed that the magnetic Fe 3 O 4 nanorings prepared have the advantages of good crystallinity, controllable morphology, and excellent magnetic response. The Fe 3 O 4 nanorings had an outer diameter of ~160–180 nm, inner diameter of ~80–110 nm, and height of 70 to ~110 nm. The amount of BSA adsorbed by magnetic Fe 3 O 4 nanorings increased with increasing protein concentration; when the concentration of BSA was ~2.75 mg·mL -1 the adsorption amount approached saturation. When the pH value of the solution was ~5, the Fe 3 O 4 nanorings absorption of BSA was greatest. With increasing adsorption time, the amount adsorbed increased gradually. Adsorption equilibrium was reached after 3 h. According to the formula, the saturated adsorption capacity of BSA per gram of magnetic Fe 3 O 4 nanorings was 325.2 mg.
.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 11
·4578-4591
·
IF 3.442
Diao Shuai,Liu Huie,Chen Shuang,Xu Wenlong,Yu Anran
Graphene aerogels with different pore sizes, volumes and degrees of reduction were prepared through Pickering emulsion method. The controllable preparation of aerogels was achieved. The graphene aerogels prepared were characterized by FTIR and XPS. The adsorption capacity of pure oil by graphene aerogel was investigated. The graphene aerogels can adsorb pure oil quickly and hardly adsorb water. Linear relation exists between saturated adsorption capacities of graphene aerogels on oil and the densities of the oil adsorbed. The volume of the adsorbed organics on unit mass of the aerogel is 186.46 cm 3 g −1 . The occupancy rate in the aerogel pores is 73.71%. The factors affecting its adsorption rate on emulsified oil were investigated. The adsorption curves of graphene aerogels on emulsified oil conform to the pseudo-second-order kinetic model. The larger the inner diameter of the pore size in the graphene aerogels and the larger the outer surface area, the faster the adsorption rate of the emulsified oil would be. The adsorption rate of the rough internal with higher hydrophobicity decreases slightly, but as the degree of reduction increases, the hydrophobicity gradually increases and the adsorption rate increases gradually, so there should exist an optimum hydrophobicity value of aerogels for the adsorption of emulsified oil in water.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 27
·期 2
·1888-1897
·
IF 2.914
Wang Ying,Wang Luxing,Deng Xiaoyan,Gao Hongtao
Waste biomass can be recycled to prepare biochar for soil restoration, in which process soil fertility would not be lost. In this work, biochar was prepared from waste pomelo peel, combined with ZnO, to be used to immobilize Cu(II) in contaminated soil, whose maximum adsorption capacity was up to 216.37 mg g −1 . Due to combination of ZnO, the BET surface area of biochar increased from 2.39 to 18.53 m 2 g −1 . Meanwhile, the surface functional groups increased, which was conducive to fixation of metal ion on the surface of biochar. Both pseudo-second-order kinetics and Langmuir isotherm model fit the experimental data well. Adsorption was easy to happen since the adsorption site on the surface of biochar/ZnO had a strong affinity with Cu(II). In addition, mechanism investigation indicated that Cu(II) was bond with biochar/ZnO mainly by non-bioavailable state (75.6%) primarily. It inferred that biochar/ZnO was an efficient and promising passivator in reducing heavy metal risk in soil.
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高影响因子
CELLULOSE
·
2019
·Vol. 27
·期 3
·1341-1355
·
IF 3.917
Zhang Xueqin,Luo Wenhan,Xiao Naiyu,Chen Mingjie,Liu Chuanfu
Abstract The aim of this study is to prepare functional hemicellulose (HC) films with flexibility, thermoplasticity and UV-shielding ability. HC was firstly esterified with vinyl benzoate and then reinforced with poly(vinyl alcohol) (PVA) and nano-zinc oxide (ZnO). After esterification, the solubility of benzoated HC (BH) increased, while the thermal stability decreased. Moreover, esterification could transform HC into crystalline nature and endow HC with tunable transition temperature ( T g ). Adding equivalent mass of PVA and 1% ZnO increased the thermal stability of BH/PVA/ZnO films. XRD and DSC analyses showed the new crystalline structure and the decreased T g of films, probably due to the interactions among BH, PVA and ZnO. From SEM, the cross sections of films were dense, rough, and were connected to form the network structure, promoting the uniform insertion of ZnO into the matrix. The films showed moderate tensile strength and good flexibility with the maximum elongation at break of 87.18%. In addition, the water vapor permeability (WVP) and oxygen permeability (OP) values of BH/PVA/ZnO film were 2.08 × 10 −10 g/m s Pa and 0.95 cm 3 μm/m 2 d kPa, respectively. Moreover, the film with 1% ZnO exhibited excellent UV-shielding properties with the percentage blocking of UV-A and UV-B of 99.34% and 99.99%, respectively. Graphic abstract
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2020
·Vol. 412
·期 3
·621-633
·
IF 3.637
Liu Congmin,Wang Yudan,Zhang Lei,Qin Jia′an,Dou Xiaowen,Fu Yanwei,Li Qian,Zhao Xue,Yang Meihua
We produced a prometryn-specific monoclonal antibody and propose a strategy for convenient on-site detection of prometryn residues in herbs for the first time. This strategy has perfect applicability in a complex herbal medicine matrix. The strategy combines a semiquantitative immunochromatographic strip assay with a heterologous indirect competitive ELISA. When there was no matrix interference, the ELISA had a half-maximal inhibitory concentration of 2.6 ng·mL -1 and a limit of detection of 0.2 ng·mL -1 . The immunochromatographic strip assay can be completed within 5 min with a visual limit of detection of 1 ng·mL -1 . Although the sample matrix had different effects on the sensitivity of the antibody, excellent repeatability and accuracy were achieved. The method was successfully applied for the screening and determination of prometryn residue in multiple complex herb samples for the first time, and the results were in good agreement with those obtained by liquid chromatography–tandem mass spectrometry. The proposed strategy is rapid, of high-throughput, and of low cost, and may be a promising choice for on-site detection of prometryn in different kinds of herbs.
Graphical abstract
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高影响因子
危险品化学品经营许可证（带存储）