Catalysis Science & Technology
·
2018
·Vol. 8
·期 18
·4718-4725
·
IF 5.365
Jiang-Wei Shen,Jia-Mei Qi,Xiao-Jian Zhang,Zhi-Qiang Liu,Yu-Guo Zheng
Candida antarctica lipase B (CALB) is a versatile and robust lipase with high activity and enantioselectivity in the resolution of alcohols and amines. Poor specific activity toward carboxylic esters that are branched or substituted in close proximity to the carboxyl group limits the application of CALB. In this study, a semi-rational engineering approach was successfully applied to tailor CALB for efficient synthesis of the moxifloxacin chiral intermediate through enzymatic resolution of cis-(±)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate. The combinatorial active-site saturation test was performed on CALB and two key residue sites, 189 and 190, were identified in the determination of hydrolytic activity. The specific activity and catalytic efficiency (kcat/Km) of the best variant mut-I189K were increased by 286- and 193-fold, respectively, without impacting its enantioselectivity. With 0.1 g L−1 of purified mut-I189K loading, 1 M substrate was asymmetrically hydrolyzed with 49.9% conversion within 5 h, resulting in a space–time yield of 583.8 g L−1 d−1. These results demonstrated that mut-I189K is a competitive biocatalyst for large-scale preparation of the moxifloxacin chiral intermediate.
✓ 已验证
产品关联
DOI
高影响因子
Environmental Science-Nano
·
2017
·Vol. 4
·期 12
·2395-2404
·
IF 6.047
Hong-Wei Luo,Xin Zhang,Jie-Jie Chen,Han-Qing Yu,Guo-Ping Sheng
Although the existence of Fe(III) (hydr)oxide nanoparticles (NPs) in natural environments has been recently recognized, their migration and transformation, which are substantially affected by the microbial reduction process, remain unclear. In this study, hematite bioreduction and magnetite formation induced by Shewanella oneidensis MR-1, a typical metal-reducing bacterial strain, were investigated using an integrated approach that combined experiments and computational simulations at the molecular scale. High-resolution transmission electron microscopy coupled with selected area electron diffraction (SAED), Raman spectroscopy and magnetic property analyses confirmed the biogenic magnetite formation. The electron paramagnetic resonance (EPR) spectra show a decay of the EPR intensity with incubation time, implying that the biotransformation of hematite to magnetite led to concurrent changes in their contents and local structures. X-ray absorption fine spectroscopy (XAFS) identified a time-resolved structural evolution of Fe(II)/Fe(III) coordination. The octahedral configuration upon Fe(II) production was subsequently validated by DFT calculations. Microbial reductive dissolution provided various intermediate states and new chemical environments regarding Fe(II)/Fe(III) complexes, such as monodentate and bidentate coordination patterns. Bioreduction caused the breakage of iron–oxygen bonds in hematite and the concomitant formation of Fe complexing microstructures for biogenic magnetite production. All these findings reveal the underlying mechanisms for the biotransformation of Fe minerals at the molecular scale and may allow us to better understand the speciation, immobilization and bioavailability of hematite NPs in natural systems.
✓ 已验证
产品关联
DOI
高影响因子
TEXTILE RESEARCH JOURNAL
·
2017
·
IF 1.443
Liu Liu,Yeping Xiang,Ruiyun Zhang,Bei Li,Jianyong Yu
In this study, different dosages of NaClO were used in the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase degumming system to remove non-cellulosic materials, and their effects on the structure of hemp fibers were analyzed and discussed. A scanning electron microscope was used to depict the surface morphology of fibers after oxidative degumming under various dosages of NaClO in the TEMPO-laccase degumming system. Chemical composition analysis was used to determine the content changes of the different components. Meanwhile, the content of functional groups was also discussed. Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray diffraction were employed to evaluate the microstructural changes of degummed hemp fibers obtained from the degumming processes with different dosages of NaClO. The results showed that after the TEMPO-laccase system degumming process with a NaClO dosage of 16%, the cleanest and smoothest surface of degummed fibers could be observed and the non-cellulosic materials were significantly removed without any crystalline transformation or damage in the cellulose. This research could shed light on determining favorable operation parameters for hemp oxidation degumming and increasing the degumming efficiency, as well as in the oxidation control and quality assurance of hemp fibers for textile downstream end uses.
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2017
·
IF 2.714
Yun-Xia Wang,Kiran Gupta,Jian-Rong Li,Baoling Yuan,Jia-Cheng E. Yang,Ming-Lai Fu
A novel easily separated magnetic chalcogenide composite, KMS-1/L-Cystein/Fe 3 O 4 (KCF), was successfully synthesized using bifunctional linker (L-Cystein) to connect KMS-1 and Fe 3 O 4 nanoparticles, and was examined to remove ciprofloxacin (CIP) from aqueous solution. The composite was thoroughly characterized by XRD, SEM, EDX, FTIR and magnetization measurements techniques. The adsorption experiments were carried out and investigated under different conditions, such as contact time and pH of solution. The CIP removal reaction was found to better follow a pseudo-second-order kinetic model than the pseudo-first-order. The Langmuir adsorption isotherm was employed to understand the removal process. The pH of solution is critical for the adsorption of CIP on KCF, and the maximum adsorption (181.32 mg/g) of CIP could be reached under pH 6. In addition, the KCF adsorbent showed magnetization and operational stability, and it could be readily separated from solution by applying an external magnetic field. The high stability, performance, inexpensive, and easily recyclable KCF composite may serve as a promising adsorbent for water treatment.
✓ 已验证
产品关联
DOI
高影响因子
Molecular Biomedicine
·
2025
·Vol. 6
·期 1
·1-14
·
IF 10.1
Ao Danyi,Peng Dandan,He Cai,Ye Chunjun,Hong Weiqi,Huang Xiya,Lu Yishan,Shi Jie,Zhang Yu,Liu Jian,Wei Xiawei,Wei Yuquan
Despite the declared end of the COVID-19 pandemic, SARS-CoV-2 continues to evolve, with emerging JN.1-derived subvariants (e.g., KP.2, KP.3) compromising the efficacy of current XBB.1.5-based vaccines. To address this, we developed an mRNA vaccine encoding the full-length spike protein of JN.1, incorporating GSAS and 2P mutations and encapsulated in lipid nanoparticles (LNPs). The JN.1-mRNA vaccine elicited robust humoral and cellular immune responses in mice, including high JN.1-specific IgG titers, cross-neutralizing antibodies, and increased T follicular helper (Tfh) cells, germinal center (GC) B cells, and T cell cytokines. Importantly, immunity persisted for up to six months and induced RBD-specific long-lived plasma cells. We also compared the immune responses induced by homologous and heterologous vaccination regimens, and our results demonstrated that the heterologous regimen—combining JN.1-mRNA with a recombinant protein vaccine (RBD JN.1 -HR)—induced stronger responses. These findings highlight the JN.1-mRNA vaccine constitutes an effective prophylactic approach against JN.1-related variants, as it induces potent neutralizing antibody responses across all tested lineages. This enhanced immunogenicity is expected to significantly reduce hospitalization rates and mitigate post-COVID complications associated with JN.1 and KP.3 infections. This study emphasizes the need for timely vaccine updates and the adaptability of mRNA vaccines in addressing emerging pathogens, providing a framework for combating future infectious diseases. Collectively, these results offer critical insights for vaccine design and public health strategies in response to emerging SARS-CoV-2 variants.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY
·
2025
·
IF 2.5
Zhuoqi Chen,Chaochao Gong,Shaowei Wang,Han Lu,Yang Zhu,Ren-shan Ge,Yunbing Tang,Yingfen Ying
Benzophenone (BP) UV-filters have been extensively used for the prevention of UV-induced adverse effects in personal care products. Their potential to interfere with steroidogenesis in the female reproductive system remains uncertain. 17β-Hydroxysteroid dehydrogenase 1 (17β-HSD1) facilitates the conversion of estrone to estradiol, playing a key role in estrogen activation. This study delves into the effects of eleven BPs on human and rat 17β-HSD1, while also analysing the 3D-quntitative structure-activity relationship (3D-QSAR) and the underlying mechanisms. The inhibitory potency of inhibiting human placental 17β-HSD1 was found to be in the order of BP-2 (IC 50 , 11.42 μM) > BP-1 (14.17 μM) > BP-4 (49.05 μM) > BP-6 (63.49 μM) = BP-8 (63.46 μM) > others. BP-1 and BP-2 markedly inhibited estradiol secretion by human placental BeWo cells at ≥ 1 μM. In contrast, the inhibitory strength of suppressing rat ovarian 17β-HSD1 activity was found to be in the order of BP-2 (IC 50 , 13.33 μM) > BP-1 (15.09 μM) > BP-4 (22.68 μM) > BP-12 (31.12 μM) > BP (119.99 μM) > others. Mode action analysis revealed that these BP compounds acted as mixed inhibitors of both human and rat 17β-HSD1. The introduction of a 4-hydroxyl substitution in the benzene ring was found to markedly increase the inhibitory potency against human and rat 17β-HSD1. BP-1 and BP-2 demonstrated the ability to penetrate human BeWo cells and inhibit estradiol secretion at ≥ 1 μM. Docking analysis revealed that the 2-hydroxyl group of BP-1 and BP-2 forms a hydrogen bond with catalytic residue Ser142 of human 17β-HSD1. 3D-QSAR pharmacophore analysis showed that there are hydrophobic regions and hydrogen bond donor can interact with BPs. In conclusion, this study establishes that BP-2 is the most potent inhibitors of human 17β-HSD1 among the BPs under investigation, highlighting a significant difference in the structure-activity relationship.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Soft Matter
·
2015
·Vol. 11
·期 23
·4717-4722
·
IF 4.029
Tianxiang Yin,Jiequn Wu,Shuzhen Wang,Weiguo Shen
The aggregation behaviors of surface active ionic liquid 1-butyl-3-methylimidazolium bis(2-ethylhexyl) sulfosuccinate in aqueous solutions were investigated by conductometry, densimetry, fluorimetry, 1H nuclear magnetic resonance (1H NMR) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM), which confirmed two distinguished critical concentrations. The first critical concentration was believed to be the critical aggregation concentration (CAC), where two different types of aggregates were formed, namely, micelles with the size of 10 nm and vesicles with the size of 100 nm. The second critical concentration at two-fold CAC was suggested to be resulting from the insertion of the imidazolium cations into aggregates.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Mufan Wang,Shiying Fan,Xinyong Li,Jugong Shi,Yan Mao,Yaqi Yang,Gao Li
Efficiently upgrading 5-hydroxymethylfurfural (HMF) into high-value-added products, such as 2,5-diformylfuran (DFF) and 2,5-furan dicarboxylic acid (FDCA), through a photocatalytic process by using solar energy has been incessantly pursued worldwide. Herein, a series of transition-metal (TM = Ni, Fe, Co, Cu) single atoms were supported on Ti4+αTi3+1-αO2−δ nanofibers (NFs) with certain defects (Ov), denoted as TM SAC-Ti4+αTi3+1-αO2−δ NFs (TM = Ni, Fe, Co, Cu), aiming to enhance the photocatalytic conversion of HMF. A super HMF conversion rate of 57% and a total yield of 1718.66 μmol g–1 h–1 (DFF and FDCA) surpassing that of the Ti4+αTi3+1-αO2−δ NFs by 1.6 and 2.1 times, respectively, are realized when TM is Co (Co SAC-Ti4+αTi3+1-αO2−δ NFs). Experiments combined with density functional theory calculation (DFT) demonstrate that the TM single atoms occupy the Ti site of Ti4+αTi3+1-αO2−δ NFs, which plays a dominant role in the photo-oxidation of HMF. Raman, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) characterizations confirm the strong electron local exchange interaction in TM SAC-Ti4+αTi3+1-αO2−δ NFs and demonstrate the substitution of Ti by the TM SACs. The projected density of states and charge density difference reveal that the strong interaction between metal-3d and O-2p orbitals forms Ti–O–TM bonds. The bonds are identified as the adsorption site, where TM single atoms on the surface of Ti4+αTi3+1-αO2−δ NFs reduce HMF molecule adsorption energy (Eads). Furthermore, the TM single atom modulates the electronic structure of TM SAC-Ti4+αTi3+1-αO2−δ NFs through electron transfer, leading to narrow band gaps of the photocatalysts and enhancing their photocatalytic performance. This study has uncovered a newer strategy for enhancing the photocatalytic attributes of semiconducting materials.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Frontiers in Microbiology
·
2016
·
IF 4.165
Han Rui,Li Fangbai,Liu Tongxu,Li Xiaomin,Wu Yundang,Wang Ying,Chen Dandan
It is widely recognized that the outer membrane c-type cytochromes (OM c-Cyts) of metal-reducing bacteria play a key role in microbial metal reduction processes. However, the in situ redox status of OM c-Cyts during microbial metal reduction processes remain poorly understood. In this study, diffuse-transmission UV/Vis spectroscopy is used to investigate the in situ spectral reaction of Cr(VI) reduction by c-Cyts in intact Shewanella oneidensis MR-1 cells under different incubation conditions. The reduced c-Cyts decreased transiently at the beginning and then recovered gradually over time. The Cr(VI) reduction rates decreased with increasing initial Cr(VI) concentrations, and Cr(III) was identified as a reduced product. The presence of Cr(III) substantially inhibited Cr(VI) reduction and the recovery of reduced c-Cyts, indicating that Cr(III) might inhibit cell growth. Cr(VI) reduction rates increased with increasing cell density. The highest Cr(VI) reduction rate and fastest recovery of c-Cyts were obtained at pH 7.0 and 30∘C, with sodium lactate serving as an electron donor. The presence of O2 strongly inhibited Cr(VI) reduction, suggesting that O2 might compete with Cr(VI) as an electron acceptor in cells. This study provides a case of directly examining in vivo reaction properties of an outer-membrane enzyme during microbial metal reduction processes under non-invasive physiological conditions.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
HIGH PERFORMANCE POLYMERS
·
2017
·
IF 1.179
Gongyi Liu,Zijun Xia,Shanshan Jin,Xiaoxia Guo,Jianhua Fang
A series of novel cross-linked blend membranes have been successfully prepared from poly(2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole) (OPBI) and partially quaternized poly(1-vinylimidazole) (QPVI) at varied polymer weight ratios using 1,6-dibromohexane as the cross-linker. The resulting cross-linked blend membranes are ductile and transparent. Cross-linking causes slight increase in tensile strength and significant improvement in immobilization of the QPVI. The effect of the QPVI content on membrane properties such as mechanical properties, thermal stability, ion exchange capacity, water uptake, swelling ratio, and anion conductivity is investigated. The charge–discharge performance of the single cells assembled with the cross-linked blend membranes has also studied and compared with that of the one assembled with Nafion 117. The cross-linked blend membranes exhibit three to four orders lower VO2+ permeability than Nafion 117 leading to much slower self-discharge rate and significantly higher coulombic efficiency of the former. The single cells assembled with the cross-linked blend membranes show higher coulombic efficiency and energy efficiency at low current densities than the one assembled with Nafion 117. Furthermore, the single cell assembled with the cross-linked blend membrane OPBI/QPVI(3:7, weight ratio)-Cross-linked (CL) shows little decay in energy efficiency after 300 charge–discharge cycles test at 80 mA cm−2 indicating good durability of this membrane.
✓ 已验证
产品关联
DOI
高影响因子
BIOTECHNOLOGY AND APPLIED BIOCHEMISTRY
·
2016
·Vol. 64
·期 2
·251-258
·
IF 1.429
Hong-De Yan,Zhao Wang,Jun-Qing Qian
A mycelium-bound lipase from Aspergillus oryzae (AOL) exhibited excellent enantioselectivity for kinetic resolution of ( RS )-1-phenylethanol (( RS )-1-PE) in organic solvent. The various reaction parameters affecting the conversion and enantioselectivity were studied, including type of acyl donor, solvent, molar ratio, temperature, enzyme amount, and substrate concentration. The optimum reaction conditions were found to be transesterification with vinyl acetate at 30 °C in methyl tert -butyl ether with a vinyl acetate: ( RS )-1-PE molar ratio of 1:1 and an enzyme concentration of 60 g/L. At the optimum reaction conditions, the conversion could reach above 46% with >99% enantiomeric excess of the product, ( R )-1-phenylethyl acetate, when the substrate concentration was below 1.4 M. The enzyme displayed an excellent enantioselectivity with an E -value of >200 and a strong tolerance for high substrate concentration of up to 1.8 M. Those results indicated that AOL was a promising biocatalyst in the kinetic resolution of ( RS )-1-PE.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Feng Xu,Ying Yu,Jian Yan,Qibin Xia,Haihui Wang,Jing Li,Zhong Li
An ultrafast synthesis method is developed for the preparation of composites of graphite oxide and HKUST-1, GrO@HKUST-1. Fast synthesis of GrO@HKUST-1 composites can be quickly achieved at room temperature within 1 min. The synthesized composites were characterized by XRD, SEM, N 2 adsorption, FTIR and TGA. The isotherms of CO 2 and N 2 on the as-synthesized materials were measured and the isosteric heats of CO 2 adsorption were estimated. The CO 2 /N 2 adsorption selectivities were predicted by means of ideal adsorbed solution theory (IAST). Results show that the GrO@HKUST-1 composites have higher BET surface area and pore volume than the parent HKUST-1. The CO 2 adsorption capacity of 2GrO@HKUST-1 (2% of GrO) is up to 9.02 mmol/g at 1 bar and 273 K, giving an increase of 32% in comparison of the parent HKUST-1. The isosteric heat of CO 2 adsorption on 2GrO@HKUST-1 is slightly higher than that of HKUST-1, suggesting the stronger interaction between CO 2 molecules and 2GrO@HKUST-1. The CO 2 /N 2 adsorption selectivity of 2GrO@HKUST-1 is significantly enhanced over pristine HKUST-1. At 1 bar, the CO 2 /N 2 adsorption selectivity of 2GrO@HKUST-1 is up to 186, while that of parent HKUST-1 is only 103. This rapid room temperature synthesis route is promising for new MOF-based composites.
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）