BIOTECHNOLOGY AND APPLIED BIOCHEMISTRY
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2021
·Vol. 69
·期 4
·1428-1437
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IF 2.431
Di Liu,Linbo Gou,Yajun Bai,Tai-Ping Fan,Xiaohui Zheng,Yujie Cai
In this study, the 3-quinuclidinone reductase from Agrobacterium tumefaciens (AtQR) was modified by site-directed mutagenesis. And we further obtained a saturation mutant library in which the residue 197 was mutated. A single-point mutation converted the wild enzyme that originally had no catalytic activity in reduction of ethyl 4-chloroacetoacetate (COBE) into an enzyme with catalytic activity. The results of enzyme activity assays showed that the seven variants could asymmetrically reduce COBE to ethyl ( S )-4-chloro-3-hydroxybutyrate (( S )-CHBE) with NADH as coenzyme. In the library, the variant E197N showed higher catalytic efficiency than others. The E197N was optimally active at pH 6.0 and 40°C, and the catalytic efficiency ( k cat / K m ) for COBE was 51.36 s –1 ·mM –1 . This study showed that the substrate specificity of AtQR could be changed through site-directed mutagenesis at the residue 197.
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MICROCHIMICA ACTA
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2021
·Vol. 188
·期 8
·1-8
·
IF 5.833
Hu Cong Yi,Jiang Zhong Wei,Huang Cheng Zhi,Li Yuan Fang
Based on the laccase-mimicking activity of Cu 2+ -modified University of Oslo (UiO) metal–organic framework (UiO-67-Cu 2+ ), we developed a colorimetric sensor array for distinguishing a series of phenols with different number and position of substituted hydroxyl group (-OH) and different substituent group on the benzene ring, including phenol, catechol, quinol, resorcinol, pyrogallol, phloroglucinol, o -chlorophenol, o -aminophenol, and o -nitrophenol. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of phenolic compounds were obtained by theoretical calculation. The results show that the lower the LUMO energy level, the easier the chromogenic reaction occurs. The UiO-67-Cu 2+ -catalyzed phenol chromogenic reaction showed a good linearity in the range from 0.1 to 200 μM with limit of detection approximately 61 nM. Through the detection of phenol in tap water and river water, the recovery rate and RSD ( n = 3) were calculated as 94.1~103% and 1.0~3.3, respectively, showing good recovery, reliable results, and outstanding stability. Therefore, the proposed colorimetric sensor array will have a great potential for the detection of phenols in the environment. Graphical abstract
Schematic presentation of a simple and sensitive colorimetric strategy based on the laccase-mimicking activity of Cu 2+ -modified UiO-type metal–organic framework (MOFs, Uio-67-Cu 2+ ) to distinguish phenols with analogous structures.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2021
·
IF 4.539
Jinming Ma,Huizhen Deng,Zhe Zhang,Lexin Zhang,Zhihui Qin,Yaru Zhang,Lili Gao,Tifeng Jiao
In this study, a series of Ag 3 PO 4 /PPy/PANI ternary composite catalysts were fabricated by adjusting the mixed solution of pyrrole and aniline with different volume ratios of 4:1, 3:2, 1:1, 2:3, and 1:4, and combining with the in-situ synthesis method. The synthesized Ag 3 PO 4 /PPy/PANI nanoparticles were examined by XRD , SEM, TEM and EDX , Raman spectroscopy . When the ratio of pyrrole and aniline is 1:1, the polymerized PPy/PANI acted as the supporting matrix to effectively immobilize and prevent the aggregation of Ag 3 PO 4 nanoparticles. The catalytic performances of the Ag 3 PO 4 /PPy/PANI composites were confirmed for reduction of 2-nitroaniline (2-NA) and 4-nitrophenol (4-NP) in the presence of NaBH 4 at room temperature by UV–vis spectroscopy. Results showed that the catalytic reduction effect of the Ag 3 PO 4 /PPy/PANI (1:1) on 2-NA is obviously better than that on 4-NP, which followed the pseudo-first-order kinetic, and the corresponding rate constants are 0.0053 min −1 and 0.022 min −1 , respectively, indicating that it has potential application in wastewater treatment in industries.
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APPLIED CLAY SCIENCE
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2021
·
IF 5.467
Fushuai Wang,Fei Pan,Guoliang Li,Peiqing Zhang,Ning Wang
Developing cost-effective catalysts for the reduction of carcinogenic and highly toxic 4-nitrophenol to chemical and pharmaceutical intermediate 4-aminophenol has received considerable attention in recent years. Here, spherical montmorillonite (SMt) supported Cu-based catalyst doping with a covalent organic framework (COF) was constructed. Microsized SMt could be easily picked up from the mixture due to its self-sedimentary ability, which could easily solve the recycling issues of catalysts. Furthermore, granular SMt with uniform morphology and structure facilitated supporting and preparing catalysts with homogeneous properties. Moreover, SMt with a large specific surface area was suitable as the substrate for loading catalysts with high content. COF acted as a cocatalyst to accelerate the reaction processing. Cu + /Cu 2+ ions presented considerable catalytic ability for 4-nitrophenol removal due to their electron transferability and low cost. The valence of Cu ions on the prepared catalyst was analyzed and an apparent reduction rate constant ( K app ) of 5.3 min −1 and turnover frequency (TOF) of 955.5 h −1 were obtained at pH = 5 and 40 °C. The mechanism of the pH influence on the catalytic activity of our prepared heterostructure was further investigated. Moreover, the prepared heterostructure could be easily recovered and reused without any devices, and K app could be maintained after being recycled 5 times. Our strategy to fabricate cost-effective heterogeneous catalysts may provide a promising way to apply for these kinds of catalysts.
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ANALYST
·
2019
·Vol. 145
·期 5
·1801-1809
·
IF 4.019
Kaiqiang Wang,Da-Wen Sun,Hongbin Pu,Qingyi Wei
In this study, a 4-aminobenzenethiol-functionalized core–shell silver-coated gold nanoparticle (Au@Ag-4ABT NP) system was designed for the rapid sensing of carbendazim (CBZ) using a combination of naked-eye colorimetry and surface-enhanced Raman spectroscopy (SERS) dual-channel approach. Under alkaline conditions, the deprotonated CBZ species could interact with Ag surfaces via the N–Ag–O and N–Ag–N bonds. As a result, the neighboring Au@Ag-4ABT NPs would come closer through π–π interactions inducing the aggregation of Au@Ag-4ABT NPs. The aggregation of nanoparticles caused changes in the optical properties of the colloidal system, allowing observation with naked eyes, while the generation of more localized surface plasmon resonance “hotspots” between the adjacent Au@Ag nanoparticles permitted monitoring by the SERS technique. The proposed method showed effective sensitivity toward CBZ with limit of detection and limit of quantitation values of 37 and 122 ppb, respectively. In addition, the proposed dual-channel assay could serve as a simple and rapid method for sensing CBZ in tap water, cauliflower, and pear juice within 30 min.
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DESALINATION
·
2019
·
IF 6.035
Shao-Lu Li,Pengfei Wu,Juntao Wang,Jing Wang,Yunxia Hu
It is well known that the water flux and antifouling performance of polyamide (PA) membrane are strongly associated with their surface characters, especially for surface hydrophilicity , roughness, and charge. In this study, a zwitterionic surface TFC reverse osmosis (RO) membrane was fabricated by small molecule 3-bromopropionic (3-BPA) modification on the pristine membrane that fabricated through interfacial polymerization (IP) technique using a new aqueous monomer 4-morpholinobenzene-1,3-diamine (MpMPD) and trimesoyl chloride (TMC). The as-fabricated RO membranes were well analyzed by various techniques, that the zwitterionic MpMPD-PA membrane surface exhibited greatly enhanced hydrophilicity with water contact angle of 28.1° and surface roughness as low as 26.0 nm. The water permeability of membrane MpMPD-PA reached 1.65 L m −2 h −1 bar −1 , which exhibited ~24% increase compared to our lab-made MPD membrane, meanwhile kept a high NaCl rejection of 97.8%. In addition, the dynamic fouling experiments illustrated that the zwitterionic surface RO membrane possess excellent fouling resistance to protein BSA, polysaccharides SA , and surfactant SDS. Therefore, this work provide a simple and convenient way to fabricate novel zwitterionic surface RO membrane with high performance from the molecular level design.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2019
·
IF 2.298
Yuting Chu,Muhammad Asim Khan,Mingzhu Xia,Wu Lei,Fengyun Wang,Sidi Zhu
4-Acetaminophenol (PCT) is a kind of micropollutant in nature, and its existence has caused serious harm to the biological environment. In this work, sodium montmorillonite (Na-Mt) was modified with amino acids, l-histidine hydrochloride (His), l-arginine hydrochloride (Arg), and l-methionine (Met), to investigate the adsorption of PCT in the wastewater. The adsorption capacities of the modified adsorbents for PCT under the same conditions were Arg-Mt-1.0 (8.45 mg/g) > His-Mt-1.0 (8.23 mg/g) > Met-Mt-1.0 (7.18 mg/g) > Na-Mt (4.84 mg/g). The investigation showed that Na-Mt and Met-Mt-1.0 conformed to the Temkin model in the temperature range of 15 to 55 °C. The adsorption of His-Mt-1.0 to PCT was consistent with the D–R model within the studied temperature range. The adsorption of Arg-Mt-1.0 on PCT at 15 and 35 °C was consistent with the Freundlich model, and the adsorption of PCT at 55 °C was consistent with the Langmuir model, indicating that when the temperature was high, the adsorption sites tended to be the same. The adsorption of PCT by the modified adsorbents was exothermic, and all the adsorption processes were in accordance with pseudo-second-order kinetic characteristics. Amino acid’s modified montmorillonite can improve the adsorption capacity for PCT because the interlayer spacing was increased.
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PHYTOMEDICINE
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2019
·
IF 4.18
Licong Zhao,Jiaqi Zhang,Lingyun Pan,Long Chen,Yu Wang,Xinhua Liu,Lisha You,Yiqun Jia,Cheng Hu
Background Acetaminophen (APAP) overdose is a leading cause of drug-induced acute liver failure in clinic. Fisetin (FST) is a phenolic compound that has been isolated from many natural products. Purpose Our aim is to study the protection effect and mechanisms of FST on APAP-induced hepatotoxicity in endogenous metabolism and metabolomics in vitro and in vivo . Methods FST was i.g. administered to mice at 10 , 20 and 40 mg/kg for 7 days and a single dose of APAP (400 mg/kg) was given on the last day. Serum and tissue were collected for biochemical analysis . L-02 cells were used to assess cell viability . LC–MS was used to study the metabolic fingerprinting in vivo and vitro . PCA and OPLS-DA were used to search the potential biomarkers (VIP > 1, p < 0.05). The pathway analysis was conducted on Metaboanalyst 4.0. Then liver oxidative stress indices and glutathione markers were examined using PCR and kits. Results ALT , AST, liver histological observation and cell viability results showed that FST could reverse APAP induced toxicology in mice and L-02 cells. In metabolomics study, 26 metabolites in vitro and 60 metabolites in vivo were identified by searching in the library and most of them decreased to normal level in FST treatment . It is observed in pathway analysis that the most significant pathway was glutathione metabolism. Furthermore, the results of mRNA and immunofluorescence showed that FST suppressed ROS formation in liver tissue and L-02 cells, as well as restored the expression of GPX1 , GST and other antioxidative enzymes genes. Conclusion Our results indicate that FST prevented APAP-induced hepatotoxicity by regulating glutathione metabolism and the expression of related antioxidative signals.
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BRITISH JOURNAL OF PHARMACOLOGY
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2019
·Vol. 176
·期 14
·2627-2641
·
IF 6.583
Zheng Xu,Chunpeng Zou,Weihui Yu,Sujing Xu,Lan Huang,Zia Khan,Jingying Wang,Guang Liang,Yi Wang
Background and Purpose Hypertension adversely affects the kidney and is the second leading cause of kidney failure. Overproduction of angiotensin II greatly contributes to the progression of hypertensive kidney disease. Angiotensin II has recently been shown to activate STAT3 in cardiovascular cells. However, the underlying mechanisms of STAT3 activation by angiotensin II and downstream functional consequences in the kidneys are not fully understood. Experimental Approach C57BL/6 mice were treated with angiotensin II by subcutaneous infusion for 1 month to develop nephropathy. Mice were treated with either adeno-associated virus expressing STAT3 shRNA or STAT3 inhibitor, S3I-201. Human archival kidney samples from five patients with hypertension and five individuals without hypertension were also examined. In vitro, STAT3 was blocked using siRNA or STAT3 inhibitor S3I-201 in the renal proximal tubular cell line, NRK52E, after exposure to angiotensin II. Key Results Angiotensin II activated STAT3 in kidney epithelial cells through engaging toll-like receptor 4 (TLR4) and JAK2, which was independent of IL-6/gp130 and angiotensin AT 1 receptors. Angiotensin II-mediated STAT3 activation increased fibrotic proteins and resulted in renal dysfunction. Both STAT3 inhibition by the low MW compound S3I-201 and TLR4 deficiency normalized renal fibrosis and dysfunction caused by Ang II in mice, without affecting hypertension. Conclusions and Implications Our study reveals a novel mechanism of STAT3 activation, induced by angiotensin II, in kidney tissues and highlights a translational significance of a STAT3 inhibitor as potential therapeutic agent for hypertensive kidney disease.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2019
·
IF 2.298
Yue Sun,Weisheng Zheng,Rajendra Prasad Singh,Li Chen
In the current work, poly(4-vinylpyridine) (P4VP) was grafted on a macroporous polystyrene resin via free-radical polymerization by using the pendent vinyl group. The grafting conditions such as swelling agent, initiator concentration, reaction temperature, and amount of 4-vinylpyridine (4VP) monomer were optimized, and three resins with different 4VP monomer amounts (SC-1, SC-2, and SC-3) were chosen as adsorbents. P4VP-grafted resins were characterized by scanning electron microscopy, N2 sorption/desorption isotherms, Fourier transform infrared, and X-ray photoelectron spectroscopy. The sorption properties of 2-naphthalenesulfonic acid (NSA) on three resins were comparatively investigated. The experimental data revealed that the sorption process on three resins fitted well with the pseudo-second-order kinetics equation, and the equilibrium isotherms were in good agreement with the Langmuir model. The NSA sorption onto resins was an endothermic and spontaneous process, and SC-3 loaded with NSA can be efficiently regenerated by NaOH and ethanol mixed solution after sorption. The maximum sorption capacities of three resins indicated that P4VP-grafted resins possess good sorption ability toward NSA.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Yufeng Yao,Jia Fan,Ming Shen,Weizheng Li,Bin Du,Xue Li,Jingtao Dai
In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO–Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag + to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO–Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO–Ag nanocomposites. HRCA-capped ZnO–Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that O 2 − and h + are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO–Ag nanocomposite system. HRCA-capped ZnO–Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.
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EUROPEAN POLYMER JOURNAL
·
2019
·
IF 3.621
Peng Zhang,Lei Kan,Xinyue Zhang,Rui Li,Chuanqi Qiu,Ning Ma,Hao Wei
Multiple hydrogen bonds have been widely used to form a supramolecular network and endow materials with enhanced mechanical strength, good elasticity, and/or self-healing properties. In this study, 2-ureido-4[1H]-pyrimidone (UPy) compounds were synthesized and chemically grafted onto the side chain of epoxy resins. The UPy-modified epoxy resin demonstrated substantial improvements in toughness and elasticity compared with unmodified epoxy resin as proven by a tensile test and distortion test. The breaking elongation of the UPy-modified epoxy resin was 5 times higher than that of unmodified epoxy resin under a tensile test. In addition, the fracture mechanism of the modified epoxy resin matched with the ductile fracture rather than the brittle fracture of unmodified epoxy resins. The introduction of quadruple hydrogen bonds by chemical modification may provide a simple and effective way to design and prepare highly flexible thermosetting resin materials.
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