BIOTECHNOLOGY LETTERS
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2019
·Vol. 41
·期 10
·1223-1232
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IF 2.154
Zhang Yin-Jun,Chen Chang-Sheng,Liu Hao-Tian,Chen Jia-Lin,Xia Ying,Wu Shi-Jin
Objective To purify an esterase which can selectively hydrolyze ( R,S )-ethyl indoline-2-carboxylate to produce ( S )-indoline-2-carboxylic acid and characterize its enzymatic properties. Results An intracellular esterase from Bacillus aryabhattai B8W22 was isolated and the purified protein was identified as a carboxylesterase by MALDI-TOF mass spectrometry. The enzyme (named BaCE) was 59.03-fold purification determined to be of approximately 35 kDa. Its specific activity was 0.574 U/mL with 20% yield. The enzyme showed maximum activity at pH 8.5 and 30 °C and was stable at 20–30 °C using p NPB as the substrate. The K m , V max , k cat and k cat /K m of the esterase were 0.52 mM, 6.39 μM/min, 26.87 min −1 and 51.67 mM/min, respectively. The esterase demonstrated high enantioselectivity toward ( S )-ethyl indoline-2-carboxylate with 96.55% e.e. p at 44.39% conversion, corresponding to an E value of 133.45. Conclusions In this study, a new esterase BaCE with an apparent molecular mass of 35 kDa was purified to homogeneity for the first time. The esterase from Bacillus aryabhattai B8W22 was isolated with a purification more than 59-fold and a yield of 20% by anion exchange chromatography and hydrophobic interaction chromatography. And its biochemical characterization were described in detail with p NPB as substrate. It displayed high enantioselectivity toward ( S )-ethyl indoline-2-carboxylate. We next plan to highly express esterase BaCE in Escherichia coli , and apply it to industrial production of ( S )-indoline-2-carboxylic acid.
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CARBOHYDRATE POLYMERS
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2019
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IF 6.044
Jing Zhang,Lingdong Chen,Biao Shen,Liqun Chen,Jie Feng
Hydrogels with good mechanical properties are promising for various applications. In this work, a simple yet effective method for preparing a novel double-network hydrogel was reported. First, nonfouling polymer, poly( N- (2-hydroxyethyl)acrylamide) (PHEAA), was crosslinked through covalent bonds. Antibacterial polysaccharide, chitosan (CS), was then crosslinked by chelation between the N- glucosamine units on the CS and citrate or sulfate ions. The poly( N- (2-hydroxyethyl)acrylamide)/chitosan double-network hydrogels (PHEAA/CS DN hydrogels) exhibited high tensile strength (3.8 MPa), strong elastic modulus (0.6 MPa). And the dynamic ionic crosslinking in CS network provided the DN gels with fast self-recovery ability as well as excellent fatigue resistance. Furthermore, the mechanical properties of the DN gels were enhanced after stretching and relaxing because of the molecular orientation and reconstruction of chitosan network. More importantly, the hydrogels have excellent antifouling and antibacterial properties, which is called “repelling and killing”, making them competitive candidates for applications in the biomedical field.
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ACS Catalysis
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2019
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IF 12.221
Yaqi Liu,Hong-Yan Ma,Da Lei,Lan-Lan Lou,Shuangxi Liu,Wuzong Zhou,Gui-Chang Wang,Kai Yu
The aerobic oxidation of alcohols and aldehydes over noble metal catalysts is a critical reaction for the catalytic conversion of carbohydrates into value-added chemicals from biomass. However, to fully understand the reaction mechanism, in particular, the role of O2 and the generated active oxygen species in these reactions is still a challenging target. In the present work, the sub-10 nm Pt nanocrystals with cubic (Pt-NCs), octahedral (Pt-NOs), and spherical (Pt-NSs) morphologies were synthesized and used as catalysts in aerobic oxidation of 5-hydroxymethyl-2-furfural (HMF). Through experimental and computational investigations, the facet-dependent O2 conversion pathway and catalytic oxidation performance were discussed. The molecular O2 tends to be dissociated to generate •OH on a Pt(100) surface but prefers to be reduced to •O2– on a Pt(111) surface. Moreover, Pt-NCs enclosed by the {100} facets exhibited significantly enhanced catalytic activity compared to Pt-NOs enclosed by the {111} facets and Pt-NSs, in particular, for the alcohol oxidation step. On the basis of the experimental data and density functional theory (DFT) calculations, an active oxygen species promoted dehydrogenation mechanism for aerobic oxidation of HMF was proposed. The dehydrogenation of the alcohol group is more favorable on the Pt(100) surface with assistance of •OH, which is the dominant active oxygen species on the Pt(100) surface. We anticipate that this work would provide new insight into the role of active oxygen species in aerobic oxidation of alcohols and aldehydes over noble metal catalysts.
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MATERIALS TECHNOLOGY
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2019
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IF 1.82
Xinyu Jiang,Wenbo Cheng,Huijie Hu,Yiming Hu,Yunpeng Cao,Shengnan Yan,Ruixin Di,Xiaoze Wang,Li Hou
As an excellent electrode material for supercapacitors, it should have high capacitance like transition metal oxides and good stability like carbon materials. In this work, we reported a novel composite electrode material, Co-Ni(OH)2/carbon sphere, obtained by a solvothermal method. At first, the activated carbon spheres with an uniform size of about 4µm were synthesized, and then the sheet-like Co-Ni(OH)2 adsorbed on the cracks and outer surface of the carbon spheres to form the Co-Ni(OH)2/carbon sphere composite. The influence of mass ratio of Co-Ni(OH)2 to carbon spheres on capacitance performance was investigated. Benefitting from the unique composite structure, the synthesized Co-Ni(OH)2/carbon sphere presents a high specific capacitance up to 959.7 F/g in 6 M KOH at current density of 1 A/g. Meanwhile, the capacitance retention maintains its 75% after 3000 cycles, which is about 2.8 times higher than that of the pure Co-Ni(OH)2, indicating a good stability.
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NEUROGASTROENTEROLOGY AND MOTILITY
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2019
·Vol. 31
·期 6
·e13555
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IF 3.803
Mengjuan Lin,Lei Chen,Yong Xiao,Baoping Yu
Background Irritable bowel syndrome (IBS) is a common disease with intestinal dysmotility, whose mechanism remains elusive. The endocannabinoid system is emerging as an important modulator of gastrointestinal (GI) motility in multiple diseases, but its involvement in IBS is unknown. We aimed to determine whether cannabinoid 2 (CB2) receptor modulates intestinal motility associated with stress-induced IBS. Methods A rat IBS model was established by chronic water avoidance stress (WAS). Colonic pathological alterations were detected histologically and intestinal motility was assessed by intestinal transit time (ITT) and fecal water content (FWC). Visceral sensitivity was determined by visceromotor response (VMR) to colorectal distension (CRD). Real-time PCR, western blot, and immunostaining were performed to identify colonic CB2 receptor expression. Colonic muscle strip contractility was studied by isometric transducers and nitric oxide (NO) was detected by the Griess test. The effects of AM1241, a selective agonist of CB2 receptors, on colonic motility were examined. Key Results After 10 days of WAS exposure, ITT was decreased and FWC elevated while VMR magnitude in response to CRD was significantly enhanced. Colon CB2 protein and mRNA levels increased and density of CB2-positive macrophages in the mucosa and enteric neurons in the myenteric plexus was higher than in controls. Pharmacological enhancement of CB2 activity by AM1241 relieved colonic hypermotility in WAS rats in a concentration-dependent manner via inhibition of p38 phosphorylation and elevation of NO production. Conclusion CB2 receptor may exert an important inhibitory effect in stress-induced colonic hypermotility by modulating NO synthesis through p38 mitogen-activated protein kinase signaling. AM1241 could be used as a potential drug to treat disorders with colonic hypermotility.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Wenxiu He,Hengrui Qiu,Jing Meng,Bin Liu,Jinlong Cui,Yongqiang Zhang
A nanoscale petal-like α-Ni(OH) 2 /reduced graphene oxide (α-Ni(OH) 2 /RGO) composite was synthesized with the one-step microwave method. α-Ni(OH) 2 particles with sizes of approximately 200 nm are uniformly distributed on the reduced graphene oxide sheet in the sample. When used as an electrode for alkaline rechargeable batteries, the discharge capacity of the α-Ni(OH) 2 /RGO composite reaches 333.5 mAh/g at 0.2C and 247.1 mAh/g at 10 C, respectively, with an excellent rate capability. After 2000 cycles, the capacity of the electrode is insignificantly attenuated, indicating a high capacity retention and cycling stability. The outstanding electrochemical properties are attributed to the nanoscale petal-like structure α-Ni(OH) 2 anchoring on the RGO sheets, which facilitates ion diffusion and increases the active surface, which is effectively reacting with the electrolyte. The nanoscale petal-like electrode material fabricated in this study provides clues to address the problem of energy applications of high-performance alkaline rechargeable batteries.
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Analytical Methods
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2019
·Vol. 11
·期 11
·1516-1521
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IF 2.378
Fujuan Luan,Zuhong Yu,Ling Yin,Xia Leng,Yuxue Shi,Jie Wang,Haibin Shi,Weichang Chen
Matrix metalloproteinase-2 (MMP-2) plays an important role in tumorigenesis and metastasis of gastric cancer. Therefore, specific and sensitive detection of MMP-2 is of great significance for clinical diagnosis and therapeutic evaluation of gastric cancer. Herein, we developed a new approach for accurate detection of MMP-2 activity both in gastric cancer cells and clinical tissues using a fluorescent probe Dab-PLGVRGY-FITC. The capability of the probe for detecting MMP-2 was systematically evaluated in gastric cancer MGC-803 cells and clinical gastric cancer tissues. Around 40-fold fluorescence enhancement at a wavelength of 520 nm was determined for the assays of the probe with recombinant MMP-2. The detection limit of MMP-2 was as low as 42 ng mL−1. Strong fluorescence signals were detected in MGC-803 cells and mouse gastric cancer tissues. Fluorescence signal enhancements of 11 clinical gastric cancer tissue lysates were 5.8 ∼ 9 times (7.53 ± 0.77 on average) higher than those from gastritis patients. This probe could be potentially used for early diagnosis of gastric cancer in clinics.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2019
·
IF 5.107
Changlin Yu,Hongbo He,Wanqin Zhou,Zhen Liu,Longfu Wei
An interesting rugby-ball-like Zn 3 (PO 4 ) 2 @C 3 N 4 photocatalyst with well- controlled structures as high-efficient visible-light photocatalysts was synthesized via two steps of solvothermal-grinding calcination method. The composition, structure, morphology, and optical absorption properties of as-synthesized Zn 3 (PO 4 ) 2 @C 3 N 4 samples were intensively characterized by XRD, N 2 physical adsorption, SEM, TEM, FT-IR, UV–vis DRS, XPS, PL and photoelectrochemical measurements, respectively. The formation of C 3 N 4 shell obviously increased the surface area and induced the rich pore structures. The intimate interface between Zn 3 (PO 4 ) 2 and C 3 N 4 phase obviously enhanced the transport rate of photogenerated carriers and restrained the recombination of photogenerated electrons and holes. The optimal Zn 3 (PO 4 ) 2 @C 3 N 4 (35 wt%) exhibited the highest adsorption and photocatalytic activity in the degradation of methylene blue (MB), which was 150 and 7.5 times as high as C 3 N 4 , respectively. Moreover, the robust Zn 3 (PO 4 ) 2 @C 3 N 4 nanoheterojunctions fabricated by this grinding-calcination route have high stability in recycling reactions.
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INTERNATIONAL JOURNAL OF CHEMICAL KINETICS
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2019
·Vol. 51
·期 4
·258-265
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IF 1.417
Zhongyu Du,Siyu Duan,Mingfang Ma,Xiangyu Xu,Zhenquan Li,Lingdong Kong,Jun Liu
The rate constants of two redox reactions and in the critical solution of 2-butoxyethanol and water have been measured by using the UV spectrophotometry at the initial reaction stage. It was found that the rate constants at various temperatures for two reactions were well described by the Arrhenius equation in the noncritical region. The critical slowing down effect was detected in the critical region. The critical slowing down exponents were determined to be 0.044 ± 0.004 and 0.046 ± 0.005 for reactions and , respectively. The values of the critical slowing down exponents showed that only dynamic critical slowing down effect, and no thermodynamic singularity could be observed for the two reactions.
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JOURNAL OF MOLECULAR STRUCTURE
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2019
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IF 2.12
Qiang Liu,Peijun Cai,Xiangyu Wan,Shuai Zhang,Kai Du,Qiang Yin
Two neodymium β -diketonates metal-organic complexes, Nd(TTA) 3 TPTZ ( 1 ) and Nd(BFA) 3 TPTZ ( 2 ), have been synthesized by using two β -diketone ligands 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (HTTA) and 4,4,4-trifluoro-1-phenyl-1,3-butanedione (HFBA), and a macrocyclic conjugate ligand, 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ). The crystal structures of these two complexes were determined by single crystal X-ray diffraction. The X-ray diffraction analysis showed that each neodymium ion in the two complexes formed a Nine-Coordinated structure with six oxygen atoms of HTTA (or HBFA) ligands and three nitrogen atoms of TPTZ ligand by the characteristic of triclinic with P 1 ( — ) space group both. In the crystal structure of the two complexes, a very obvious aromatic donor-acceptor interaction can be observed between adjacent TPTZ ligand molecules, which play an important role in the formation of three-dimensional structures. The complexes were also characterized by infrared spectroscopy , elemental analysis, thermogravimetric and fluorescence spectra . Fluorescence analysis showed that the two complexes exhibited characteristic neodymium-centered emission due to the significant antenna effect of these ligands.
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JOURNAL OF CELLULAR BIOCHEMISTRY
·
2018
·Vol. 120
·期 3
·4463-4471
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IF 2.959
Xingda Wu,Zhe Liu,Kejia Guo,Gang Ma,Shaowei Song
Objective This work aimed to study the activating transcription factor 2 or AMP-dependent transcription factor-2 (ATF-2) inhibition mediated gemcitabine sensitivity in human pancreatic cancer cells. Methods The protein and messenger RNA expressions of ATF-2 in 42 pancreatic cancer tissues and adjacent nontumorous tissues were detected. Kaplan-Meier survival analysis was performed based on the expression level of ATF-2 protein in tumor tissues. Then the pancreatic cancer cells were transduced with ATF-2-expressing lentivirus and small interfering RNAs (siRNAs) to investigate the effect of ATF-2 on pancreatic cancer cell invasion, epithelium to mesenchyme transition, apoptosis, and gemcitabine sensitivity. Results The expression of phosphorylated (p)-ATF-2 protein was upregulated in pancreatic cancer tissues compared with adjacent nontumorous tissues. Patients with relative higher p-ATF-2 level showed significantly lower survival time. Then we found that the transfection ATF-2 siRNA into BxPC3 cells inhibited cell proliferation, invasion, and epithelium to mesenchyme transition, but enhanced cell apoptosis. These changes could be enhanced by the additional administration of gemcitabine. In addition, we confirmed that the overexpression of ATF-2 in Panc-1 cells promoted cell invasion and epithelium to mesenchyme transition. Conclusion We concluded that inhibition-promoted ATF-2 expression was responsible for epithelium to mesenchyme transition and invasion of pancreatic cancer cells, while the inhibition of ATF-2 confers to gemcitabine sensitivity in human pancreatic cancer cells in vitro.
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SYNTHESIS-STUTTGART
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2019
·Vol. 51
·期 16
·3085-3090
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IF 2.867
Menglan Wang,Yudong Li,Qing-An Wu,Shuping Luo,Yuehui Li
Indole scaffold synthesis relies primarily on oxidative C–H amination of N-protected alkenylanilines for C–N intramolecular cyclization reactions. Herein, for the first time, without N-protection, various readily prepared 2-alkenylanilines were transformed into the desired indole products in good yields by using K2S2O8 as oxidant in the presence of catalytic amounts of FeF2. The K2S2O8/FeF2 system offers a direct and benign synthetic route to 3-arylindoles and it is applicable to a wide range of substituted indoles including drug intermediates.
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