查找使用阿拉丁产品的科研文献

Direct Synthesis of 5-Methylfurfural from d-Fructose by Iodide-Mediated Transfer Hydrogenation

Jianwang Xu,Xinge Miao,Lei Liu,Yantao Wang,Weiran Yang

Graphical Transfer hydrogenation : 5-Methylfurfural (5-MF), a promising C 6 platform molecule, is directly produced from biomass-derived carbohydrates by iodide-mediated transfer hydrogenation. Under the optimized conditions, 30–50 % of 5-MF is yielded from low-cost sugars and starch with 5-MF productivity as high as 103 mmol g cat −1 h −1 . The catalytic system is simple, robust, recyclable, and preferable to other approaches for the production of 5-MF. Herein, a robust catalytic system was developed for the green synthesis of 5-methylfurfural (5-MF) by iodide-mediated transfer hydrogenation. Around 50 % of 5-MF was yielded from d -fructose within 7.5 min using NaI as the catalyst and formic acid as both the hydrogen source and co-catalyst. The catalytic system was used for six consecutive cycles without any decrease in the yield. Various starch and raw biomass could be used as promising starting materials for 5-MF synthesis with moderate yields, and the productivity of 5-MF from corn starch reached 103 mmol g cat −1 h −1 , which is comparable with the best result from l -rhamnose. Moreover, the co-production of 5-MF and furfural from raw biomass makes this methodology more competitive than other routes.

Highly Efficient Extracellular Production of Recombinant Streptomyces PMF Phospholipase D in Escherichia coli

Jing Wang,Sheng Xu,Yang Pang,Xin Wang,Kequan Chen,Pingkai Ouyang

To achieve efficient bio-production of phospholipase D (PLD), PLDs from different organisms were expressed inE.coli. An efficient secretory expression system was thereby developed for PLD. First, PLDs fromStreptomycesPMF andStreptomyces racemochromogeneswere separately over-expressed inE.colito compare their transphosphatidylation activity based on the synthesis of phosphatidylserine (PS), and PLDPMFwas determined to have higher activity. To further improve PLDPMFsynthesis, a secretory expression system suitable for PLDPMFwas constructed and optimized with different signal peptides. The highest secretory efficiency was observed when the PLD * (PLDPMFwith the native signal peptide Nat removed) was expressed fused with the fusion signal peptide PelB-Nat inE. coli. The fermentation conditions were also investigated to increase the production of recombinant PLD and 10.5 U/mL PLD was ultimately obtained under the optimized conditions. For the application of recombinant PLD to PS synthesis, the PLD properties were characterized and 30.2 g/L of PS was produced after 24 h of bioconversion when 50 g/L phosphatidylcholine (PC) was added.Keywords:phospholipase D;phosphatidylserine;secretory expression;enzymatic catalysis

D-serine reduces memory impairment and neuronal damage induced by chronic lead exposure

Jian-Zhu Bo,Ling Xue,Shuang Li,Jing-Wen Yin,Zheng-Yao Li,Xi Wang,Jun-Feng Wang,Yan-Shu Zhang

Although exogenous D-serine has been applied as a neural regulatory intervention in many studies, the role played by D-serine in hippocampal injuries caused by lead exposure remains poorly understood. Rat models of chronic lead exposure were established through the administration of 0.05% lead acetate for 8 weeks. Simultaneously, rats were administered 30 or 60 mg/kg D-serine, intraperitoneally, twice a day. Our results showed that D-serine treatment shortened the escape latency from the Morris water maze, increased the number of times that mice crossed the original platform location, and alleviated the pathological damage experienced by hippocampal neurons in response to lead exposure. Although D-serine administration did not increase the expression levels of the N-methyl-D-aspartate receptor subtype 2B (NR2B) in the hippocampi of lead-exposed rats, 60 mg/kg D-serine treatment restored the expression levels of NR2A, which are reduced by lead exposure. These findings suggested that D-serine can alleviate learning and memory impairments induced by lead exposure and that the underlying mechanism is associated with the increased expression of NR2A in the hippocampus. This study was approved by the Animal Ethics Committee of North China University of Science and Technology, China (approval No. LX2018155) on December 21, 2018.

Real-Time QCM-D Monitoring of the Adsorption–Desorption of Expansin on Lignin

Mei Cui,Yuhao Duan,Yuanyuan Ma,Khaled W.A. Al-Shwafy,Yudong Liu,Xudong Zhao,Renliang Huang,Wei Qi,Zhimin He,Rongxin Su

Expansin has nonhydrolytic disruptive activity and synergistically acts with cellulases to enhance the hydrolysis of cellulose. The adsorption–desorption of expansin on noncellulosic lignin can greatly affect the action of expansin on lignocellulose. In this study, three lignins with different sources (kraft lignin (KL), sodium lignin sulfonate (SLS), and enzymatic hydrolysis lignin (EHL)) were selected as the substrates. The real-time adsorption–desorption of Bacillus subtilis expansin (BsEXLX1) on lignins was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The effects of temperature and Tween 80 on the adsorption–desorption behaviors were also investigated. The results show that BsEXLX1 exhibited high binding ability on lignin and achieved maximum adsorption of 283.2, 273.8, and 266.9 ng cm–2 at 25 °C on KL, SLS, and EHL, respectively. The maximum adsorption decreased to 148.2–192.8 ng cm–2 when the temperature increased from 25 to 45 °C. Moreover, Tween 80 competitively bound to lignin and significantly prevented expansin adsorption. After irreversible adsorption of Tween 80, the maximum adsorption of BsEXLX1 greatly decreased to 33.3, 37.2, and 10.3 ng cm–2 at 25 °C on KL, SLS, and EHL, respectively. Finally, a kinetic model was developed to analyze the adsorption–desorption process of BsEXLX1. BsEXLX1 has a higher adsorption rate constant (kA) and a lower desorption rate constant (kD) on KL than on SLS and EHL. The findings of this study provide useful insights into the adsorption–desorption of expansin on lignin.

Selective Capture and in Situ Controllable Detection of d-Glucose in Cerebral Systems

Juan Qiao,Han Wu,Huan Wei,Lanqun Mao,Tie Wang,Li Qi

To monitor d-glucose (Glu) in complex aqueous media with a high specificity, a conceptually new “selective capture and controllable detection” nanoreactor was explored. We designed and synthesized poly maleic anhydride-styrene-N-isopropylacrylamide-(4-aminophenyl) boronic acid [P(MAn-St-NIPAm-PBA)] to fabricate the nanoreactor. On the surface of the self-assembled, micelle-based nanoreactor, the stereo precise placement PBA provided a recognition unit in the block copolymer structure to boost the selective capture of Glu over other saccharides. P(MAn-St-NIPAm) served as the thermal sensitive moiety of the nanoreactor, which embedded with glucose oxidase and myoglobin-based catalyst in order to realize the controllable enzymolysis of Glu through temperature alteration. Once the nanoreactor was mixed with Glu, an obvious change in the UV–visible intensity of quinine produced in the multienzymolysis was observed. Glu in the rat microdialysates of brain ischemia was successfully monitored by the nanoreactor method, demonstrating the feasibility of constructing high-specificity nanoreactors for cerebral system applications.

Chiral PDTDH-based electrode modification material for L/D-tartaric acid electrochemical sensing

Han Shuo,Peng Yanyan,Tao Shengyun,Hu Ying,Lan Tianqi,Hu Chengkang,Cao Jing

In this work, a kind of chiral helical polymer PDTDH of 9,9-dipropynylfluorene skeleton structure were prepared. The structure and chiral properties of the obtained polymer were characterized by Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) Spectroscopy. These chiral PDTDH polymers were used to fabricate chiral sensors and to investigate the enantioselective recognition of D−/L- tartaric acid enatiomer. The results indicated that the (S)-PDTDH/GCE sensor showed obvious response toward the tested tartaric acid enantiomer, which was confirmed by two parameters: Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) tests. These findings expand the scope for the application of chiral polymer as electrode modification material in the electrochemical chiral recognition field.

Ternary deep eutectic solvents catalyzed d-glucosamine self-condensation to deoxyfructosazine: NMR study

Pengfei Liu,Christian Marcus Pedersen,Jiaojiao Zhang,Rui Liu,Zhenzhou Zhang,Xianglin Hou,Yingxiong Wang

Ternary deep eutectic solvents (TDESs) comprising choline chloride (ChCl), glycerol and l -arginine were synthesized as catalysts and solvents for the conversion of d -glucosamine (GlcNH 2 ) into deoxyfructosazine (DOF). The interactions between these three components in the prepared TDESs were studied by 1 H-, 35 Cl-NMR spectra and 1 H diffusion-ordered spectroscopy (DOSY) measurements. The chemical shift changes of active hydrogen in the 1 H-NMR spectra of TDES system and widening of signals in the 35 Cl-NMR spectra confirmed the hydrogen bonding interaction between the components, which was further supported by the decrease of diffusion coefficients ( D ) of the TDES components according to 1 H DOSY measurements. The influences of reaction temperature and l -arginine content in the TDESs on the yield of DOF were also studied. The experimental results have shown that when the molar ratio of ChCl, glycerol, and l -arginine was 1:2:0.1, DOF was the major product with a yield of 22.6% at 90 °C for 120 min. The chemical shift titration indicated that the carboxyl group of l -arginine in the TDES is the catalytical active site, so the mechanism of the catalytic reaction between GlcNH 2 and the TDES was proposed. Moreover, a reaction intermediate, dihydrofructosazine, was identified in the self-condensation reaction of GlcNH 2 by an in situ 1 H NMR technique.

A Hybrid Wireless Electrodeless QCM-D for the Discrimination of Volatile Organic Compounds

Ruifen Hu,Xuefei Su,Ye Wang,You Wang,Adrian Carl Stevenson,Guang Li

Saikosaponin-d regulates angiogenesis in idiopathic pulmonary fibrosis through angiopoietin/Tie-2 pathway

Yan Wu,Jun Zhang,Xintian Wang,Yuncong Xu,Jinxu Zheng

Objective Idiopathic pulmonary fibrosis (IPF) is considered as a chronic interstitial lung disease with underlying mechanism of IPF remaining unclear, while there are no definitive treatment options. In recent years, scientists have gradually paid attention to the influence of angiogenesis on IPF. Because IPF is a progressive with microvascular remodeling disorder, scientists have postulated that angiogenesis may also be one of the initiating and contributing factors of the disease. Bupleurum is a common natural Chinese herbal medicine with antibacterial, anti-inflammatory, anti-tumor and other pharmacological effects. As the most important active monomer of Bupleurum, Saikosaponin-d (SSd) is a new discovery with anti-pulmonary fibrosis (PF) activity. This study attempts to investigate the role of SSd in the interference of PF through regulation of angiogenesis in IPF through Angiopoietin (Angpt) /Tie receptor 2 (Tie2) pathway. Methods Randomly, we allocated C57BL/6 mice into four groups (n = 20 in each group). Afterwards, establishment of IPF model was accomplished via intratracheal administration of bleomycin (BLM, 5 mg/kg), while corresponding drug intervention was given accordingly. On 3rd, 7th, 14th and 28th days after modeling, we performed histopathological examination through staining. Meanwhile, immunohistochemistry (IHC) of PF and the expression of related factors were observed, while Ang/Tie2 pathway was assessed by ELISA with the effect of SSd on angiogenesis related proteins in IPF being explored with IHC and Western Blot technique. Results Our results showed that SSd could reduce inflammation and PF levels in lung tissue of experimental mice, while levels of angiogenesis-related factors, namely Tie-2, Ang-1 and ANGPT2 (Ang-2), fibrosis- associated factors like Alpha-smooth muscle actin (α-SMA), collagen-I and hydroxyproline in SSd and dexamethasone (DXM) mice were significantly reduced at each time point compared to BLM (p < 0.01). Additionally, we discovered substantial decreased expressions of Ang-1, Ang-2, Tie-2, α-SMA and collagen-I at protein level in SSd and DXM mice at each time point compared to BLM (p < 0.05). Besides, insignificant differences were observed between SSd and DXM groups (p > 0.05). Conclusion This study has demonstrated that SSd could down-regulate the expression of ANG-1, Ang-2 and Tie2 in the Ang/Tie2 pathway, and may reduce lung inflammation and PF in BLM-induced mice via inhibition of angiogenesis.

Chemoenzymatic Approach to (S)-1,2,3,4-Tetrahydroisoquinoline Carboxylic Acids Employing D-Amino Acid Oxidase

Shuyun Ju,Mingxin Qian,Gang Xu,Lirong Yang,Jianping Wu

Optically pure 1,2,3,4-tetrahydroisoquinoline carboxylic acids constitute an important class of building blocks for the synthesis of natural products and synthetic pharmaceuticals. However, redox deracemization of racemic 1,2,3,4-tetrahydroisoquinoline carboxylic acids as an attractive method is still challenging for the lack of suitable oxidoreductases. Herein, a D-amino acid oxidase from Fusarium solani M-0718 ( Fs DAAO) with broad substrate scope and excellent enantioselectivity was exploited through genome mining, and applied for the kinetic resolution of a number of racemic 1- and 3-carboxyl substituted tetrahydroisoquinolines to yield the corresponding ( S )-enantiomers with excellent enantiomeric excess ( ee ) values (up to >99%). By using Fs DAAO in combination with ammonia-borane in one pot, deracemization of these racemic carboxyl-substituted tetrahydroisoquinolines was achieved with conversions up to >98% and >99% ee . Preparative-scale deracemization of racemic 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid and 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid was also demonstrated with good isolated yields (82% and 73%, respectively) and ee >99%. Our study provides an effective method for the synthesis of enantiomeric pure 1,2,3,4-tetrahydroisoquinoline carboxylic acids. This method is expected to provide access to chiral carboxyl-substituted 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydro-ß-carbolines.

A 3-D-Silicon Nanowire FET Biosensor Based on a Novel Hybrid Process

Xiaofeng Gong,Rui Zhao,Xiaomei Yu

Single-silicon nanowire field-effect transistor (SiNW-FET) devices are powerful tools for the detection and quantification of biochemical molecules. However, traditional SiNW-FET-based biosensors demonstrate low output signals and high fluctuation noises, which results from the tiny scale of a single channel and electrical property deterioration caused by the dry etching process. To improve the performance of the SiNW-FET biosensors, here we developed a 3-D-SiNW-FET by using a hybrid process of deep reactive ion etching and isotropic wet etching with HF, HNO3 and HAc (HNA) mixed solution. The 3-D-SiNW-FET that included 5 × 7 nanowire channels with a wire diameter of approximately 300 nm was successfully fabricated with the novel hybrid process. Compared with the performance of single-and 2-D-SiNW-FETs, the 3-D-SiNW-FET showed a fairly good ability to stabilize and enhance the source-drain current by parallelizing the signals of the multiple channels. With the fabricated 3-D-SiNW-FET, immunoglobulin G was detected at a concentration as low as 5 fM.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals

Siyuan Liu,Xiaoxi Li,Ling Chen,Lin Li,Bing Li,Jie Zhu

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.