Polymer Chemistry
·
2023
·Vol. 14
·期 10
·1124-1134
·
IF 4.6
Yaodong Wang,Lijia Liu,Yudan Wang,Kexiao Sang,Chunhong Zhang,Toshifumi Satoh
An L-phenylalanine dipeptide (L-Phe-L-Phe-OMe) monomer was cross-linked to form a heterogeneous chiral porous polymer skeleton, HCP(L-Phe-L-Phe-OMe), which was then modified with L-proline (L-Pro) to produce an HCP(L-Pro-L-Phe-L-Phe-OMe) catalyst with a higher specific surface area of 261.68 m2 g−1. Asymmetric Michael addition and Mannich reactions were successfully catalyzed using HCP(L-Pro-L-Phe-L-Phe-OMe); compared to the case of L-Pro-L-Phe-L-Phe-OMe, the reaction time for the Michael reaction of cyclohexanone with trans-β-nitrostyrene was shortened from 7 d to 4 d, and the enantiomeric excess (ee) value increased from 71% to 97%. Such significant improvements were also observed in asymmetric Mannich reactions. In addition, the optimum conditions for catalytic reactions are discussed with time, solvent and catalyst amount as variables, and the applicability of the catalyst was investigated using the substrate structure. The catalyst is recyclable via simple filtration and it exhibits good recycling performance. Preparing high-performance asymmetric catalysts using affordable amino acids is thus an effective strategy.
研究领域:
化学
·
催化
·
有机合成
·
材料科学
✓ 已验证
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2011
·Vol. 5
·期 4
·409-415
·
IF 0
Cao Hongfei,Feng Yakai,Wang Heyun,Zhang Li,Khan Musammir,Guo Jintang
By using the corresponding L -amino acid sodium as initiator, ɛ -caprolactone-depsipeptides CL-Ala and CL-Leu were prepared by the reactions of ɛ -caprolactone (CL) with L -alanine and L -leucine, respectively, and p -dioxanone-depsipeptide (PDO-Leu) was prepared by the reaction of p -dioxanone (PDO) with L leucine. Two poly( ɛ -caprolactone) oligomers (PCL-Ala and PCL-Leu) of different molecular weights with depsipeptide unit were synthesized by controlling the feed ratio of L -amino acid sodium and CL. The presence of the depsipeptide structure in these obtained products was confirmed by 1 H NMR spectra and the molecular weight of the poly( ɛ -caprolactone) oligomers was measured by gel permeation chromatography (GPC). These products contain a hydroxyl group and a carboxyl group in one molecule, which means they could act as bifunctional monomers for further polymerization to prepare high molecular weight polymers. By this way, the depsipeptide unit could be introduced into the polymers and the biodegradation rates of the novel polymers could be well controlled in vivo by the tailored molecular structures.
研究领域:
有机化学
·
高分子化学
·
生物材料学
✓ 已验证
DOI
CHEMICAL PAPERS
·
2019
·Vol. 74
·期 6
·1831-1838
·
IF 1.246
Cai Zhifeng,Zhang Caifeng,Jia Kang
A fast, simple, green and low-cost synthesis method in aqueous solution was successfully established for the preparation of l -tyrosine protected Cu nanoclusters (Cu NCs). Subsequently, the as-prepared Cu NCs was characterized by UV–vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It exhibited good water solubility, excellent photostability and high stability toward high concentration of sodium chloride. The Cu NCs revealed maximum excitation and emission peaks at 430 and 477 nm, respectively. Importantly, the Cu NCs showed a rapid response, a liner relation over the pH ranges from 5.02 to 11.92 and could be repeated for five consecutive cycles without fluorescence decay. Further, the as-prepared Cu NCs was applied for the determination of pH value in water samples. Simultaneously, all above features showed that l -tyrosine protected Cu NCs had great potential for sensing of pH in biological field.
研究领域:
生物化学
·
材料科学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 9
·1-10
·
IF 5.705
Khan Md. Zaved H.,Liu Xiaoqiang,Tang Yunfei,Zhu Jinhua,Hu Weiping,Liu Xiuhua
A glassy carbon electrode (GCE) was modified with poly(L-arginine) (P-Arg), reduced graphene oxide (rGO) and gold nanoparticle (AuNP) to obtain an electrode for simultaneous determination of dopamine (DA), serotonin (5-HT) and L-tryptophan (L-Trp) in the presence of ascorbic acid (AA). The modified GCE was prepared via subsequent ‘layer-by-layer’ deposition using an electrochemical technique. The surface morphology of the modified electrode was studied by scanning electron microscopy, and electrochemical characterizations were carried out via cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode showed excellent electrocatalytic activity toward DA, 5-HT and L-Trp at pH 7.0. Figures of merit for the differential pulse voltammetric reponse are as follows: (a) Response to DA is linear in two intervals, viz. 1.0–50 nM and 1.0–50 μM DA concentration range, the typical working voltage is 202 mV (vs. Ag/AgCl), and the detection limit is 1 nM (at an S/N ratio of 3). For 5-HT, the respective data are 10 to 500 nM and 1.0 to 10 μM, 381 mV, and 30 nM. For L-Trp, the respective data are 10–70 nM and 10–100 μM, 719 mV, and 0.1 μM. The modified GCE is fairly selective. It was successfully applied to the simultaneous determination of DA, 5-HT, and L-Trp in spiked urine samples, and high recovery rates were found.
Schematic presentation of the voltammetric sensor based on a glassy carbon electrode modified with poly(L-arginine), reduced graphene oxide (rGO) and gold nanoparticle (GCE/P-Arg/ErGO/AuNP) for simultaneous determination of dopamine (DA), serotonin (5-HT) and L-tryptophan (L-Trp).
研究领域:
分析化学
·
生物医学工程
·
神经科学
✓ 已验证
DOI
PubMed
高影响因子
ENZYME AND MICROBIAL TECHNOLOGY
·
2022
·
IF 3.705
Jinbin Liu,Kaipeng Wang,Mian Wang,Huaxiang Deng,Xiaodong Chen,Yueling Shang,Xiaochen Liu,Xiaohong Yu
An engineered Escherichia coli was constructed by co-expressing L -amino acid deaminase, α-keto acid decarboxylase, alcohol dehydrogenase , and glucose dehydrogenase through two plasmids for tyrosol production. The activity of the rate-limiting enzyme L -amino acid deaminase from Cosenzaea myxofaciens (CmAAD) toward tyrosine was improved by structure-guided modification. The enzyme activity of triple mutant CmAAD V438G/K147V/R151E toward tyrosine was ~5.12-fold higher than that of the wild-type CmAAD. Secondly, the plasmid copy numbers and the gene orders were optimized to improve the titer of tyrosol. Finally, the recombinant strain CS-6 transformed 10 mM tyrosine into 9.56 ± 0.64 mM tyrosol at 45 ℃, and the space-time yield reached 0.478 mM·L −1 ·h −1 . This study proposes a novel idea for the efficient and natural production of tyrosol, which has great potential for industrial application.
研究领域:
生物技术
·
酶学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Biotechnology Journal
·
2024
·Vol. 19
·期 11
·e202400527
·
IF 3.2
Chaoqun Tang,Lu Zhang,Junyi Wang,Congjia Zou,Yalin Zhang,Jifeng Yuan
Saccharomyces boulardii , as a probiotic yeast, has shown great potential in regulating gut health and treating gastrointestinal diseases. Due to its unique antimicrobial and immune-regulating functions, it has become a significant subject of research in the field of probiotics. In this study, we aim to enhance the antioxidant properties of S. boulardii by producing l -ergothioneine (EGT). We first constructed a double knockout of ura3 and trp1 gene in S. boulardii to facilitate plasmid-based expressions. To further enable effective genome editing of S. boulardii , we implemented the PiggyBac system to transpose the heterologous gene expression cassettes into the chromosomes of S. boulardii . By using enhanced green fluorescent protein (EGFP) as the reporter gene, we achieved random chromosomal integration of EGFP expression cassette. By using PiggyBac transposon system, a great variety of EGT-producing strains was obtained, which is not possible for the conventional single target genome editing, and one best isolated top producer reached 17.50 mg/L EGT after 120 h cultivation. In summary, we have applied the PiggyBac transposon system to S. boulardii for the first time for genetic engineering. The engineered probiotic yeast S. boulardii has been endowed with new antioxidant properties and produces EGT. It has potential applications in developing novel therapeutics and dietary supplements for the prevention and treatment of gastrointestinal disorders.
研究领域:
微生物学
·
遗传工程
·
营养学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Shiyang Li,Chenchen Zheng,Longdou Tu,Dajian Cai,Yangxiang Huang,Congjie Gao,Yeqiang Lu,Lixin Xue
Tight ultra-filtration (TUF) membranes were constructed by in situ growing zinc imidazole frameworks micro-crystalline leaves (ZIF-L) in polyethylene imine (PEI) and polydopamine (PDA) deposit layers on porous polyethylene (PE) substrates. The effects of preparation conditions on the surface physical and chemical structures as well as on the dye/salt separation performance of the formed TUF membranes were systematically investigated. By inserting selective water permeation channels and increasing contacting surface areas, in situ-grown ZIF-L arrays tightly cross-linked in the coating matrix greatly increased water permeation without trading off dye/salt retention selectivity. The morphology of the included ZIF-L particles could be varied by adjusting the ligand/Zn molar ratio (α) in the preparation processes. Optimized PDA-PEI/ZIF-L@PE TUF membranes containing ZIF-L of cross-cross block morphology showed very high pure water permeability of 180 ± 20 L·m −2 ·h −1 ·bar −1 (LMHB) and retention selectivity (S CR/Na2SO4 and S MB/Na2SO4 ) of 267 and 43, respectively, as well as excellent stability and anti-fouling properties.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2012
·Vol. 19
·期 12
·1-8
·
IF 1.733
Ma Chi,Wang Bing,Xiong Cheng-Dong,Chen Dong-Liang,Xiong Zuo-Chun
Control of dimensional stability is crucial for using electrospun membranes in biomedical and tissue engineering applications. In this study, the contraction of electrospun membranes of poly( l -lactide-co-glycolide) (PLLGA) after stretch was investigated. Then, by adding PLLGA-b-polyethylene glycol (PLLGA-PEG), the contraction of the membranes was controlled. In addition, the mechanical properties of the membranes were investigated. On the basis of the strain–stress behavior of the membranes, an elongation of 50 % was used to investigate the orientation degrees of the membrane fibers. On the basis of the morphology of the stretched membranes, the contraction was found to depend on the orientation degree of fibers after stretch. A linear relationship between the contraction and degree of orientation after stretch was confirmed. Two-dimensional fast Fourier transform (2D FFT) analysis of the scanning electron microscopy (SEM) images of the membranes was used to quantify the orientation degree. It was surmised that the different orientation degrees were responsible for the different morphologies and thermal behaviors of the membranes.
研究领域:
生物医学工程
·
组织工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2015
·
IF 4.891
Jingxiang Yang,Yongli Wang,Hongxun Hao,Chuang Xie,Ying Bao,Qiuxiang Yin,Junbo Gong,Chen Jiang,Baohong Hou,Zhao Wang
L-Tryptophan was successfully crystallized in the form of spherulites by introducing trace amounts of gelatin into the crystallization solution. The physicochemical properties of L-tryptophan products were significantly improved by using this polymer-induced spherulitic growth strategy. This newly developed polymer-induced spherulitic growth strategy provides another choice for controlling the size distribution of particles. Furthermore, the formation and growth of these spherulites under different conditions was monitored in situ by using particle vision measurement and microscopy. It was found that the morphologies of spherulites could be influenced by the additives, the crystallization temperature, and the initial concentration of L-tryptophan. The influence of temperature on the growth rate of spherulites was investigated. It was found that the growth rate is constant at given temperatures. A population-based empirical model was developed and used to explain the spherulitic growth of L-tryptophan spherulites. It was verified that the growth of L-tryptophan spherulites is interface kinetics controlled.
研究领域:
化学工程
·
材料科学
·
药物结晶
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
·
2017
·
IF 2.269
Kai Huang,Tao Zhang,Bo Jiang,Wanmeng Mu,Ming Miao
l -Ornithine, a non-protein amino acid, is widely used as a food supplement and nutrition product that is usually produced by the enzymatic hydrolysis of l -arginine. However, urea, a by-product, complicates purification of l -ornithine. Here, we describe a highly efficient coupled system, which involves Rummeliibacillus pycnus arginase and Jack bean urease, for the production of l -ornithine without urea residue. Although R. pycnus arginase exhibited the highest enzyme activity at pH 9.5 with Mn 2+ , it could be activated by Ni 2+ at 70 °C and pH 6.5. Kinetic study showed that, compared with Mn 2+ -containing arginase, Ni 2+ -containing arginase had a higher substrate affinity and catalysis efficiency. Based on the properties of commercial Jack bean urease and recombinant arginase, both enzymes showed robust activity at pH 6.5 and 40–50 °C. Using a coupled system involving arginase and urease for bioconversion, l -ornithine production of 37.8 g l −1 was achieved with a 99.7% molar yield within 5 h. Thus, this coupled system represents an applicable strategy for the biosynthesis of l -ornithine.
研究领域:
生物化学
·
酶工程
·
生物技术
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 12
·2317
·
IF 4.967
Juliene Oliveira Campos de França,Deborah da Silva Valadares,Mateus Freitas Paiva,Sílvia Cláudia Loureiro Dias,José Alves Dias
Poly(lactic acid) (PLA) is an important polymer that is based on renewable biomass resources. Because of environmental issues, more renewable sources for polymers synthesis have been sought for industrial purposes. In this sense, cheaper monomers should be used to facilitate better utilization of less valuable chemicals and therefore granting more sustainable processes. Some points are raised about the need to study the total degradability of any PLA, which may require specific composting conditions (e.g., temperature, type of microorganism, adequate humidity and aerobic environment). Polymerization processes to produce PLA are presented with an emphasis on D,L-lactic acid (or rac-lactide) as the reactant monomer. The syntheses involving homogeneous and heterogeneous catalytic processes to produce poly(D,L-Lactic acid) (PDLLA) are also addressed. Additionally, the production of blends, copolymers, and composites with PDLLA are also presented exemplifying different preparation methods. Some general applications of these materials mostly dedicated to the biomedical area over the last 10–15 years will be pointed out.Keywords:poly(lactic acid)-PLA;polymerization based on D,L-lactic acid;D,L-lactide;stereo polymerization of D,L-lactic acid;blends of PLA;poly(DL-lactide-co-polymer);composites of PDLLA
研究领域:
高分子化学
·
生物材料学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2025
·Vol. 26
·期 4
·1558
·
IF 4.9
Jiabin Huang,Haotian Wu,Ranran Gao,Lan Wu,Mengyue Wang,Yang Chu,Yuhua Shi,Li Xiang,Qinggang Yin
L-ascorbic acid (vitamin C, AA) is widely present in plants, but humans lack the ability to synthesize it independently. As a potent reducing agent, AA is susceptible to oxidation, making the enhancement of its stability crucial. 2-O-β-D-glucopyranosyl-L-ascorbic acid (AA-2βG) is a stable natural derivative of AA with glycosylation, initially discovered in the fruits ofLycium barbarum. Understanding the biosynthesis of AA-2βG is crucial for enhancing its production inL. barbarum. While the established biosynthesis pathway of AA constitutes the upstream of AA-2βG biosynthesis, the conclusive step of β-glycosylation remains unclear. We identified aL. barbarumcultivar by UPLC, ZN01, with a high content of AA-2βG, and compared its leaves, immature fruits, and mature fruits to a normal AA-2βG contentL. barbarumcultivar for metabolomic and transcriptomic analysis. The RNA-seq and RT-qPCR analysis revealed that the expression levels of genes involved in the AA biosynthesis pathway did not consistently correlate with AA-2βG content, suggesting that the final glycosylation step may be a key determinant of AA-2βG accumulation. Subsequently, utilizing phylogenetic and co-expression analysis, we identified ten UDP-glycosyltransferases (UGTs) and three β-glucosidases (BGLUs) which may be involved in the crucial step of the conversion from AA to AA-2βG, and the UGTs’ activities were predicted through molecular docking. Lastly, we speculated that the presence of the glycosylation process of AA might have a crucial role in maintaining AA homeostasis inL. barbarum, and deliberated on potential correlations between AA, carotenoids, and anthocyanins. Our integrated multi-omics analysis provides valuable insights into AA-2βG biosynthesis inL. barbarum, identifying thirteen candidate genes and highlighting the complex interplay between AA, carotenoids, and anthocyanins. These findings have implications for improving AA-2βG content inL. barbarum.
研究领域:
植物学
·
代谢组学
·
转录组学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）