查找使用阿拉丁产品的科研文献

Metabolic responses of tea (Camellia sinensis L.) to the insecticide thiamethoxam

Weiting Jiao,Ping Zhang,Chuanjian Cui,Min Yan,Qing X. Li,Yongfeng Tang,Nan Zhang,Xinyi Wang,Ruyan Hou,Rimao Hua

Background Thiamethoxam (TMX) is insecticidal, but also can trigger physiological and metabolic reactions of plant cycles. The objective of this work was to evaluate the physiological and metabolic effect of TMX on tea plants and its potential benefits. Results In this study, dose of TMX (0.09, 0.135 and 0.18 kg a.i./ha) were tested. Except for peroxidase (POD) and glutathione S-transferase (GST), chlorophyll, carotenoid, catalase (CAT) and malondialdehyde (MDA) were significantly affected compared with the controls. The CAT activity was increased by 3.38, 1.71, 2.91 times, respectively, under three doses of TMX treatment. The metabolic response between TMX treatment and control groups on the third day was compared using a widely targeted metabolomics. A total of 97 different metabolites were identified, including benzenoids, flavonoids, lipids and lipid-like molecules, organic acids and derivatives, organic nitrogen compounds, organic oxygen compounds, organoheterocyclic compounds, phenylpropanoids and polyketides, and others. Those metabolites were mapped on the perturbed metabolic pathways. The results demonstrated that the most perturbation occurred in flavone and flavonol biosynthesis. The beneficial secondary metabolites luteolin and kaempferol were upregulated 1.46 and 1.31 times respectively, which protect plants from biotic and abiotic stresses. Molecular docking models suggest interactions between TMX and flavonoid 3-O-glucosyltransferase. Conclusion Thiamethoxam spray positively promoted the physiological and metabolic response of tea plants. And this work also provided the useful information of TMX metabolism in tea plants as well as rational application of insecticides. © 2023 Society of Chemical Industry.

Preparation of 2D ZIF-L and Its Antibacterial and Antifouling Properties

Jingyu Li,Yang Zhang,Haichao Zhao,Guoxin Sui

The excessively leached metal ions from traditional metallic antimicrobial nanoparticles are harmful to biological and human tissues. Metal-organic frameworks (MOFs) coordinating bioactive metal ions to organic bridging ligands can potentially address this issue, avoiding the excessive leaching of metal ions and simultaneously exhibiting high effective antibacterial activities. Here, we report the preparation of a 2-dimensional leaves-like zeolitic imidazolate framework (ZIF-L) for potential antibacterial and anti-algae applications. The ZIF-L nanosheet exhibits complete inactivation ofEscherichia coli(phosphate buffer saline: 4 h) andBacillus subtilis(seawater: 0.5 h). The ZIF-L/epoxy composite has excellent antibacterial effect, poisoning effect and anti-adhesion effect on a variety of marine algae. It is worth noting that the removal rate (Escherichia coli) for ZIF/epoxy composite can be reached to 90.20% by only adding ZIF-L (0.25 wt%). This work will inspire researchers to develop more metal-organic frameworks materials for applications in the antibacterial and anti-algae fields.Keywords:ZIF-L;two dimensional;antibacterial;anti-algae

Synthesis, surface and interface tension of N-lauroyl-L-Valine sodium

Cong Luo,Bo Yang,Jian Yang,Yawen Zhou,Changyao Liu,Baocai Xu

A coupled system involving arginase and urease for l-ornithine production

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.

Preparation and characterization of chitosan-graft-poly(L-lactic acid) microparticles

Shiping Zhan,Nan Liu,Weijing Wang,Shuhua Chen,Jingchang Wang

To improve the properties of chitosan (CS) and poly(L-lactic acid) (PLLA) and obtain fully biodegradable materials, CS- g -PLLA copolymers were prepared using 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxyl succinimide (NHS) as a coupling agent. The copolymers were characterized by Fourier transform infrared analysis (FTIR), 1 H nuclear magnetic resonance ( 1 H NMR), elemental analysis, differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained by FTIR and 1 H NMR showed that CS and PLLA were grafted successfully via an amide bond. DSC and XRD results showed that the thermal stability of CS had been significantly improved by grafting PLLA to the molecular chains of CS and the crystallinity of the CS- g -PLLA copolymers decreased significantly. Elemental analysis showed that the achieved the maximum degree of substitution of PLLA was 60.88%, while the concentration of CS was 2 mg/mL, the PLLA molecular weight was 10,000, and the EDC/NHS ratio was 2:1. Images from SEM demonstrated that the copolymers had a spherical shape and smooth surface. Moreover, the products were well dispersed without any aggregation. POLYM. ENG. SCI., 56:1432–1436, 2016. © 2016 Society of Plastics Engineers

Controllable synthesis of Pd@ZIF-L catalysts by an assembly method

Hong Jiang,Songlin Xue,Yefei Liu,Rizhi Chen,Weihong Xing

The Pd@ZIF-L catalysts with uniform crosshair-star shape and a size of about 20 μm were fabricated by an assembly method that enables the crystallization of ZIF-L in water with the presence of polyvinylpyrrolidone (PVP)-stabilized Pd nanoparticles (NPs). The physical and catalytic properties of the Pd@ZIF-L catalysts are greatly affected by the molar ratios of 2-methylimidazole (2-MeIM)/Zn2+ and PVP/Zn2+. Their catalytic activities were evaluated by the catalytic reduction of p-nitrophenol to p-aminophenol. The results indicate that a lower molar ratio of 2-MeIM/Zn2+ is beneficial for the increase of Pd loading and p-nitrophenol conversion, but a suitable molar ratio (≥20) of 2-MeIM/Zn2+ is helpful to the crystallization of ZIF-L and the encapsulation of the Pd NPs within the ZIF-L framework. The Pd@ZIF-L catalyst synthesized at a lower PVP/Zn2+ molar ratio has higher Pd loading and p-nitrophenol conversion due to the easy adsorption of PVP–Pd NPs onto the ZIF-L surfaces. This work would aid the development of high-performance Pd@ZIF-L catalysts.

Ferroferric oxide/L-cysteine magnetic nanospheres for capturing histidine-tagged proteins

Xueyan Zou,Kun Li,Yanbao Zhao,Yu Zhang,Binjie Li,Chunpeng Song

Ferroferric oxide/L-cysteine (Fe3O4/Cys) nanospheres (NSs) have been successfully synthesized via a facile solvothermal route. Fe3O4/Cys NSs possessed high thiol group density and saturation magnetization (Ms) of 84.6 emu g−1. The prepared magnetic NSs are biocompatible and manipulatable by an external magnetic force. After chelating Ni2+ ions, Fe3O4/Cys-Ni2+ NSs were used to enrich and purify histidine-tagged (His-tagged) proteins directly from the mixture of lysed cells without pretreatment. It has been found that Fe3O4/Cys-Ni2+ NSs present negligible nonspecific protein adsorption and high protein binding activity with the saturation capacity being 53.2 μg mg−1 and they are especially suitable for rapid purification of His-tagged proteins.

Dispersion polymerization of L-lactide/ε-caprolactone in supercritical carbon dioxide

Zhan Shiping,Qi Qingchun,Wang Weijing,Chen Shuhua,Wang Jingchang,Li Mingming,Ding Shiqiang

The dispersion polymerization of L-lactide(LA) /ε-caprolactone(CL) with stannous octoate (Sn(Oct) 2 ) as a catalyst and n-butanol as an initiator in supercritical carbon dioxide (ScCO 2 ) was studied. The effects of operating parameters, such as pressure, temperature, stirring rate and monomer rate of LA/CL, on the characteristics of L-lactide and ε- caprolactone copolymer (PCLA) were investigated. The experimental results show that the pressure has the greatest effect on the morphology of the copolymer, and the temperature is the most decisive factor in the conversion ratio of the monomer. The changes of the conversion rate of the monomer were observed when the temperature risen from 90 to 110 °C. At the pressure of 18 MPa, the best morphology of the product can be got. Under the optimum reaction condition, PCLA with various ratio of LA/CL were obtained. Finally, fine powder particles of L-lactide and ε-caprolactone copolymer (PCLA) with high molecular weight were obtained.

Fabrication of Magnetic Poly(L-lactide) (PLLA)/Fe3O4 Composite Electrospun Fibers

Zhu Liu,Yufu Zheng,Lizhong Lin,Xiaofei Liu,Na Qiang

Electrospinning technology is widely used for preparing biological tissue engineering scaffolds because of its advantages of simple preparation, accurate process parameters, and easy control. Poly(L-lactide) (PLLA) is regarded as a promising biomass-based polymer for use in electrospinning. The incorporation of Fe3O4nanoparticles (NPs) could improve the osteogenic differentiation and proliferation of cells in the presence or absence of a static magnetic field (SMF). In this work, these two materials were blended together to obtain electrospun samples with better dispersibility and improved magnetic properties. First, composite PLLA and Fe3O4NP fibers were prepared by means of electrospinning. The influence of electrospinning conditions on the morphology of the composite fibers was then discussed. Changes in magnetic properties and thermal stability resulting from the use of different PLLA/Fe3O4mass ratios were also considered. Next, the morphology, crystal state, thermodynamic properties, and magnetic properties of the electrospun samples were determined using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and vibration sample magnetization (VSM). The results showed that the fibers prepared using PLLA withMn= 170,000 exhibited good morphology when electrospun at 12 KV. The magnetic properties of PLLA/Fe3O4composite electrospun fibers increased with the NP content, with the exception of thermal stability. The results of the present study may help to promote the further development of PLLA/Fe3O4composite materials in the biomedical field.

Controlled Synthesis of Crystalline and Helical N-Alkyl Poly(l-alanine)

Wenxiao Liu,Xuehua Deng,Yutong Dong,Sunting Xuan,Zhengbiao Zhang

The synthesis of N-substituted polypeptides is challenging due to steric hindrance. Here, N-alkyl poly(l-alanine)s, with controlled molecular weights (Mns) and narrow distributions, were efficiently synthesized by primary amine-initiated and acetic acid-catalyzed ring-opening polymerizations of N-alkyl-(l)-alanine N-carboxyanhydrides [NAlkyl-(l)-Ala-NCAs] in toluene of low polarity and low proton-accepting ability. The N-alkyl poly(l-alanine)s, with chiral centers at backbones and different alkyl substituents at side chains, showed a relatively extended helical structure similar to that of the PPII-helix of poly(l-proline). The elongation of the alkyl side chains and the increase in temperatures had negligible effects on the helix structure, as revealed by the circular dichroism measurements. The differential scanning calorimetry and X-ray diffraction measurements showed that the polymers were crystalline. Besides, the NAlkyl-(l)-Ala-NCAs were capable of copolymerizing with other monomers, producing structurally diverse copolymers. The efficient synthesis of N-alkyl poly(l-alanine)s, combined with the structural tunability, hydrophobicity, crystallinity, protein-like skeleton, enzymatic stability, and stable helix, makes the polymers attractive structural units in self-assembly and the biomedical field.

An Antibacterial Hemostasis Sponge of Gelatin/ε-Poly-L-Lysine Composite

Yifan Lu,Xiangxin Lou,Wenxin Wang,Ziting Yang,Haochen Yao,Jinglei Wu

Massive bleeding and bacterial infection of wounds may be life-threatening or even lead to death. Nowadays, gelatin-based hemostatic sponges have been widely used, but gelatin is not antibacterial and has poor structural stability. In this study, we mixed an antibacterial polypeptide, ε-poly-L-lysine (EPL), into gelatin. A gelatin/ε-poly-L-lysine (Gel/EPL) sponge with hemostatic and antibacterial functions was prepared by ultraviolet (UV) crosslinking lyophilized Gel/EPL composite. Scanning electron microscopy showed that the sponge had an interconnected porous structure. The incorporation of EPL increased the hydrophilicity and water absorption capacity of the Gel/EPL sponge. The sponge had better structural stability after UV crosslinking. The antibacterial assay showed that bacteria could not grow normally around the Gel/EPL sponge. The contact between blood components and the sponge initiated coagulation via exogenous pathway activation, and no hemolysis occurred. In addition, in vivo experiments confirmed that the sponge has a faster clotting time and lower blood loss. These findings show that the developed Gel/EPL sponge has great potential as a novel hemostatic agent that can quickly stop bleeding and fight bacterial infections.

A Close Cognition of Charged Poly(l-methionine) Derivatives for Antifreeze

Binlin Chen,Yueqi Deng,Qingjing Niu,Kongying Zhu,Lixia Ren,Xiaoyan Yuan

Ice formation poses a significant challenge across various fields, from industrial processes to biological preservation. Developing antifreeze agents and recognizing the antifreeze mechanism have gained considerable attention. Herein, a series of poly(l-methionine) derivatives, poly(S-carboxymethyl-l-methionine sulfonium) (PMetA), poly(S-methyl-l-methionine sulfonium chloride) (PMetM), and poly(S-carbamidomethyl-l-methionine sulfonium chloride) (PMetAM), with carboxyl, methyl, and acetamide groups, respectively, are synthesized and investigated for antifreeze. The relationship between the polymer structure and the ice recrystallization inhibition (IRI) activity is examined, suggesting that zwitterionic PMetA shows the highest IRI activity, about 27.0 ± 3.9% at 10 mg mL–1 relative to that of water. Results of low-field nuclear magnetic resonance and differential scanning calorimetry indicate that the IRI activity is associated with the activation energy for hydrogen bond breakage. PMetA exhibits acceptable cytocompatibility at 10.0 mg mL–1 and a good cryoprotective efficiency. This finding provides a valuable insight into the antifreeze mechanism, contributing to the development of potent cryoprotectants.