离子交换色谱法对大肠杆菌表达的人重组骨形态发生蛋白-7的纯化

带有BMP 7基因的大肠杆菌可以用来高量表达重组的人骨形态发生蛋白 7。升温诱导表达后 ,每升培养液大约可得到菌体湿重 3g ,其中目的蛋白约占菌体总蛋白量的 40 %。裂解离心 ,用低浓度变性剂洗涤初步纯化包涵体 ,上清中无目的蛋白损失 ,目的蛋白纯度提高到 60 %,将包涵体溶解于高浓度变性剂溶液中 ,然后在不同条件下用离子交换色谱法对变性状态下的蛋白质进行纯化 ,绝大部分杂蛋白被除去 ,目的蛋白纯度达 95 %以上 ,改变条件 ,可以减少rhBMP 7损失。并做Westernblot对目的蛋白进行特异性鉴定。     

Bactericidal silver ion delivery into hydrophobic coatings with surfactants

A much studied oil-soluble surfactant, bis[2-ethylhexyl]sulfosuccinate, sodium salt, was ion exchanged into the silver ion form and dissolved into microemulsions of immiscible polyurethane step monomers. Coating and curing of these microemulsions produced polyurethane coatings that exhibit bactericidal activity against representative Gram negative bacteria. After 24 h exposure, 0.006–0.012% weight Ag relative to coating weight (0.0013–0.0025 μmol Ag/cm²) results in the three-log reduction in Escherichia coli. A slightly higher level of 0.031% weight Ag relative to coating weight (0.006 μmol Ag/cm²) killed all of the E. coli after 12 h exposure. Similar results were obtained for Pseudomonas aeruginosa. Since the double-tail surfactant anion promotes reverse micelle formation in many different kinds of oils and solvents, it appears an excellent vector for incorporating low and effective amounts of silver ion into many industrial, hospital, and household coating formulations.     

Silver bullets: A new lustre on an old antimicrobial agent

Silver was widely used in medicine to treat bacterial infections in the 19th and early 20th century, up until the discovery and development of the first modern antibiotics in the 1940s, which were markedly more effective. Since then, every new antibiotic introduced to the clinic has led to an associated development of drug resistance. Today, the threat of extensive bacterial resistance to antibiotics has reignited interest in alternative strategies to treat infectious diseases, with silver regaining well-deserved renewed attention. Silver ions are highly disruptive to bacterial integrity and biochemical function, with comparatively minimal toxicity to mammalian cells. This review focuses on the antimicrobial properties of silver and their use in synergistic combination therapy with traditional antibiotic drugs.     

Biosynthesis of silver nanoparticles formation from Caesalpinia pulcherrima stem metabolites and their broad spectrum biological activities

The present work illustrates eco-friendly, rapid and cost effective method of AgNPs synthesis using C. pulcherrima stem extract. Initially, various physico chemical factors were optimized. Characterization was done by different spectroscopic and microscopic analysis. AgNPs were spherical in shape with an average size of 8?nm. AgNPs showed good synergistic antimicrobial, antibiofilm and antioxidant activity. The cytotoxicity effect against HeLa cancer cell line was dose dependent while genotoxic study revealed the non toxic nature of AgNPs at lower concentration. The results suggest that AgNPs from C. pulcherrima stem extract have great potential in biomedical applications.     

Synthesis and comparative study on the antimicrobial activity of hybrid materials based on silver nanoparticles (AgNps) stabilized by polyvinylpyrrolidone (PVP)

Hybrid materials based on polyvinylpyrrolidone (PVP) with silver nanoparticles (AgNps) were synthesized applying two different strategies based on thermal or chemical reduction of silver ions to silver nanoparticles using PVP as a stabilizer. The formation of spherical silver nanoparticles with diameter ranging from 9 to 16 nm was confirmed by TEM analysis. UV-vis and FTIR spectroscopy were also applied to confirm the successful formation of AgNps. The antibacterial activity of the synthesized AgNPs/PVP against etalon strains of three different groups of bacteria—Staphylococcus aureus (S. aureus; gram-positive bacteria), Escherichia coli (E. coli; gram-negative bacteria), Pseudomonas aeruginosa (P. aeruginosa; non-ferment gram-negative bacteria), as well as against spores of Bacillus subtilis (B. subtilis) was studied. AgNps/PVP were tested for the presence of fungicidal activity against different yeasts and mold such as Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, and Aspergillus brasiliensis. The hybrid materials showed a strong antimicrobial effect against the tested bacterial and fungal strains and therefore have potential applications in biotechnology and biomedical science.     

Synthesis and structural characterization of silver nanoparticles using bacterial exopolysaccharide and its antimicrobial activity against food and multidrug resistant pathogens

A green, simple, and effective approach was performed to synthesize potent silver nanoparticles (SNPs) using bacterial exopolysaccharide as both a reducing and stabilizing agent. The synthesized SNPs were characterized using UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and Fourier-transform-infrared spectra analyses. The SNPs varied in shape and were multidispersed with a mean diameter of 10 nm ranging from 2 to 15 nm and were stable up to 2 months at room temperature. The antimicrobial activity of the SNPs was analyzed against bacterial and fungal pathogens using the agar well diffusion method. Dose dependent inhibition was observed for all bacterial pathogens. The multidrug resistant pathogens P. aeruginosa and K. pneumonia were found to be more susceptible to the SNPs than the food borne pathogen L. monocytogenes. The fungi Aspergillus spp. exhibited a maximum zone of inhibition compared to that of Penicillum spp. These results suggest that exopolysaccharide-stabilized SNPs can be used as an antimicrobial agent for various biomedical applications.     

Preparation, characterization and antimicrobial activity of a bio-composite scaffold containing chitosan/nano-hydroxyapatite/nano-silver for bone tissue engineering

In this study, a bio-composite scaffold containing chitosan/nano-hydroxyapatite/nano-silver particles (CS/nHAp/nAg) was developed by freeze drying technique, followed by introduction of silver ions in controlled amount through reduction phenomenon by functional groups of chitosan. The scaffolds were characterized using SEM, FT-IR, XRD, swelling, and biodegradation studies. The testing of the prepared scaffolds with Gram-positive and Gram-negative bacterial strains showed antibacterial activity. The scaffold materials were also found to be non-toxic to rat osteoprogenitor cells and human osteosarcoma cell line. Thus, these results suggested that CS/nHAp/nAg bio-composite scaffolds have the potential in controlling implant associated bacterial infection during reconstructive surgery of bone.     

Stereoselective total synthesis of a novel regiomer of herbarumin I and its cytotoxic and antimicrobial activities

Stereoselective synthesis of a novel regiomer of the natural nonenolide, herbarumin I has been accomplished. The synthesis involves the coupling of the alcohol and acid fragments of the molecule using Yamaguchi protocol followed by intramolecular ring closing metathesis. The cytotoxic and antimicrobial properties of the synthetic regiomer have been studied.     

A physico-chemical and biological study of novel chitosan-chloroquinoline derivative for biomedical applications

This paper describes an elegant cross-linking technique for the preparation of chitosan-chloroquinoline derivative by using a greener technique. Chitosan solution in aqueous acetic acid was treated with 2-chloroquinoline-3-carbaldehyde solution to form hydrogel; the resulting hydrogel was subjected to solvent exchange. Combining the results of FTIR and XRD confirmed that 2-chloroquinoline-3-carbaldehyde have been reacted to chitosan. The morphology of the derivative was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of the derivative was examined by thermogravimetric analysis (TGA). The photoluminescence (PL) spectra of chitosan-chloroquinoline derivative show red-shifted emission maximum. The microbiological screening has demonstrated the antimicrobial activity of the derivative against bacteria viz. Staphylococcus aureus, Escherichia coli and Candida albicans. The obtained results showed that the chitosan-chloroquinoline derivative might be a promising candidate for novel antimicrobial agents for biomedical applications.     

Silver nanoparticles as a new generation of antimicrobials

Silver has been in use since time immemorial in the form of metallic silver, silver nitrate, silver sulfadiazine for the treatment of burns, wounds and several bacterial infections. But due to the emergence of several antibiotics the use of these silver compounds has been declined remarkably. Nanotechnology is gaining tremendous impetus in the present century due to its capability of modulating metals into their nanosize, which drastically changes the chemical, physical and optical properties of metals. Metallic silver in the form of silver nanoparticles has made a remarkable comeback as a potential antimicrobial agent. The use of silver nanoparticles is also important, as several pathogenic bacteria have developed resistance against various antibiotics. Hence, silver nanoparticles have emerged up with diverse medical applications ranging from silver based dressings, silver coated medicinal devices, such as nanogels, nanolotions, etc.     

Design,synthesis, in vitro anticancer,antioxidant and antibacterial activity; DNA/BSA binding,photoleavage and docking studies of Cu(II) ternary metal complexes

Abstract

Three mononuclear, mixed ligand ternary Cu(II) complexes of 3-((Z)-1-(2-hydroxyphenylimino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (HEHMP) viz; [Cu-(Phen) (HEHMP)] (1a), [Cu-(Bpy)(HEHMP)] (1?b) and [Cu-Bpy(NCS)(HEHMP)] (1c) were synthesized and characterized by data obtained from various spectral techniques. The binding affinities of these complexes with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein were explored by absorption and fluorescence quenching titrations. The results indicated strong affinity of the title compounds to bind with both CT-DNA and BSA. The antioxidant properties of the synthesized compounds evaluated by free-radical scavenging method using spectrophotometric technique indicated their affirmative potential activity. Gel electrophoresis experiments revealed the efficacy of metal complexes in resulting the cleavage of pBR322 supercoiled DNA. In vitro cytotoxicity studies of these complexes evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against HeLa and MCF-7 cancer cell lines indicated relatively high effectiveness of the complex 1c. Confocal microscopy signified the potential of the complexes to induce apoptosis in HeLa cell lines. In addition, the antibacterial activity of the compounds carried out by disc diffusion method revealed significantly enhanced antibacterial activity in Cu (II) ternary complexes compared to the activity of ligands in unbound form signifying the implicit role of metal ion in inducing lipophilic character.