Elucidating the Antibacterial Potential of PEG Modified Silver Nanoparticles

The present study provides an insight of antibacterial potential of PEG modified AgNPs. AgNPs were found to be ~26 nm by XRD analysis apart from exhibiting its ultravoilet spectra peak at 250 nm. The Fourier transform-infrared spectroscopy further confirmed the observance of peaks between 650 to 500 cm‑1 in the synthesized AgNPs. Antimicrobial characterization was monitored by colony forming units (CFU) on agar plates. AgNPs showed 20x109/ml CFU after 24 hrs of incubation at 20 mM AgNPs concentration as against 29x109/ml CFU under similar incubation conditions in the modified AgNPs. Moreover, zone of inhibition (ZOI) appeared as 3.1 and 3.8 cm at 0.2 and 0.4 mM at AgNPs, respectively in E.coli in contrast to 3.5 and 4.5 cm, respectively for modified AgNPs under similar conditions. ZOI for S. aureus showed 3.2 and 3.8 cm, respectively at 0.2 and 0.4 mM concentration for AgNPs while modified AgNPs exhibited ZOI at 3.8 and 4.4 cm, respectively under similar incubation conditions. Their toxic effect was demonstrated by MTT assay to point out their relevance as antimicrobial agent

Studies on calcium alginate-pectin gel entrapped concanavalin A-bitter gourd (Momordica charantia) peroxidase complex

609-615Ammonium sulfate fractionated proteins of bitter gourd (Momordica charantia) were precipitated using jack bean extract as a source of concanavalin A. Concanavalin A-bitter gourd peroxidase retained nearly 86% original activity. This complex was entrapped into calcium alginate-pectin gel. Entrapped concanavalin A-peroxidase complex retained 51% original activity. Soluble and immobilized peroxidase preparations exhibited maximum activity at 40°C and pH 5.5. Concanavalin A-peroxidase complex and entrapped concanavalin A-enzyme complex retained greater fraction of catalytic activity at higher temperatures as compared to soluble form and also showed more broadening in pH-activity profiles, indicating a marked increase in stability. Concanavalin A-bitter gourd peroxidase and calcium alginate-pectin entrapped concanavalin A-bitter gourd peroxidase preparations were more stable as compared to soluble counterpart against denaturation induced by heat, pH, urea, organic solvents and detergents

CARBOXYLATION OF SILVER NANOPARTICLES FOR THE IMMOBILIZATION OF β-GALACTOSIDASE AND ITS EFFICACY IN GALACTO-OLIGOSACCHARIDES PRODUCTION

The present study investigated the carboxylation of silver nanoparticles (AgNPs) by 1:3 nitric acid-sulfuric acid mixtures for immobilizing Aspergillus oryzae β-galactosidase. Carboxylated AgNPs retained 93% enzyme upon immobilization and the enzyme did not leach out appreciably from the modified nanosupport in the presence of 100 mmol L-1 NaCl. Atomic force micrograph revealed the binding of β-galactosidase on the modified AgNPs. The optimal pH for soluble and carboxylated AgNPs adsorbed β-galactosidase (IβG) was observed at pH 4.5 while the optimal operating temperature was broadened from 50 ºC to 60 ºC for IβG. Michaelis constant, Km was increased two and a half fold for IβG while Vmax decreases slightly as compared to soluble enzyme. β-galactosidase immobilized on surface functionalized AgNPs retained 70% biocatalytic activity even at 4% galactose concentration as compared to enzyme in solution. Our study showed that IβG produces greater amount of galacto-oligosaccharides at higher temperatures (50 ºC and 60 ºC) from 0.1 mol L-1 lactose solution at pH 4.5 as compared to previous reports

Role of Glutaraldehyde in Imparting Stability to Immobilized β-Galactosidase Systems

ABSTRACT This review article highlights the role of glutaraldehyde as a matrix activator/stabilizer in imparting higher operational and thermal stability to β-galactosidase (βG) for biotechnological applications. Glutaraldehyde has been used extensively as a crosslinking agent as well as for functionalization of matrices to immobilize β-galactosidase. Immobilized β-galactosidase systems (IβGS) obtained as a result of glutaraldehyde treatment has been employed to hydrolyze whey and milk lactose in batch reactors, continuous packed-bed and fluidized bed reactors under various operational conditions. Moreover, these IβGS have also been utilized for the production of galactooligosaccharides in food, dairy and fermentation industries. It was observed that glutaraldehyde provided remarkable stability to immobilize βG against various physical/chemical denaturants, thus enhancing thermal/operational stability and rendering it more suitable for repeated utilization in industrial scale operations

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Investigating the antibacterial potential of agarose nanoparticles synthesized by nanoprecipitation technology

Herein, an effort was made to investigate the antibacterial potential of agarose nanoparticles (ANPs) and poly(quaternary ammonium) modified ANPs (mANPs) against Escherichia coli (gram-negative bacterium) and Staphylococcus aureus (gram positive bacterium) in liquid systems as well as on agar plates. ANPs were synthesized by nanoprecipitation technology and characterized by XRD, TEM, TGA, DTA and DLS. The particle size estimated was 30 nm while atomic force microscopy was used to observe the interaction of ligand on ANPs. Antimicrobial characterization was monitored by colony forming units (CFU) as a function of ANPs concentration on agar plates. It was observed that ANPs showed 15 × 109/ml CFU after 24 hours of incubation at 20 mM ANPs concentration while the modified ANPs exhibited 21 × 109/ml CFU under similar incubation conditions. Moreover, zone of inhibition (ZOI) was 2.9 and 3.8 cm, respectively for E. coli by ANPs at 0.2 and 0.4 mM, respectively while it was 3.2 and 3.8 cm respectively by modified ANPs under similar conditions. Similarly, ZOI for S. aureus by ANPs at 0.2 and 0.4 mM was observed at 3.1 and 4.0 cm, respectively, while these values were 3.5 and 4.1 cm, respectively for modified ANPs under similar incubation conditions