Preparation of functional and reactive nanosilver nanogels using oxidized carboxymethyl cellulose

Abstract

The designing of functional and reactive nanosilver has been carried out by in-situ reduction of silver nitrate using oxidized carboxymethyl cellulose (OCMC). The reduction process is also accompanied by the stabilization of nanoparticles using the OCMC polymer chain, leading to the formation of a structure where nanosilver is entrapped within OCMC gel. The silver nanogels characterized using transmission electron microscopy (TEM) are found to be ∼22 nm. By virtue of the presence of dialdehyde functionality around the silver nanogels, they have the ability to react with a polymer having a complementary functional group. The nanogels have exhibited prominent antimicrobial activity against both gram-negative and gram-positive bacteria. It has been observed that a 0.3 mM concentration of silver nanogel is active in inhibiting bacterial growth. The antibacterial activity of the synthesized Ag nanogels was dose-dependent, with 99.9 % of E. coli and S. aureus destroyed within 5 h at a concentration of 0.4 mM Ag nanogels. The nanogels disrupted the bacterial cell wall and generated reactive oxygen species inside the cell, which resulted in cell death. This investigation provides a very interesting application as a coating for biomedical implants and devices.

Keywords: Bactericidal nanogels; CMC; Silver nanogels.