Hydrogel based silver nanocomposites as antimicrobials

Abstract

New generation nanomaterials provide an alternative approach for water disinfection systems. The development of such materials has an obligation to deal with some challenges to emerge out as the most efficient antimicrobial agents. Successful water disinfection systems should include the capability of destroying microorganisms in water without forming toxic byproducts and harming the environment. Currently few materials possess these characteristics but are practically limited by factors such as, mechanical instability, aggregation, leaching and toxicity etc. The present study describes the development of nano-silver based hydrogel nanocomposite consisting of porous networks of natural biopolymer chitosan and poly vinyl alcohol with well dispersed silver nanoparticles (CHT/PVA/Ag) synthesized by in situ chemical reduction. Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS/EDX), and Fourier Transform Infra-Red spectroscopy (FTIR) were employed to characterize the CHT/PVA/Ag hydrogel. The 3D structure of the hydrogel provided space for generation of AgNPs and acted as template matrix for their subsequent immobilization. Hydrogels exhibited excellent swelling capacities with improved structural rigidity. Disinfection experiments performed against three test microorganisms i.e. E.coli, Bacillus licheniformis, and Lysinibacillus fusiformis showed that the CHT/PVA/Ag hydrogels exhibited good antibacterial efficacy while the maximum time to achieve complete disinfection time was calculated to be 90 minutes. The Zone of inhibition (ZOI) studies indicated Lysinibacillus fusiformis as the most sensitive strain with clear zone diameter of 18mm. It is assumed the leaching level of Ag or AgNPs is considerably lower than drinking water standard due to its retention by hydrogel matrix. Therefore, this study sheds new light on developing nanomaterials for its application in water disinfection purposes.