Antibacterial properties of silk fabric treated with Aloe Vera and silver nanoparticles

Abstract

Silk is one of the important textile fibres used in apparel application. Since it is hygroscopic proteinous fibre, it is affected by microbes during usage and storage. Hence, antimicrobial treatment is desired to contain with this problem. Antimicrobial treatment is done using natural and synthetic agents. Nanoparticles have been added as antimicrobial agent for the application. In the present work, composite treatment of silk with Aloe Vera– a natural product and silver nanoparticles is done through crosslinking of 1,2,3,4-butane tetra carboxylic acid (BTCA) with silk in the presence of sodium hypophosphite (SHP). Effect of varying the concentration of BTCA, Aloe Vera and silver nanoparticles has been investigated. Untreated and treated silk fabrics have been characterized by FTIR, SEM and XRD to elucidate the effect of the treatment in terms of binding of Aloe Vera and silver nanoparticles, morphological changes and degree of crystallinity. Mechanical properties have been evaluated and analysed to illustrate the effect of the treatment. Further, the antimicrobial properties of the treated samples were evaluated against S. aureus (gram positive) and K. pneumoniae (gram negative) bacteria and the antimicrobial activity is found to be excellent. In order to assess the durability of the treatment, dry-cleaning has been done and subsequently antimicrobial properties have been assessed. Treated silk fabric samples after dry-cleaning upto 5 cycles exhibited satisfactory antimicrobial activity indicating that the treatment is durable in all the recipes. It is inferred that Aloe Vera chemically binds with silk through BTCA crosslinking while silver nanoparticles get adhesively bound or entrapped in the fibre matrix resulting in durable antimicrobial activity.