Silk functionalization by caffeic acid assisted in-situ generation of silver nanoparticles

This paper reports a simple one-step process for the in-situ synthesis and deposition of silver nanoparticles (AgNPs) on silk fabric by employing caffeic acid as an eco-friendly reductant. The formation of AgNPs was confirmed by visible colour changes and UV-visible spectra. The surface plasmon resonance band of AgNPs was observed at λmax ∼414-420 nm indicating spherical or roughly spherical AgNPs, which was further confirmed by TEM and SEM measurements. The surface of AgNPs treated silk showed roughness due to the deposition of AgNPs and the uniform distribution of roughly spherical AgNPs on silk surface was observed in SEM images. EDS analysis also confirmed the presence of silver in treated silk. An increase in the amount of caffeic acid and silver nitrate resulted in more silver being deposited on silk fabric. The caffeic acid assisted in-situ generation of AgNPs imparted golden yellow colour and good multi-functional properties to silk fabric. The treated fabrics showed excellent fastness towards washing, rubbing and light. The antibacterial effect was highly durable as more than 90% bacterial reduction was observed even after 10 washing cycles.