Antibacterial and Antifungal Thioglycolic Acid-Capped Silver Nanoparticles and Their Application on Wool Fabric as a Durable Antimicrobial Treatment

Currently used silver nanoparticle-based antimicrobial treatments are effective against bacteria and certain fungi but they have limited durability to washing. In this work, the surface of silver nanoparticles was modified with thioglycolic acid (TGA) to further enhance their antimicrobial activities and also to enable their binding to the surface of wool fibre. Silver nanoparticles were characterised by FTIR, UV-vis spectroscopy and TEM. The TGA-capped silver nanoparticles were covalently bonded to wool fibre surface by using 1-ethyl-3-[3-dimethylaminopropyl]-carbodiimide hydrochloride in combination with N-hydroxysuccinimide to provide enhanced durability to multiple washings, which is an issue for the nanosilver-based treatments used in wool textiles. The antimicrobial activities of this treated wool fabric were compared with the wool fabric treated with trisodium citrate (TSC)-capped silver nanoparticles (bonded by a silicone resin). The TGA-capped silver nanoparticle-treated wool fabric not only showed superhydrophilicity and excellent durability to washing but also excellent antibacterial activity along with moderate to excellent antifungal activity. The wool fabric treated with TSC-capped silver nanoparticles showed strong hydrophobicity and antibacterial activity but no antifungal activity. This work demonstrates that silver nanoparticles can be made antifungal by the capping with TGA and also the durability of the treatment to washing can be considerably enhanced.