Antimicrobial functionalization of cotton fabric with silver nanoclusters/silica composite coating via RF co-sputtering technique

Antibacterial functionality of cellulosic fibers has become an integral requirement for various applications. Silver is widely studied to functionalize textiles with antimicrobial properties and it can be applied via different routes, classified in wet and dry processes. Wet treatments can potentially influence the bulk properties of the textiles negatively and cause environmental concerns and high water and energy consumption. Dry routes including sputtering are considered ecofriendly processes and offer the advantage of modifying only the textile surface. In this study, antimicrobial silver nanoclusters/silica composite coatings of different thicknesses were deposited by radio frequency co-sputtering on cotton fabric. The samples were characterized in terms of morphology, composition, silver contents, silver leaching behaviour in water, antimicrobial properties, in vitro silver permeation through human skin, water contact angle, moisture management properties and air permeability. FESEM, EDX and XPS analysis confirmed the successful deposition of the coating composed of silver nanoclusters uniformly distributed and embedded in the silica matrix. Silver leaching test showed a gradual release of ionic silver in water. The composite coating exhibited antimicrobial activity against the tested microbial strains of Staphylococcus aureus, Escherichia coli and Candida albicans in disk diffusion test. The total amount of silver permeated through the human skin was found to be 3.21 +/- 0.63 ngcm(-2) during 24 h in vitro skin diffusion test. The water wettability of the fabric increased whereas air permeability was found to be unchanged after coating deposition.