Sustainable antibacterial cotton fabrics with in situ formed silver nanoparticles by bio-inkjet printing

A green digital printing process and innovative pretreatment combination endow sustainable, non-toxic, economical, and eco-friendly antimicrobial products. A sustainable inkjet printing technique was developed herein to fabricate antimicrobial cotton fabrics with enhanced wash-fastness properties in situ bio-synthesized with silver nanoparticles using an aqueous solution. The silver salt precursor was used to form silver nanoparticles by sustainable inkjet printing deposition. Silver salt could be dissolved in water to form green aqueous ink solutions, to eliminate nozzle clogging and simplify the deposition process. Before printing, the cotton fabrics were pretreated with biodegradable natural carbohydrate polymers, sodium alginate, and aloe vera, in concentrations of 15 g, 25 g and 30 g acting as bio-reducing agents. The formulated ink was printed via a digital printing process repeatedly to fabricate in situ biosynthesized silver nanoparticles. Green antimicrobial cotton fabrics appeared resistant to S. aureus, E. coli and C. albicans by consecutive bio-printings. Pretreating cotton fabric with sodium alginate induced higher antimicrobial properties and wash-fastness with respect to the aloe vera pretreated ones. The inhibition zone of inkjet-printed pretreated cotton fabric with sodium alginate increased from 14 mm for one layer to 17 mm for ten layers against S. aureus without yellowing on cotton fabric.