Scaling up the sono-enzymatic coating of cotton textiles with antimicrobial silver-phenolated lignin nanocomposites

The pressing demand for controlling infections in healthcare facilities has prompted the development of highly efficient antimicrobial textiles. Herein, we present a simple and scalable approach for engineering durable antimicrobial cotton textiles using a single-step sono-enzymatic process. The coating process involves simultaneous laccase enzyme-catalysed gallic acid (GA) oxidation under ultrasonic conditions (20 kHz frequency, 17.30 W/cm² power intensity, 35 % amplitude, 50 °C, 30 min) using a Ti-horn ultrasonic transducer, generating a bio-based adhesive network that engages both GA and the oxidised phenolic shell of antimicrobial silver phenolated lignin nanoparticles (AgPLNPs), and their deposition on the fabrics. Three coating formulations were investigated: cotton fabric ultrasonicated with AgPLNPs alone (M1), with AgPLNPs and laccase (M2), and with AgPLNPs, GA, and laccase (M3). The AgPLNPs are firmly embedded on the cotton fabric, eliminating the need for fabric pre-activation or post-treatment. They are biocompatible, possess broad-spectrum antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria, and have significantly less propensity to induce bacterial resistance than conventional antibiotics, showing only 2-4 fold increases in MIC compared to 128-2048 fold increases for ciprofloxacin and ampicillin. The resulting AgPLNPs-GA-coated textiles (M3) demonstrated durable antibacterial properties, retaining >95 % antibacterial efficacy after 60 hospital laundry cycles at 75 °C, following international thermal disinfection guidelines (98.6-99.8 % depending on bacterial strain). Additionally, the coated fabrics were biocompatible and hydrophobic (contact angle: 116.1 ± 1.5°), enhancing their benefits in medical environments where body fluid repellence is crucial for maintaining hygiene and preventing the spread of pathogens. The coating was successfully scaled up from laboratory samples (10 × 10 cm) to industrial-scale processing of textiles with dimensions 5 × 0.5 m using a continuous roll-to-roll sonochemical pilot. This novel coating approach shows promise for creating exceptionally durable antimicrobial and biocompatible fabrics for medical purposes.