From lab to pilot: sonochemical coating of PDDA-based polymer dots for scalable, wash-durable antibacterial textiles

Poly(diallyldimethylammonium chloride) (PDDA) is a cationic polymer with strong antibacterial activity, but its coating applications are hindered by limited stability and dose-dependent cytotoxicity. Nanoformulating PDDA into polymer dots (PDDA-based PDs) via hydrothermal synthesis with boric acid offers enhanced biocompatibility, stability, and antimicrobial efficacy. The synthesised PDs demonstrated potent antibacterial activity against Gram-positive (S. aureus) and Gram-negative bacteria (E. coli and P. aeruginosa) with MIC values of 0.056-0.112 mg/mL and superior biofilm inhibition capabilities. Significantly lower antimicrobial resistance development was observed, with only 4-8 fold MIC increase after 30 days compared to 128-2048 fold increase for conventional antibiotics. Sonochemical coating onto cotton fabrics achieved exceptional washing durability, retaining strong antibacterial activity even after 60 high-temperature hospital laundry cycles with log reductions of 4.72 for S. aureus, 2.31 for P. aeruginosa, and 3.26 for E. coli. The multi-targeted antimicrobial mechanism of the PDs involves ROS generation, disruption of bacterial metabolism, and physical damage to membrane integrity. The coating process was successfully upscaled using a roll-to-roll sonochemical pilot system, demonstrating industrial feasibility. PDDA-based PDs offer a promising platform for developing sustainable, wash-durable antimicrobial textiles suitable for healthcare applications.