Nano-enabled enzyme-assisted layer-by-layer coating prevents biofilm formation on urinary catheters

The ability of bacterial pathogens to colonise indwelling medical devices, particularly urinary catheters, and to establish drug-resistant biofilms accounts for approximately 60 % of all nosocomial infections, underscoring the urgent need for effective strategies to mitigate biofilm development on catheter surfaces. In this study, we developed a multilayer nano-composite coating for urinary catheters, assembled via sequential deposition of bioadhesive catechol-functionalised chitosan (catCS), hyaluronic acid (HA), and antimicrobial aminated lignin nanoparticles (N-LigNPs). Sono-enzymatically phenolated, aminated, and formulated lignin nanoparticles (NPs) served as both structural and functional components within the coatings, whose assembly was monitored in real time using a quartz crystal microbalance with dissipation. Atomic force microscopy was employed to characterise the coating topography, complemented by surface zeta potential measurements and lubricity analysis. Cross-linking of N-LigNPs with catCS, catalysed by the oxidative enzyme laccase, increased the mechanical integrity of the coating beyond that afforded by electrostatic interactions alone. This translated into durable antimicrobial and antibiofilm performance of the functionalised catheters over 7 days in a hydrodynamic model simulating a catheterised human bladder, reducing S. aureus and Escherichia coli biofilm formation by more than 60 %, while exhibiting no cytotoxic effects on mammalian cells. Moreover, the clinical, histological, and microbiological data obtained from in vivo studies in a rabbit model demonstrated that the coating was biocompatible and effectively prevented catheter-associated urinary tract infections during a 10-day indwelling period. STATEMENT OF SIGNIFICANCE: Catheter-associated urinary tract infections (CAUTIs) remain a major clinical challenge due to biofilm formation and rising antimicrobial resistance. This study presents a bio-based, multilayer nanocomposite coating for urinary catheters that combines catechol-functionalised chitosan, hyaluronic acid, and aminated lignin nanoparticles, stabilised through laccase-mediated cross-linking. Unlike conventional electrostatic coatings, this enzymatically reinforced system exhibits enhanced mechanical durability, sustained antimicrobial and antibiofilm activity under physiologically relevant hydrodynamic conditions, and biocompatibility. Importantly, its efficacy is demonstrated both in vitro and in vivo. This work highlights a sustainable, antibiotic-sparing strategy with strong translational potential for preventing CAUTIs and could be extended to other biofilm-prone medical devices.