Ag nanoparticles embedded in microcapsules within a hydrogel coating on urinary catheters: lubricity, antibacterial, and antibiofouling properties

Catheter-associated urinary tract infections (CAUTIs) pose a significant challenge, primarily due to biofilm formation on conventional urinary catheters (UCs). Although hydrogels demonstrate favorable biocompatibility, their limited mechanical strength and absence of inherent antibacterial properties have restricted their applications. This study presents a novel polyelectrolyte-induced hydrogel coating for UCs, which integrated silver nanoparticle (AgNP)-loaded alginate (SA)-chitosan (CS) microcapsules (AgNPs@(SA-CS) 5 , referred to as AgSC) within a polyvinyl alcohol (PVA)-polyacrylic acid (PAA)- [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) (PPMA) hydrogel matrix. The AgSC microcapsules were synthesized through a layer-by-layer assembly of alginate and chitosan, followed by AgNPs loading and template removal, facilitating sustained antibacterial release. The resulting AgSC-PPMA hydrogel was securely immobilized onto polydopamine-modified UCs (AgSC-PPMA@PUCs). The AgSC-PPMA hydrogel coating exhibited exceptional mechanical properties (storage modulus ∼30,780 Pa; tensile strength 0.16 MPa; toughness 33.71 MJ m −3 ), ultra-low friction (coefficient of friction of 0.014 ± 0.001, which was 1/64 that of pristine UCs), high hydrophilicity (water contact angle 24.3 ± 2.4°), and sustained antibacterial activity (>99.99% against E. coli , K. pneumoniae , and P. aeruginosa ; inhibition zone of 16.0 ± 1.4 mm against E. coli , retained at 13.0 mm after 60 d of thermal aging). Furthermore, the AgSC-PPMA@PUCs demonstrated significant antibiofouling properties (protein adsorption: 7.76 ± 2.86 μg cm −2 ), resistance to bacteria-protein complex adhesion, and excellent biocompatibility (cell viability >70%; hemolysis rate