Antibacterial AgNPs-PAAm-CS-PVP nanocomposite hydrogel coating for urinary catheters

Catheter-associated urinary tract infections (CAUTI) account for 40% of all hospital-acquired infections and more than 1 million CAUTIs occur annually in the United States and Europe with increased morbidity and mortality. Although anti-bacterial coating is an effective way to solve this problem, so far only limitted progress has been made. In this paper we prepared a novel antibacterial silver nanoparticles poly(acrylamide)-chitosan-polyvinylpyrrolidone (AgNPs-PAAm-CS-PVP) composite hydrogel coating on latex urinary catheters by a simple dipping method. The average particle size, the size distribution as well as the polydispersity index (PDI) value of the AgNPs were examined by using TEM analysis. The surface morphology and roughness, the element contents, the functional groups, the static contact angles, and the surface energy of the coatings were characterized by using SEM, EDS, AFM, FTIR, XPS, and a video optical contact angle instrument, respectively. The amount of the total Ag released from the hydrogel was tested by ICP-MS. The antibacterial and antiadhesion efficacies against Gram-negative E. coli of the coated urinary catheters were evaluated with an inhibition zone test and fluorescence microscopy. A synergistic antibacterial mechanism of AgNPs and CS was also presented. The results showed that the synthesized AgNPs in the hydrogel had a spherical shape with an average diameter of 25.9 nm. The AgNPs-PAAm-CS-PVP hydrogel had a more durable release of the antibacterial agents of AgNPs and Ag⁺, which explains why the coated urinary catheters had long-term antibacterial activity. The mathematical modelling of Ag release kinetics supported Case I or Fickian diffusion mechanism for the AgNPs-PAAm-CS-PVP hydrogel. The hydrogel-coated urinary catheters became smoother and more hydrophilic which further explains why the coated urinary catheter decreased bacterial adhesion. More importantly, bacterial activity and bacterial adhesion assays showed that both the outer and inner surfaces of the AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters had strong antibacterial property against E. coli. Furthermore, the hydrogel-coated urinary catheters showed high hemocompatibility and cytocompatibility for promising biomedical applications. The AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters have great potential for decreasing CAUTIs.