Fabrication of antibacterial Fe³⁺-carboxymethylcellulose-polyacrylamide-Ag nanoparticles hydrogel coating for urinary catheters

Catheter-associated urinary tract infections (CAUTIs) are one of the most common hospital-acquired infections. In this study, a new Fe³⁺-carboxymethylcellulose (CMC)-polyacrylamide (PAAm) - Ag nanoparticles (AgNPs) interpenetrating hydrogel coating with antibacterial properties on the surfaces of latex urinary catheters was prepared with a simple dipping method. The morphology, chemical composition, surface roughness, and contact angles of the coated urinary catheters were characterized by using SEM, EDS, ATR-FTIR, XPS, AFM, and contact angle instruments, respectively. The antibacterial performance of the coated urinary catheters was characterized by the inhibition zone tests. Furthermore, the toxicity profile of the coated urinary catheters was also evaluated in vitro via MTT assay and hemolysis test. The experimental results showed that the Fe³⁺-CMC-PAAm-AgNPs hydrogel-coated urinary catheters had strong antibacterial effects. The concentration of AgNPs after the release of 30 days was still higher than the effective antibacterial concentration of the total Ag (0.1 ppb) and was lower than the toxic concentration of human cells (10 ppm). The inhibition zone tests of the coated urinary catheter against E. coli (ATCC25922) showed that both the CMC-PAAm-AgNPs hydrogel coatings and the Fe³⁺-CMC-PAAm-AgNPs hydrogel coatings had clear inhibition zones in the culture medium. The addition of Fe³⁺ exhibited synergistic antibacterial effects with AgNPs. Moreover, the coatings also showed admirable biocompatibility and hemocompatibility. The synergistic antibacterial mechanism was also proposed. The novel Fe³⁺-CMC-PAAm-AgNPs hydrogel coatings for urinary catheters would have great potential in reducing CAUTIs.