Gold-Silver Nanoshell-Embedded Polydimethylsiloxane Films for Near-Infrared Photothermal Eradication of Bacteria

Catheter-related infections (CRIs) pose a significant threat to patient safety; therefore, the development of effective strategies to prevent and treat these infections is imperative. In this study, a photothermal system based on gold-silver nanoshell (AuAgNSh)-modified catheter surfaces was developed for the rapid eradication of the pathogenic bacterium Enterococcus faecalis (E. faecalis) using near-infrared (NIR) irradiation. The morphology and elemental composition of AuAgNShs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The optical and photothermal properties were acquired by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy and thermographic imaging with an IR camera, respectively. Bacterial survival studies on AuAgNSh-modified surfaces irradiated with and without NIR light were evaluated using a colony-formation assay. The results demonstrated that AuAgNSh-modified surfaces, when illuminated with NIR light, effectively killed E. faecalis on silicone surfaces in less than 10 min. The system is stable and reusable throughout multiple cycles and has the potential to serve as a rapid, localized adjunct to traditional antibiotic therapy for CRIs. By harnessing the thermal energy produced by AuAgNShs in response to NIR irradiation, this hyperthermia technique can potentially serve as a broad-spectrum antibiotic that kills adhered pathogens rapidly.