Polymeric composites incorporating Near Infrared-responsive nanoparticles as antibacterial coatings for medical devices

Catheter is a widely used medical device including cardiovascular, urological, gastrointestinal, and neurovascular applications. When bacteria adhere to the surface of catheters, they form biofilms, making infections harder to treat and increasing the risk of sepsis and antibiotic resistance. In this study, the development of an innovative nanocomposite for antibacterial catheter coatings is described. To prepare this nanocomposite, Indium tin oxide (ITO) nanoparticles (NPs) were synthesized and incorporated into a Polydimethylsiloxane (PDMS) matrix using a cross-linking approach, with weight concentrations ranging from 0% to 5%. By using the ability of ITO to absorb infrared (IR) light, the composite creates localized surface plasmon resonance, which is supposed to kill bacteria adhered to the composite material by producing heat up to 90°C. Ultraviolet-visible–near-infrared (UV–vis–NIR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM) were used to characterize both the NPs and nanocomposites. FTIR analysis showed that apart from intensity, there was no extra peak for the nanocomposite as compared to PDMS alone. However, only the ITO NPs showed a metal oxide peak. UV–vis–NIR showed that 0% ITO sample exhibits the maximum transmittance across all wavelengths. With larger ITO concentrations, transmittance gradually decreases because of higher light absorption. Plain PDMS showed 80% transmission, whereas 1.5% ITO/PDMS yields the transmittance reduced to ~5%. The viable bacterial count was calculated in colony-forming units (CFU), showing a significant reduction to 38000 from 86000 in CFU for both irradiated nanocomposites compared to the inoculum. This result indicates that the warming effect of the lamp alone contributes to bacterial death. However, a much lower bacterial count was observed, 1000 CFU, in the 5% ITO samples compared to the 0% ITO samples, suggesting that NPs enhance bactericidal activity and improve antimicrobial performance. ANOVA analysis was used to confirm high reliability p-value of less than 0.001 which indicates the data is significant. Polymeric composites containing ITO nanoparticles were highlighted for their ability to generate heat through IR absorption, making them suitable for antibacterial coatings on medical devices.