Plasmonic photothermal based quick sterilization of surgical tools and pathogen suspensions

This study investigates the efficacy of plasmonic photothermal technique for quick sterilization of surgical tools and pathogen suspensions for the elimination of a high load of broad-spectrum pathogens viz. ESKAPE pathogens - Candida albicans (5 × 10⁷ CFU/mL of each pathogen). Here, the contaminated surgical tools and the corresponding pathogens suspension to be sterilized, are irradiated with electromagnetic radiation (Visible-NIR) in the presence of synthesized triangular silver nanoplates leading to localized heat generation through plasmonic photothermal phenomenon. The irradiation source including the sterilization device prototype is developed In-house and is used for the sterilization of reusable surgical tools. The sterilization is achieved at lower temperatures of ∼65-70 °C, at atmospheric pressure within 10 min of total duration. Also, sterility of the nanoplates suspension after a treatment cycle is confirmed for its re-use for multiple subsequent sterilization cycles. The demonstrated sterilization efficacy ∼7.69 Log₁₀ reductions of each pathogen, meets the required sterility assurance level (SAL) norms of 6 Log₁₀ reduction. Further, the mechanism behind sterilization efficacy of plasmonic photothermal technique shows the morphological alterations & membrane lysis along with the combined impact of reactive oxygen species (ROS), which disrupts cellular metabolic pathways within the cells. In-vivo investigation of the use of a surgical blade sterilized through plasmonic photothermal technique, on BALB/C mice, further strengthens the real-time application and safety. Contrary to the antimicrobial studies reported in literature for such phenomenon, as far as we are aware, it is the first reported instance of the sterilization for reusable surgical tools through plasmonic photothermal technique.