Photothermic Release of Curcumin for Antimicrobial Photodynamic Therapy

Drug delivery systems (DDS) are promising tools to enhance antimicrobial Photodynamic Therapy (aPDT) by improving the targeted delivery and controlled release of photosensitizers. In this study, we introduce a light-responsive DDS based on curcumin-loaded mesoporous silica nanoparticles featuring a gold nanostar core and paraffin capping, designed specifically for near-infrared (NIR)-triggered photothermal release. This multicomponent nanoplatform uniquely combines photothermal activation with light-controlled drug delivery for antimicrobial applications. The synthesized nanoparticles exhibited a mean diameter below 500 nm, a polydispersity index of 0.154, and a surface charge of -21.9 mV. Upon NIR irradiation at 1200 J/cm², curcumin release was approximately 90%. In planktonic bacterial cultures, aPDT mediated by this system led to reductions of 3.16 log₁ ₀ and 2.18 log₁ ₀ in colony-forming units (CFUs) for <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i>, respectively. For bacterial biofilms, a higher curcumin concentration (1000 μg/mL) resulted in CFU reductions of 2.16 log₁ ₀ and 1.77 log₁ ₀ for <i>S. aureus</i> and <i>P. aeruginosa</i>, respectively. This study demonstrated a NIR-activated nanocarrier for the controlled release of curcumin and effective inactivation of both planktonic and biofilm-associated bacteriaoffering a new approach to improve the precision and efficacy of aPDT.