Photoactive coating based on waterborne polyurethane and carbon quantum dots as a prevention strategy for bacterial resistance

This study aims to develop photoactive coatings based on carbon quantum dots (CQDs) and waterborne polyurethane (WPU), capable of preventing the formation of bacterial biofilms. CQDs synthesized by microwaveassisted pyrolysis showed spherical morphology with an average size of 10.6 +/- 3.1 nm, containing chemical groups with oxygen and nitrogen on the peripheral surface and photoluminescence at 460 nm and quantum yield of 63.2 % under excitation at 360 nm. Subsequently, CQDs were incorporated during WPU polymerization to form nanocomposites. The WPU/CQDs nanocomposites showed superior mechanical, rheological, and thermal properties concerning the pure WPU, due to the interaction of the nanoparticles with the polymeric matrix. The nanocomposites exhibited transparency and high photoluminescence, confirming the efficiency of the polymeric matrix in protecting the nanoparticles against photoluminescence extinction in the solid state. In addition, the WPU nanocomposite generates reactive oxygen species (ROS) after irradiation with blue light. The materials did not show cytotoxicity for BALB/3T3 murine fibroblasts after 24 h incubation. After illumination, the nanocomposite showed photodynamic activity against Pseudomonas aeruginosa (Gram-negative), thus validating its potential as a photoactive coating with sterilizing properties.