CQDs as antibacterial photoactive agents in polyurethane coating

Abstract

Bacterial infections can easily spread over frequently touched surfaces like plastic, woоd and metal, due to the growth of bacterial biofilms. Antibacterial materials that we can put on critical surfaces can eliminate or inhibit the growth of bacteria. In this study, we produced photoactive polyurethane coatings on the basis of carbon quantum dots (CQDs). This material has showed antibacterial activity against gram-positive (Staphylococcus aureus, MRSA, Enterococcus faecalis) and gram-negative (Escherichia coli, Acinetobacter baumannii) bacteria after 1 h of exposure to blue light. CQDs were synthesized using one-pot solvothermal method. Nicotinamide was used as started precursor. Polyurethane composites on the basis of CQDs were obtained by swelling-encapsulating-shrinking process. Obtained CQDs and their composites were structurally, chemically and optically analyzed. AFM and TEM images of CQDs have showed core-shell structure with average diameter of 45,9 ± 1,5 nm. Homogeneous encapsulation has been demonstrated using confocal Raman mapping. Production of ROS was investigated using spectroscopic methods (UV/Vis, PL and EPR). Therefore, it is assumed that ¹O₂ and •OH have a synergistic effect to bacteria membranes, causing their damage and the death of bacteria. The good biocompatibility of the obtained composites was investigated by MTT and hemolytic assays and their effect was analyzed on the HaCaT cells and erythrocytes. These materials have potential application as antibacterial coatings in healthcare and other institutions where control of the spread of bacterial infections is needed.