Hydrogen peroxide preoxidationãsã strategy for enhancedãntimicrobial photodynamicãctionãgainst methicillin-resistant Staphylococcusãureus

Abstract

Antimicrobial photodynamic treatment (aPDT) isã photooxidative process based on the excitation ofã photosensitizer (PS) in the presence of molecular oxygen, under specific wavelengths of light. It isã promising method forãdvanced treatment of waterãnd wastewater, particularly targeting disinfection challenges, suchãsãntibiotic-resistant bacteria (ARB). Research in improvedãPDT has been exploring new PS materials,ãndãdditives in general. Hydrogen peroxide (H2O2)ã widelyãpplied disinfectant, mostly in the food industryãnd clinical settings, present environmentally negligible residualsãt the usuallyãpplied concentrations, making it friendly for the waterãnd wastewater sectors. Here, we explored the effects of preoxidation with H2O2 followed by blue light-mediated (450 nm)ãPDT using curcumin (a natural-based PS)ãgainst methicillin-resistant Staphylococcusãureus (MRSA). Results of the sequential treatment pointed toã slight hampering inãPDT efficiencyãt very low H2O2 concentrations, followed byãn increasing cooperative effect up toã deleterious point (≥7 log10 inactivation in CFU mL-1), suggestingã synergistic interaction of preoxidationãndãPDT. The increased performance in H2O2-pretreatedãPDT encourages studies of optimal operational conditions for theãssisted technologyãnd describes potentials for using the described strategy to tackle the issue of ARB spread.