A novel tricationic fullerene C_(60) as broad-spectrum antimicrobial photosensitizer: mechanisms of action and potentiation with potassium iodide

摘要

A novel amphiphilic photosensitizing agent based on a tricationic fullerene C_(60) (DMC_(60)~(3+) ) was efficiently synthesized from its non-charged analogue MMC_(60) . These fullerenes presented strong UV absorptions, with a broad range of less intense absorption up to 710 nm. Both compounds showed low fluorescence emission and were able to photosensitize the produc- tion of reactive oxygen species. Furthermore, photodecomposition of l -tryptophan sensitized by both fullerenes indicated an involvement of type II pathway. DMC_(60)~(3+) was an effective agent to produce the photodynamic inactivation (PDI) of Staphylococcus aureus, Escherichia coli and Candida albicans. Mechanistic insight indicated that the photodynamic action sensitized by DMC_(60)~(3+) was mainly mediated by both photoprocesses in bacteria, while a greater preponderance of the type II pathway was found in C. albicans. In presence of potassium iodide, a potentiation of PDI was observed due to the forma- tion of reactive iodine species. Therefore, the amphiphilic DMC_(60)~(3+) can be used as an effective potential broad-spectrum antimicrobial photosensitizer.