Fullerene derivatives in photodynamic inactivation of microorganisms

Abstract

Fullerene derivatives are accepted as nanoparticles with several potential biomedical applications. The combination of visible light absorption and a long lifetime of triplet excited state allow fullerenes to act as efficient photosensitizers. Interesting results have been found using amphiphilic cationic fullerenes as photosensitizers to photoinactivate microorganisms. The triplet excited state of these compounds may interact with ground state molecular oxygen to produce ROS. This process can occur by energy transfer to produce singlet molecular oxygen, O2(1g) or by electron transfer to form superoxide anion radical (O2.-). In contrast to O2(1g) generation, the electron transfer type of reaction is favored in polar solvents, particularly in the presence of reducing agents. Moreover, fullerenes can be attached to light-harvesting antenna structures. Thus, cationic fullerenes can selectively bind to microbial cells, inducing an efficient photoinactivation of pathogenic microorganisms. Therefore, functionalized fullerenes are interesting nanostructures with applications as antimicrobial photosensitizing agents.