Light-harvesting antenna and proton-activated photodynamic effect of a novel BODIPY-fullerene C60 dyad as potential antimicrobial agent

M. L. AGAZZI; J. E. DURANTINI; N. S. GSPONER; A. M. DURANTINI; S. G. BERTOLOTTI; DURANTINI E. N.

Chemphyschem

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2019

1439-4235

A covalently linked BODIPY-fullerene C60 dyad (BDP-C60) was synthesized as a two segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C60 to inactivate bacteria. Absorption spectrum of the BDP-C60 was a superposition of the spectra of its constitutional moieties, while the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C60. Spectroscopic, calculations and redox studies indicated a competence between photoinduced energy and electron transfer. The addition of an acid medium was used to protonate the dimethylaminophenyl substituent leading to a substantial increase in thefluorescence emission, triplet excited state formation and singlet molecular oxygen production. Atphysiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 µM BDP- C60 exhibited a 4.5 log decrease of cell survival (>99.997%) after 15 min irradiation. Similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activatedphotodynamic action of BDP-C60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP-C60 is an interesting photosensitizing structure in which the light- harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria.