Light-HarvestingAntennaand Proton-ActivatedPhotodynamicEffectof a NovelBODIPY

AGAZZI, MAXIMILIANO L.; DURANTINI, JAVIER E.; GSPONER, NATALIA S.; DURANTINI, ANDRÉS M.; BERTOLOTTI, SONIA G; DURANTINI, EDGARDO N.

Chemphyschem

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2019 vol. 20 p. 1110 - 1125

1439-4235

A covalently linked BODIPY􀀀 fullerene C60 dyad (BDP􀀀 C60) wassynthesized as a two-segment structure, which consists of a visiblelight-harvesting antenna attached to an energy or electronacceptor moiety. This structure was designed to improve thephotodynamic action of fullerene C60 to inactivate bacteria. Theabsorption spectrum of BDP􀀀 C60 was found to be a superpositionof the spectra of its constitutional moieties, whereas thefluorescence emission of the BODIPY unit was strongly quenchedby the fullerene C60. Spectroscopic, calculations, and redox studiesindicate a competence between photoinduced energy andelectron transfer. Protonating the dimethylaminophenyl substituentthrough addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited stateformation, and singlet molecular oxygen production. At physiologicalpH, photosensitized inactivation of Staphylococcus aureusmediated by 1 μM BDP􀀀 C60 exhibited a 4.5 log decrease of cellsurvival (>99.997%) after 15 min irradiation. A similar result wasobtained with Escherichia coli using 30 min irradiation. Moreover,proton-activated photodynamic action of BDP􀀀 C60 turned thisdyad into a highly effective photosensitizer to eradicate E. coli.Therefore, BDP􀀀 C60 is an interesting photosensitizing structure inwhich the light-harvesting antenna effect of the BODIPY unitcombined with the protonation of dimethylaminophenyl groupcan be used to improve the photoinactivation of bacteria.