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Light‐Harvesting Antenna and Proton‐Activated Photodynamic Effect of a Novel BODIPY−Fullerene C 60 Dyad as Potential Antimicrobial Agent
Author(s) -
Agazzi Maximiliano L.,
Durantini Javier E.,
Gsponer Natalia S.,
Durantini Andrés M.,
Bertolotti Sonia G.,
Durantini Edgardo N.
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900181
Subject(s) - bodipy , photochemistry , chemistry , photosensitizer , singlet oxygen , protonation , fullerene , fluorescence , oxygen , organic chemistry , ion , physics , quantum mechanics
Abstract A covalently linked BODIPY−fullerene C 60 dyad (BDP−C 60 ) 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 C 60 to inactivate bacteria. The absorption spectrum of BDP−C 60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C 60 . Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 μM BDP−C 60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton‐activated photodynamic action of BDP−C 60 turned this dyad into a highly effective photosensitizer to eradicate E. coli . Therefore, BDP−C 60 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.