Riboflavin-mediated photooxidation of gold nanoparticles and its effect on the inactivation of bacteria.

RIVAS AIELLO, MARÍA BELÉN; GHILINI, FIORELA; MARTÍNEZ PORCEL, JOAQUÍN; GIOVANETTI, LISANDRO J.; SCHILARDI, PATRICIA LAURA; MÁRTIRE, DANIEL OSVALDO

LANGMUIR

AMER CHEMICAL SOC

Año: 2020

0743-7463

Photodynamic inactivation (PDI) of microorganisms, based on the ability of photosensitizers to produce reactive oxygen species (ROS) under adequate irradiation, emerges as a promising technique to face the increasing bacterial resistance to conventional antimicrobials. In this work, we analyze the combined action of Riboflavin (Rf) and pectin-coated gold nanoparticles (PecAuNP) on Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) as suitable PDI strategy. We demonstrate that gold ions can be generated upon Rf-photosensitized oxidation of PecAuNP. Transient absorption spectroscopy shows that the Rf cationic radical can accept an electron from the nanoparticles to yield Au(I) ions, which in aqueous medium disproportionate to Au0 and Au(III). Microbiological assays showed that the presence of PecAuNP enhanced the antibacterial activity of photoirradiated Rf towards S. aureus and P. aeruginosa, in line with the well-known antibacterial activity of gold ions. Moreover, irradiation of Rf solutions containing about 100 µM PecAuNP were found to be bactericidal against both bacteria.