Oxidative stress on Staphylococcus aureus ATCC 29213 and Escherichia coli BLEE by AuNPs irradiated with green LEDs

M. JAZMÍN SILVERO; ARGÜELLO, GERARDO; M. CECILIA BECERRA

Congreso; 16 th international congress on photobiology; 2014

Previuos results from our group have shown that a total inhibition of Staphylococcus aureus ATCC 29213 and an extended-spectrum beta-lactamases-producing Escherichia coli growth were observed when incubated with 2mM AuNPs and irradiated with LEDs at 525 nm for 12 h. [1] The goal of this work was to determine the possible mechanism of cell death. Trasmision Electronical Microscope images displayed the AuNPs selectively arranged around the outer bacteria membrane. On the other hand, pictures taken with Fluorescence Microscope and XXprobe, showed that irradiation of AuNPs (4 hours with 525 nm LED) already attached to the peptidoglican wall promotes the generation of Reactive Oxygen Species (ROS) in both strains. This could be due to the photothermal effect of plasmon excitation. In addition, bacterial macromolecules damage was evaluated through the detection of Advance Oxidation Protein Products (AOPP) at 340 nm with KI and acetic acid. This experiment shows that aftr 4 hours of irradiation, ......