Metal-Enhanced Photosensitization of Singlet Oxygen (ME1O2) from Brominated Carbon Nanodots on Silver Nanoparticle Substrates

The deleterious effects of reactive oxygen species (ROS), including singlet oxygen (1O2), on biological systems have cultivated widespread interest in fields ranging from therapeutic techniques to sterilization materials. Researchers have, for example, sought to capitalize on the oxidative damage from singlet oxygen to treat tumors as well as to kill antibiotic resistant bacteria. To generate 1O2 in a controllable manner, photosensitizers are optimized to generate 1O2 from ground state oxygen (3O2) when excited by light. When considering applications of photosensitization, favorable properties include high 1O2 yield, low synthetic complexity, and minimal cost. Previously, studies have shown that plasmonic nanoparticles are able to amplify the photosensitization of 1O2 from small molecule photosensitizers in a mechanism similar to metal-enhanced fluorescence (MEF), thereby improving yield. A recent study from our lab has demonstrated that brominated carbon nanodots, which are an inexpensive and simple-to-collect as a hydrocarbon combustion byproduct, generate reactive oxygen species that can be used for antimicrobial photodynamic inactivation of bacteria. Herein we investigate the combination of these advantageous properties. Using the turn-on fluorescent probe Singlet Oxygen Sensor Green™ to detect 1O2, we report the metal-enhanced photosensitization of 1O2 by brominated dots in silvered Quanta Plate™ wells. These results provide a promising direction for the potential optimization of carbon nanodot-based agents in light-activated antimicrobial materials.