Correlation of Carbon Dots' Light-Activated Antimicrobial Activities and Fluorescence Quantum Yield

This study investigated the photo-activated antibacterial function of a series of specifically prepared carbon dots with 2,2'-(ethylenedioxy)bis(ethylamine) as the surface functionalization molecule (EDA-CDots), whose fluorescence quantum yields (Φ_F) ranged from 7.5% to 27%. The results revealed that the effectiveness of CDots' photo-activated bactericidal function was correlated with their observed Φ_F values. The antimicrobial activities of these EDA-CDots against both Gram negative and Gram positive model bacterial species (E. coli and Bacillus subtilis, respectively) were also evaluated under conditions of varying other experimental parameters including dot concentrations and treatment times. Optimization of the bactericidal effect of the EDA-CDots by a combination of the selected Φ_F, concentration and treatment time was explored, and mechanistic implications of the results are discussed.