Light-induced pathogenic bacterial deactivation by using graphene quantum dot and methylene blue

Graphene quantum dots (GQD) is one of the most promising antimicrobial agents with promising potential in photodynamic therapy. GQD was obtained from benzene by focusing high power nanosecond laser pulses. Detailed characterization was performed with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectra. Later, we have attached Methylene Blue (MB), a standard photosensitizer, to graphene quantum dots. The effectiveness of the MB/GQD compound was evaluated on different strains of bacteria such as Escherichia coli and Micrococcus luteus. In addition, MTT assay was used to study human cellular side-effects, cancer and noncancer cellular viability under dark conditions. Combining MB with GQDs caused enhanced singlet oxygen generation and a higher deactivation rate compared to MB and GQD only. These results suggest that the MB/GQD combination is a promising form of photodynamic therapy. Further, ongoing experiments on the germicidal effects of different nanoparticles such as silver (Ag), and aluminum (Al) with MB will be presented.