Photodeactivation of pathogenic bacteria using methylene blue and graphene quantum dot

A biocompatible photodynamic therapy agent that generates a high amount of~singlet oxygen with high water dispersibility and excellent photostability~is desirable. In this work, a graphene-based biomaterial which is a~promising alternative to a standard photosensitizers was produced and its efficiency compared to a standard photosensitizer, methylene blue. Graphene quantum dots (GQDs) were synthesized by irradiating benzene~and nickel oxide mixture using nanosecond laser pulses. High-resolution~transmission electron microscopy (HR-TEM) results show GQDs whose~size less than 5 nm with very good water dispersibility were successfully obtained. UV-Vis spectra and photoluminescence spectra shows~that GQDs have an absorption peak around 270 nm and maximum emission at 430 nm with the excitation wavelength of 310 nm. Deactivation of Escherichia coli (E. coli) a gram-negative bacterium with methylene blue and carbon nanoparticles was studied by irradiating with different wavelengths. The results show a significant decrease in the number of colony forming units of E. coli. Our results show that GQDs can potentially~be used to develop therapies for the eradication of pathogens in open~wounds, burns, or skin cancers.