Photosensitizer conjugated carbon dots@dopamine-copper sulfide nanocomposites: Advanced photoactive agents for antibacterial applications through experimental and theoretical insights

Abstract

The massive use and abuse of antibiotics has given birth to drug-resistant bacteria and emergence of severe bacterial infections in people. Intriguingly, light activated antimicrobial activity i.e. antimicrobial photodynamic therapy has gained enhanced therapeutic potential and efficacy in killing the bacterial cells. Therefore, the present study investigates the efficacy of employing advanced nanocomposites for biocidal inhibition of bacterial growth through enhanced sterilization capabilities. Specifically, dopamine functionalized CuS NPs combined with carbon dots (CDs@Dop-CuS) were selected for their remarkable photodynamic potential when used in conjunction with methylene blue (MB). Comparative and synergistic application of Dop-CuS, CDs, and MB revealed the superior singlet oxygen generation potency of MB/CDs@Dop-CuS. Furthermore, the structural changes in the E. coli bacterial cells membrane were elucidated through scanning electron microscopy imaging, demonstrating superior inhibition rates of MB/CDs@Dop-CuS compared to MB alone under 660 nm irradiation. The commendable docking score and binding potential of CDs@Dop-CuS nanocomposites obtained via molecular docking simulations further validate their efficacy as photosensitizers against E. coli bacterial cells. Thus, this novel MB/CDs@Dop-CuS photosensitizer provides enhanced efficacy as an alternative to traditional antibiotic treatments, offering a superior disinfection for public utility services and addressing the growing issue of drug-resistant bacterial infections.