Efficient anchoring of CuO nanoparticles on Ugi four-component-functionalized graphene quantum dots: colloidal soluble nanoplatform with great photoluminescent and antibacterial properties

Abstract

In this work, the sustainable functionalization of graphene quantum dots (GQDs) obtained from citric acid via a novel, green, facile, and straightforward approach for effectively anchoring CuO nanoparticles (CuO NPs) and accordingly improving their colloidal solubility and antibacterial activity is reported. The GQDs were first synthesized through a green hydrothermal method and participated in a Ugi four-component reaction (Ugi-4CR) in water for carboxamide functionalization. Finally, in situ anchoring of CuO NPs was applied towards the Ugi-functionalized GQDs to synthesize the GQD-Ugi@CuO core–shell nanostructure. The constructed nanomaterials were characterized using XRD, FT-IR, NMR, TEM, DLS, UV-vis, and PL techniques. Significant antibacterial activity was observed for GQD-Ugi@CuO against both E. coli (MBC: 32 μg mL⁻¹, MIC: 16 μg mL⁻¹) and S. aureus (MBC: 64 μg mL⁻¹, MIC: 32 μg mL⁻¹) bacteria. The MTT assay reveals a good cytocompatibility for GQD-Ugi@CuO towards human skin fibroblast (HFF-1) cells. The results indicate that the synthesized GQD-Ugi@CuO has the potential to be employed as a safe photoluminescent nanoplatform with great antimicrobial activity.