Antibacterial Characteristics of CuS Nanoplates Anchored onto g-C3N4 Nanosheets, Suspended in PMMA Matrix

Nowadays, due to bacterial antibiotic resistance, the design of new high-performance antibiotics to maintain human health has been a significant challenge. Accordingly, photothermal antibiotics have been developed based on semiconductor materials such as graphene. Herein, copper sulfide (CuS) nanoplates and graphitic carbon nitride (g-C3N4)/CuS were synthesized as salient antibacterial agents and their antibacterial features were assessed using polymethyl methacrylate (PMMA) as a practical matrix. The morphology and structure of nanostructures were characterized by X-ray diffraction (XRD), ultraviolet (UV)-visible (Vis) diffuse reflectance spectroscopy (DRS), and field emission scanning electron microscopy (FESEM). Based on the results obtained by the UV-Vis light absorption, the g-C3N4, CuS, and g-C3N4/CuS nanostructures illustrated strong absorptions in the visible light region while demonstrated 2.92, 1.20, and 0.27 eV band gaps, respectively. Eventually, the study of the antibacterial properties of the nanostructures exhibited that the zone of inhibition is augmented by anchoring the CuS nanoplates onto the g-C3N4 surface. Interestingly, g-C3N4/CuS nanocomposite brought 12 and 17 mm zone of inhibitions for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. More significantly, the results attested that inserting the g-C3N4 nanostructures promote the antibacterial features of CuS nanoplates, originated from its nucleation effect boosting surface area to volume ratio of the sulfides, amplifying interfacial interaction, and elevating established reactive oxidative species (ROS) killing the bacteria. The presented research opens new windows toward augmenting the antibacterial features of biomedical polymers.