Green synthesis and biomedical potential of l-ascorbic acid-stabilized copper sulfide nanoparticles as antibacterial and antioxidant agents

Background: Inorganic metal nanoformulations are potential therapeutic agents for a variety of biomedical applications, particularly as antimicrobial and antioxidant agents. The main objective of this study was to synthesize copper sulfide nanoparticles (CuS NPs) and evaluate their efficiency as an antioxidant and antibacterial agent. Methods: CuS NPs were prepared in a single step process using l-ascorbic acid as the stabilizing agent. Systematic structural and morphological characterization was performed using standard techniques of X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Further, agar well disk-diffusion method was applied for determination of the antibacterial sensitivity and minimum inhibitory concentration (MIC) of CuS NPs against multiple pathogenic bacterial strains. Their antioxidant potential was evaluated as total reduction capability, and nitric oxide (NO) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activities at multiple doses, with l-ascorbate as the reference. Results: The results indicated amorphous nature of the CuS NPs with the size range of 8.17–9.63 nm. FT-IR confirmed presence of several bioactive functional groups required for the reduction of copper ions. Additionally, CuS NPs showed robust antibacterial activities against bacterial species such as Escherichia coli and Staphylococcus aureus in the agar well diffusion assays, with zone of inhibition values ranging between 21 and 23 mm. CuS NPs also showed potent dose-dependent antioxidant activity. Conclusion: CuS NPs prepared in this study in a cost- and time-efficient manner have excellent antibacterial and antioxidant properties with the potential to be used for different biomedical applications.