Synthesis and Characterization of CuO NPs Integrated Polyamidoxime–Sodium Alginate Hydrogel Nanocomposites for Antimicrobial Applications

Hydrogel nanocomposites with antimicrobial properties are increasingly gaining attention to combat bacterial antimicrobial resistance (AMR). In this research, we presented the development of polyamidoxime–sodium alginate (PAO-SA)-based hydrogel beads that were developed as a platform for the incorporation of copper oxide nanoparticles (CuO NPs). Two different strategies were employed to incorporate the CuO NPs: encapsulation, PAO-SA/CuO (enc) in which a relatively higher concentration of CuO NPs was localized in the core than in the shell of the hydrogel beads, and surface incorporation PAO-SA/CuO (sup) in which the CuO NPs were predominantly localized in the shell. The prepared CuO NPs and nanocomposite hydrogels were characterized by FTIR, AAS, XRD, TGA, FESEM-EDS, and HR-TEM methods. The antimicrobial activity of the CuO NP-containing PAO–SA hydrogel nanocomposites was evaluated against Staphylococcus aureus and Escherichia coli. The synthesized CuO NPs exhibited significant antimicrobial properties, with MIC and MBC values of 125 and 250 mg/L for S. aureus and E. Coli, respectively. Furthermore, bacterial growth kinetics demonstrate that the surface-supported PAO-SA/CuO (sup) nanocomposite exhibits superior antibacterial efficacy compared to its encapsulated counterpart. The in silico cytotoxicity was calculated; the IC50 values were approximately 24.4 mg L−1 for A549, 22.3 mg L−1 for BEAS-2B, 28.3 mg L−1 for MRC-5, and 40.5 mg L−1 for HaCaT. Overall, these results indicate that the predicted IC50 values are within a comparable range to the experimentally reported values for CuO nanoparticles. These results indicate that surface incorporation of CuO NPs into PAO-SA/CuO (sup) nanocomposites can be used effectively as an antimicrobial material to address bacterial AMR.