Polysaccharide-stabilized biogenic CuO/SeO2 nanocomposites: green synthesis, physicochemical characterization, and enhanced antioxidant, antimicrobial, and selective anticancer activities.

A green-assisted synthesis route was employed for the preparation of copper oxide/selenium dioxide (CuO/SeO2) and their polysaccharide-functionalized counterpart (CuO/SeO2/polysaccharide NCs), using clove extract as a reducing, chelating, and stabilizing agent. The formation of a crystalline CuO/SeO2 framework was confirmed through comprehensive characterization using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and zeta potential analysis, while a core-shell-like hybrid structure was suggested based on morphological observations. Phytochemical analysis revealed a reduction in phenolic compounds during the nanoparticle formation process, whereas an appreciable increase was observed in carbohydrates after the addition of the polysaccharide. The CuO/SeO2/polysaccharide NC exhibited enhanced antioxidant activity, with a DPPH IC50 value of 0.0096 ± 0.001 mg mL-1. Antibacterial activity exhibited strong, species-dependent inhibition, reaching a maximum of 38 ± 0.08 mm against Klebsiella pneumoniae with enhanced activity observed particularly against Gram-positive bacteria. Notably, the results obtained from the cytotoxicity assays demonstrated selective anticancer activity with low cytotoxicity against WI-38 normal fibroblasts (IC50 = 328.2 µg mL-1) and significant inhibitory effects against cancer cell lines, PC3 (IC50 = 18.42 µg mL-1), HeLa (13.70 µg mL-1), HT-29 (13.03 µg mL-1), and A549 (14.14 µg mL-1). The results demonstrate that polysaccharide-functionalized CuO/SeO2 nanocomposites exhibit enhanced physicochemical stability and tunable biological properties, highlighting their potential for further investigation in antioxidant, antimicrobial, and anticancer applications.