Biogenic synthesis of Co3O4 nanoparticles: a multifunctional approach to antibacterial, antioxidant, DNA binding, and drug degradation studies

Cobalt oxide nanoparticles (Co₃O₄ NPs) were synthesized using an eco-friendly green synthesis approach employing Aegle marmelos plant extract as a natural reducing and capping/stabilizing agent. UV–Vis spectroscopy confirmed the successful formation of Co₃O₄ NPs, exhibiting a band gap energy of 2.1 eV. XRD analysis verified the crystalline nature of the nanoparticles, while FE-SEM revealed a rock-like shape with an average particle size of 60.50 nm. The biosynthesized Co₃O₄ NPs demonstrated excellent antibacterial activity, showing maximum zones of inhibition (20 mm) against S. saprophyticus, E. coli, and E. faecalis, with the least activity (12 mm) observed against S. typhimurium. Furthermore, the nanoparticles exhibited notable antioxidant activity (8.8%) and significant interaction with calf thymus DNA, suggesting potential genotoxic modulation. Furthermore, the Co₃O₄ NPs successfully degraded the pharmaceutical compound ciprofloxacin, demonstrating their photocatalytic ability. These findings highlight the multifunctional potential of green-synthesized Co₃O₄ NPs for biomedical, environmental, and therapeutic applications, warranting further exploration. Graphical Abstract