Equisetum diffusum –Mediated Synthesis of Cobalt Oxide Nanoparticles for Multifaceted Biomedical Applications

The present study reports, for the first time, the green synthesis of cobalt oxide nanoparticles (Co 3 O 4 NPs) using aqueous extract of Equisetum diffusum as a natural reducing and stabilizing agent. The synthesized ED@Co 3 O 4 NPs were comprehensively characterized using various techniques: UV–Vis spectroscopy revealed an absorption peak at 323 nm; FTIR confirmed the presence of functional groups in the ED extract and ED@Co 3 O 4 NPs. XRD confirmed the formation of crystalline spinel‐phase Co 3 O 4 with an average crystallite size of 15.17 nm, whereas SEM analysis showed uniformly distributed spherical nanoparticles with an average diameter of 58.56 nm. DLS and zeta potential (−32 mV) indicated good colloidal stability. The biological potential of ED@Co 3 O 4 NPs was evaluated, demonstrating significant antibacterial activity against Pseudomonas aeruginosa (25 mm), Escherichia coli (22 mm), and Staphylococcus epidermidis (12 mm). Antioxidant assays revealed a concentration‐dependent increase in activity, with DPPH scavenging percentages from 38.75% to 80.41% and FRAP reducing power from 26.05 (mg AAE/g) to 70.44 (mg AAE/g). Hemolytic activity ranged from 0.10% at (0.5 μg/μL) to 3.76% at (5 μ g/μL), indicating low toxicity at lower concentrations. Preliminary anticoagulant and thrombolytic assays suggested a promising hemostatic modulation potential. These findings highlight the potential of ED@Co 3 O 4 NPs for various biomedical applications.