Chitosan-coated superparamagnetic iron oxide nanoparticles synthesized using <i>Carica papaya</i> bark extract: Evaluation of antioxidant, antibacterial, and anticancer activity of HeLa cervical cancer cells

Abstract This study presents an eco-friendly approach for synthesizing chitosan-coated superparamagnetic iron oxide nanoparticles (Ch-SPIONs) using Carica papaya bark extract as a green reducing and stabilizing agent. The phytochemicals present in the bark extract facilitate the formation of SPIONs with well-defined magnetic characteristics. Comprehensive characterization through UV-visible spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy confirmed the successful synthesis of Ch-SPIONs. The nanoparticles exhibited an average size range of 50–80 nm with a rectangular morphology and a UV-vis absorption peak at 300 nm. The antioxidant potential of Ch-SPIONs was evaluated, revealing concentration-dependent scavenging activity that surpassed standard antioxidants at higher concentrations. Antibacterial assays demonstrated significant efficacy against Klebsiella pneumoniae (15 mm inhibition zone) and Staphylococcus aureus (20 mm inhibition zone). Furthermore, in vitro cytotoxicity studies on HeLa cervical cancer cells showed dose-dependent cell death, with an IC 50 value of 18 ± 0.4 μg·mL −1 , compared to 11 ± 0.5 μg·mL −1 for doxorubicin. Apoptotic induction and cell cycle disruption were further validated through fluorescence microscopy and flow cytometry. These findings underscore the potential of Carica papaya -mediated Ch-SPIONs as a sustainable, biocompatible nanomaterial for anticancer and antimicrobial applications, offering a promising alternative to conventional synthesis methods.