Evaluation of <i>Jussiaea repens</i> ‐Derived Carbon Nanosphere and Its Polyaniline Composites for Biomedical Applications

ABSTRACT Carbon nanostructures derived from biomass precursors have attracted attention for biomedical applications due to their surface functionality and biocompatibility. In this study, fluorescent carbonaceous nanostructures were synthesized from Jussiaea repens via a solvothermal route and subsequently integrated with polyaniline (PANI) to form a hybrid composite. Electron microscopy revealed spherical carbon nanostructures with an average size of ∼68 nm, while dynamic light scattering showed a hydrodynamic diameter of ∼149 nm, indicating aggregation in aqueous media. Raman and XPS analyses confirmed a defect‐rich carbon framework with oxygen‐ and nitrogen‐containing functional groups. The carbon nanostructures exhibited excitation‐dependent photoluminescence with a quantum yield of ∼2% (quinine sulfate reference), attributed predominantly to surface‐state emission. Zeta potential measurements (−10.6 mV) indicated moderate colloidal stability. In vitro studies demonstrated strong antioxidant activity, non‐hemolytic and minimal reactive oxygen species (ROS) generation in CHO‐K1 cells, indicating biocompatibility. In contrast, J. repens ‐derived carbon dot like nanostructure (JCD) and PANI and CDs nanocomposite (PJCD‐2) exhibited potent anticancer activity in melanoma cancer cells (B16F10) by inducing cell cycle arrest, enhancing ROS production, and inhibiting cell migration by the disruption of cytoskeleton organization and actin filaments. Western blot analysis further revealed a significant upregulation of the pro‐apoptotic protein BAX, accompanied by a marked downregulation of Bcl‐2 and Cyclin B1. These alterations in protein expression strongly support apoptosis‐mediated cytotoxicity and indicate activation of the intrinsic apoptotic pathway. The genotoxicity studies revealed the non‐significant mitotoxic and clastogenic effects of JCD, PANI, and PJCD‐2 in CHO‐K1 cells when compared to mitomycin‐C positive control, supporting their safety.