Bio-mediated synthesis of zinc oxide nanoparticles from Crossandra infundibuliformis leaves: A potent inducer of apoptosis in lung cancer cells.

Zinc oxide nanoparticles (ZnO-NPs) have gained attention as potential anticancer agents due to their selective cytotoxicity and ability to induce apoptosis. In this study, we evaluated the anticancer efficacy and apoptotic mechanism of biosynthesised ZnO nanoparticles prepared using the aqueous leaf extract of Crossandra infundibuliformis (CI-ZnO-NPs) in human lung adenocarcinoma (A549) cells. The synthesised CI-ZnO-NPs exhibited a characteristic UV-Visible absorbance peak at 277 nm. while FT-IR analysis confirmed the involvement of phytochemical functional groups in nanoparticle formation and stabilisation. XRD analysis revealed the crystalline nature of CI-ZnO-NPs, while SEM and TEM images depicted the semi-spherical agglomerated nanoparticles with an average grain size of 37.26 ± 0.92 nm. The surface charge was measured at -25 mV with the hydrodynamic particle size of 248.7 nm. The anti-cancer activity of CI-ZnO-NPs, evaluated through the MTT assay, showed a concentration-dependent response, with an IC of 47.71 µg/ml. Mechanistic studies revealed elevated intracellular reactive oxygen species (ROS) levels, activation of caspase-3, DNA damage, upregulation of pro-apoptotic genes (TP53 and bax), and downregulation of the anti-apoptotic gene bcl-2. These findings indicate that CI-ZnO-NPs induce caspase-mediated apoptosis in lung cancer cells through oxidative stress-dependent mechanisms, highlighting their promise as a biogenic nanotherapeutic approach for treating lung cancer.