Trigger of apoptosis in human liver cancer cell line (HepG2) by titanium dioxide nanoparticles functionalized by glutamine and conjugated with thiosemicarbazone

The incidence of liver cancer, the third cause of cancer-associated death, has been growing, worldwide. The increasing trend of liver cancer incidence and mortality indicates the inefficiency of current therapeutic approaches, especially anticancer chemotherapy. Owing to the promising anticancer potential of Thiosemicarbazone (TSC) complexes, this work was conducted to synthesize titanium oxide nanoparticles conjugated with TSC through glutamine functionalization (TiO₂@Gln-TSC NPs) and characterize their anticancer mechanism in HepG2 liver cancer cells. Physicochemical analyses of the synthesized particles, including FT-IR, XRD, SEM, TEM, Zeta potential and DLS, and EDS-mapping confirmed the proper synthesis and conjugation of TiO₂@Gln-TSC NPs. The synthesized NPs were almost spherical, with a size range of 10-80 nm, a zeta potential of - 57.8 mV, a hydrodynamic size of 127 nm, and without impurities. Investigation of the cytotoxic effect of TiO₂@Gln-TSC in HepG2 and HEK293 human normal cells indicated significantly higher toxicity in cancer cells (IC₅₀ = 75 µg/mL) than normal cells (IC₅₀ = 210 µg/mL). Flow cytometry analysis of TiO₂@Gln-TSC treated and control cells showed that the population of apoptotic cells considerably increased from 2.8 to 27.3% after treatment with the NPs. Moreover, 34.1% of the TiO₂@Gln-TSC treated cells were mainly arrested at the sub-G1 phase of the cell cycle, which was significantly greater than control cells (8.4%). The Hoechst staining assay showed considerable nuclear damage, including chromatin fragmentation and the appearance of apoptotic bodies. This work introduced TiO₂@Gln-TSC NPs as a promising anticancer compound that could combat liver cancer cells through apoptosis induction.