Bioactivity Assessment of Functionalized TiO2 Powder with Dihydroquercetin

Biological activities, including cell viability, oxidative stress,genotoxicity/antigenotoxicity, and antimicrobial activity, were evaluated for a visiblelight-responsive TiO2-based ICT complex with dihydroquercetin (DHQ) and comparedwith pristine TiO2, its inorganic component. Pristine TiO2 did not induce cytotoxicity inMRC-5 or HeLa cells within the tested concentration range (1–20 mg/mL), whileTiO2/DHQ displayed a significant reduction in cell viability in both cell lines at higherconcentrations (≥10 mg/mL). The analysis of reactive oxygen species (ROS) productionrevealed that TiO2/DHQ significantly reduced ROS levels in both cell types (MRC-5 andHeLa), with HeLa cells showing a more substantial reduction at lower concentrations.Genotoxicity assessment using the comet assay demonstrated that TiO2 induced DNAdamage in MRC-5 cells, while TiO2/DHQ did not, indicating that DHQ mitigates thegenotoxic potential of TiO2. Furthermore, TiO2/DHQ exhibited antigenotoxic effects byreducing H2O2-induced DNA damage in MRC-5 cells, supporting its protective roleagainst oxidative stress. Preliminary antimicrobial tests revealed that TiO2/DHQ exhibitsantimicrobial activity against E. coli under visible-light excitation, while TiO2 does not.These findings suggest that the TiO2-based ICT complex with DHQ with enhancedantioxidant properties can potentially serve as a safe, non-toxic biocide agent.