In the present study, an eco-friendly and cost-effective green synthesis approach was employed to generate titanium dioxide nanoparticles (TiO2 NPs) using aqueous extracts of Star Anise (Illicium verum) flowers. The generated TiO2 NPs were systematically characterized using X-ray diffraction (XRD), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy (FE-SEM). XRD analysis confirmed the formation of phase-pure rutile TiO2 NPs with a body-centered tetragonal crystal structure, exhibiting high crystallinity and an average crystallite size of approximately 18 nm. UV-Vis spectroscopy revealed strong absorption in the UV–visible region with a maximum absorption peak at 380 nm, and the calculated direct band gap energy was 3.26 eV. FE-SEM micrographs showed agglomerated, quasi-spherical NPs with sizes ranging from 19 to 25 nm, while FT-IR spectra indicated the presence of bioactive functional groups from the plant extract, suggesting their role in nanoparticle formation and stabilization. The antibacterial activity of the green-synthesized TiO2 NPs was evaluated against clinically relevant Gram-positive and Gram-negative bacterial strains using the agar well diffusion method. The NPs exhibited significant antibacterial efficacy, with the highest inhibition zone observed against Staphylococcus aureus (19 mm), followed by Klebsiella pneumoniae, Veillonella parvula, and Streptococcus pneumoniae. Furthermore, cytotoxicity studies using the MTT assay demonstrated that the TiO2 NPs effectively inhibited the proliferation of MDA-MB-231 breast cancer cells, with an IC₅₀ value of 54.05 µg/mL. These findings highlight the potential of green-synthesized rutile TiO2 NPs as antibacterial and anticancer agents, serving as an in vitro proof-of-concept for future biomedical applications.
Vijayakumar et al. (Fri,) studied this question.