Breast cancer has become a global health burden, and therefore requires necessitating action against the development of affordable, target-oriented, and safe chemotherapeutic agents to mitigate its prevalence worldwide. In the present report, titanium oxide (TiO2) nanocrystals (NCs) were synthesized using the green route utilizing Ocimum basilicum leaf extract (OBLE). X-ray diffraction (XRD) studies revealed that TiO2 NCs exhibit tetragonal crystal configuration with anatase-type symmetry with \(I{4}_{1/}amd\) space group. The phenolic groups (–OH) present in OBLE were detected as the bend appeared at 3420 cm− 1 in the infrared spectrum. The characteristic hump positioned at 331 nm in the UV–visible diffuse reflectance spectrum (UV–DRS) of biosynthesized TiO2 NCs confirmed the formation of nanoparticles and the optical band gap of TiO2 NCs was found to be 3.41 eV as evaluated from Tauc’s plot. The surface morphology of TiO2 NCs showed minute agglomeration with an average particle size of 11.8 ± 0.66 nm as obtained from statistical analysis of the particle size distribution. The cytotoxic activity of TiO2 NCs was investigated against MDA–MB 231 cancer cells and dose-dependent cell inhibition was observed with a low IC50 value of 13.35 µg/mL after 48 h of incubation time. The present study underscores the remarkable cytotoxicity demonstrated by TiO2 NCs against breast cancer cell lines.
