Enhanced photodynamic therapy with riboflavin@ dual minerals doped hydroxyapatite nanoparticles: A promising in vitro approach for bladder cancer

This research examines the efficacy of pure dual minerals (cerium and zinc) doped hydroxyapatite DHA and riboflavin (RFA)-coated DHA nanoparticles (NPs) (RFA@DHA NPs) in the treatment of bladder cancer. X-ray diffraction and Fourier-transform infrared spectroscopy validated the successful coating of RFA while preserving the core crystal structure of DHA. High-resolution transmission electron microscopy demonstrated the presence of spherical NPs, which exhibited a minor increase in size following RFA coating. Both NPs formulations exhibited significant concentration-dependent anticancer activity against T24 bladder cancer cells in the absence of UV irradiation, with RFA@DHA showing superior efficacy (IC₅₀ values of 36.3 and 38.6 μg/mL, respectively). UV irradiation enhanced the effects of photodynamic therapy (PDT), with RFA@DHA demonstrating greater cytotoxicity (IC₅₀ values of 27.9 and 32.6 μg/mL for RFA@DHA and pure DHA, respectively). Live/dead cell assays and nuclear condensation assays demonstrated that both NPs induced apoptosis in a time-dependent manner. The RFA coating mechanistically increased the production of reactive oxygen species (ROS) in both dark conditions and under UV irradiation, resulting in a notable disruption of the mitochondrial membrane potential, which is a critical event in the apoptotic pathway. The findings indicate that RFA-coated DHA NPs may serve as effective photosensitizers for bladder cancer therapy.