Enhanced photodynamic therapy of mixed phase TiO2(B)/anatase nanofibers for killing of HeLa cells

Photodynamic therapy (PDT), which is a procedure that uses photosensitizing drug to apply therapy selectively to target sites, has been proven to be a safe treatment for cancers and conditions that may develop into cancers. Nano-sized TiO2 has been regarded as potential photosensitizer for UV light driven PDT. In this study, four types of TiO2 nanofibers were prepared from proton tri-titanate (H2T3O7) nanofiber. The as-obtained nanofibers were demonstrated as efficient photosensitizers for PDT killing of HeLa cells. MTT assay and flow cytometry (FCM) were carried out to evaluate the biocompatibility, percentage of apoptotic cells, and cell viability. The non-cytotoxicity of the as-prepared TiO2 nanofibers in the absence of UV irradiation has also been demonstrated. Under UV light irradiation, the TiO2 nanofibers, particularly the mixed phase nanofibers, displayed much higher cell-killing efficiency than Pirarubicin (THP), which is a common drug to induce the apoptosis of HeLa cells. We ascribe the high cellkilling efficiency of the mixed phase nanofibers to the bandgap edge match and stable interface between TiO2(B) and anatase phases in a single nanofiber, which can inhibit the recombination of the photogenerated electrons and holes. This promotes the charge separation and transfer processes and can produce more reactive oxygen species (ROS) that are responsible for the killing of HeLa cells.