Backgrounds and Objective: Titanium dioxide (TiO₂) is a potent photosensitizer in photodynamic therapy (PDT) and is activated upon ultraviolet (UV) irradiation.The aim of this study was the assessment of the effect of nitrogen –nano doped of titanium dioxide in human A-375 melanoma cancer cell line.

Materials and Methods: N-TiO₂ nanoparticles were prepared by mechanical mixing of urea with TiO₂ powder in a 4:1 weight ratio. A-375 cells were treated with different concentrations of N-TiO₂ for various time intervals in the presence or absence of visible light. The growth and viability of A-375 cells were determined by means of trypan blue exclusion test and MTT assay, respectively. Acridine orange/Ethidium bromide double staining and DNA gel electrophoresis were applied to determine apoptosis.

Results: The results showed that visible light activated N-TiO₂ could induce growth inhibition in a dose (0.01-100 μg/ml ) and time dependent manner. In concentration of 0.5 μg/ml a significant difference was observed between the treated and the control samples.Decrease in viability was observed in 100 μg/ml concentration and the results of fluorescent microscopy showed  DNA fragmentation due to apoptotic cell death[G1]  at this concentration.

Conclusion: Based on the anti-cancer effects of N-TiO₂ on A-375 cells, further evaluation of these nanoparticles as a new photosensitizer in photocatalytic therapy of skin cancer can be proposed.