The application of titanium dioxide (TiO2) nanoparticles in the photo-thermal therapy of melanoma cancer model

Photo-thermal therapy (PTT) is a therapeutic method in which photon energy is converted into heat to induce hyperthermia in malignant tumor cells. In this method, energy conversion is performed by nanoparticles (NPs) to enhance induced heat efficacy. The low-cytotoxicity and high optical absorbance of NPs used in this technique are very important. In the present study, titanium dioxide (TiO2) NPs were used as agents for PTT. For increasing water dispersibility and biocompatibility, polyethylene glycol (PEG)-TiO2 NPs (PEGylated TiO2 NPs) were synthesized and the effect of these NPs on reducing melanoma tumor size after PTT was experimentally assessed. To improve the dispersibility of TiO2 NPs in water, PEG was used for wrapping the surface of TiO2 NPs. The formation of a thin layer of PEG around the TiO2 NPs was confirmed through thermo-gravimetric analysis and transmission electron microscopy techniques. Forty female cancerous mice were divided into four equal groups and received treatment with NPs and a laser diode (λ = 808 nm, P = 2 W & I = 2 W/cm2) for seven min once in the period of the treatment. Compared to the mice receiving only the laser therapy, the average tumor size in the mice receiving TiO2-PEG NPs with laser excitation treatment sharply decreased. The results of animal studies showed that PEGylated TiO2 NPs were exceptionally potent in destroying solid tumors in the PTT technique.