Selective apoptosis induction in cancer cells using folate-conjugated gold nanoparticles and controlling the laser irradiation conditions.

In this study, we explained in detail a targeted nano-photo-thermal therapy (NPTT) method to induce selective apoptosis in cancer cells. Folate-conjugated gold nanoparticles (F-AuNPs) were synthesized by tailoring the surface of AuNPs with folic acid to enhance the specificity of NPTT. KB cancer cells, as a folate receptor over-expressing cell line, and L929 normal cells with low level of folate receptors were incubated with the synthesized F-AuNPs and then irradiated with various laser intensities and exposure durations. Following various regimes of NPTT, we assessed the level of cell viability and the ratio of apoptosis/necrosis. No significant cytotoxicity was observed for both cell lines at concentrations up to 40 μM of F-AuNPs. Moreover, no significant cell lethality occurred for various laser irradiation conditions. The viability of KB and L929 cells incubated with F-AuNPs (40 μM; 6 h) and then irradiated by laser (1 W/cm2; 2 min) was 57 and 83%, respectively. It was also demonstrated that the majority of cancer cell death is related to apoptosis (41% apoptosis of 43% overall cell death). In this process of F-AuNPs based NPTT, it may be concluded that the main factor determining whether a cell dies due to apoptosis or necrosis depends on laser irradiation conditions. In this study, we explained in detail a targeted nano-photo-thermal therapy (NPTT) method to induce selective apoptosis in cancer cells.