Selective photothermal efficiency of citrate capped gold nanoparticles for destruction of cancer cells.

Gold nanoparticles are recently having much attention because of their increased applications in biomedical fields. In this paper, we demonstrated the photothermal efficacy of citrate capped gold nanoparticles (AuNPs) for the destruction of A431 cancer cells. Citrate capped AuNPs were synthesized successfully and characterized by UV-visible-NIR spectrophotometry and High Resolution Transmission Electron Microscopy (HR-TEM). Further, AuNPs were conjugated with epidermal growth factor receptor antibody (anti-EGFR) and applied for the selective photothermal therapy (PTT) of human epithelial cancer cells, A431. PTT experiments were conducted in four groups, Group I--control cells, Group II--cells treated with laser light alone, Group III--cells treated with unconjugated AuNP and further laser irradiation and Group IV--anti-EGFR conjugated AuNP treated cells irradiated by laser light. After laser irradiation, cell morphology changes that were examined using phase contrast microscopy along with the relevant biochemical parameters like lactate dehydrogenase activity, reactive oxygen species generation and caspase-3 activity were studied for all the groups to determine whether cell death occurs due to necrosis or apoptosis. From these results we concluded that, these immunotargeted nanoparticles could selectively induce cell death via ROS mediated apoptosis when cells were exposed to a low power laser light.