Selective heat generation in cancer cells using a combination of 808 nm laser irradiation and the folate-conjugated Fe2O3@Au nanocomplex

Photothermal therapy (PTT) is a nanotechnology-assisted cancer hyperthermia approach in which the interaction between laser light and plasmonic nanoparticles (NPs) generates localized heating. The exploitation of plasmonic NPs in association with active targeting moieties causes the preferential accumulation of NPs inside cancer cells, thereby providing targeted PTT. Herein, we evaluate the effect of folic acid (FA) as an active targeting agent in enhancing the photothermal efficiency of multifunctional Iron (III) Oxide (Fe 2 O 3 )@Au core- shell NPs. Fe 2 O 3 @Au NPs were synthesized, modified with FA and then characterized. Human nasopharyngeal (KB) cancer cells were treated with different concentrations of Fe 2 O 3 @Au, with and without FA modification and the temperature rise profiles of the cells were measured upon administration of the near-infrared (NIR) laser (808 nm, 6 W/cm 2 , 10 min). The recorded temperature profiles of the cells were used for thermal dose calculation. Finally, the level of induced apoptosis was determined by flow cytometry using an annexin V-fluorescein isothiocyanate/propidium iodide apoptosis detection kit. The characterization data showed that the Fe 2 O 3 @Au NPs are spherical, with a hydrodynamic size of 33 nm. The data corroborated the successful conjugation of the NPs with FA. The thermometry results indicated the superior temperature elevation rate of the cells in the presence of the NPs upon NIR irradiation. Meanwhile, the higher heating rate and the higher thermal dose were obtained for the cells exposed to FA-targeted Fe 2 O 3 @Au rather than the non-targeted nanocomplex. Flow cytometry studies revealed that FA-targeted Fe 2 O 3 @Au induced higher level of apoptosis than non-targeted Fe 2 O 3 @Au NPs. In conclusion, our findings suggest that the synthesized FA-targeted Fe 2 O 3 @Au NP has high potentials to be considered as an efficient thermosensitizer in the process of targeted cancer hyperthermia.