Gold nanoparticle-enhanced photodynamic therapy: effects of surface charge and mitochondrial targeting

Aim: The authors aimed to further improve the efficiency and selectivity of gold nanoparticle (Au NP)-assisted photodynamic therapy by modulating the surface charge of Au NPs and delivering Au NPs particularly to mitochondria of breast cancer cells. Methods: Solid gold nanospheres (similar to 50 nm) with negative and positive surface charge were synthesized respectively, and mitochondria-targeting Au NPs were prepared by conjugating with triphenylphosphonium molecules. Conclusion: Positively charged Au NPs were preferably taken up by breast cancer cells. Combination of positive surface charge with mitochondria-targeting domain onto Au NPs allowed their accumulation in the mitochondria of breast cancer cells to significantly elevate reactive oxygen species formation in 5-aminolevulinic-acid-enabled photodynamic therapy and improve selective destruction of breast cancer cells.