|Using hydroxyl peroxide as a reducing agent at an alkaline condition, a series of gold nanoparticles with confeito-like shapes can be obtained in the presence of a biocompatible protector but without toxic byproducts. The obtained confeito-like nanoparticles (C-AuNPs) could be safely taken to living cancer cells by aid of folic acid. Thus the C-AuNP can be used for biomedical applications.
Meanwhile, cancer cells (HeLa cells) are killed by a short-time irradiation of a near-infrared laser (at wavelength of 785 nm) when the C-AuNP exists in the cells. This carcinolysis is likely due to the strong plasmon absorption of the C-AuNP at the near-infrared region.
On the other hand, the cancer cells including the C-AuNP can survive for the irradiation at the wavelength of 633 nm, which is near the plasmon absorption band of the C-AuNP. In this condition, the C-AuNP is quickly converted to small spherical nanoparticles, and the resulted small nanoparticles are less photoactive than the C-AuNP. This conversion suggests that the C-AuNP is useful for the controlled drug-releasing devises.