Towards the Standardization of Photothermal Measurements of Iron Oxide Nanoparticles in Two Biological Windows.

A systematic study on laser-induced heating carried out in two biological windows (800 nm and 1053 nm) for FeO nanoparticles in water suspension showed evidence of the strong dependence of the specific absorption rate (SAR) on extrinsic parameters such as the vessel volume or laser spot size. The results show that a minimum of 100 μL must be used in order to obtain vessel-size-independent SARs. In addition, at a constant intensity but different laser powers and spot size ratios, the SARs can differ by a three-fold factor, showing that the laser power and irradiated area strongly affect the heating curves for both wavelengths.