Advances in the non-linear optical investigation of lyotropic-like low-density human lipoproteins in the native and oxidised states

The Z-Scan optical technique was recently used to measure the non-linear optical response of human lipoproteins, in particular low-density lipoprotein (LDL) particles, regarding their oxidative (atherogenic) state. The higher is the oxidation degree of the LDL particle, the smaller is their non-linear optical response. The main physical process involved in this phenomenon is the increase in the thermal diffusivity of the aqueous LDL solution, as a function of the oxidation degree. The responsible for the heat diffusion across the sample are the hydroperoxides generated by the oxidation. Other human lipoproteins were shown to present non-linear optical responses in the thermal timescale regime. The non-linear optical response of LDL solutions may be used in the development of new tools to quantify the atherogenic particles in the human blood.