Protein Adsorption on Gold Nanoparticle and Protein Surfaces Probed by Second Harmonic Light Scattering

Abstract

Second harmonic light scattering (SHLS) is a highly sensitive technique to probe reactions at interfaces/surfaces because of symmetry breaking at the interface/surface produces a large surface polarization which gives rise to large SHLS. In the electric dipole approximation, when the bulk solution is isotropic, the surface is the sole source of SH signal. Second harmonic scattering signal from surfaces/interfaces is non-destructive, does not require any particular chemical species and can be carried out in situ. The first report on the observation of SH signal from the particle−solvent interface after adsorption of an organic dye, malachite green on a micron size colloidal polystyrene particle had opened up new possibilities for SHLS to examine all kinds of interaction at the colloidal surface. Gold nanoparticles are known to bind to proteins and peptides and have been implicated in drug delivery mission at the cellular level. In this thesis, I have investigated adsorption of proteins on gold nanoparticle surface or protein surface by SHLS in solution and extracted many equilibrium properties of the adsorbed proteins at the interface which will help quantify delivery capability of GNP based formulations