Plasmon resonance measurements of the adsorption and adsorption kinetics of a biopolymer onto gold nanocolloids

A shift in plasmon surface resonance is measured for colloidal solutions of gold nanoparticles upon adsorption of polyampholyte (gelatin). It is demon strated that the shift in wavelength of the absorption maximum can quantita tively yield measurements of the adsorbed amount as well as information abo ut the structure of the adsorbed polymer layer. Semiquantitative agreement is found with calculations based on the Mie theory in the quasi-static Limi t. The method is demonstrated to provide quantitative measurements of the k inetics of biopolymer adsorption onto colloidal nanoparticles in solution.