Polarized Angular Dependent Light Scattering Properties of Bare and PEGylated Gold Nanoshells

Metal nanoshells have found promising applications in biomedical imaging and cancer therapy. To facilitate the application of nanoshells in scattering based imaging techniques, it is essential to characterize their light scattering properties. We have studied the light scattering from nanoshells at the quadrupolar and octupolar frequencies of the surface plasmon resonance, and our measurements are in good agreement with Mie theory calculations for both wavelengths. For in vivo use of nanoparticles in biomedical imaging and therapy, surface modification is of great importance in enhancing the stability and biocompatibility of these particles, and polyethylene glycol is commonly used for the surface modification of metal and semiconductor nanoparticles. However, the influence of surface modification on the optical properties of nanoparticles has not been systematically studied yet. Here, we also report the study on the polarized and angularly- resolved light scattering properties of gold nanoshells before and after polyethylene glycol modification. We find that polyethylene glycol does not influence the extinction profile of gold nanoshells. Furthermore, there is no significant change in the scattering phase function of nanoshells after polyethylene glycol modification.