Differentiating surface and bulk interactions using localized surface plasmon resonances of gold nanorods.

We demonstrate a novel localized surface-plasmon resonance sensor that can distinguish surface binding interactions from interfering bulk effects. This is accomplished by utilizing the longitudinal and transverse plasmon modes of gold nanorods. We have investigated, both numerically and experimentally, the effect of change in background refractive index and surface binding on the two resonances of a gold nanorod on an indium tin oxide coated glass substrate.