Label-free Biosensor Using Polyion-modified Gold Nanorods Adsorbed on a Glass Substrate

Gold nanorods (NRs), which were modified with polyions, were fixed on polycation-modified glass substrates. Adsorption of antibodies and antigens on the glass substrates induced large peak shifts (44 nm) of longitudinal surface plasmon bands in the near-infrared region. The shifts were assignable to changes of refractive indices of polyion layers at the glass surfaces.