New Strategy for Streptavidin Detection Using AuNRs/PAAm Hydrogel Composites

Localized surface plasmon resonance (LSPR) is a collective oscillation of free electrons induced by the incident light in nanometric surfaces of conductive materials. Gold nanorods (AuNRs) have been studied for plasmonic devices due to their anisotropic properties. Herein, we report the construction of a specific biosensor using polyacrylamide (PAAm) as the gold nanorods support and test its efficiency with specific streptavidin interaction using biotinylated substrates. First, the hydrogels were synthesized by electropolymerization using cyclic voltammetry on ITO/glass substrates and swallowed with AuNRs. The AuNRs were characterized by visible absorption spectroscopy and transmission electron microscopy. The substrates were characterized by scanning electron microscopy and their plasmonic sensitivities were evaluated using sucrose solutions with different concentrations. The results showed a sensitivity of ca. 226.4 nm RIU-1 with linear correlation of 0.9974. Furthermore, this composite presented reliable detection of the streptavidin biomolecule in the gold surface with good signal-to-noise ratio (SNR).