LSPR Biosensor Signal Enhancement Using Nanoparticle−Antibody Conjugates

A method to amplify the wavelength shift observed from localized surface plasmon resonance (LSPR) bioassays is developed using gold nanoparticle-labeled antibodies. The technique, which involves detecting surface-bound analytes using gold nanoparticle conjugated antibodies, provides a way to enhance LSPR shifts for more sensitive detection of low-concentration analytes. Using the biotin and antibiotin binding pair as a model, we demonstrate up to a 400% amplification of the shift upon antibody binding to analyte. In addition, the antibody-nanoparticle conjugate improves the observed binding constant by 2 orders of magnitude, and the limit of detection by nearly 3 orders of magnitude. This amplification strategy provides a way to improve the sensitivity of plasmon-based bioassays, paving the way for single molecule-based detection and clinically relevant diagnostics.