A new methodology for quantitative LSPR biosensing and imaging

A new quantitative analysis methodology for localized surface plasmon resonance (LSPR) biosensing which determines surface-receptor fractional occupancy, as well as an LSPR imaging technique for the spatiotemporal mapping of binding events, is presented. Electron beam nanolithography was used to fabricate 20 × 20 arrays of gold nanostructures atop glass coverslips. A single biotinylated array was used to measure the association kinetics of neutravidin to the surface by spectroscopically determining the fractional occupancy as a function of time. By regenerating the same array, a reliable comparison of the kinetics could be made between control samples and neutravidin concentrations ranging from 1 μM to 50 nM. CCD-based imagery of the array, taken simultaneously with the spectroscopic measurements, reveals the binding of neutravidin to the surface as manifested by enhanced scattering over the majority of the resonance peak. The temporal resolution of the LSPR imaging technique was 200 ms and the spatial resolution was 8 μm(2).