Aptamer-mediated detection of thrombin using silver nanoparticle signal enhancement

We present the first assay combining a dual aptamer sandwich format with detection by anodic stripping voltammetry with ionic silver amplification. This assay format lends itself to rapid point-of-care tests, where the use of aptamers could improve the overall stability of the assay. We have used human alpha-thrombin as a model system, and demonstrate a detection limit of 6.09 mu g L-1. We present the optimization of the aptamer-silver colloid attachment chemistry and the final assay format to achieve sensitive analyte detection. The use of a sandwich assay coupled with magnetic separation and ionic silver amplification, generates an assay with similar sensitivity than those reported in the literature in a format that can be used in rapid, portable testing regimes.