Aptamer-based surface-enhanced Raman scattering detection of ricin in liquid foods

A "two-step" aptamer-based surface-enhanced Raman scattering (SERS) detection assay was developed for ricin in liquid foods. Ricin B chain was first captured out of food matrices by aptamer-conjugated silver dendrites and then the spectrum was directly read on the silver dendrites. Aptamer use in this assay promotes ease of manipulation as well as improved sensitivity compared to antibody-based approaches. The limit of detection for ricin B chain was 10 ng mL^-1 in phosphate buffered saline (PBS), 50 ng mL ^-1 in orange juice, and 100 ng mL^-1 in milk based on principal component analysis (PCA) of measured spectra. This assay shows great promise as a rapid (< 40 min), sensitive, and simple "Yes/No" method to detect bio-weapons like ricin in liquid foods.