Quantification of ricin concentrations in aqueous media

Abstract Described is a sensor for quantification of ricin in aqueous media such as water, blood or serum. The detection chemistry uses a sandwich complex of anti-ricinus antibody–ricin–alkaline phosphatase (AP)-conjugated rabbit anti-ricinus antibody on the sensor surface, with biocatalytic precipitation used to amplify the mass change associated with antigen–antibody binding events on the surface of a magnetoelastic sensor. The remote query nature of the magnetoelastic sensors enables them to be monitored from within a sealed one-shot disposable container, in which the liquid test sample is placed. The resulting non-reversible ricin concentration-dependent mass change on the sensor surface in turn shifts both the resonance frequency of the sensor and the resonance quality factor Q . The biosensor demonstrates a linear shift in resonance frequency with ricin concentrations ranging from 10 ng/ml to 100 μg/ml, with a detection limit of 5 ng/ml.