A novel platform for highly surface-sensitive fluorescent measurements applying simultaneous total internal reflection excitation and super critical angle detection

A highly surface-sensitive fluorescent measurement platform for chemical and biochemical analysis is presented. The core component of the platform is a polystyrene parabolic lens that is utilised in simultaneous total internal reflection excitation and super critical angle fluorescence detection. Both the theoretical calculations and the experimental results of the immunological model assays show that the system is extremely sensitive to the surface bound fluorescence. The binding of analytes at concentrations down to 5 pmol/l has been detected in real time while the unbound fluorescent labels in the sample liquid did not show any response until at three decades higher concentrations.