Additive assay for the repeated measurements of immunosensor without regeneration step

A reuse method of immunosensor called “additive assay” is developed. Generally, the reuse of an immunosensor has required regeneration of the immunoaffinity layer (IA layer) in order to remove already bound analyte from the IA layer. The additive assay aims to realize the multiple measurements without any regeneration process. In the additive assay, the concentration of additively injected sample is calculated from actually measured sensor signal by using the correlation curve between accumulated signal and accumulated concentration. In this work, the binding of anti-BSA antibodies to the BSA layer was used as a model of immunoaffinity interaction to demonstrate the additive assay. The additive assay was tested by two surface plasmon resonance (SPR) biosensors (Spreeta™ and Biocore 3000) and the accuracy of the additive assay was estimated to be 4.5%.