The apparent limitation of current immunosensors, that is, the slow response for antibody-antigen systems with high levels of sensitivity, has to be resolved for developing practical immunosensors. A novel approach as proposed in this study is to control the local pH at the transducer/aqueous interface so as to dissociate the antigen-antibody complexes rapidly at the transducer surface. Such surface regeneration mechanism will be achieved by manipulating the surface potential at the transducer/aqueous interface. The surface potential will be controlled by using an electric field across the transducer. A total internal reflection fluorescence system with the application of an evanescent wave will be used as a transducer for detecting the antigen-antibody binding event close to or at the surface. The complex of protein A with immunoglobulin G (IgG) conjugated with fluorescein isothiocyanate (FITC) is chosen as a model antibody-antigen system for this study. The dissociation efficiency and kinetics of the protein A- IgG complexes at the interface by using the proposed surface regeneration mechanism will be investigated both experimentally and theoretically with the proposed capacitor model. To implement and design the proposed surface regeneration mechanism as a regenerable fiber optic immunosensor, a field effecw nx?C8P.y ??<~?a6I`a? ??xC&|?p`??d??O|?? ?`?S?o?S#s ??aaGy?G7?f??| ?`??????? ??? fluorescence signal into/out of the device; 2) efficient generation of an electric field at the interface for the control of the surface potential; 3) small in size but can be made in an array for collecting enough fluorescence signal and/or for multisample measurements. The proposed field effect-waveguide is a potential route to a reagentless, regenerable, and portable """"""""probe"""""""" in situ using immunotechnology for biomedical applications and medical diagnoses.
