Electric-Field-Mediated In-Sensor Alignment of Antibody's Orientation to Enhance the Antibody-Antigen Binding for Ultrahigh Sensitivity Sensors.

Applying an electric-field (E-field) during antibody immobilization aligns the orientation of the antibody on the biosensor surface, thereby enhancing the binding probability between the antibody and antigen and maximizing the sensitivity of the biosensor. In this study, a biosensor with enhanced antibody-antigen binding probability was developed using the alignment of polar antibodies (immunoglobulin G [IgG]) under an E-field applied inside the interdigitated electrodes. The optimal alignment condition was first theoretically calculated and then experimentally confirmed by comparing the impedance change before and after the alignment of IgG (a purified anti-β-amyloid antibody). With the optimized condition, the impedance change of the biosensor was maximized because of the alignment of IgG orientation on the sensor surface; the detection sensitivity of the antigen amyloid-beta 1-42 was also maximized. The E-field-based in-sensor alignment of antibodies is an easy and effective method for enhancing biosensor sensitivity.