AVS 49th International Symposium
    Biomaterials Tuesday Sessions
       Session BI-TuP

Paper BI-TuP12
In-situ Single-Molecular Detection of Antibody-Antigen Binding by Tapping-Mode Atomic Force Microscopy

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Biointerfaces and Surfaces I
Presenter: L. Li, University of Washington
Authors: L. Li, University of Washington
S. Chen, University of Washington
S. Jiang, University of Washington
Correspondent: Click to Email
Ever since its invention atomic force microscopy (AFM) has been widely used in biotechnology and biomedical research, including imaging, force mapping and sensor application. In this work, we have performed studies on AFM-based single-molecule detection. Target molecules are detected by directly comparing two tapping-mode AFM topographical images at the same location before and after exposing an immobilized antibody to a solution containing its antigen, or vise visa. Two pairs of antigen/antibody systems were investigated: chorionic gonadotropin (hCG) and monoclonal antibody (MAb) to hCG, goat anti-hCG and MAb to goat immunoglobulin (IgG). Antibody molecules are chemically immobilized on uniform mixed self-assembled monolayers (SAMs) terminated with COOH and OH, which allow the detection of the individual antigens, antibodies, and antigen/antibody complexes. The advantages of the in-situ detection at the same location include the detection of antigen/antibody binding at single-molecule resolution and the distinction of non-specific interactions from specific ones. This AFM-based immunoassay is more sensitive and reliable.