title: Quantitative analysis of the number of antigens immobilized on a glass surface by AFM.
abstract: To develop force measurements using an atomic force microscope (AFM) in a quantitative manner, it is necessary to estimate the number density of target molecules on a sample surface, and for this, the sensitivity of detection should be known. In this study, the AFM was used as a mechanical detector and an antigen and its antibody were used as a model to evaluate the sensitivity of detection. Antigens were immobilized on a glass surface and number density was estimated by monitoring optical absorbance due to product formation by the reaction of crosslinkers. The concentration of antigen was controlled by mixing control peptides. A microbead was used as a probe and antibodies were immobilized on the bead. AFM force measurements were then made for a range of number densities in the order of 10-10(6) antigen molecules per square micrometer of surface and were compared to evaluate the sensitivity of detection. Our result establishes the reliability of estimating a number of molecules like receptors on the cell surface, and indicates that the AFM is useful as a mechanical detector with high sensitivity.
authors.affiliation: Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan. hkim@bio.titech.ac.jp
authors.forename: Hyonchol
authors.initials: H
authors.lastname: Kim
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuruta
authors.forename: Hideo
authors.initials: H
authors.lastname: Arakawa
authors.forename: Toshiya
authors.initials: T
authors.lastname: Osada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ikai
mesh_terms: D000595:Amino Acid Sequence; D000941:Antigens / Q000032:analysis*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008969:Molecular Sequence Data
chemical_list: D000941:Antigens