Quantitative analysis of the number of antigens immobilized on a glass surface by AFM.
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.
Kim
Hyonchol
H
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
Tsuruta
Satoshi
S
Arakawa
Hideo
H
Osada
Toshiya
T
Ikai
Atsushi
A
D000595:Amino Acid Sequence; D000941:Antigens / Q000032:analysis*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008969:Molecular Sequence Data
D000941:Antigens