Liquid-phase binding assay of alpha-fetoprotein using DNA-coupled antibody and capillary chip electrophoresis.
An immunoassay using DNA-coupled antibody for bound/free separation in a liquid-phase binding assay format is described. Anti-alpha-fetoprotein monoclonal antibody was conjugated with DNA, mixed with alpha-fetoprotein (AFP), and incubated, and then 1 muL of the mixture was applied to capillary electrophoresis on a microchip. The DNA molecule of the antibody-DNA conjugate and the DNA-conjugated immune complex peak were detectable fluorophotometrically using intercalator dye within 90 s, whereas the Alexa-labeled antibody was detected as a broad and slower migrating peak. The electrophoretic mobility of the immune complex could be optimized for resolution and sharpness by changing the length of the DNA coupled to the antibody. The detection limit of AFP was approximately 300 pM in a sample. This immunoassay method utilizing a liquid-phase binding assay format is simple and convenient for antigen measurements on microchips.
Kawabata
Tomohisa
T
New Diagnostics Business and Technology Development Department, Wako Pure Chemical Industries, Ltd., Osaka, Japan.
Watanabe
Mitsuo
M
Nakamura
Kenji
K
Satomura
Shinji
S
D000906:Antibodies / Q000737:chemistry / Q000276:immunology*; D004247:DNA / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D019075:Electrophoresis, Capillary / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D008024:Ligands; D017430:Prostate-Specific Antigen / Q000032:analysis / Q000276:immunology; D011485:Protein Binding; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000276:immunology
D000906:Antibodies; D008024:Ligands; D000509:alpha-Fetoproteins; D004247:DNA; D017430:Prostate-Specific Antigen