An Open Sandwich Immunochromatography for Non-competitive Detection of Small Antigens

• Published in: Analytical Sciences Vol. 37; no. 3; pp. 455 - 459
• Main Authors: HARADA, Yoshitaka, TSUNA, Mika, OHMURO-MATSUYAMA, Yuki, UEDA, Hiroshi
• Format: Journal Article
• Language: English
• Published: Singapore The Japan Society for Analytical Chemistry 10.03.2021; Springer Nature Singapore; Nature Publishing Group
• Subjects: Amino acids; Analytical Chemistry; Antibodies; Antigens; Antigens - analysis; Biomedical materials; bone Gla protein; Cellulose; Cellulose - chemistry; Cellulose esters; Cellulose nitrate; Chemistry; Chromatography, Affinity; Competition; Fragments; Immunoassay; immunochromatography; lateral flow assay; Molecular weight; Open sandwich immunoassay; Osteocalcin; Osteocalcin - analysis; Target detection; Variable region; Open sandwich immunoassay; immunochromatography; lateral flow assay; bone Gla protein
• ISSN: 0910-6340; 1348-2246; 1348-2246
• DOI: 10.2116/analsci.20SCP06

Immunochromatography assay is an easy and rapid on-site detection method. However, conventional sandwich immunochromatographies using two antibodies can only detect target molecules above a threshold size. Small molecules below 1000 in molecular weight are usually detected using competitive immunoassay. However, competitive immunoassay is not suitable for visual detection of low concentration samples. Based on the principles of open sandwich immunoassay, which detects small molecules via interchain interaction of separated variable region fragments (VH and VL) from a single antibody, we developed non-competitive open sandwich immunochromatography. Bone Gla protein (BGP)-C7, a peptide containing the seven C-terminal amino acids of human osteocalcin, was selected as the target. By using VL fragments fixed on a nitrocellulose membrane, and colored cellulose bead-labeled VH fragments, we specifically detected 10 ng/mL of BGP-C7. This is the first report of open sandwich immunochromatography, which is an easy and rapid method for on-site, signal-on detection of small molecules.