Measurement of cardiac troponin I by sandwich immunobiosensor prepared with the polyclonal antibody

Cardiac and skeletal muscle troponin I(cTnI, sTnI) were purified from human left ventricular tissue and skeletal muscle tissue by affinity chromatographic method, respectively. The specific polyclonal antibody to cTnI was prepared by immuned pure New Zealand rabbit with the purified cTnI and purified by nitrocellulose membrane filtration-affinity chromatography with sTnI A specific immunobiosensor for cTnI was developed by using surface plasmon resonance (SPR) biosensor with biotin as an intermediate layer and with the biotinylated-specific polyclonal antibody as capture antibody and used in a direct detection of cTnI in sera with the lowest detection limit of 2.5 mug/L. A more sensitive sandwich immunobiosensor for cTnI was developed. by using biotinylated specific polyclonal antibody as capture antibody (the first antibody) and polyclonal antibody as the second antibody. The sandwich immunoassay showed an excellent sensitivity of 0.5 mug/L and the detection range of 0.5-20 mug/L and within-run variation of 3.5% - 4. 9% and between-run variation of 6.1% - 7.4%. The cTnI's in the sera of 40 healthy donors and 20 patients with acute myocardial infarction(AMI) wore monitored by using the sandwich immunoassay and the Lifesign MI Troponin I test device, respectively and it was found that the coincidence of the two assays was 95%, indicating that the developed sandwich immunoassay with SPR biosensor is suitable in clinical determination.