Magnetic Bead-Based Chemiluminescent Metal Immunoassay with a Colloidal Gold Label

摘要

A novel, sensitive chemiluminescent (CL) immunoassay has been developed by taking advantage of a magneticseparation/mbong process and the amplification feature of colloidal gold label. First, the sandwich-type complexis formed in this protocol by the primary antibody immobilised on the surface of magnetic beads, the antigenin the sample, and the second antibody labeled with colloidal gold. Second, a large number of Au~3+ ions fromeach gold particle anchored on the surface of magnetic beads are released after oxidative gold metal dissolutionand then quantitatively determined by a simple and sensitiVe Au~3+-catalyzed luminol CL reaction. Third, thisprotocol is evaluated for a noncompetitive immunoassay of a human immunoglobulin G, and a concentration aslow as 3.1 x 10~-12 M is determined, which is competitive with colloidal gold-based anodic stripping voltammetry(ASV), colorimetric ELISA, or immunoassnys based on fluorescent europium chelate labels. The high performance of this protocol is related to the sensitive CL determination of Au~3+ ion (detection limit of 2 x 10~-10 M), which is 25 times higher than that by ASV at a singleuse carbon-based screen-print6d electrode. From the analytical chemistry point of view, this protocol will be quite promising for numerous applications in immunoassay and DNA hybridizahon.