Figure 33.
Scheme of amplification strategies for detection of protein cancer biomarkers in EC immunoassays. Surface-immobilized primary antibody (Ab1) captures an antigen, which is then detected using, for example, (a) a simple secondary antibody/enzyme (Ab2/enzyme) or (b) antibody/nanoparticle (Ab2/NP) bioconjugate, which are now often replaced with more sophisticated systems, in which the secondary antibody is coupled with, for example, (c) biotin/streptavidin/enzyme,882 (d) different quantum dots (Ab2/QD),883 (e) enzyme-modified carbon nanotubes (Ab2/CNT/multienzyme),689 (f) magnetic beads bearing cluster of enzymes (Ab2/MB/multienzyme),882 or (g) quantum dot-dendrimer nanocomposites (Ab2/dendrimer/QD).884