Figure 3.
Aptamer-integrated circDNA for sensitive bioanalysis. (A) RCA assay using a structure-switching aptamer that circularizes upon target binding. Reprinted from 30, copyright (2007) The American Chemical Society Publishing Group. (B) Schematic of the aptamer assay for protein detection using RCA coupled with thrombin catalysis. Protein target is captured by an antibody coated on microplate, and then bound with the conjugate of aptamer-primer in which the aptamer binds to a protein target. The template encoding complementary sequence of the thrombin aptamer hybridizes with the primer, and is circularized by ligase to form circDNA as the templates of RCA. The resulting long DNA generated from RCA binds with multiple thrombin molecules, achieving multiple thrombin labeling in sandwich complex. Thrombin catalyzes the cleavage of small peptide substrates into detectable product. Reprinted from 31, copyright (2016) Springer-Verlag Berlin Heidelberg. (C) RCA-mediated assay based on target binding-induced desorption of aptamers from GO. Reprinted from 32, copyright (2014) The American Chemical Society Publishing Group.