Activation of catalytic DNAzyme by binding-induced DNA displacement for homogeneous assay.

The sensitive assays for protein, especially for the DNA-based assay, are often dependent on the amplification procedure with assistance of enzyme. Compared with a protein enzyme, deoxyribozyme (DNAzyme) exhibits similar catalytic activity and specificity and better flexibility. In this work, we streamlined the binding induced DNA displacement (BINDD) strategy for the activation of DNAzyme cleavage. Since the intrinsic element of DNAzyme is the nucleic acids, it is easy to join the BINDD by hybridization with an affinity probe. The activity of DNAzyme was initiated by the BINDD reaction mediated by the recognition affinity probe with target proteins. Upon DNAzyme release, it was able to catalyze and cleave the predesigned substrates, generating the enhanced fluorescence signal indicating the protein concentration. Such a constructed homogeneous assay is available and effective in human serum when it was used for detection of platelet derived growth factor-BB (PDGF-BB) and prostate specific antigen (PSA), with detection limits of 100 pM and 200 pM, respectively.