Amplified fluorescence detection of serum prostate specific antigen based on metal-dependent DNAzyme assistant nanomachine

An amplified fluorescence biosensing strategy for serum prostate specific antigen (PSA) was developed on the basis of DNAzyme. In presence of cofactor Zn2+, Zn2+ -dependent DNAzyme could cleave the hairpin substrate probes which were dispersed in solution and generate remarkable fluorescent signal. Taking advantage of the magnetic beads as a carrier, one target protein could bring plentiful hairpin substrate probes on to the electrode through a sandwich structure (Ab1/PSA/biotin-Ab2). Moreover, during the cleavage process of as formed DNAzyme, DNAzyme did not be destroyed and could further react with other hairpin probes, then generated continuous fluorescent signal. Benefited by this amplified strategy, the limit of detection (LOD) was low to 0.05 ng mL−1, which was much lower than our previous reports. This method could be applied to detect different protein biomarkers in serum without corresponding aptamers by changing the corresponding antibodies and thus showed a remarkable prospect in clinical application. An amplified fluorescence biosensing strategy for serum prostate specific antigen (PSA) was developed on the basis of Zn2+-dependent DNAzyme as the catalytic unit for the cleavage of hairpin substrate probe. [Display omitted] •A novel signal amplified biosensing strategy for fluorescence detection of serum PSA was developed on the basis of DNAzyme.•Zn2+-dependent DNAzyme was selected as the catalytic unit for the cleavage of hairpin substrate probe.•This biosensing approach provided a new strategy for protein biomarkers immunoassay and clinical application.