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

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.