An ultrasensitive aptasensor for prostate specific antigen assay based on Exonuclease T-aided cyclic cleavage

Abstract

An ultrasensitive electrochemical aptasensor is presented for prostate specific antigen (PSA) detection. DNA tetrahedron-aptamer is designed, which not only facilitates the molecular self-assembly events, but also improves the recognition efficiency between PSA and aptamer sequence on the electrode interface. The DNA conformation on top of DNA tetrahedron changes accordingly, which can be further digested by Exonuclease T (Exo T), a type of single-strand specific nuclease. Electrochemical species are removed synchronously and the initial PSA level can thus be determined. A linear range from 0.5 pg mL −1 to 50 ng mL −1 is achieved with the limit of detection (LOD) as low as 0.15 pg mL −1 . Moreover, this proposed method is highly selective and is successfully applied to determine PSA in human serum samples.