Ultrasensitive Electrochemical Detection of Prostate-Specific Antigen by Using Antibodies Anchored on a DNA Nanostructural Scaffold

The high occurrence of prostate cancer in men makes the prostate-specific antigen (PSA) screening test really important. More importantly, the recurrence rate after radical prostatectomy is high, whereas the traditional P SA immunoassay does not possess the sufficient high sensitivity for post-treatment PSA detection. In these assays, uncontrolled and random orientation of capture antibodies on the surface largely reduces their activity. Here, by exploiting the rapidly emerging DNA nanotechnology, we developed a DNA nanostructure based scaffold to precisely control the assembly of antibody monolayer. We demonstrated that the detection sensitivity was critically dependent on the nanoscale-spacing (nanospacing) of immobilized antibodies. In addition to the controlled assembly, we further amplified the sensing signal by using the gold nanoparticles, resulting in extremely high sensitivity and a low detection limit of 1 pg/mL. To test the real-world applicability of our nanoengineered electrochemical sensor, we evaluated the performance with 11 patients' serum samples and obtained consistent results with the "gold-standard" assays.