A nucleic acid-based magnetic potentiometric aptasensing platform for indirect detection of prostate-specific antigen with catalytic hairpin assembly

Abstract

In this work, a new nucleic acid-based magnetic potentiometric aptasensing platform was designed for in situ amplified measurement of prostate-specific antigen (PSA) with the catalytic hairpin assembly (CHA). The nucleic acid biosensor was constructed by immobilizing thiolated hairpin DNA1 (HP1) on a screen-printed gold electrode (SPGE). PSA-specific aptamers were conjugated onto magnetic beads through the avidin–biotin reaction, followed by hybridization with partially complementary DNA (cDNA). Introduction of target PSA could cause the detachment of cDNA from magnetic beads because of the PSA–aptamer reaction. The detached cDNA opened the immobilized HP1 on the SPGE to induce the catalytic hairpin assembly between HP1 and hairpin DNA2 (HP2), thereby resulting in the recycling of cDNA for repeated utilization. In this case, numerous HP1 and HP2 probes were opened to form many double-stranded DNA molecules on the electrode. Relative to the HP1-modified SPGE, the electric potential was shifted before and after hybridization with HP2. Under optimum conditions, the potential shift was proportional to the PSA concentration within the dynamic range of 0.01–30 ng mL⁻¹, and the limit of detection was estimated to be 9.3 pg mL⁻¹ PSA. The reproducibility with the inter-assay and intro-assay was below 10.58% (RSD). Good specificity and long-term stability were acquired for PSA measurement. Importantly, the method accuracy of nucleic acid-based magnetic potentiometric aptasensing was acceptable for analysis of human serum samples in comparison with that of reference human PSA ELISA kits.