Abstract:
In this work, we designed and fabricated two new “signal-on” electrochemical DNA sensors based on a sandwich-hybridization employing pyrrolidinyl peptide nucleic acid probes. The sensors comprised of a capture PNA probe (P1) immobilized on a screen-printed carbon electrode (SPCE) and an anthraquinone-labeled signaling probe (AQ-P2) designed to be partially complementary to the target DNA either at upstream (ASU) or downstream (ASD) positions on the DNA sequence hybridized to the P1 probe. In the presence of the DNA target, the ASD sensor showed a higher signal response when compared to the ASU sensor. The ASD sensor was then applied to simultaneously detect two high-risk human papillomavirus (HPV) DNA sequences. The target DNA was detected in the range of 0.5–100 nM, and the limits of detection (LODs) of 150 and 153 pM (3SDblank/slope) were obtained for HPV types 16 and 18, respectively. This developed sensor was successfully applied to detect a PCR-amplified sample derived from HPV type 16 (SiHa) and 18 (HeLa) positive human cancer cell lines. These findings are relevant for designing effective sensors, and the developed sensor can be readily applied to detect a wide range of DNA targets. © 2018