A novel and ultrasensitive label-free electrochemical DNA biosensor for Trichomonas vaginalis detection based on a nanostructured film of poly(ortho-aminophenol)

Abstract

Trichomoniasis, as a major public health concern, is the world’s most common sexually transmissible disease. This infection is caused by a protozoan parasite called Trichomonas vaginalis (TV) that can lead to reproductive and genital area problems. Accordingly, it is of great significance to expand new methods for increasing the sensitivity of TV detection. In this study, a novel label-free electrochemical DNA biosensor for TV quantitation was constructed based on an electropolymerized poly(ortho-aminophenol) thin film simultaneously acting as a transducer as well as a redox indicator. The redox-active polymeric film was utilized to covalent immobilization of a specific thiolated DNA probe. The hybridization process was then monitored by differential pulse voltammetry. The proposed biosensor detected a synthetic TV target sequence with a calibration sensitivity of − 0.0113 µA (log (concentration/mol L−1))−1, a linear concentration range of 1.0 × 10−20 to 1.0 × 10−12 mol L−1, and a detection limit of 3.9 × 10−21 mol L−1. It also showed an ability to differentiate between the complementary sequence and the base-mismatched and non-complementary sequences with a nice selectivity. Moreover, the designed biosensor was able to detect the TV genome with a calibration sensitivity of − 0.0774 µA (log (concentration/ng µL−1))−1, a linear range of 0.55–64 ng mL−1 and a detection limit of 1.0 pg µL−1.