Label-free ultrasensitive electrochemical genosensing of Trichomonas vaginalis using anisotropic-shaped gold nanoparticles as a platform, a repeated sequence of the parasite DNA as a probe, and toluidine blue as a redox marker

The widespread bacteria, parasites and viruses are considered as the potential sources of infections which can endanger the public health. Accordingly, sensitive, rapid and cost-effective analysis methods are required for identification of the pathogens to achieve an improved quality of life. Trichomonas vaginalis is among the commonly colonizing parasite which threatens human health by causing Trichomoniasis infection. In the present study, we demonstrate the fabrication and application of a novel electrochemical genosensor based on an electrodeposited gold nanostructure as a transducer combined with toluidine blue (TB) as a redox marker. A specific DNA sequence was immobilized on the transducer and the hybridization process was detected using differential pulse voltammetry. The genosensor showed excellent performance towards detection of TV with high sensitivity and good selectivity. A linear correlation was obtained between the electrochemical response of the genosensor with a complementary-sequence DNA concentration in the range of 1.0 × 10−19 to 1.0 × 10−12 mol L−1 with a limit of detection as low as 3.1 × 10−20 mol L−1. Moreover, the prepared genosensor could discriminate between the complementary-sequence, base-mismatched-sequences and a non-complementary-sequence oligonucleotides via TB binding. Comparison of the actual human samples analyzed by both the prepared genosensor and the standard gel electrophoresis confirmed the practical applicability of the genosensor.