Ultrasensitive electrical biosensing of syphilis DNA using target-guided formation of polyaniline based on enzyme-catalyzed polymerization

An ultrasensitive assay for electrical biosensing of syphilis DNA was proposed by using target-guided formation of polyaniline (PANI) based on an enzymatically catalyzed method. The sensitive biodetection relies on the DNA hybridization and biotin–streptavidin interaction. After coupling of biotinylated catalase with streptavidin-modified hybrids, a head-to-tail structure of PANI templated by hybridized DNA was formed. The current response of PANI was linearly related to target DNA concentration between 1.0 pM and 1.0 nM with a correlation coefficient of 0.998. The detection limit was determined to be 0.5 pM with the signal-to-noise ratio of 3. The synergistic performances of DNA hybridization, strong biotin–streptavidin binding ability, and highly efficient polymerization provide a general platform for simple, highly sensitive and selective biosensor for the detection of the specific polA gene fragment of T. pallidum. It is expected that the proposed biosensor holds great promise for diagnosing disease in practice.