Electrochemistry of toluidine blue O in situ bound to a DNA-modified electrode

In this work, we report a new method for direct, in situ coupling of a redox label to a gold-bound oligo probe for E-DNA sensors. The Salmonella gyrB gene specific oligo probe with 5´ thiol and 3´ amine modifications was anchored on Au via the thiol-gold interaction. Toluidine blue O (TBO) was covalently bound to the probe as a redox label via terephthaloyl chloride-mediated electro-oxidative coupling (Fig. 1(a)). As a result, an E-DNA sensor showing a suppressed redox signal in response to target hybridization will be made.