A miniaturized electrochemical platform with an integrated PDMS reservoir for label-free DNA hybridization detection using nanostructured Au electrodes

Abstract

We report the fabrication and characterization of a miniaturized electrochemical platform for the label-free detection of DNA hybridization. The proposed platform is fabricated using microfabrication and electrodeposition techniques. Comprising a Ti working electrode with electrodeposited Au nanostructures, and Pt/Au pseudo-reference and counter electrodes, the device accounts for a limit of detection of 0.97 fM and a sensitivity of 20.78 (μA μM⁻¹) cm⁻² with respect to Dengue virus specific consensus primer detection in the range of 10 fM–1 μM. Here, the incorporation of nanostructured Au in the active sensing area not only enhances the current response by increasing the overall surface area, but it also facilitates facile probe DNA immobilization by gold–thiol self-assembly. We have used differential pulse voltammetry analysis in this study to monitor the changes in reaction kinetics with respect to target hybridization. Furthermore, the evaluation of reproducibility of the biosensor and its selectivity against interference has yielded acceptable outcomes. Additionally, in order to evaluate the system's selectivity, we have successfully distinguished PCR amplified wild type and mutant target DNAs corresponding to the BRCA1 specific gene. Here, the mutant and the wild type target DNAs differ by a two base deletion, and the fact that the system is able to differentiate even such minute dissimilarities under hybridization conditions is indicative of its superior performance.