Using Electropolymerization-based Doping for the Electro-addressable Functionalization of a Multi-electrode Array Probe for Nucleic Acid Detection

Even though large number of individually addressable electrodes can be effectively assembled in a small area, electrochemical detection methods have a relatively limited ability to detect multiple analytes compared to microdialysis probes and other analytic techniques. Here, we report a facile method for the electro-addressable functionalization of a probe comprising of closely spaced three individually addressable carbon fiber electrodes (CFEs) for the detection of nucleic acids. First, a multi electrode array probe comprising three adjacent CFEs was fabricated through pulling a three barrel glass capillary with a single carbon fiber in each barrel. Second, electropolymerization based doping was used for the electro-addressable functionalization of the multi-electrode array probe. To demonstrate that the current strategy works, anti-miR-34a was electrografted on only one of three electrodes by the electropolymerization of pyrrole on a specific electrode. A second electrode was coated only with polypyrrole (PPy) and the third was left unmodified. The results demonstrate that the present strategy has great potential for constructing multiplex nucleic acid micro/nano biosensors for local and in situ detection of multiple nucleic acid molecules, such as miRNAs at a time.