Detection of positional mismatch in oligonucleotide by electrochemical method

Detection of single base mismatch in DNA has been achieved by various techniques. However, the detection of position of that mismatch in the DNA duplex sequence has not been adequately addressed. In the present work, sensing of positional change of DNA base mismatch is achieved, with enhanced detection limit, using methylene blue as a redox indicator in electrochemical differential pulse voltammetric method (DPV). Interfacially synthesized Gold Polyaniline nanocomposites (Au-PAni) is coated on Pt electrode and attached with thiol modified single stranded DNA to construct the sensor electrode. Position sensitive detection of a single base mismatch in oligomeric duplexes is achieved here, with a detection limit for concentration as low as 10(-8) M for mixed oligomeric sequences and 10(-6) M for dA-dT duplexes. In this case, the sensitivity of the electrode is 0.12 mu ApM(-1) cm(-2). Reusable sensor electrode coated with Au-PAni nanocomposites was employed without compromising the sensitivity of the system. This is the first step in developing a highly sensitive method for detecting the effect of varying position of single base mismatch in the DNA. (C) 2014 Elsevier B.V. All rights reserved.