E-DNA biosensors of M. tuberculosis based on nanostructured polypyrrole

The objective of this paper is to demonstrate the potential of nanostructured polypyrrole formed by template free as platform for amperometric detection of DNA. The nanowires of polypyrrole (nw-PPy) are formed through electrochemical polymerization and chemically modified by electrochemical oxidation of ethylene diamine or dendrimers PAMAM to obtain aminated surface. The DNA probe and ferrocenyl group, as redox reporter, were covalently linked to the surface of nw-PPy. The chemical structure of nanostructured platform was characterized through SEM, FT-IR and XPS and the electrochemical properties through cyclic voltammetry and electrochemical impedance spectroscopy (EIS). We show that the properties of nw-PPy such as, hydrophilic character and large surface area have large effect on the electronic properties. Thus, the electrochemical performance is increased compared to others nanomaterials considering the obtained value of the rate of electron transfer of 18 s^-1. These properties allow enhanced DNA sensing where detection limit of 0.36 atomolar without any amplification step. The biosensor can be applied in detection of genomic DNA of Mycobacterium tuberculosis and the mutated one which present the resistance to rifampicin and large selectivity was demonstrated. We believe that nw-PPy modified with redox marker is a promising platform for electrochemical biosensors and can be applied for various diagnosis prospects.