LAUSR

This work reports the development of simple, practical, cost effective and label free genosensor prepared by electropolymerization of polypyrrole on pencil graphite electrode (PGE) for the determination of miRNA-34a from total RNA extracted from breast cancer cell lysate. The electrochemical entrapment of the probe (antimiRNA-34a) into polypyrrole (PPy) was carried out by electropolymerization using cyclic voltammetry method with a scan rate of 25 mV.s−1 versus Ag/AgCl. The electrochemical detection of the hybridization between the doped probe antimiRNA-34a with its complementary target, miRNA-34a was monitored by electrochemical impedance spectroscopy (EIS) by comparison of charge transfer resistance (Rct) values before and after hybridization. The established biosensor can detect miRNA-34a down to 0.2 μg.mL−1 (which correspond to 2 pmol/100 μL) with a linear range of 5–80 μg.mL−1 and discriminate target miRNA from other non-complementary sequences (miRNA-21, miRNA-122, and miRNA-192) with a high selectivity. The genosensor shows a better performance in analysis of human breast cancer cells samples (MCF-7) suggesting the real-time usability of the genosensor.