A sensitive and label-free electrochemical microRNA biosensor based on Polyamidoamine Dendrimer functionalized Polypyrrole nanowires hybrid.

The potential of functionalized polypyrrole nanowires (PPyNWs) are demonstrated as a platform for lable-free miRNA detection using electrochemical impedance spectroscopy (EIS). MicroRNAs (miRNAs) detection methods and sensors are mainly challenged by very low concentrations in physiological samples and high similarity among family members. Herein, a sensitive and selective miRNA biosensor was constructed based on electrochemically synthesized PPyNWs, which were functionalized with polyamidoamine dendrimer (PAMAM) by an electro-oxidation method. The prepared PPyNWs/PAMAM hybrid combines the excellent electrical conductivity of conducting polymer PPyNWs with high surface to volume ratio of PAMAM. DNA probes were immobilized onto the PPyNWs/PAMAM hybrid for the construction of the miRNA biosensor. Using the sensitive EIS technique to monitor DNA/miRNA hybridization, the developed biosensor demonstrated excellent sensing performances, such as wide linear range (10−14 M-10−8 M) and low detection limit (0.34 × 10−14 M). Even more encouraging, the response sensitivity of the biosensor was 3.12 times higher than that of the bulk PPy-modified sensor, which proved that the microstructure of the PPy nanowires array can greatly improve the performance of the biosensor. [ABSTRACT FROM AUTHOR]