An ultrasensitive biosensor based on three-dimensional nanoporous conducting polymer decorated with gold nanoparticles for microRNA detection

Abstract The rapid, selective and ultrasensitive assaying of biomarkers remains a challenge relevant to biosensor/diagnostic applications. Herein, a promising electrochemical biosensor based on three-dimensional (3D) nanoporous conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) decorated with gold nanoparticles (AuNPs) was developed, in which methylene blue (MB) was employed as redox indicator for microRNA24 (miRNA24) detection. The unique porous construction was fabricated by a simple hard-template method and cyclic voltammetry (CV) electrochemical technique. AuNPs were electrodeposited onto the porous PEDOT surface to increase the interface conductivity and provide more active sites to load identification elements. The obtained porous biosensor based on conducting polymer PEDOT and AuNPs exhibited significantly enlarged specific surface area (about 2.4 times) and enhanced sensitivity (about 2.1 times), compared to the biosensor based on planar PEDOT. The developed porous biosensor achieved a miRNA24 quantification range from 1 fM to 10 nM with satisfying stability, high selectivity, and a low limit of detection (0.38 fM). The construction of biosensors based on porous conducting polymers decorated with AuNPs offers an effective strategy to increase the electroactive surface area of the sensing interfaces, so as to effectively enhance the sensitivity.