Electrochemical preparation of polyaniline capped Bi2S3 nanocomposite and its application in impedimetric DNA biosensor

Abstract A highly sensitive impedimetric DNA biosensor based on rod-like bismuth sulfide nano (rBi 2 S 3 ) and polyaniline (PANI) nanocomposite film modified ionic liquid-carbon paste electrode (IL-CPE) has been developed. The rBi 2 S 3 particles were first dropt on IL-CPE that was constituted with 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF 6 ) and graphite powder, and then the PANI polymer was deposited on the surface of rBi 2 S 3 through potentiodynamic polymerization using aniline as the source, forming the PANI capped Bi 2 S 3 nanocomposite. The morphologies and electrocatalytic property of the composite were characterized by scanning electron microscopy (SEM) and electrochemical techniques including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. The integrated advantages such as the large surface area, excellent electronic conductivity, easy to fabrication, and good biocompatibility make the electrode favorable for DNA immobilization and hybridization detection. It was found that remarkable increase of electrochemical impedance was observed after the probe DNA modified electrode was hybridized with the target DNA. The dynamic detection range was determined to be from 1.0 × 10 −15 to 1.0 × 10 −11  M with a detection limit of 4.37 × 10 −16  M. The DNA biosensor also displayed good regeneration ability, reproducibility and stability.