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

•The rod-like Bi2S3 were prepared through a simple solvothermal method.•PANI film electrochemically prepared on the surface of rBi2S3, resulting in the PANI capped rBi2S3 nanocomposite.•Electric conductivity and accessible surface area of the electrode was greatly enhanced by the PANI/rBi2S3.•A novel impedimetric DNA biosensor was successfully fabricated on PANI/rBi2S3. A highly sensitive impedimetric DNA biosensor based on rod-like bismuth sulfide nano (rBi2S3) and polyaniline (PANI) nanocomposite film modified ionic liquid-carbon paste electrode (IL-CPE) has been developed. The rBi2S3 particles were first dropt on IL-CPE that was constituted with 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) and graphite powder, and then the PANI polymer was deposited on the surface of rBi2S3 through potentiodynamic polymerization using aniline as the source, forming the PANI capped Bi2S3 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 1.0×10−11M with a detection limit of 4.37×10−16M. The DNA biosensor also displayed good regeneration ability, reproducibility and stability.