A novel electrochemical aptasensor based on f-MWCNTs/AuNPs nanocomposite for label-free detection of bisphenol A

A new label-free electrochemical aptasensor was constructed for sensitive and selective determination of bisphenol A (BPA) based on functionalized multiwall carbon nanotubes/gold nanoparticles (f-MWCNTs/AuNPs) nanocomposite film modified gold electrode. The f-MWCNTs/AuNPs nanocomposite was synthesized chemically and the structure of the prepared nanocomposite was characterized by UV-Vis spectrophotometry, Fourier transform infrared (FT-IR) spectrometry, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The fabrication process of the electrochemical sensor was also investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of [Fe(CN)6]3−/[Fe(CN)6]4− as an electrochemical active probe. The molecular dynamic (MD) simulations were used to study the interaction between BPA and its aptamer molecules. The effect of several parameters influencing the performance of the aptasensor was investigated and they were optimized. Under the optimized experimental conditions, the square wave voltammetry (SWV) was applied as a sensitive analytical method for determination of BPA in solutions and a good linear relationship was observed between the BPA concentration and the peak current within the range of 0.1-10 nM with a detection limit of 0.05 nM. The effect of interfering species on the determination of BPA was investigated and it was found that the proposed aptasensor is highly selective to BPA. Also, the reproducibility and stability of the sensor were all found to be satisfactory. Finally, the developed aptasensor was successfully applied for determination of BPA in real samples such as mineral water, orange juice and milk.