Detection and quantitation of bisphenol A -BPA- level in food samples and environment are of great signifcance. In this research work, a new electrochemical aptasensor was developed for ultrasensitive detection of BPA, based on MWCNT/SiO2@Au nanocomposite. Molecular dynamic -MD- simulation was carried out in order to better understand the interaction between the target molecules and the aptamer from molecular point of view. The detection strategy of the proposed electrochemical aptasensor, is based on [Fe -CN-6]3-/4- as a label free redox probe. In the absence of BPA molecules, the aptamers remain unfold so that the long tunnels for receiving the [Fe-CN-6]3-/4- redox probe are formed at the surface of the electrode. But, upon addition of BPA molecules, strong interactions between the BPA molecules and the aptamer are occurred. Therefore, the entrance of the tunnels is closed which results in a hard electron exchange between the redox probe and the electrode surface. Therefore, the electrochemical signal is decreased in the presence of BPA molecules. The proposed electrochemical aptasensor shows a high selectivity toward BPA molecules with a limit of detection -LOD- as low as 10 pM. The fabricated electrochemical aptasensor was successfully applied for detection of BPA in food samples.

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