In Situ Monitoring Of Circulating Tumor Cell Adhered On Three-Dimensional Graphene/Zno Macroporous Structure By Resistance Change And Electrochemical Impedance Spectroscopy

A three-dimensional (3D) graphene macroporous foam substrate with ZnO nanorod array was developed for specific and non-invasive detection of circulating tumor cells (CTCs). With the help of the epithelial cell adhesion molecule antibody (anti-EpCAM) and the array structure, the EpCAM-positive CTCs can adhere on the detection substrate (rGO-ZnO-antiEpCAM foam). Moreover, the resistance and the electrochemical impedance spectroscopy (EIS) of the rGO-ZnO-antiEpCAM foam was changing during the CTCs adhering process with high sensitivity. Compared to the EpCAM-negative cancer cell, the resistance of the substrate is rising with the amount of the EpCAM-positive CTCs. The possible reason is that the negative charges of CTCs affected the conductivity of the p-type reduced graphene oxide (rGO), and when CTCs were adhering to the rGO-ZnO-antiEpCAM foam, the resistance of the rGO-ZnO-antiEpCAM foam increased. In addition, the EIS measurement also shows the regular changes during the adhering process. From the equivalent circuit modeling of EIS, the charge transfer resistance (R-ct) on the surface of the rGO-ZnO-antiEpCAM foam electrode had a linear growth. This may be due to the fixation of negatively charged Breast cancer cells (MCF-7) on the substrate, the charge transfer process was hindered, which caused the semicircle domain of the EIS curve to expand significantly with time. These results reveal that CTCs can not only be specifically adhered on the rGO-ZnO-antiEpCAM foam, but also the electrical microenvironment of the detection substrate was changed during CTCs adhering process. The construction of the detection substrate, the measurement and analysis methods of the electrical signals are of great significance in CTCs acquisition and sensing, which will provide an effective strategy for the real-time monitoring of CTCs at the clinic. (C) 2021 Elsevier Ltd. All rights reserved.