Detection of circulating tumor cells in prostate cancer based on carboxylated graphene oxide modified light addressable potentiometric sensor

Circulating tumor cells (CTCs) are a group of rare cancer cells that have detached from a primary tumor and circulate in the bloodstream. Herein, light addressable potentiometric sensor (LAPS) was exploited in the label-free detection of CTCs in the prostate cancer. To this end, the mouse anti-human epithelial cell adhesion molecule (anti-EpCAM) monoclonal antibody was selected as the probe to capture CTCs according to our western blot experiments, and therefore the anti-EpCAM was immobilized on the surface of carboxylated graphene oxide (GO-COOH) modified LAPS. Spiking experiments confirmed that LAPS' voltage decreased with the increasing of CTCs' concentration both in phosphate buffer (PBS) and blood, and as few as 10 CTCs in 1 ml of blood could be detected, illustrating the high sensitivity of the proposed strategy. The analysis of healthy blood samples revealed no change in electrical signal, confirming the specificity of the system. Ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and immunofluorescent assay (IFA) were conducted to characterize GO-COOH, testify its existence on LAPS and validate CTCs' capturing by anti-EpCAM grafted on GO-COOH modified substrates. It is indicated that LAPS could be a potential platform for CTCs detection and may provide a powerful tool for downstream analysis.