Fabrication of folic acid immobilized graphene oxide-silica (FA@GO-SiO2) for the electrochemical detection of circulating tumor cells

Circulating tumor cells (CTCs) shed from primary tumors, enter bloodstream, and can be enriched from millions of blood cells as valuable biomarkers due to the overexpression of surface receptors. However, their enrichment is challenging because of millions of white blood cells (WBCs) compared to their low abundance in blood i.e., 1–10 CTCs per mL. Herein, graphene oxide (GO) - silica (SiO 2 ) nanocomposite functionalized with folic acid (FA@GO-SiO 2 ) is developed for the selective and sensitive detection of CTCs from blood. The synthesized material is characterized by SEM, FTIR, and XRD. A549 (lung cancer) cells are applied as the model target and detected by cyclic voltammetry (CV) using FA@GO-SiO 2 coated glassy carbon electrode (GCE). A calibration curve with R 2 = 0.9851 is obtained for 50–50,000 cells/mL with LOD of 1 cell/mL. Electrochemical analysis of CTCs by fabricated biosensor can offer early cancer diagnosis from blood samples without complicated pretreatment steps. • Electrochemical biosensor for CTCs based on folic acid immobilized graphene oxide-silica. • Limit of detection of the fabricated sensor for standard is 12 μL. • Circulating tumor cells are detected from 30 μL real plasma sample. • Signals are recorded in the form of cyclic voltammogram, LSV, and impedance. • CTCs are detected from spiked cell lines and real blood samples.