A dual-signal-amplified electrochemical biosensor for sensitive and accurate detection of cancer cells.

The accurate and highly sensitive detection of circulating tumor cells (CTCs) is crucial for cancer diagnosis, treatment, and metastasis monitoring. In this study, a dual-signal-amplified electrochemical biosensor specifically for identifying targeted CTCs. 3D polyvinylidene difluoride mixed with chitosan (PVDF/CS) nanofibers mesh was fabricated on polydimethylsiloxane (PDMS) micropillars using electrospinning technology. The nanofibers are modified with a graphene oxide-streptavidin--epithelial adhesion molecule (GO-SA-EpCAM) antibody complex, which serves as an affinity molecule to capture the EpCAM positive cancer cells. Subsequently, a carboxylated multi-walled carbon nanotube-horseradish peroxidase-carbohydrate antigen 153 (MWCNTs-COOH-HRP-CA153) antibody complex is incubated to enhance capture efficiency, resulting in significantly amplified electrochemical signals for quantifying target CTCs. Detectable signals occur only when both antibodies are simultaneously present on the cell membrane, greatly enhancing the accuracy of CTCs analysis. The electrochemical biosensor developed in this study exhibited exceptional selectivity in distinguishing target cells from a wide array of cancer cells, achieving a detection threshold as low as 10 cells per milliliter. The biosensor remains stable in the whole blood environment during detection, indicating strong resistance to interference. This dual-signal-amplified electrochemical biosensor shows significant potential for clinical applications in cancer diagnosis and personalized medical treatments.