A dual-recognition-controlled electrochemical biosensor for accurate and sensitive detection of specific circulating...

Accurate and sensitive assay of specific circulating tumor cells (CTCs) is of importance for the diagnosis, treatment, and metastasis monitoring of cancer. Herein, we have proposed a dual-recognition-controlled electrochemical biosensor in this work for the detection of specific CTCs. To this sensor, two aptamer hairpin probes are designed to be able to separately bind to two adjacent proteins on the cell membrane to activate the associative toehold for strand displacement reaction, which will then trigger a dimer-like rolling cycle amplification reaction, and finally produce significantly amplified electrochemical signals for sensitive quantification of target CTCs. In our design, only the case that the two proteins are simultaneously expressed on the cell membrane can result in obvious signal responses, which may greatly improve the accuracy of CTCs analysis. The proposed biosensor can possess excellent selectivity to distinguish target cells from different cancer cells. Moreover, the combination of rolling cycle amplification and DNA nanostructure capture probes can effectively lower the detection limit to 3 cells mL^-1. Notably, our biosensor can be applied to the assay of the target CTCs in the complex whole blood matrixes, verifying its strong stability and anti-interference. Thus, the as-proposed dual-recognition-controlled electrochemical biosensor may exhibit great promise in clinical cancer diagnosis and personalized medicine.