Dual Recognition Strategy-Based Ratiometric Electrochemical Assay for Ultrasensitive and Accurate Detection of Specific Circulating Tumor Cells

cells/mL with an effectively lower detection limit of 1 cells/mL (S/N = 3). Furthermore, the biosensor was able to accurately enumerate MCF-7 cells in human serum samples with excellent results. In this work, the developed ratiometric electrochemical biosensor offers a reliable and sensitive strategy for the quantitative determination of circulating MCF-7 human breast cancer cells as well as an effective approach for the clinical detection of rare cancer cells, especially in early stage cancer diagnosis.