Highly Sensitive Electrochemical Biosensor for Circulating Tumor Cells Detection via Dual-Aptamer Capture and Rolling Circle Amplification Strategy

A fast and simple strategy for early detection of circulating tumor cells (CTCs) is urgently required because of cancer metastasis. In this work, we assembled an electrochemical biosensor by two aptamers that could form hairpin and specifically recognize K562 cells. The thiolated capture aptamer was fixed on the gold electrode surface. The detection aptamer was linked with a primer at 3' end which could trigger rolling circle amplification to prolong the sequence of aptamer. The dual-aptamer model was fabricated to improve the capture specificity and efficiency for K562 cells. The rolling circle amplification improved the detection sensitivity by inhibiting electron transfer of [Fe(CN)(6)](3-/4-) which could be measured by differential pulse voltammetry. The detection limit of 25 cells mL(-1) and linear ranges of 1 x 10(2) to 1 x 10(5) cells mL(-1 )were obtained under optimal experimental conditions. Our work exhibited a label-free and simple method for detecting CTCs using cell-specific aptasensor, showing an expected possibility for further CTCs-related study and clinical applications of this novel method.