间质性循环肿瘤细胞（mCTCs）的鉴定和检测对于肿瘤转移的早期预警非常重要。目前大多数常规的CTC检测方法依赖于上皮生物标志物的识别，而对于具有上皮-间质转化（EMT）诱导表型改变的CTCs的检测具有技术挑战。本研究构建了一个无标记生物传感器，用于对mCTCs进行敏感的电化学测定。在我们的设计中，捕获探针能够高特异性地识别mCTCs表面过表达的波形蛋白（vimentin）。同时，基于胆固醇分子与细胞膜之间的高亲合性，多个G-四链体/血红素复合物和多个胆固醇分子的网络状DNA纳米探针可以被嫁接到细胞表面。由于G-四链体/血红素复合物模拟辣根过氧化酶的作用，可以获得强电化学响应，从而对mCTCs进行敏感定量测定，检测限为8个细胞/mL。此外，该生物传感器能够有效克服阴性维植高分泌维植方面的干扰，并能在全血样本中实现高准确度的恢复测试，从而进一步促进临床上对癌症的诊断和个体化治疗。版权所有 © 2023 Elsevier B.V.。保留所有权利。

The identification and detection of mesenchymal circulating tumor cells （mCTCs） is important for early warning of tumor metastasis. The majority of conventional detection methods for CTCs rely on the recognition of epithelial biomarkers, which is technically challenging for detecting CTCs with epithelial-mesenchymal transition (EMT)-induced phenotypic alteration. In this work, we have constructed a label-free biosensor for sensitive electrochemical assay of mCTCs. In our design, the capture probe can recognize the vimentin overexpressed on the surface of mCTCs with high specificity. Meantime, the network-like DNA nanoprobes with multiple G-quadruplex/hemin complexes and multiple cholesterol molecules can be grafted to the cell surface based on the high affinity between cholesterol molecules and cell membrane. Owing to the mimic horseradish peroxidase of G-quadruplex/hemin complexes, strong electrochemical responses will be obtained for sensitive quantification of mCTCs with a detection limit of 8 cell mL-1. Moreover, the biosensor can effectively overcome the interference of vimentin negative cells or secretory vimentin, and realize the recovery tests in whole blood with high accuracy, thereby may further promoting the diagnosis and personalized treatment of cancer in clinic.Copyright © 2023 Elsevier B.V. All rights reserved.