Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences , Suzhou 215163 , P. R. China.
Department of Chemistry , New York University , New York 10003 , United States.
Anal Chem. 2019 Dec 3;91(23):15187-15192. doi: 10.1021/acs.analchem.9b04000. Epub 2019 Nov 12.
Sensitive and accurate quantification of circulating tumor cell (CTC) can provide new insights for early diagnosis and prognosis of cancers. Herein, we have developed a multipedal DNA walker for ultrasensitive detection of CTC for the first time. Generally, a number of walker strands are simply modified on gold nanoparticle (AuNPs). The integrated aptamer sequence can specially interact with the transmembrane receptor protein of CTC and facilitate the enrichment of AuNPs on the surface of cells. After a low speed centrifugation, the complex of CTC and AuNPs could be precipitated and the supernate represents decreased UV-vis absorbance response of AuNPs. On the other hand, since multiple walker strands are modified on a single AuNP, hybridization with several tracks on the electrode occurs simultaneously for the following nicking endonuclease-catalyzed cleaving. Experimental results verify that the rate of multipedal walking is much faster. In addition, TCEP-mediated electrochemical amplification is employed to further enhance the electrochemical signal. By comparing the variations of electrochemical and UV-vis absorbance responses, ultrahigh sensitivity for CTC assay is achieved. The limit of detection is down to 1 cell/mL. The results of selectivity confirmation and blood sample test are also satisfactory. This AuNPs-based multipedal DNA walker offers a speedy analysis of CTC and shows great potential use for early clinical diagnosis and treatment of cancers.
循环肿瘤细胞（CTC）的灵敏和准确定量可以为癌症的早期诊断和预后提供新的见解。本文首次开发了一种多足 DNA walker 用于超灵敏检测 CTC。通常，在金纳米粒子（AuNPs）上简单修饰多个 walker 链。整合的适体序列可以特异性地与 CTC 的跨膜受体蛋白相互作用，促进 AuNPs 在细胞表面的富集。低速离心后，CTC 和 AuNPs 的复合物可以沉淀，上清液代表 AuNPs 的紫外可见吸收响应降低。另一方面，由于多个 walker 链修饰在单个 AuNP 上，因此杂交在电极上的几个轨道上同时发生，随后进行缺口内切酶催化的切割。实验结果验证了多足行走的速度要快得多。此外，还采用 TCEP 介导的电化学生物放大进一步增强电化学信号。通过比较电化学和紫外可见吸收响应的变化，实现了对 CTC 测定的超高灵敏度。检测限低至 1 个细胞/mL。选择性确认和血液样本测试的结果也令人满意。基于 AuNPs 的多足 DNA walker 为 CTC 的快速分析提供了一种方法，并显示出在癌症的早期临床诊断和治疗中的巨大应用潜力。
