Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Key Laboratory of Biomedical Functional Materials, School of Science , China Pharmaceutical University , Nanjing , 211198 , China.
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210093 , China.
Anal Chem. 2019 Apr 2;91(7):4413-4420. doi: 10.1021/acs.analchem.8b04908. Epub 2019 Mar 12.
In this work, we developed a simple electrochemical method for ultrasensitive and label-free detection of circulating tumor cells (CTCs) based on direct plasmon-enhanced electrochemistry (DPEE). After plasmonic gold nanostars (AuNSs) were modified on the glassy carbon (GC) electrode, the aptamer probe was immobilized on the AuNSs surface, which can selectively capture the CTCs in samples. Upon localized surface plasmon resonance (LSPR) excitation, the electrochemical current response can be enhanced remarkably due to efficient hot electrons transport from AuNSs to the external circuit. The captured cells on the AuNSs surface will influence the hot electrons transport efficiency, leading to a decreased current response. Using ascorbic acid (AA) as the electroactive probe, it was found that the current responses of the AuNSs/GC electrode upon light irradiation decrease with the cell concentration. Due to the special molecular recognition of the aptamer and enhanced electrochemical performance of the plasmon, the proposed method enables an ultrasensitive and label-free detection of CTCs with excellent selectivity. The experimental results show that CCRF-CEM cell concentrations as low as 5 cells/mL can be successfully detected, which is superior to most reported work up to now. Using the present method, MCF-7 cells as low as 10 cells/mL can be also successfully detected, indicating the universality of the proposed method for CTCs detection. Furthermore, the cytosensor can successfully distinguish CTCs from normal cells in blood samples. The as-proposed strategy provides a promising application of DPEE in the development of novel biosensors for nondestructive analysis of biological samples.
在这项工作中，我们开发了一种基于等离子体增强电化学（DPEE）的简单、灵敏、无需标记的循环肿瘤细胞（CTC）检测电化学方法。在金纳米星（AuNSs）修饰玻碳（GC）电极后，将适配体探针固定在 AuNSs 表面，该表面可以选择性地捕获样品中的 CTC。在局域表面等离子体共振（LSPR）激发下，由于 AuNSs 向外部电路高效传输热电子，电化学电流响应得到显著增强。AuNSs 表面捕获的细胞会影响热电子传输效率，导致电流响应降低。使用抗坏血酸（AA）作为电活性探针，发现光照下 AuNSs/GC 电极的电流响应随细胞浓度的增加而降低。由于适配体的特殊分子识别和等离子体增强的电化学性能，该方法实现了对 CTC 的超灵敏、无需标记检测，具有优异的选择性。实验结果表明，可成功检测到浓度低至 5 个细胞/mL 的 CCRF-CEM 细胞，优于迄今为止大多数报道的结果。使用该方法，还可成功检测到浓度低至 10 个细胞/mL 的 MCF-7 细胞，表明该方法在 CTC 检测方面具有通用性。此外，该细胞传感器可成功区分血液样本中的 CTC 和正常细胞。所提出的策略为 DPEE 在用于生物样品无损分析的新型生物传感器的开发中提供了有前途的应用。
