Rapid and efficient detection of tumor marker at the early stages is one of the crucial challenges in cancer diagnostics and therapy. In this study, an ultrasensitive electrochemical biosensor was fabricated by dual-amplified strategy for the detection of ultra-trace microRNA-141 (miRNA-141). Firstly, two split sequences contained G-quadruplex were connected by click chemistry-mediated nucleic acid strands self-assembly and the obtained complete G-quadruplex was complementary with miRNA-141 to formed DNA-RNA hybrid duplexes. Subsequently, the formed DNA-RNA hybrid duplexes were specifically recognized by duplex-specific nuclease (DSN), and the DNA part of the duplexes were cleaved and the miRNA-141 were released to trigger next cycle, which acquired a primal signal amplification by enzyme-assisted target recycling (EATR). Moreover, amino and thiol group multi-labeled functionalized fullerene nanoparticles (FC60) with a larger surface active sites and better biocompatibility, were designed rationally to modify the Au electrodes, which produced multiply-enhanced amplified signal. This dual-amplified sensing system exhibited a remarkable analytical performance for the detection of miRNA-141 in concentrations ranging from 0.1 pM to 100 nM and the detection limit of 7.78 fM was obtained. Compared with the biosensor with single amplification strategy such as EATR, this electrochemical biosensor based on dual-amplified strategy exhibited an excellent discrimination capability and higher analytical performance. Therefore, this electrochemical biosensor might hold a great potential for further applications in biomedical research and early clinical diagnosis.

中文翻译：

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基于点击化学介导的酶辅助靶物回收和功能化的富勒烯纳米颗粒的microRNA-141检测中超灵敏电化学生物传感器的双放大策略。

在早期阶段快速有效地检测肿瘤标志物是癌症诊断和治疗中的关键挑战之一。在这项研究中，通过双重扩增策略制造了一种超灵敏的电化学生物传感器，用于检测超痕量microRNA-141（miRNA-141）。首先，通过点击化学介导的核酸链自组装连接包含G-四链体的两个分裂序列，并且获得的完整G-四链体与miRNA-141互补以形成DNA-RNA杂合双链体。随后，形成的DNA-RNA杂交双链体被双链特异性核酸酶（DSN）特异性识别，双链体的DNA部分被切割，miRNA-141被释放以触发下一个循环，从而通过酶获得了原始信号的扩增。辅助目标回收（EATR）。而且，合理设计了具有较大表面活性位和较好生物相容性的氨基和巯基多标记的功能性富勒烯纳米粒子（FC60），以修饰Au电极，从而产生倍增的放大信号。该双扩增传感系统在浓度范围从0.1 pM到100 nM的miRNA-141的检测中表现出卓越的分析性能，并获得了7.78 fM的检测限。与单扩增策略如EATR的生物传感器相比，这种基于双扩增策略的电化学生物传感器具有出色的判别能力和更高的分析性能。因此，该电化学生物传感器在生物医学研究和早期临床诊断中的进一步应用可能具有巨大的潜力。