Building a precise, sensitive, and selective sensing platform is highly significant for microRNA (miRNA) detection. Herein, an innovative ratiometric electrochemical biosensor sensitized with carbon nanoparticles-functionalized SnS₂ nanoflowers (C@SnS₂ NFs) and enzyme-assisted target recycling was explored for analysis of miRNA-21. In this strategy, the application of hierarchical C@SnS₂ NFs structure as electrode material not only enhanced the surface loading capability for subsequent reactions but also improved the interfacial electron transfer. After introducing enzyme-assisted target recycling, single-target miRNA-21 could initiate the cleavage of multiple capture DNA strands by duplex-specific nuclease (DSN), leading to numerous rest single-strand DNAs on the electrode. Two probes, methylene blue-labeled probe 1 (probe 1-MB) and ferrocene-labeled probe 2 (probe 2-Fc), could selectively and competitively hybridize with the capture DNA and the rest single-strand DNA, depending on the completeness of DNA hybridization. By measuring the peak current intensity ratio of Fc and MB, miRNA-21 was quantified in a wide concentration range from 1 fmol/L to 10 pmol/L, with a detection limit of 300 amol/L. Moreover, this sensing system showed good analytical performance in the presence of interfering sequences and complex matrices, illuminating excellent selectivity and practical application potential of the hierarchical C@SnS₂ NF sensing interface.

建立精确，灵敏和选择性的传感平台对于microRNA（miRNA）检测具有非常重要的意义。在这里，探索创新的比例电化学生物传感器用碳纳米粒子官能化的SnS ₂纳米花（C @ SnS ₂ NFs）和酶辅助的靶标回收进行了研究，用于miRNA-21的分析。在这种策略中，分层C @ SnS _2的应用作为电极材料的NFs结构不仅增强了后续反应的表面负载能力，而且还改善了界面电子传递。引入酶辅助的靶标回收后，单靶标miRNA-21可以通过双链特异性核酸酶（DSN）引发多条捕获DNA链的切割，从而在电极上产生大量剩余的单链DNA。亚甲基蓝标记的探针1（探针1-MB）和二茂铁标记的探针2（探针2-Fc）这两种探针可以根据捕获的DNA的完整性与捕获的DNA和其余的单链DNA选择性和竞争性地杂交。 DNA杂交。通过测量Fc和MB的峰值电流强度比，可以在1 fmol / L至10 pmol / L的宽浓度范围内对miRNA-21进行定量，检测极限为300 amol / L。而且，_2个NF感应接口。