本研究成功合成了具有高效电化学发光（ECL）和优异生物相容性的硒氮共掺杂的碳点（SeN-CDs），并以S2O82-作为共反应剂，构建了用于敏感检测微小RNA-221（miRNA-221）的生物传感器。值得注意的是，相较于N掺杂的CDs，SeN-CDs表现出优越的ECL性能，在其中硒具有优异的氧化还原活性，作为核反应加速剂，有利于S2O82-的电还原，从而显著提高了ECL效率。此外，靶诱导的T7外切酶（T7 Exo）辅助的双循环扩增策略能够将微量目标miRNA-221转化为大量的输出DNA，以捕获大量载有ECL信号猝灭剂的三维（3D）纳米结构（DTN-Au NPs-DOX-Fc）。构建的生物传感器可实现超敏感检测miRNA-221，并具有检测限下降至2.3 aM的低检出限，成功应用于Hela和MHCC97-L癌细胞裂解液中miRNA-221的检测。本研究探索了一种增强CDs的ECL性能，构建敏感检测生物标志物和疾病诊断的ECL生物传感平台的新方法。版权所有 © 2023. Elsevier B.V.发表。

In this work, selenium and nitrogen co-doped carbon dots (SeN-CDs) possessing highly efficient electrochemiluminescence (ECL) and excellent biocompatibility were synthesized as a new emitter with S2O82- as a coreactant for constructing a biosensor to detect microRNA-221 (miRNA-221) sensitively. Notably, the SeN-CDs exhibited superior ECL performance compared with the N-doped CDs, in which selenium with excellent redox activity served as a coreaction accelerator for facilitating the electroreduction of S2O82- to significantly improve ECL efficiency. Furthermore, target-induced T7 exonuclease (T7 Exo)-assisted double cycle amplification strategy could convert traces of target miRNA-221 into large amounts of output DNA to capture three-dimensional (3D) nanostructures (DTN-Au NPs-DOX-Fc) loaded with large amounts of ECL signal quencher. The constructed biosensor could realize ultrasensitive detection of miRNA-221 and has a low detection limit reaching 2.3 aM, with a successful application to detect miRNA-221 in lysate of Hela and MHCC97-L cancer cell. This work explored a novel method to strengthen the ECL performance of CDs to construct an ECL biosensing platform with sensitive detecting of biomarkers and disease diagnosis.Copyright © 2023. Published by Elsevier B.V.