Herein, we constructed an ultrasensitive electrochemiluminescence (ECL) biosensor for detecting microRNA-21 (miR-21) based on in-situ generation of copper nanoclusters (Cu NCs) as luminophore and titanium dioxide (TiO₂) as coreaction accelerator. First, numerous AT-rich double-stranded DNA (dsDNA) was produced from the conversion of a small amount of target miR-21 via the combination of exonuclease III (Exo III)-assisted amplification and hybridization chain reaction (HCR), which could reduce the aggregation-caused self-etching effect of Cu NCs and improve the emitting of Cu NCs. Simultaneously, the introduction of TiO₂ in the sensing interface not just acted as the immobilizer of dsDNA-stabilized Cu NCs, more than acted as the coreaction accelerator to accelerate the reduction of the coreaction reagent (S₂O₈²⁻) for significantly enhancing the ECL efficiency of Cu NCs. The biosensor showed an excellent linear relationship in the concentration range from 100 aM to 100 pM with the detection limit of 19.05 aM Impressively, the strategy not only opened up a novel and efficient preparation method for the Cu NCs, but expanded the application of Cu NCs in ultrasensitive biodetection owing to the addition of coreaction accelerator.

在这里，我们构建了一个超灵敏的电化学发光（ECL）生物传感器，该传感器基于原位产生的铜纳米团簇（Cu NCs）作为发光体和二氧化钛（TiO ₂）作为共作用促进剂来检测microRNA-21（miR-21）。首先，通过核酸外切酶III（Exo III）辅助扩增和杂交链反应（HCR）的结合，从少量目标miR-21的转化中产生了许多富含AT的双链DNA（dsDNA）。降低Cu NCs的聚集引起的自蚀刻效应，并改善Cu NCs的发射。同时引入TiO ₂在传感界面中，它不仅充当了dsDNA稳定化的Cu NCs的固定剂，而且还充当了共同作用促进剂，以加速共同作用试剂（S ₂ O ₈ ^2-）的还原，从而显着提高了Cu NCs的ECL效率。该生物传感器在100 aM至100 pM的浓度范围内显示出极好的线性关系，检测限为19.05 aM。令人印象深刻的是，该策略不仅为Cu NCs开辟了一种新颖而有效的制备方法，而且扩大了Cu NCs的应用范围。由于添加了共作用促进剂，因此在超灵敏生物检测中具有优势。