脱嘌呤/脱嘧啶核酸内切酶1（APE1）作为重要的碱基切除修复酶，对于维持基因组完整性和稳定性至关重要，其异常表达与恶性肿瘤密切相关。在此，我们通过将纳米限制的ECL银纳米团簇（Ag NCs）与X形DNA识别器触发的级联扩增相结合，构建了一种电化学发光（ECL）生物传感器，用于检测APE1活性。具体来说，使用一锅法制备Ag NC并将其限制在戊二醛交联壳聚糖水凝胶网络中，与离散的Ag NC相比，产生了强烈的ECL响应和出色的稳定性。此外，自组装的X形DNA识别器专为APE1检测而设计，不仅由于识别位点的有序排列而改善了反应动力学，而且通过利用识别器触发的链置换扩增（SDA）级联扩增实现了高灵敏度）和 DNAzyme 催化。正如预期的那样，该生物传感器在1.0 × 10-3 U·μL-1至1.0 × 10-10 U·μL-1范围内实现了APE1的灵敏ECL检测，检测限为2.21 × 10-11 U·μL- 1，使其成为生物标志物检测的理想方法。

Apurinic/apyrimidinic endonuclease 1 (APE1), as a vital base excision repair enzyme, is essential for maintaining genomic integrity and stability, and its abnormal expression is closely associated with malignant tumors. Herein, we constructed an electrochemiluminescence (ECL) biosensor for detecting APE1 activity by combining nanoconfined ECL silver nanoclusters (Ag NCs) with X-shaped DNA recognizer-triggered cascade amplification. Specifically, the Ag NCs were prepared and confined in the glutaraldehyde-cross-linked chitosan hydrogel network using the one-pot method, resulting in a strong ECL response and exceptional stability in comparison with discrete Ag NCs. Furthermore, the self-assembled X-shaped DNA recognizers were designed for APE1 detection, which not only improved reaction kinetics due to the ordered arrangement of recognition sites but also achieved high sensitivity by utilizing the recognizer-triggered cascade amplification of strand displacement amplification (SDA) and DNAzyme catalysis. As expected, this biosensor achieved sensitive ECL detection of APE1 in the range of 1.0 × 10-3 U·μL-1 to 1.0 × 10-10 U·μL-1 with the detection limit of 2.21 × 10-11 U·μL-1, rendering it a desirable approach for biomarker detection.