癌症是人类死亡的最重要原因之一，对人类健康构成严重威胁。作为癌症生物标志物，微小RNA-155（miRNA-155）在各类癌症组织中高表达，并参与肿瘤细胞的增殖。因此，开发具有高特异性和敏感性的miRNA-155检测技术对于肿瘤的早期发现、准确治疗和预后评估具有重要意义。在这里，我们开发了一种荧光检测方法，使用核酸外切酶 III 辅助的靶标循环和催化发夹组装 (CHA) 作为信号放大技术。本研究开发了一种用于检测 miRNA-155 的生物传感器，利用 DNA 发夹 (Hp) 进行目标识别并生成双链 DNA (dual-Hp-T)。双链DNA的3'平端可以被核酸外切酶III切割，实现目标循环，大量的单链DNA（燃料）可以触发CHA，实现信号放大。同时，H1和H2末端带有不同荧光标记的信号探针的荧光共振能量转移（FRET）与CHA反应一起发生。获得的两个荧光信号可用于交叉验证实验结果。该生物传感器具有高回收率、高灵敏度和高可操作性的优异性能，可实现miRNA-155的特异性检测，检测限低至8.3 pM。此外，在人血清环境中的检测效果也非常令人满意。该技术为核酸探针的开发以及癌症的诊断和治疗提供了强有力的技术支撑，具有显着的实际应用价值。

Cancer is one of the most important causes of human death and poses a serious threat to human health. As a cancer biomarker, microRNA-155 (miRNA-155) is highly expressed in various types of cancer tissues and is involved in the proliferation of tumor cells. Therefore, developing a miRNA-155 detection technology with high specificity and sensitivity is of great significance for the early detection, accurate treatment and prognostic evaluation of tumors. Here, we developed a fluorescence detection method using exonuclease III-assisted target cycling and catalytic hairpin assembly (CHA) as a signal amplification technique. This study developed a biosensor for the detection of miRNA-155, utilizing a DNA hairpin (Hp) for target recognition and generating double-stranded DNA (dual-Hp-T). The 3' flat end of the double-stranded DNA can be cleaved by exonuclease III to achieve the target cycle, and a large amount of single-stranded DNA (fuel) can trigger CHA to achieve signal amplification. Simultaneously, the fluorescence resonance energy transfer (FRET) of signal probes with different fluorescence labels on H1 and H2 ends occurs with the CHA reaction. The two fluorescence signals obtained can be used to cross-validate the experimental results. The biosensor exhibits excellent performance of high recovery, high sensitivity and high operability, which can achieve the specific detection of miRNA-155 with a detection limit as low as 8.3 pM. Additionally, the detection efficacy in a human serum environment is also highly satisfactory. This technology provides strong technical support for the development of nucleic acid probes and the diagnosis and treatment of cancer, demonstrating significant practical application value.