小分子核酸(miRNA)与疾病紧密相关，在人体内发挥着重要作用。高选择性、高灵敏度miRNA检测是实现癌症的早期诊断和组织分型的前提，有利于医生对患者及时实施手术治疗、高效药物治疗以及准确分析预后。本课题拟结合高阶杂交链式反应和核酸酶催化反应，实现miRNA的体外检测、细胞成像和基因调控。首先利用荧光共振能量转移信号输出机制实现miRNA体外检测和细胞内成像分析。进一步构建杂交链式反应动力学模型，模拟分子反应动力学过程，优化探针设计和反应调控。最后将核酸酶序列整合到高阶杂交链式反应中，实现进一步信号扩增和基因沉默干扰；特别重要的是，当核酸酶被设计为剪切信使核酸时，借助多功能纳米材料载体，可以实现高效细胞调控。作为一种集“传感-响应-处理”为一体的智能小分子调控分析工具，高阶杂交链式反应激发核酸酶体系将会在癌症诊断辅助治疗方面得到广泛应用。

MicroRNA (miRNA) plays an important role in living organism, as it is intrinsically related with various biotransformations. Amplified and selective detection of miRNA is a prerequisite for early cancer diagnose and histological classification. It can facilitate the implementation of accurate surgical and drug treatments on patients, and the accompanying prognosis. Here hyperbranched hybridization chain reaction (hHCR) has been constructed for sensitive miRNA detection and intracellular imaging, and efficient gene silencing. By Foster resonant energy transfer (FRET) transduction, hHCR enabled an ultrasensitive detection of miRNA in clinical samples. Computer-aided modeling of this isothermal autonomous reaction provided a powerful tool to probe the underlying reaction process and to optimize the present hHCR design. After miRNA triggers hHCR-mediated DNAzyme activation, leading to the cleavage of messenger RNA (mRNA) in living cells, then the corresponding DNAzyme can be applied for efficient gene-silencing therapy. As a smart “sense-treat-act” tool, hHCR-DNAzyme system will be extensively applied for cancer diagnosis and treatment in the near future.