miR-200a与多种癌症的发生、发展密切相关，我们发现miR-200a还抑制葡萄糖醛酸转移酶1A1的表达, 因此，可以作为疾病诊断、预后判断及治疗的生物标志物和药物靶标。然而,目前对于miRNA体内测定存在定量不够精确、基质干扰大、操作繁琐复杂、费时、对仪器要求高等问题。因此，开发一种能排除生物基质干扰、简便快速、灵敏度高、低成本的测定分析技术是其功能研究的关键。本课题拟根据我们前期研究结果，构建基于嵌合有链霉亲合素适配体的分子信标构象变化和信号放大的miR-200a化学发光分析新方法，主要致力于设计和优化嵌合有多种识别单元的构象变化型分子信标；应用链替换等温循环和纳米粒子等放大技术，提高方法测定灵敏度和选择性；验证分析方法，并与qRT-PCR方法比较；用于miR-200a抑制UGT1A1的作用研究。本方法易于拓展至其它miRNA测定，有助于miRNA功能的深入研究。

The Evidences accumulated from many studies have uncovered that distinct patterns of that miR-200a play important roles in a number of cancers. We found miR-200a inhibit UGT 1A1. So, miR-200a represents promising biomarker and target candidates for informative diagnostics and treatment. Therefore, a simple, low-cost, and highly sensitive and selective method for miRNA detection is desirable. We design a novel chemiluminescence (CL) based on conformational swith-based aptasensors fitted with one streptavidin-related aptamer for the detection of miR-200a in this project. Several amplification techniques including the hybridization chain reaction and nanoparticle amplification will be used for the improvement of method sensitivity and selectivity. By using this method, we study that miR-200a regulates UGT1A1 activity. This novel analytical technique can be easily extended to the determination of other miRNA and promote the study of miRNA functions.