肿瘤标志物的检测对恶性肿瘤的早期诊断和治疗都有非常重要的意义，高灵敏、高特异、多组分、高通量的肿瘤标志物分析技术仍是科学家们的重要研究兴趣。核酸适体由于其亲和力高、特异性强、靶分子广、易于体外合成与修饰等特点，正逐渐取代抗体成为肿瘤标志物分析的重要探针分子。但目前已报道的基于核酸适体的肿瘤标志物分析策略绝大多数仅限于检测一种肿瘤标志物，不利于相关肿瘤的确诊。另外，由于核酸适体探针和其目标分子的结合常数相对较低，传统的传感策略还很难获得较高的检测灵敏度。为了解决这些问题，本项目拟通过巧妙设计多功能化的核酸适体探针以达到可以平行或者同时检测多种肿瘤标志物的目的，并且借助等温循环链置换聚合信号放大技术，实现对肿瘤标志物目标分子的高灵敏检测。通过对多种肿瘤标志物的高灵敏、联合分析为恶性肿瘤的早期准确诊断提供重要的方法指导及理论基础。

Detection of tumor markers is of significant importance for early diagnosis and treatment of the malignant tumor. Analysis techniques for tumor markers with high sensitivity，high specificity, multicomponent and high throughput are still important research interests for scientists. Due to the peculiar properties such as high affinity and specificity, wide target molecules, easy synthesis and modification, aptamers are gradually taking place of the antibodies to become important probe molecules for the assay of tumor markers. However, at present, the reported analysis strategies for tumor markers are mostly limited to detecting only one kind of tumor marker, which is not unfavourable for the accurate diagnosis of related tumors. In addition, since the binding constant of the aptamer probe and the target molecule is relative low, conventional sensing strategies are difficult to obtain high detection sensitivity. To solve these problems, the proposed project intends to design multifunctional aptamer probes for parallel or simultaneous detection of multiple tumor markers. Moreover, by using the amplification technology of isothermal circular strand-displacement polymerization, it is hopeful to achieve ultrahigh detection sensitivity for the tumor markers-target molecules. By highly sensitive and associated anlysis of the multiple tumor markers, the present project will provide important methods and fundamental principle for accurate early diagnosis of the malignant tumor.