本课题拟开展基于足点域介导的DNA链置换信号放大技术的构建及食源性致病菌高灵敏度检测研究。课题拟利用足点域杂交反应和分支迁移技术，以目标物适体互补序列为催化剂C、基质S和燃料F实现催化剂C的循环利用，产生大量信号链SP，建立足点域介导的DNA链置换信号放大新方法；结合功能化磁性微珠的捕获和分离功能，以一对一识别的化学发光三胶体金纳米粒子为探针，构建基于足点域介导的DNA链置换信号放大化学发光分析新技术；以鼠伤寒沙门氏菌为模式分析测定对象构建高灵敏度和高选择性食源性致病菌分析测定新方法。利用微生物检验标准方法以及分子生物学方法对照等对新方法进行评价，并对实际样品中鼠伤寒沙门氏菌进行测定；对建立的分析测定新方法进行拓展。解决现有DNA循环信号放大技术中需要酶参与反应的限制性科学问题，丰富和发展信号放大的理论；为高灵敏度食源性致病菌检测提供有效的设计思路及实验依据。

A novel signal amplification strategy based on toehold-mediated strand displacement will be developed for the ultrasensitive detection of food pathogenic bacteria. In the presence of the target, the catalyst C will be released from the dsDNA. After the substrate S and fuel F being added, the catalyst C will be recycled through the toehold hybridization and branch migration reaction and amount of signal strand SP will be released. Strong signal can be gained by detecting the SP. The new signal amplification strategy, which no need of nuclease, based on toehold hybridization coupling branch migration reaction will be firstly fabricated by detecting the released SP through the recycle and strand displacement. This signal amplification strategy can solve the scientific problems of needing the nuclease in DNA-based signal amplification. It also can enrich and develop the theory of signal amplification. The one-to-one recognition chemiluminescence triple Au nanoparticles (OR-CLTri-AuNPs) probe will be prepared with gold nanoparticles, chemiluminescence reagent, recognition and occupation DNA. The Salmonella typhimurium, choosed as the interested target, will be sensitively and selectively detected with the developed signal amplification strategy combined with the magnetic bead capturing and separation and OR-CL-Tri-AuNPs probe. The feasibility and reliability of the developed method will be evaluated by the determination of Salmonella typhimurium in real samples and microbiological examination controlled experiment and molecular biological detection. This study will provide a new and effective design idea and experimental basis for high sensitive food pathogenic bacteria determination and new analytical method and technology.