研究表明，血清特异microRNA(miRNA)的异常表达与胃癌的发生、进展密切相关。我国胃癌死亡率居高不下，早期检出率非常低。缺乏胃癌早期生物标志物以及高灵敏、价格低廉的诊断方法是重要原因之一。本项目拟选择最近发现的与早期胃癌关联的血清生物标志物miR-378以及与胃癌进展关联的miR-21为研究对象，结合氧化石墨烯（GO）、猝灭基团高效猝灭单链DNA标记荧光体（Cy5、荧光可调金属纳米簇等）的特点，利用miRNA高效特异结合与之互补单链DNA的性质，设计基于荧光分子开关-miRNA生物传感体系，对胃癌细胞进行miRNA荧光成像研究。进一步借助双链特异性核酸酶（DSN酶）特异降解杂交双链中DNA链的特点，释放miRNA，产生荧光信号放大效应，对血清miR-378、miR-21进行高特异、超灵敏检测，以期实现对胃癌的早期诊断，辅助预测胃癌分期进展，为把握胃癌最佳治疗时间提供理论基础。

Recent studies indicate that abnormal activation of serum-specific microRNA (miRNA) is associated with early gastric cancer and its pathologic processes. High mortality rate of gastric cancer was observed in China, due to the absence of specific symptoms and early detection of diagnosis. In this project, we focus on early detection of the gastric cancer-associated biomarker miR-378 and miR-21. A graphene oxide (GO) based miRNA biosensor, which allows cellular imaging in living cells and quantitative monitoring of miR-378 and miR-21 in serum is developed. For the strong affinity between GO (known as fluorescence quencher) and fluorescence-labeled single-stranded DNA probe and its high specific recognition for target miRNAs, a fluorescent molecular switch based on GO, duplex-specific nuclease (DSN) enzyme and metal nanoclusters was constructed and applied to the investigation of gastric cancer early diagnosis. We provide a theoretical basis for revealing the optimal duration of treatment of gastric cancer.