数字式SERS成像技术同时分析多种microRNAs用于癌症早期诊断

MicroRNAs（miRNAs）是液体活检中重要的生物标志物，传统的miRNAs检测方法是统计大量目标物产生的平均信号，灵敏度较低。而数字式检测模式可以在稀释背景信号的同时提高低丰度目标物的信噪比，提高检测灵敏度。表面增强拉曼散射（SERS）灵敏度高、半峰宽窄有利于多种目标物同时分析。该项目拟结合微阵列芯片和高灵敏的SERS探针实现无需核酸扩增的数字式多靶标miRNAs分析。每次反应后，对微阵列芯片进行SERS成像，选定靶标分子的特征峰，划定阈值，统计阳性微孔数来进行分析。一方面，拉曼散射峰很窄，不容易重叠。含有多个靶标分子的复杂样品，可以在同一块芯片上实现高灵敏度分析。另一方面，通过合成高灵敏的SERS探针，使足够多的拉曼信号分子负载到检测探针上，单个靶标分子被捕获后便可以得到相应阳性信号。通过建立数据库，比较不同癌细胞外泌体中不同miRNA含量，为癌症早期诊断和治疗提供更多有用的信息

MicroRNAs (miRNAs) are important biomarkers in liquid biopsy. Conventional methods for miRNAs analysis are based on the average signal of a great number of target molecules to analyze the target miRNAs in real samples, which is lack of sensitivity. However, the digital detection mode can improve the signal-to-noise ratio of the target with low abundance through diluting the background signal, improving the detection sensitivity. Moreover, the digital detection is not susceptible to the influence of the external environment and therefore, the experimental results are much more consistent. Surface-enhanced Raman scattering (SERS) as a highly sensitive detection technique can even reach single-molecule level sensitivity under certain conditions. The narrow distribution of Raman spectral peaks avoids their potential overlaps and is conducive to multiplexed analysis of miRNAs. Therefore, this project aims to combine microarray chip with highly sensitive SERS probe to realize digital analysis of multiplexed miRNAs without nucleic acid amplification. After the hybridization reaction, SERS imaging is performed on the microarray chip, and the number of each target molecule could be analyzed by selecting their characteristic peaks and counting the number of positive micropores. Complex samples containing multiple target molecules can be analyzed simultaneously with high sensitivity on a single chip. On the other hand, by synthesizing highly sensitive SERS probes, a sufficient number of Raman signal molecules can be introduced to the detection probes, and the corresponding positive signals could be obtained after a single target molecule is captured. By establishing a database to compare the content of different miRNAs in the exosomes of different cancer cells, more useful information on the inherent correlations between the levels of miRNAs and the cancer subtypes can be provided for the early diagnosis and treatment of cancer.