基于DNA滚环扩增的痕量铀识别机制与超灵敏现场分析研究

The radioactive substances such as uranium seriously harm the ecological environment and human health & safety. Thus, it is significant to develop emergency monitoring methods for trace radioactive elements in the environment. However, the classical laboratorial analytical techniques suffer from complex and time-consuming procedures, could hardly meet the requirement of emergency response for on-site analysis. Rolling circling amplification (RCA) possesses high specificity and amplification efficiency. This advantage will remarkably increase the efficiency and specificity of the molecular probe recognition process, and enhance the sensitivity of on-site assays. This program plans to study the DNAzyme-uranyl recognition mechanism via thermodynamic and kinetic analysis, and design RCA probes for uranyl with enhanced recognition efficiency and specificity. Then, we will construct high-efficient signal conversion and amplification method based on rolling circling amplification (RCA) reaction. Furthermore, combined with digitized colorimetric technique, this program will integrate the RCA probes with a microfluidic chip system to build a rapid and ultrasensitive analytical platform for on-site analysis of trace uranium. This program aims to study the interaction mechanism and dynamics between uranyl and DNA probes, and provide a useful assay for efficient recognition and quantitative analysis of trace uranium in the environment. This assay would have applications in emergency monitoring of environmental radioactive contamination.

铀等放射性物质严重危害生态环境与人类健康安全，建立对环境中痕量放射性物质的快速应急监测手段非常重要。然而，传统的实验室分析方法流程复杂、耗时长，无法满足现场分析的应急响应需求。DNA滚环扩增（RCA）反应具备高特异性、高扩增效率的优势，可显著提升分子探针的特异性与识别效率、以及现场分析的灵敏度。本项目拟通过热力学与动力学分析探究脱氧核酶序列与铀酰的识别机制，从而设计并制备特异性与识别效率增强的RCA探针；基于RCA反应构建高效的信号转换与放大方法；进一步，将RCA探针整合于微芯片上，结合数字化比色分析手段发展快速、超灵敏的痕量铀现场分析平台。本项目旨在研究DNA分子探针与铀酰的识别机制与动力学行为，为环境中痕量铀的高效识别与快速、准确定量分析提供方法，并应用于环境放射性污染应急监测中去。

铀具有放射性和化学毒性，其大量排放到环境中将严重危害生态环境和人类健康，建立对环境中痕量铀酰离子的快速准确测量技术非常重要。截至目前，很多实验室都建立了铀的测量技术，但由于环境水体的复杂性，这些方法通常需要预处理过程，耗时长，并需要大型仪器，无法满足现场应急响应的需求。本项目主要目标是铀酰离子的快速可视化检测，围绕探针的特异性识别动力学、信号转换和放大开展了探究。设计了基于核酶（DNAzyme）修饰微球的功能化探针，在高效特异性识别复杂水样中铀酰离子后，通过DNA滚环扩增信号放大，实现了痕量铀酰离子的可视化比色检测，目视检测限为5 nM，紫外可见光谱测量的检测限达到0.48 nM。对环境水样中铀的测量准确，回收率良好（96~106%）。全部过程仅需40分钟。还设计并试验了一种层流微流控芯片实现水溶液中铀酰的快速萃取，铀酰的萃取效率为80%。此外，完成了浊点萃取结合电化学差分伏安法测量环境样品中的铀、贵金属纳米颗粒对铀酰的电化学催化，以及环境中痕量铀同位素质谱测量技术等相关研究。本项目中建立的检测方法均有潜力应用于环境放射性污染应急监测中。