智能响应的功能核酸-水凝胶的设计及其在可视化检测中的应用

Visual detection is an increasingly attractive method in many fields because both qualitative and semiquantitative assessment can be performed in real time without any advanced or complicated instrumentation. It is especially useful for diagnostics in the developing world as a tool for first responders in disaster situations, in home healthcare settings and environmental monitoring in field due to visualization by naked eyes. In this proposal, we would like to develop a visual method by creating a DNA-based hydrogels that use functional DNA as simultaneous crosslinking and ligand sensing moieties, including DNAzyme, aptamer and special T-Hg-T base pairing. The gel-sol phase transition can be easily regulated by interaction between target and functional DNA. We use this unique ligand induced gel-to-sol transition property to create a sensitive and universal platform for visual detection by trapping gold nanoparticles or enzymes inside the hydrogel network. Upon introduction of targets, the hydrogel melts and the trapped agents are released and detected visually. Gold nanoparticles with intense red color were employed for system study due to their chemical and physical stability. We also tested the release of the enzyme to react with substract and induce color change to further improve the sensitivity. Moreover, to realize portable quantitative detection, the glucosemeter will be employed with the hydrogel system to give a quantitative readout. Because of the flexibility of this design, it could be easily applied for visual detection of other chemical or biological targets and used for forensic analysis, medical diagnostics, and environmental monitoring.

可视化检测方法由于其成本低廉、操作简便、实时快速等优势在贫困地区医疗、疫情早期预警、家庭保健防护、食品卫生监控、和野外环境监测中具有重大的发展潜力和应用价值。本项目以DNA核酸酶、核酸适体、T-Hg-T等功能核酸分子为特异性识别元件，利用DNA碱基互补配对原则与功能核酸分子-靶分子相互作用构建智能响应水凝胶体系，结合高效酶催化信号放大方法，发展一类新型的可视化便携式高灵敏检测平台。利用功能核酸分子针对靶标发生的特异性构象变化,实现对水凝胶溶液状态和凝胶状态的可逆调控。通过包被显色物质和信号放大酶，水凝胶根据对靶标的响应，改变溶胶状态，特异性地释放所贮存的信号分子,实现可视化信号输出。此外，与血糖计的结合，使得快速便携的定量检测成为可能。项目预期将建立一系列用于快速、高灵敏、高选择性检测环境、食品中各种有毒有害物质的先进可视化方法，为环境监控和防治、食品卫生安全监控等领域提供重要的分析手段。

即时检测方法由于其成本低廉、操作简便、实时快速等优势在贫困地区医疗、疫情早期预警、家庭保健防护、食品卫生监控、和野外环境监测中具有重大的发展潜力和应用价值。本项目在信号放大与转化方面，发展了基于碳纳米颗粒、氧化石墨烯、多巴胺纳米球等与核酸酶结合的靶标循环放大检测方法用于ATP、miRNA等生物分子的检测；发展基于DSN酶的靶标循环放大检测方法，以及T7核酸外切酶与RCA联用的双重信号放大方法用于miRNA的高灵敏检测。在特异性探针筛选方面，发展了快速、高效的表面展示核酸适体筛选新方法，针对肿瘤细胞、肿瘤标志蛋白、食品毒素等进行了核酸适体的筛选。在可视化便携检测方面，建立了核酸适体-水凝胶个人用血糖计联用的便携式定量检测平台；建立了基于距离变化的核酸适体水凝胶-滑动芯片联用的便携式定量检测平台；提出基于气压的便携定量检测方法；成功实现了可卡因、ATP、铅离子、赭曲霉毒素、PSA等重要靶标的可视化定量检测。共发表标注基金的SCI论文30篇，其中影响因子5.0以上25篇，包括1篇J Am Chem Soc，2篇Angew Chem In Ed，4篇ACS Appl. Mater. Interfaces，9篇Anal Chem，6篇Chem Comm，1篇Chem Eur J，1篇Scientific Reports和 1篇Biosen Bioelectron。