基于零背景和多元信号放大的新型核酸生物传感器的构建及其对癌症标记物的高灵敏检测

Highly sensitive and selective detection of specific cancer marker is of great importance in early clinical diagnoses and treatment. Functional nucleic acid fluorescent sensors have attracted great interest in the field of biomedical analysis, due to their high sensitivity, good selectivity and low cost. High background signal and weak signal output rate are two main factors that directly influence the sensitivity of nucleic acid fluorescent sensors. This project aims to design the novel DNA biosensor with zero background signal and multiple signal amplification for highly sensitive and selective detection of cancer biomarker. Two-dimensional magnetic nanomaterial (-FeOOH nanosheet) is introduced into the sensing system to realize zero background signal by tacking advantages of excellent fluorescence quenching ability and magnetic separation properties of -FeOOH nanosheet. By combining enzymatic amplification and surface plasma enhanced fluorescence, the sensing system could realize efficient cascade signal amplification. In order to achieve an efficient synergistic effect in the signal amplification process, the effect of environmental factors (such as pH, temperature and the concentration of enzyme) on the sensitivity of sensor system are systematically investigated. The results of this work will be not only to extend the two-dimensional magnetic nanomaterial applications in the biomedical aspects, but also to provide theoretical and technical support in designing zero background biosensor for early clinical diagnoses and treatment.

对癌症标记物的高灵敏、高选择性检测在癌症的早期诊断与治疗方面具有重要意义。功能核酸荧光传感器因其灵敏度高、选择性好、检测成本低等优点在生物医学分析领域吸引了大家的关注。但是，背景信号高、信号输出比率弱是影响荧光核酸传感器检测灵敏度的两个主要因素。本项目拟构建具有零背景和多元信号放大技术联用的核酸生物传感器，并应用于癌症标记物的高灵敏、高选择性的检测。通过把磁性二维纳米材料(-FeOOH)引入到传感体系，利用-FeOOH的荧光猝灭能力以及磁分离性能，来实现体系的零背景。通过把酶循环放大和表面等离子增强荧光这两种信号放大机制联用实现目标物产生的信号级联放大。探讨信号放大过程中环境因子（如pH，温度、酶浓度等）对传感体系的影响，并优化使其发挥最佳的协同作用。本项目的研究不仅拓展了磁性二维纳米材料在生物医学方面的应用，而且为癌症的早期诊断和治疗方面提供理论和技术支持。

癌症标记物的定量检测在疾病的早期诊断与治疗方面具有非常重要的意义。针对目前检测癌症标记物的方法中存在的检测灵敏度低，背景信号高的问题，本项目以磁性二维羟基氧化铁纳米片为载体，利用磁分离和酶循环放大策略，构建具有零背景的新型纳米核酸传感器用于癌症标记物的检测研究。主要开展了一下几个工作：利用静电相互作用将Si QDs与透明质酸修饰的δ-FeOOH进行自组装，构建了一种检测透明质酸酶的纳米探针。使用δ-FeOOH纳米片作为荧光猝灭剂可以极大降低甚至消除背景信号，透明质酸酶检测的灵敏度比传统的荧光检测方法提高了1000倍以上；利用酶协助的目标物循环放大和δ-FeOOH的荧光猝灭及磁吸作用，构建一种新颖的具有零背景的荧光信号放大生物传感平台用于超灵敏的DNA检测。使用δ-FeOOH作为荧光猝灭剂，可以有效的猝灭发色团的荧光，同时利用磁吸作用，可以把溶液中残存的背景荧光，进而实现传感器的零背景信号，提高传感器的灵敏度；利用δ-FeOOH 对单链、双链和三链DNA具有不同的吸附能力这一特性，构建一种新型的可磁控二维纳米-DNA荧光传感器，用于碱性磷酸酶活性的灵敏和选择性检测；采用水热法成功地制备了二维层状WS2/Bi2MoO6 纳米复合光催化剂，探究其光催化性，为下一步纳米复合材料通过光动力治疗肿瘤打下了基础。本项目的开展对于某些疾病的早期诊断和治疗具有十分重要的理论意义和应用价值。