基于双重保护机制构建具有高光稳定性的单/双光子激发的共轭聚合物荧光探针及其生物应用研究

This research plan is dedicated to explore an efficient strategy to circumvent the longstanding problem of photostability that the fluorescent probes constructed from organic small molecules or conjugated polymers usually encounter. Specifically, we will design and fabricate highly photostable fluorescent probes, using conjugated polymers with one-(or two-) photon excited fluorescence features as the photoactive components, via dual protection mechanism and investigation on the biological applications of the as-prepared probes. We will construct the core-shell type fluorescent polymeric nanoparticles via the way of microemulsion copolymerization strategy. Specifically, the oxygen permeability of the host polymer matrix of the nanoparticles will be optimized, for the purpose of separating the conjugated polymers susceptible to photodegradation and photobleaching from the oxygen components, and the small molecule additives such as triplet quenchers will be integrated into the nanoparticles via the way of covalent bonding for efficient scavenging the photo-generated triplet reactive species. Such dual-protection mechanism based strategy is expected to efficiently suppress the generation of highly reactive oxygen species (ROS) by the synergistic effect of reducing the molecule oxygen source and decreasing the concentration of triplet sensitizing components. As a result, the ROS-mediated photooxidation and photodegradation of the conjugated polymers are markedly suppressed, which is expected to significantly contribute to the enhancement of the resistance ability of the fluorescent nanoparticles to photobleaching. Additionally, unlike the organic small molecules that are embedded in the polymer network, the conjugated polymers are expected to entwine with the cross-linked host polymer matrix during the formation and increase of the polymer chains. Thus the as-prepared nanoparticles will not suffer from the dye leaching problem that the conventional fluorescent nanoparticles with embedded small-molecule-weight dyes usually encounter. We will try to explore the way of integrating the molecule oxygen blocking components and the triplet quenching components into the optically transparent polymer host matrix during the loading process of conjugated polymer components, which means the photoactive polymer may benefit from the abovementioned dual protection without the requirement of molecular modification on the conjugated polymer themselves. Unequivocally, such a way improves the suitability of the dual protection mechanism for the construction of photostable fluorescent nanoprobes based on various conjugated polymers.

本项目拟基于双重保护机制协同作用，设计构建具有抗光漂白特性和结构稳定性的共轭聚合物荧光纳米探针，探索应对有机小分子/共轭聚合物荧光探针长期存在的光稳定性问题的有效方案。我们将以具有单/双光子激发荧光聚合物为光学活性组份，通过微乳液聚合途径来构建“核-壳”结构的聚合物荧光纳米颗粒；通过优化聚合物主体基质组份对氧的通透性使得共轭聚合物与环境中的氧进行有效的隔离，同时以共价键连接的方式将三重态淬灭剂等有机小分子功能添加物组份集成到纳米颗粒中；基于这种双重保护机制协同作用，从减少氧来源和降低三重态敏化组份浓度两个方面有效地抑制光照射情况下高反应活性单重态的生成；从而减少因光氧化导致的共轭聚合物组份的光降解和光漂白，最终达到提高探针光稳定性和发光亮度的目的。我们还将探索将氧隔离和三重态淬灭剂等功能组份集成到主体基质中，在不需对共轭聚合物进行修饰的前提下实现对其的双重保护，提高探针的光稳定性。

本项目拟基于双重保护机制协同作用，设计构建具有抗光漂白特性和结构稳定性的半导体聚合物荧光纳米探针，探索解决有机小分子/半导体聚合物荧光探针长期存在的光稳定性问题的有效方案。我们将以具有单/双光子激发荧光聚合物为光学活性组份，通过微乳液聚合途径来构建“核-壳”结构的聚合物荧光纳米颗粒；通过优化聚合物主体基质组份对氧的通透性使得共轭聚合物与环境中的氧进行有效的隔离，同时以共价键连接的方式将三重态淬灭剂等有机小分子功能添加物组份集成到纳米颗粒中；基于这种双重保护机制协同作用，从减少氧来源和降低三重态敏化组份浓度两个方面有效地抑制光照射情况下高反应活性单重态的生成；从而减少因光氧化导致的半导体聚合物组分的光降解和光漂白，最终达到提高探针光稳定性和发光亮度的目的。我们还将探索将氧隔离和三重态淬灭剂等功能组份集成到主体基质中，在不需对半导体聚合物进行修饰的前提下实现对其的双重保护，提高探针的光稳定性。