可见光调控的二芳基乙烯荧光分子开关超分辨荧光成像探针

For the conventional diarylethenes, there are a series of limitations for their application as they must rely on the ultraviolet (UV) light source which is harmful. To solve the above problem, we will focus on the design and synthesis of the visible-light-actived photoswitchable fluorescent diarylethenes in this proposal. By connecting visible-light sensitizer groups with diarylethene conjugate, the ring-closing photo-isomerization will be responded on visible light irradiation. The improvement of photochromism properties will be completed by changing the regulating groups on the other terminal of diarylethene core. We will link optimized visible-light-actived photochromism structures on fluorescent groups via different spacers to construct visible-light-actived photoswitchable fluorescent diarylethenes. The regulatory mechanism for how regulating-groups affect the fluorescence photoswitching properties will be explored. In order to dramatically improve the fluorescence photoswitching ability, two to four visible-light-actived photochromic diarylethene groups will be integrated on one fluorescent core through the optimized spacers. This kind of high performance photowitchable fluorescent molecules can be directly used as super-resolution imaging probes, or transformed to polymerizable monomers by a further derivatization before use. These photowitchable fluorescent monomers will be copolymerized with targeting-monomer and other functional monomer to produce photowitchable fluorescent plolymer probes with targeting ability and good compatibility. They will be used for in situ and real-time super resolution imaging of both biological and materials with nanostructures. The accomplishment of this proposed research is expected to deepen the understanding of the all-visible-light-actived fluorescence photoswitching behaviors, and provide a new generation of fluorescent photoswitching dyes for the practical applications such as in situ real-time super-resolution imaging.

针对常规二芳基乙烯荧光开关依赖于紫外光源的局限性，本申请项目聚焦于全可见光调控的二芳基乙烯荧光分子开关的创新设计与合成。采用可见光敏化基团与二芳基乙烯共轭相连的方法实现光异构化闭环反应对可见光的响应，并通过二芳基母核上另一端的调控基团来实现光致变色性能的调控。将优化后的光致变色单元与荧光团通过不同间隔基团进行连接，构造出可见光调控的荧光开关分子，研究间隔基团对荧光开关性能的调控机制。将多个可见光敏化的光致变色单元通过最优的间隔基团连接到单个荧光基团上，构造出超高荧光开关比的分子结构。将这些高性能荧光分子开关直接使用或进一步衍生化为可聚合的单体，与水溶性单体、靶向性单体等功能单体共聚制备具有靶向性且相容性良好的聚合物荧光开关探针，并用于生物或材料微纳结构的超分辨成像研究。该项目的实施将加深对二芳基乙烯的荧光开关行为受可见光调控的科学认识，为实时超分辨成像等实际应用提供新一代的荧光开关染料。

二芳基乙烯荧光分子开关普遍存在光异构闭环反应依赖于紫外光激发的问题，严重制约了其在实际中的广泛应用。鉴于此，本项目设计并合成了一系列高性能可见光响应的二芳基乙烯荧光分子开关，并详细研究了它们的光致变色性质和构效关系，提出了基于四苯基乙烯、三芳胺等给电子可见光敏化基团共轭连接二芳基乙烯来延长闭环反应响应波长的基本策略。特别地，三苯胺炔基共轭修饰的二芳基乙烯对可见光具有极高的响应性，405 nm波长光照下，开环态二芳基乙烯“准定量”转化为闭环态。通过多二芳基乙烯取代的方式，方便地构造出了多种具有高荧光开关比的全可见光调控的二芳基乙烯分子，在405 nm光照下实现了1000 : 1以上的荧光开关对比度，极大地满足了实际应用的需求。利用其优异的荧光开关性能，在仅使用可见光源的情况下成功实现了超分辨成像，获得了完整且精细的纳米结构形貌，分辨率突破30 nm，有效避免了紫外光源带来的成像系统兼容性问题和对样品与操作者的危害性，具有广泛的应用前景和实用价值。本项目对二芳基乙烯依赖紫外光源的问题提了重要的解决思路，为未来新型可见光响应荧光开关探针的设计及其超分辨成像应用提供了重要的指导意义。

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