基于铱配合物的磷光双光子探针的制备及其在细胞成像中的应用

Two-photon microscopy, which uses two photons of lower energy as the excitation source, is growing in popularity among biologists because of several distinct advantages. For example, long wavelength excitation, dark field imaging, minimum interference from tissue preparation artifacts, self-absorption, autofluorescence, photobleaching, and photodamage et al. Currently, most reported or commercial two-photon probes are based on organic luminophores. The short emission lifetime of organic luminophores is easy to be interfered by autofluorescence. In addition to organic luminophores, heavy-metal complexes with phosphorescent emission are one kind of important luminescent metal complex due to their relatively long lifetimes compared to those of purely organic luminophores. The advantageous phosphorescent emission is beneficial for them to be used in chemical or biological detection. In fact, organometallic complexes are good candidates as multiphoton imaging luminophores. Large two-photon-absorption (TPA) cross sections can be brought about by their characteristic intra/interligand and metal-to-ligand charge-transfer transitions during photoexcitation. In this project, we will choose Iridium(III) complexes as subject investigated. And we would prepare phosphorescent two-photon probes with strong two-photon cross section and high quantum efficiency by molecular designing and optimizing. Furthermore, the successful applications in phosphorescent cell imaging of these materials will be also realized by utilizing two-photon excited fluorescence lifetime imaging measurements. We hope that this project can promote innovative research in the field of two photon materials based on phosphorescent complexes and produce high-level research results with our own intellectual property rights.

双光子成像具有近红外激发、暗场成像、避免荧光漂白等特点而显著地优于单光子成像，为生命科学研究提供了更为锐利的工具。现在，大多双光子染料是基于纯有机分子的，有机荧光化合物发光寿命较短，成像中易受到背景荧光的干扰而降低信噪比。相比而言，磷光较长的发光寿命可以通过时间分辨技术有效避免体系背景荧光的干扰。此外，金属配合物具有更高的光稳定性，适于荧光成像；并且通过合理优化配体结构以及多配体的协同作用，易实现较高的双光子吸收截面。在本项目中，我们选择铱配合物作为研究对象，通过分子设计和调节合成新型的具有较大吸收截面和较高发光量子效率的磷光双光子探针，并通过分子的功能化实现在细胞成像中的应用。此外，利用磷光长寿命的特点，我们预将双光子荧光成像与新型的荧光寿命成像结合起来，实现双光子诱导下的寿命成像，来消除背景荧光的干扰。我们希望通过本项目的实施，从分子设计、材料开发和成像应用等方面做出创新性的研究工作。

双光子成像具有近红外激发、暗场成像、避免荧光漂白等特点而显著地优于单光子成像，为生命科学研究提供了更为锐利的工具。现在，大多双光子染料是基于纯有机分子的，有机荧光化合物发光寿命较短，成像中易受到背景荧光的干扰而降低信噪比。相比而言，磷光较长的发光寿命可以通过时间分辨技术有效避免体系背景荧光的干扰。此外，金属配合物具有更高的光稳定性，适于荧光成像；并且通过合理优化配体结构以及多配体的协同作用，易实现较高的双光子吸收截面。本项目的实施，获得的结果如下：我们选择铱配合物作为研究对象，通过分子设计和调节获得了具有较大吸收截面和较高发光量子效率的磷光双光子探针；通过纳米功能化，实现了水相溶液中对分子和离子的比率检测和肉眼识别；实现了在活细胞成像和检测中的应用，获得较好的双光子成像效果；证明了利用磷光长寿命的特点，采用时间分辨的方法排除检测物的背景荧光干扰。