新型上转换纳米探针光控发光损耗机理及其类STED超分辨成像

科学发展迅速，传统光学显微镜分辨率已无法满足生物医学等领域的需求。作为超分辨技术之一，受激发射损耗显微术STED从光学上打破衍射极限，有成像速度快、横向分辨率高等优势，适用范围广。但STED技术的发展遇到一些瓶颈：①短波长激光散射大，成像深度低；②常见STED荧光探针有光漂白；③双激光都与荧光光谱重叠，滤光导致荧光光谱成分牺牲，限制灵敏度。这些问题都有待解决。..本项目拟将基于稀土离子发光等理论，研究阐明光控上转换发光损耗机理，建立高效光控损耗方案，构筑新型上转换探针UCNPs实现双长波长激光的类STED成像，可控制备相应UCNPs；搭建多光子、高分辨率、大深度的超分辨成像系统；光谱不重叠，实现全荧光光谱检测；用光学窗口II区激光对脑样组织实现大深度、超分辨成像；零光漂白实现长时间持续成像。本项目将攻克三大瓶颈，对STED技术的发展意义重大，也必将推动UCNPs在生物医学应用中的长足发展。

With the rapid development of science and technology, the spatial resolution of the traditional optical microscope cannot satisfy the requirement of biomedical and life science research any more. As an important modality of super-resolution imaging techniques, Stimulated Emission Depletion (STED) microscopy can optically break the diffraction limit and has been widely applied in different areas, with the advantages of rapid imaging (without reconstruction process) as well as the ultrahigh lateral resolution. However, the following problems need to be addressed for the future development of STED, including small penetration depth (induced by short wavelength and large scattering), annoying photobleaching of STED probes, limited sensitivity caused by overfiltering the fluorescence signals due to the spectral overlap of the wavelengths of two employed lasers and the fluorescence spectrum...This project/proposal will be based on lanthanide-ions luminescent theory and clarify the effective optical depletion mechanisms of upconverting luminescence. By establishing high efficient optical depletion schemes, we will design and synthesize controllable novel upconverting probes for STED-like multiphoton microscopy, which would be demonstrated using two relatively long wavelength lasers. We will also construct multi-photon super-resolution microscopy system with ultrahigh resolution and large imaging depth. As lasers and luminescence will be separated, full luminescence spectrum will be realized. By using lasers centered at NIR-II region, sub-100-nm resolution would be obtained in the large depth of brain-like tissue. Meanwhile, long standing continuously microscopic imaging could be realized by taking the advantage of non-photobleaching property. Aiming for solving the above three issues, this project/proposal will be highly of significance for both the advance of STED technique and further development of UCNPs’ optical biomedical applications.