活体荧光多重成像技术可以同时可视化生物组织中不同分子和细胞的时空信息，正成为基础生物科学和临床医学研究中的迫切需求。目前常用的多重成像技术使用可见光发射的荧光探针，虽然在体外检测中得到了广泛应用，但是其在活体中的穿透深度和分辨率却因可见光在组织内的散射等因数而受到严重制约。在生物组织“透明”窗口（近红外二区，1000-1700 nm）中操作且光谱不重叠的荧光探针可以解决该问题，但当前的荧光探针体系仍然难以满足这一要求。针对这一科学问题，本项目拟基于卟啉类大环铒配合物，通过配体分子工程构建具有近红外激发和大于1500 nm窄发射特征的新型分子荧光探针体系，并在肿瘤转移模型的荧光多重成像中进行验证。此外，本项目拟通过瞬态吸收光谱阐明探针的发光机理，为分子功能特性的优化和设计提供理论指导。本项目的研究将丰富近红外二区的分子荧光探针工具，有望推动活体荧光多重成像在生物学和生物医学研究中的应用。

In vivo fluorescence multiplexed imaging is vital for biological and biomedical research, allowing the simultaneous visualization of multiple molecules and cells in biological tissue. Despite the wide application, established multiplexed techniques using visible emitting probes have limited optical penetration and resolution in in vivo imaging due to serious light scattering and attenuation. Spectrally distinct fluorophores that operate in the “tissue-transparent” spectral window (second near-infrared window; NIR-II; 1,000-1,700 nm) are the key to realize ideal performance for in vivo multiplexed imaging, however, current fluorescent toolbox is still difficult to meet this demand. To address this issue, we will focus on the porphyrin-erbium complex, and construct a novel molecular fluorophore system with near-infrared absorption and narrowband emission beyond 1500 nm through molecular engineering of the porphyrin macrocycle. In vivo multiplexed imaging performance of the fluorophores will be explored in a tumor metastasis model. In addition, luminescence mechanism of the novel fluorophores will be investigated through transient absorption spectroscopy, which will provide theoretical guidance for the design and functionalization of the fluorophores. We anticipate that our work can enrich the NIR-II fluorescent toolbox, thereby promoting the application of in vivo fluorescence multiplexed imaging in biological and biomedical research.