NMDA受体靶向的单胺氧化酶-A双光子荧光探针的构建及其生物成像的研究

Monoamine oxidase is the primary enzyme involved in the metabolism of amines in the human body and plays a crucial role in maintaining the dynamic balance of neurotransmitters and organic amines. Because of being encoded by distinct genes, MAO has two different isoforms: MAO-A and MAO-B, which display different functions. The abnormal activity of monoamine oxidase-A in brain tissue is closely related to various neurological diseases such as neuropsychiatric and depressive disorders. Therefore, the development of neuronal-targeted monoamine oxidase-A fluorescent probes and imaging analysis methods is of great significance in the diagnosis of related diseases. Although scientists have conducted extensive studies on monoamine oxidase probes, the reported monoamine oxidase-A probes have lacked neuronal targeting, which limits their application in biological systems, particularly in brain tissue. It is known that the NMDA receptors expressed on the synapse surface of neurons can be used as a target for localizing neural cells. Therefore, this project intends to design and synthesize two-photon fluorescence probes by combining the NMDA receptor binding moiety with the specific recognition moiety for MAO-A. The probe can detect the monoamine oxidase-A in nerve cells, realize the visualization analysis of its activity and distribution in the brain tissue, and promote the application of the monoamine oxidase-A probe in the prevention and treatment of neurological diseases.

单胺氧化酶是人体内参与胺类代谢的主要酶，在维持神经递质和有机胺类水平动态平衡方面发挥着至关重要的作用。单胺氧化酶具有A和B两种构型，且两种构型由不同基因编码因而显示不同的功能特性。脑组织中单胺氧化酶-A的活性异常与神经障碍和抑郁症等多种神经性疾病密切相关。因此，开发具有神经细胞靶向性的单胺氧化酶-A的荧光探针与成像分析方法对相关疾病的诊断研究意义重大。虽然科学家们已对单胺氧化酶探针进行了大量研究，然而目前已报道的单胺氧化酶-A探针缺乏神经细胞靶向性，限制了其在生物体系中特别是脑组织中的应用。已知神经元突触表面大量表达的NMDA受体可作为定位神经细胞的靶点，因此本项目拟设计合成含有NMDA受体靶向配体和单胺氧化酶-A的特异性识别基团的双光子荧光探针，可定位检测神经细胞中的单胺氧化酶-A，实现对其在脑组织中活性和分布状态的可视化分析，促进单胺氧化酶-A探针在神经类疾病预防与防治研究中的应用。

针对目前单胺氧化酶探针对A构型的特异性及神经细胞靶向性缺乏等的问题，本项目通过将NMDA受体靶向配体和单胺氧化酶-A的特异性识别基团结合，设计合成可定位检测神经细胞中的单胺氧化酶-A的荧光探针。同时，本项目针对多种活性物质（茶多酚、氨基酸等）、结合特异性识别基团，创新合成一系列新型荧光/磷光传感器，实现对目标检测物的特异性识别。首先，合成基于氮杂咔唑结构的四齿环金属Pt(II)和Pd(II)配合物磷光分子，系统地研究了配体结构和中心金属对其光物理性质和激发态性质的影响。其次，以硼酸酯基为识别基团、结合半菁染料设计合成荧光探针，利用与不同结构茶多酚的酯交换能力不同，从而实现对多种茶多酚的比色区分检测；最后，设计合成基于芘的荧光探针，其与三价铁离子形成的金属螯合物以荧光增强的方式实现对半胱氨酸的特异性识别。本项目通过对探针识别活性物质的机理进行深入研究，揭示影响识别性能的基本规律和决定性因素，为今后荧光探针的设计开发提供指导。