基于金属标记的同位素稀释激光剥蚀ICP-MS在脑组织中Aβ肽的原位绝对定量研究

脑组织不同脑区中Aβ肽的聚积与阿尔茨海默症(Alzheimer disease, AD)的成因、发展密切相关，实现脑组织中Aβ肽的原位、微区定量对于AD病的病理学研究具有重要意义。激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）具有对固体中元素及同位素的直接分析能力，但却无法对生物样品中蛋白等生物大分子进行原位、微区分析，因此无法实现对脑组织样品中Aβ肽的原位、微区绝对定量。本项目中，针对LA-ICP-MS难以实现大分子原位绝对定量的难题，将LA-ICP-MS与金属标记和同位素稀释技术相结合，开展脑组织切片中Aβ肽的金属标记及免疫反应条件、金属标签与Aβ摩尔比关系、金属标签与稀释剂同位素平衡条件、稀释剂形态及添加方式、原位同位素比测量等关键技术研究，建立基于金属标记-同位素稀释的LA-ICP-MS在脑组织中Aβ的原位、微区绝对定量方法，为阐明AD症的成因、发展等研究提供高准确度方法支撑。

Previous studies showed that heterogeneous accumulation of Aβ peptide in brain has close relationship with the cause and development of Alzheimer’s disease (AD). To investigate the quantitative imaging of this biomarker in different brain regions can help to understand the pathological process of AD disease. Laser ablation (LA) coupled with inductively coupled plasma mass spectrometry (ICP-MS) is a versatile tool for direct trace elemental and isotopic analysis of solids. However, it is still very challenging for in-situ quantitative imaging of macromolecules in biological samples. In this project, quantitative imaging strategy of Aβ peptide in AD mice brain tissue will be developed by using isotope dilution LA-ICP-MS in combination with metal-labelled immunoprobes. The immunochemical reaction conditions including labelling yield, labelling reproducibility, and number of labels per available antibody will be fully investigated. Moreover, the isotope dilution conditions including enriched isotopic spike addition, isotope exchange, isotope species and isotope ratio measurement will also be fully studied. This project will help to improve the accuracy of macromolecule quantitative image by LA-ICP-MS, and has the potential to be useful to understand such complex brain mechanisms of AD pathology.