Abstract：
Isotope dilution (ID) analysis is considered one of the most accurate quantitative methods. However, it has not been widely applied to the quantitative imaging of trace elements in biological samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), mainly because of difficulties in homogeneously mixing enriched isotopes (the spike) with the sample (e.g., a tissue section). In this study, we present a novel method for the quantitative imaging of trace elements (copper and zinc) in mouse brain sections using ID-LA-ICP-MS. We used an electrospray-based coating device (ECD) to evenly distribute a known amount of the spike (65Cu and 67Zn) on the sections. The optimal conditions for this process involved evenly distributing the enriched isotopes on mouse brain sections mounted on indium tin oxide (ITO) glass slides using the ECD with the 10 mg g-1 ɑ-cyano-4-hydroxycinnamic acid (CHCA) in methanol at 80 °C. The mass of the spiked isotopes and the tissue sections on the ITO slides was calculated by weighing them on an analytical balance. Quantitative images of Cu and Zn in Alzheimer\'s disease (AD) mouse brain sections were obtained using ID-LA-ICP-MS. These imaging results showed that Cu and Zn concentrations in various brain regions typically ranged from 10 to 25 μg g-1 and 30-80 μg g-1, respectively. But it is worth noting that the hippocampus contained up to 50 μg g-1 of Zn, while the cerebral cortex and hippocampus had Cu contents as high as 150 μg g-1. These results were validated by acid digestion and solution analysis with ICP-MS. The novel ID-LA-ICP-MS method provides an accurate and reliable means for quantitative imaging of biological tissue sections.
摘要：
同位素稀释(ID)分析被认为是最准确的定量方法之一。然而,激光烧蚀电感耦合等离子体质谱(LA-ICP-MS)对生物样品中微量元素进行定量成像,主要是因为富集同位素(尖峰)与样品均匀混合的困难(例如，组织切片)。在这项研究中,我们提出了一种使用ID-LA-ICP-MS对小鼠脑切片中的微量元素（铜和锌）进行定量成像的新方法。我们使用基于电喷雾的涂覆装置(ECD)将已知量的尖峰(65Cu和67Zn)均匀地分布在切片上。此过程的最佳条件包括使用ECD在80°C的甲醇中使用10mgg-1α-氰基-4-羟基肉桂酸（CHCA）将富集的同位素均匀分布在安装在氧化铟锡（ITO）载玻片上的小鼠脑切片上。通过在分析天平上称重来计算ITO载玻片上的掺杂同位素和组织切片的质量。使用ID-LA-ICP-MS获得阿尔茨海默病（AD）小鼠脑切片中Cu和Zn的定量图像。这些成像结果表明，各个大脑区域的Cu和Zn浓度通常分别为10至25μgg-1和30-80μgg-1。但值得注意的是，海马体含有高达50μgg-1的锌，大脑皮层和海马的Cu含量高达150μgg-1。这些结果通过酸消解和ICP-MS溶液分析得到了验证。新型ID-LA-ICP-MS方法为生物组织切片的定量成像提供了准确可靠的手段。
