FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA.
Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina, USA.
J Mass Spectrom. 2022 Aug;57(8):e4875. doi: 10.1002/jms.4875.
In mass spectrometry imaging (MSI) applications of infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI), an exogenous ice layer is the gold standard for an energy-absorbing matrix. However, the formation of the ice matrix requires additional time and instrument hardware, so glycerol was investigated herein as an alternative to the ice matrix to potentially improve spatial resolution and ionization, while decreasing experiment time. Glycerol solutions of varying concentrations were sprayed over top of rat liver tissue sections for analysis by IR-MALDESI and compared to the typical ice matrix condition. Additionally, we tested if combining the ice matrix and glycerol matrix would further improve analyses. Matrix conditions were evaluated by comparing ion abundance of six lipid species, the laser ablation spot diameter, and number of METASPACE annotations. The ion abundances were also normalized to the volume of tissue ablated to correct for lower abundance values due to less ablated tissue. It was observed that utilizing a 50% glycerol matrix without ice provides improved spatial resolution with lipid abundances and annotations comparable to the ice matrix standard, while decreasing the time required to complete an IR-MALDESI tissue imaging experiment.
在红外辅助激光解吸电喷雾电离（IR-MALDESI）的质谱成像（MSI）应用中，外源冰层是能量吸收基质的金标准。然而，冰基质的形成需要额外的时间和仪器硬件，因此本文研究了甘油作为冰基质的替代物，以潜在地提高空间分辨率和离子化，同时缩短实验时间。将不同浓度的甘油溶液喷洒在大鼠肝组织切片上，通过 IR-MALDESI 进行分析，并与典型的冰基质条件进行比较。此外，我们还测试了是否可以将冰基质和甘油基质结合使用以进一步改善分析。通过比较六种脂质种类的离子丰度、激光烧蚀斑点直径和 METASPACE 注释数量来评估基质条件。还将离子丰度归一化为组织烧蚀的体积，以校正由于组织烧蚀较少而导致的丰度值较低的情况。结果表明，使用不含冰的 50%甘油基质可以提高空间分辨率，并且脂质丰度和注释与冰基质标准相当，同时缩短了完成 IR-MALDESI 组织成像实验所需的时间。
