Wang Xiaodong, Han Jun, Yang Juncong, Pan Jingxi, Borchers Christoph H
University of Victoria - Genome British Columbia Proteomics Centre , Vancouver Island Technology Park, #3101-4464 Markham St. , Victoria , BC V8Z 7X8 , Canada . Email:
Department of Biochemistry and Microbiology , University of Victoria , Petch Building Room 207, 3800 Finnerty Rd. , Victoria , BC V8P 5C2 , Canada.
Chem Sci. 2015 Jan 1;6(1):729-738. doi: 10.1039/c4sc01850h. Epub 2014 Sep 16.
A novel technique, termed matrix coating assisted by an electric field (MCAEF), for enhancing tissue imaging by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was developed in this study. In this technique a static and uniform electric field is applied to sliced tissue sections during matrix spray-coating, resulting in the enrichment of positively or negatively chargeable analytes in the MALDI matrix layer. Experimental results show that MCAEF not only increased the sensitivity of lipid and protein detection across the board in the subsequent MALDI-MS analyses, but also resulted in successful imaging of a larger number of analytes. MALDI imaging enhancement with MCAEF was observed for various tissues (rat liver, rat brain, and porcine adrenal gland) and with different MALDI matrices (, quercetin, 2-mercaptobenzothiazole, dithranol, 9-aminoacridine, and sinapinic acid) and the sensitivity increases were independent of the solvent compositions and pH values of the matrix solutions. Taking rat brain as an example, MCAEF led to the on-tissue detection and imaging of 648 identified lipids by combining positive and negative ion detection by MALDI-Fourier transform ion cyclotron resonance MS and with quercetin as the matrix, as compared to only 344 lipids without MCAEF. For protein imaging, up to 232 protein signals were successfully detected in rat brain tissue sections by MALDI-time-of-flight MS within a mass range of 3500 to 37 000 Da, as compared to 119 without MCAEF. MCAEF also enabled the detection of higher molecular-weight proteins. These results demonstrate the advantages of MCAEF for overall performance improvements in MALDI imaging and we believe that this technique has the potential to become a standard practice for MALDI tissue imaging.
本研究开发了一种名为电场辅助基质包被（MCAEF）的新技术，用于通过基质辅助激光解吸/电离质谱（MALDI-MS）增强组织成像。在该技术中，在基质喷雾包被过程中对切片组织施加静态均匀电场，导致可带正电或负电的分析物在MALDI基质层中富集。实验结果表明，MCAEF不仅全面提高了后续MALDI-MS分析中脂质和蛋白质检测的灵敏度，还成功实现了更多分析物的成像。在各种组织（大鼠肝脏、大鼠大脑和猪肾上腺）以及不同的MALDI基质（、槲皮素、2-巯基苯并噻唑、地蒽酚、9-氨基吖啶和芥子酸）中均观察到MCAEF增强了MALDI成像，且灵敏度的提高与基质溶液的溶剂组成和pH值无关。以大鼠大脑为例，通过MALDI-傅里叶变换离子回旋共振质谱结合正离子和负离子检测，并以槲皮素作为基质，MCAEF实现了对648种已鉴定脂质的组织上检测和成像，而没有MCAEF时仅能检测到344种脂质。对于蛋白质成像，通过MALDI-飞行时间质谱在3500至37000 Da质量范围内成功检测到大鼠脑组织切片中多达232个蛋白质信号，而没有MCAEF时为119个。MCAEF还能够检测更高分子量的蛋白质。这些结果证明了MCAEF在改善MALDI成像整体性能方面的优势，我们相信该技术有潜力成为MALDI组织成像的标准方法。
