Nakano Shusuke, Yamagishi Takayuki, Aoyagi Satoka, Portz André, Dürr Michael, Iwai Hideo, Kawashima Tomoko
Department of Material and Life Science, Seikei University, 3-3-1, Kichijyoji-kitamachi, Musashino-shi, Tokyo 180-8633, Japan.
Institut für Angewandte Physik, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany.
Biointerphases. 2018 Jan 19;13(3):03B403. doi: 10.1116/1.5013219.
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one of the most powerful methods to analyze biomolecules in biological tissues and cells because it provides detailed chemical structure information and chemical images with a high spatial resolution. However, in terms of quantitative analysis, there are issues such as matrix effects that often cause secondary ion intensity changes regardless of the actual concentration in a sample. For instance, the intensity of secondary ions related to peptides is generally suppressed when lipids coexist. Since the evaluation of biomolecules is crucial to understand biological phenomena, it is required to analyze peptides or lipids without matrix effects. Therefore, the mechanism of matrix effects regarding peptides and lipids in TOF-SIMS was investigated in this study. Leu-enkephalin (YGGFL, molecular weight of 555.3 Da) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC, CHNOP, molecular weight 785.6 Da) were employed to prepare model samples. Model samples contain different weight ratios of these two molecules. The intensity of secondary ions related to the peptide or the lipid was compared with control samples containing pure leu-enkephalin or DOPC. As a result, it is indicated that the intensity of DOPC related secondary ions is strongly enhanced by coexisting leu-enkephalin, while the intensity of leu-enkephalin related secondary ions is suppressed by coexisting DOPC especially in a low concentration range of the peptide.
飞行时间二次离子质谱（TOF-SIMS）是分析生物组织和细胞中生物分子最强大的方法之一，因为它能提供详细的化学结构信息和具有高空间分辨率的化学图像。然而，在定量分析方面，存在诸如基质效应等问题，这些问题常常导致二次离子强度变化，而与样品中的实际浓度无关。例如，当脂质共存时，与肽相关的二次离子强度通常会受到抑制。由于对生物分子的评估对于理解生物现象至关重要，因此需要在无基质效应的情况下分析肽或脂质。因此，本研究对TOF-SIMS中肽和脂质的基质效应机制进行了研究。采用亮氨酸脑啡肽（YGGFL，分子量555.3Da）和1,2-二油酰基-sn-甘油-3-磷酸胆碱（DOPC，CHNOP，分子量785.6Da）制备模型样品。模型样品包含这两种分子的不同重量比。将与肽或脂质相关的二次离子强度与含有纯亮氨酸脑啡肽或DOPC的对照样品进行比较。结果表明，共存的亮氨酸脑啡肽会强烈增强与DOPC相关的二次离子强度，而共存的DOPC会抑制与亮氨酸脑啡肽相关的二次离子强度，尤其是在肽的低浓度范围内。
