以關鍵樣品製備技術改良醣分子質譜分析效率

Novel Sample Preparation Method Enhancing Carbohydrate Analysis Efficiency in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

王家振(Chia-Chen Wang) ； 歐育孟(Yu-Meng Ou) ； 蔡易宏(Yi-Hong Cai) ； 王亦生(Yi-Sheng Wang)

《化學》 74卷3期 (2016/09) Pp. 213-222

https://doi.org/10.6623/chem.2016019

摘要

醣類 (carbohydrates) 是生物體內極為重要的分子，但傳統分析技術卻難以有效分析此類分析物。介質輔助雷射脫附游離 (matrix-assisted laser desorption/ionization，通稱為MALDI) 法搭配飛行時間式質譜儀雖然是最重要的醣分子分析法，但此技術仍深受醣類分子游離效率低與結構複雜之限制而無法廣泛運用。在分析複雜生物樣品內之醣分子時，其低游離效率之特性更使得醣化學研究難以進行。本文深入探討MALDI 法之游離特性對於醣類分析之影響，並歸納出二種可改善MALDI 樣品結晶型態及特性之樣品製備法來增加分析效率。此二方法分別是可改善醣類分子樣品均勻度的熱對流液滴乾燥技術，及可大幅提升分析靈敏度的奈米鑽石搭配三層樣品製備法。由此實驗可知正確的樣品製備技術可大幅提升醣類分子之質譜分析效率，改善定量分析的數據可信度。

關鍵字

介質輔助雷射脫附游離法 ； 樣品結晶型態 ； 熱對流 ； 靈敏度 ； 樣品均勻度 ； 奈米鑽石

並列摘要

Carbohydrates are essential biomolecules but they are difficult to be analyzed. Matrix-assisted laser desorption/ionization (MALDI) is the widest used technique to ionize carbohydrate molecules for mass spectrometric analysis. However, application of MALDI-mass spectrometry (MS) is hindered by the low ionization efficiency and complex structure of carbohydrates; the low ionization efficiency makes identification of carbohydrates from biological mixtures highly difficult. This work thoroughly discusses critical factors of MALDI reaction affecting ionization efficiency of carbohydrates. Based on the findings in a series of mechanistic studies, the inhomogeneous MALDI-sample morphology and the high-temperature condition during laser excitation seriously reduce the efficiency of MALDI-MS for carbohydrate analysis. Two sample preparation methods are proposed in the current study to resolve the problems, including the reduction of sample inhomogeneity problem with thermal-induced hydrodynamic flows during droplet drying process, and enhancing sensitivity by using diamond nanoparticles in a trilayer sample preparation method that reduces MALDI reaction temperature. Experimental results show that the efficiency of carbohydrate identification is significantly improved by changing sample morphology and property, indicating conventional MALDI method is unable to deliver satisfactory performance. The mass spectra obtained using the novel sample preparation methods provide reliable information for quantitative analysis.

並列關鍵字

Matrix-assisted laser desorption/ionization ； Sample morphology ； Hydrodynamic flow ； Sensitivity ； Homogeneity ； Diamond nanoparticles