Institute of Chemical Technologies and Analytics, TU Wien (Vienna University of Technology), Vienna, Austria.
Department of Mechanical and Process Engineering, University of Kaiserslautern, Kaiserslautern, Germany.
Electrophoresis. 2018 May;39(9-10):1142-1150. doi: 10.1002/elps.201700382. Epub 2018 Mar 25.
Size, size distribution and molecular weight (MW) determination of nanoparticles and that are for example large polymers, are of great interest and pose an analytical challenge. In this context, nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA) is a valuable tool with growing impact. Separation of single-charged analytes according to their electrophoretic mobility diameter (EMD) starting from single-digit EMDs up to several hundred nm diameters is possible. In case of spherical analytes, the EMD corresponds to the dry nanoparticle size. Additionally, the instrument is capable of number-based, single-particle detection following the recommendation of the European Commission for nanoparticle characterization (2011/696/EU). In case an EMD/MW correlation for a particular compound class (based on availability of well-defined standards) exists, a nanoparticle's MW can be determined from its EMD. In the present study, we focused on nES GEMMA of linear and branched, water-soluble polysaccharides forming nanoparticles and were able to obtain spectra for both analyte classes regarding single-charged species. Based on EMDs for corresponding analytes, an excellent EMD/MW correlation could be obtained in case of the branched natural polymer (dextran). This enables the determination of dextran MWs from nES GEMMA spectra despite high analyte polydispersity and in a size/MW range, where classical mass spectrometry is limited. EMD/MW correlations based on linear (pullulans, oat-ß-glucans) polymers were significantly different, possibly indicating challenges in the exact MW determination of these compounds by, for example, chromatographic and light scattering means. Despite these observations, nES GEMMA of linear, monosaccharide-based polymers enabled the determination of size and size-distribution of such dry bionanoparticles.
纳米颗粒的大小、粒径分布和分子量（MW）的测定，特别是对于大聚合物而言，具有重要的研究意义和分析挑战。在这种情况下，纳米电喷雾气相电泳迁移率分子分析（nES GEMMA）是一种具有广泛影响的有价值的工具。根据电泳迁移率直径（EMD）对单电荷分析物进行分离，起始于个位数 EMD 直至几百纳米直径，这是可能的。对于球形分析物，EMD 对应于干燥纳米颗粒的大小。此外，该仪器能够根据欧洲委员会对纳米颗粒特性的建议（2011/696/EU）进行基于数量的、单颗粒检测。如果存在特定化合物类别（基于可用的明确定义的标准）的 EMD/MW 相关性，则可以从 EMD 确定纳米颗粒的 MW。在本研究中，我们专注于形成纳米颗粒的线性和支化、水溶性多糖的 nES GEMMA，并且能够获得两种分析物类别关于单电荷物种的谱图。基于相应分析物的 EMD，可以获得支化天然聚合物（葡聚糖）的出色的 EMD/MW 相关性。这使得即使在分析物高度多分散性且在经典质谱受限的大小/MW 范围内，也可以从 nES GEMMA 谱图中确定葡聚糖的 MW。基于线性（普鲁兰、燕麦-β-葡聚糖）聚合物的 EMD/MW 相关性有显著差异，这可能表明通过例如色谱和光散射手段精确测定这些化合物的 MW 存在挑战。尽管有这些观察结果，基于线性、单糖基聚合物的 nES GEMMA 仍然能够测定这些干燥生物纳米颗粒的大小和尺寸分布。
