Institute of Chemical Technologies and Analytics , Vienna University of Technology (TU Wien) , A-1060 Vienna , Austria.
Anal Chem. 2019 Mar 19;91(6):3860-3868. doi: 10.1021/acs.analchem.8b04252. Epub 2019 Feb 27.
Gas-phase electrophoresis employing a nano-electrospray differential mobility analyzer (nES DMA), aka gas-phase electrophoretic mobility molecular analyzer (nES GEMMA), enables nanoparticle separation in the gas-phase according to their surface-dry diameter with number-based concentration detection. Moreover, particles in the nanometer size range can be collected after size selection on supporting materials. It has been shown by subsequent analyses employing orthogonal methods, for instance, microscopic or antibody-based techniques, that the surface integrity of collected analytes remains intact. Additionally, native nES GEMMA demonstrated its applicability for liposome characterization. Liposomes are nanometer-sized, biodegradable, and rather labile carriers (nanoobjects) consisting of a lipid bilayer encapsulating an aqueous lumen. In nutritional and pharmaceutical applications, these vesicles allow shielded, targeted transport and sustained release of bioactive cargo material. To date, cargo quantification is based on bulk measurements after bilayer rupture. In this context, we now compare capillary electrophoresis and spectroscopic characterization of vesicles in solution (bulk measurements) to the possibility of spectroscopic investigation of individual, size-separated/collected liposomes after nES GEMMA. Surface-dried, size-selected vesicles were collected intact on calcium fluoride (CaF) substrates and zinc selenide (ZnSe) prisms, respectively, for subsequent spectroscopic investigation. Our proof-of-principle study demonstrates that the off-line hyphenation of gas-phase electrophoresis and confocal Raman spectroscopy allows detection of isolated, nanometer-sized soft material/objects. Additionally, atomic force microscopy-infrared spectroscopy (AFM-IR) as an advanced spectroscopic system was employed to access molecule-specific information with nanoscale lateral resolution. The off-line hyphenation of nES GEMMA and AFM-IR is introduced to enable chemical imaging of single, i.e., individual, liposome particles.
采用纳米电喷雾差分迁移率分析仪（nES DMA）的气相电泳，又称气相电泳迁移率分子分析仪（nES GEMMA），可根据表面干燥直径，通过基于数量的浓度检测，在气相中对纳米颗粒进行分离。此外，在选择支持材料后，可以对纳米级颗粒进行尺寸选择和收集。通过采用正交方法（例如微观或基于抗体的技术）进行的后续分析表明，收集的分析物的表面完整性保持完整。此外，原生 nES GEMMA 已被证明适用于脂质体的表征。脂质体是纳米级的、可生物降解的、相当不稳定的载体（纳米物体），由一个脂质双层封装一个水腔组成。在营养和药物应用中，这些囊泡允许对生物活性货物材料进行屏蔽、靶向运输和持续释放。迄今为止，货物的定量是基于双层破裂后的总体测量。在这种情况下，我们现在将囊泡在溶液中的毛细管电泳和光谱表征（总体测量）与 nES GEMMA 后对单个、尺寸分离/收集的脂质体进行光谱研究的可能性进行比较。表面干燥、尺寸选择的囊泡分别在氟化钙（CaF）衬底和硒化锌（ZnSe）棱镜上完整收集，以便进行后续的光谱研究。我们的原理验证研究表明，气相电泳和共焦拉曼光谱的离线联用允许检测到孤立的、纳米级的软材料/物体。此外，原子力显微镜-红外光谱（AFM-IR）作为一种先进的光谱系统，被用于以纳米级横向分辨率获取分子特异性信息。引入 nES GEMMA 和 AFM-IR 的离线联用，以实现单个脂质体颗粒的化学成像。
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