Division of Therapeutic Performance, Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland.
Division of Biology, Chemistry and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland.
Curr Protoc. 2022 Apr;2(4):e406. doi: 10.1002/cpz1.406.
The physicochemical properties of complex drug formulations, including liposomes, suspensions, and emulsions, are important for understanding drug release mechanisms, quality control, and regulatory assessment. It is ideal to characterize these complex drug formulations in their native hydrated state. This article describes the characterization of complex drug formulations in a frozen-hydrated state using cryogenic scanning electron microscopy (cryo-SEM). In comparison to other techniques, such as optical microscopy or room-temperature scanning electron microscopy, cryo-SEM combines the advantage of studying hydrated samples with high-resolution imaging capability. Detailed information regarding cryo-fixation, cryo-fracture, freeze-etching, sputter-coating, and cryo-SEM imaging is included in this article. A multivesicular liposomal complex drug formulation is used to illustrate the impact of different cryogenic sample preparation conditions. In addition to drug formulations, this approach can also be applied to biological samples (e.g., cells, bacteria) and soft-matter samples (e.g., hydrogels). © Published 2022. This article is a U.S. Government work and is in the public domain in the USA. Basic Protocol 1: Cryo-fixation to preserve the native structure of samples using planchettes Alternate Protocol: Cryo-fixation to preserve the native structure of biological samples on sapphire disks Basic Protocol 2: Sample preparation for cross-sectional cryo-SEM imaging Basic Protocol 3: Cryo-SEM imaging and microanalysis.
复杂药物制剂（包括脂质体、混悬剂和乳剂）的物理化学性质对于理解药物释放机制、质量控制和法规评估非常重要。在其水合状态下对这些复杂药物制剂进行特性描述是理想的。本文描述了使用低温扫描电子显微镜（cryo-SEM）对冷冻水合状态下的复杂药物制剂进行特性描述。与光学显微镜或室温扫描电子显微镜等其他技术相比，cryo-SEM 结合了研究水合样品的优势和高分辨率成像能力。本文包括关于 cryo-固定、cryo-断裂、冷冻蚀刻、溅射镀膜和 cryo-SEM 成像的详细信息。使用多泡囊脂质体复杂药物制剂来说明不同 cryogenic 样品制备条件的影响。除了药物制剂外，这种方法还可以应用于生物样品（例如细胞、细菌）和软物质样品（例如水凝胶）。© 2022 年出版。本文为美国政府的作品，在美国属于公有领域。基本方案 1：使用平板将样品进行 cryo-固定以保留其天然结构备选方案 1：使用蓝宝石盘将生物样品进行 cryo-固定以保留其天然结构基本方案 2：用于 cryo-SEM 成像的截面样品制备基本方案 3：Cryo-SEM 成像和微分析。
