折光率对微流成像法检测蛋白制剂不溶性微粒的影响

目的：蛋白制剂中不溶性微粒的含量是衡量样品质量的重要指标之一，为了更为准确地检测不溶性微粒的含量和粒径，本研究探讨了溶液折光率对于微流成像系统检测不溶性微粒的影响。方法：本研究以牛血清白蛋白（BSA）为例，通过常见的外界刺激条件（冷冻-解冻）制备高浓度的蛋白质不溶性微粒，并将此微粒稀释至不同折光率的溶液（由PEG1000、海藻糖制备）中，利用微流成像系统检测不溶性微粒的含量。结果：当溶液的折光率接近蛋白质不溶性微粒折光率时，利用微流成像技术检测的不溶性微粒含量低于实际的微粒含量。此外，随着溶液折光率的增加，采用微流成像技术检测出的不溶性微粒的粒径也随之减小。结论：蛋白质溶液的折光率发生改变，会影响利用微流成像技术检测不溶性微粒的准确性。因此，利用微流成像技术检测蛋白制剂中不溶性微粒时，需要考虑到制剂处方的折光率对于检测不溶性微粒的影响，必要时可以采用稀释的方法降低折光率对蛋白质颗粒的屏蔽作用。

The Eff ect of Refractive Index on Flow Imaging Detection of Subvisible Particles in Protein Formulations

Objective: The concentration of subvisible particles is one of the key factors to evaluate the quality of protein formulation. In order to accurately measure the concentration and size of subvisible particles, this study investigated the eff ect of refractive index of formulation on the subvisible particles measurement by fl ow imaging microscopy (FIM). Methods: In this study, bovine serum albumin (BSA) was taken as an example which was treated with the common stress, froze and thaw, for multiple times to generate high concentration of protein subvisible particles, and the particles were diluted by solutions with diff erent refractive indexes (prepared by trehalose, PEG1000). The concentration of subvisible particles was quantified by FIM. Results: When the refractive index of solution was similar to protein subvisible particles, the concentration of subvisible particles measured by FIM was underestimated compared to the actual result. In addition, with the increase of solution refractive index, the size of subvisible particles detected by FIM was decreased. Conclusion: The change of refractive index in protein solution will aff ect the accuracy of subvisible particles detected by FIM. Therefore, the eff ect of the refractive index of protein formulation on the measurement of subvisible particles should be carefully evaluated if using FIM to detect the concentration of subvisible particles in any protein formulations. Dilution methods may be needed to reduce the eff ect of refractive index on subvisible particle detection.