Tween (polysorbate) 20 and 80 are surfactants used for the development of parenteral protein drugs, due to their beneficial safety profile and stabilisation properties. To elucidate the mechanism by which Tween 20 and 80 stabilise proteins in aqueous solutions, either by a “direct” protein to surfactant interaction and/or by an interaction with the protein film at the air–water interface, we used spectroscopic (Infrared Reflection Absorption Spectroscopy, IRRAS) and microscopic techniques (Brewster Angle Microscopy, BAM) in combination with surface pressure measurements. To this end, the impact of both types of Tweens with regard to the displacement of the protein from the air–water interface was studied. As a model protein, human serum albumin (HSA) was used. The results for the displacement of the adsorbed HSA films by Tweens 20 and 80 can partially be understood on the basis of an orogenic displacement mechanism, which depends on the critical surface pressure of the adsorbed protein film. With increasing concentration of Tween in the sub-phase, BAM images showed the formation of different domain morphologies. IRRA-spectra supported the finding that at high protein concentration in the sub-phase, the protein film could not be completely displaced by the surfactants. Comparing the impact of both surfactants, we found that Tween 20 adsorbed faster to the protein film than Tween 80. The adsorption kinetics of both Tweens and the speed of protein displacement increased with rising surfactant concentration. Tween 80 reached significant lower surface pressures than Tween 20, which led to an incomplete displacement of the observed HSA film.

吐温（聚山梨酯）20 和 80 是用于开发肠胃外蛋白质药物的表面活性剂，因为它们具有有益的安全性和稳定性。为了阐明吐温 20 和 80 在水溶液中稳定蛋白质的机制，无论是通过蛋白质与表面活性剂的“直接”相互作用和/或通过与空气-水界面处的蛋白质膜相互作用，我们使用了光谱（红外反射吸收）光谱学，IRRAS）和显微技术（布鲁斯特角显微镜，BAM）与表面压力测量相结合。为此，研究了两种类型的吐温对蛋白质从空气-水界面位移的影响。使用人血清白蛋白（HSA）作为模型蛋白质。 Tweens 20 和 80 对吸附的 HSA 膜的置换结果可以部分地基于造山置换机制来理解，该机制取决于吸附的蛋白质膜的临界表面压力。随着亚相中 Tween 浓度的增加，BAM 图像显示不同域形态的形成。 IRRA 光谱支持以下发现：在子相中蛋白质浓度较高时，蛋白质膜不能完全被表面活性剂取代。比较两种表面活性剂的影响，我们发现吐温 20 比吐温 80 更快地吸附到蛋白质膜上。两种表面活性剂的吸附动力学和蛋白质置换速度随着表面活性剂浓度的增加而增加。 Tween 80 达到的表面压力明显低于 Tween 20，这导致观察到的 HSA 薄膜不完全位移。