The infiltration of ions into hydrogel matrix could significantly affect the microstructure and macroscopic mechanics of the gels. Here, the Hofmeister effect of various salts on the whey protein isolate hydrogels with fine-stranded and particulate microstructures is investigated by soaking the preformed hydrogels in the sodium salts of different anions. The infiltration of kosmotropic anions yield stiffer hydrogels, whereas the chaotropic anions soften the hydrogels. The hydrogels with fine-stranded microstructures are more sensitive to the salts comparing to the particulate ones due to the microscopic phase transitions and enhanced hydrophobic interactions between polymer chains occurred in fine-stranded hydrogels. Besides, despite the significant difference in water binding ability of different salts, the water holding capacity of the salt-treated hydrogels was mainly determined by the gel stiffness instead of the salt types. Similar mechanical responses of BSA and egg white protein hydrogels to the Hofmeister series was also demonstrated, suggesting that the results shown here could potentially be generalized for other globular protein hydrogels.

离子渗透到水凝胶基质中会显着影响凝胶的微观结构和宏观力学。在这里，通过将预制的水凝胶浸泡在不同阴离子的钠盐中，研究了各种盐对具有细链和微粒微结构的乳清蛋白分离水凝胶的霍夫迈斯特效应。促渗阴离子的渗透产生较硬的水凝胶，而离液阴离子使水凝胶软化。与微盐相比，具有细链微结构的水凝胶对盐更敏感，这是由于在微链水凝胶中发生了微观相变和聚合物链之间疏水性相互作用增强。此外，尽管不同盐的水结合能力差异很大，盐处理水凝胶的持水能力主要由凝胶刚度决定，而不是由盐的类型决定。也证明了BSA和蛋清蛋白水凝胶对Hofmeister系列具有相似的机械响应，这表明此处显示的结果可能会推广到其他球状蛋白水凝胶。