Effect of gelation pH on whey protein aerogel properties

Due to their bioinspired self-assembly and biocompatibility, protein-based aerogels have drawn growing interest inbiomedical applications. With its excellent gelling and self-assembly properties, whey protein isolate (WPI) represents apromising source for the fabrication of biodegradable and homogeneous tunable aerogels. Gelation pH has a significantimpact on the morphological homogeneity of protein biomaterials, which is essential for controlling tissue-implantinteractions. In this study, WPI aerogels were produced without gelation-induced agents (followed by a supercritical CO2drying process), and the effect of the gelation pH was investigated by varying its value from 2 to 11. Aerogels with a highfluid absorption capacity ( ~ 760%), specific surface area (312 m2. g−1), and pore volume (1.02 cm3. g−1) were obtained bygelation at neutral to mildly alkaline conditions (pH 7-8.5). Because of their excellent fluid absorption capacity, theseaerogels have the potential to be a biocompatible wound dressing. On the other hand, aerogels from acidic gelationconditions (pH < 3) dissolved or disintegrated during fluid absorption. Monolithic aerogels were obtained by increasing thegelation pH. However, as the gelation pH approached the WPI isoelectric region (pH 4-6) or extreme alkaline pH (pH ≥ 9),aerogels presented low specific surface area and fluid absorption capacity. Overall, this study confirms that gelation pHaffects the structural and functional properties of WPI aerogels and offers a systematic investigation of the effect of gelationpH on the resulting aerogels.