Lysozyme amyloid fibril templated phenolic-iron hydrogels cross-linked with genipin

Foods can be recognized as soft condensed matters composed with multiple ingredients. Inspired by mussel, a complex soft condensed matter was developed via the molecular physical interactions among protein amyloid fibrils, polyphenols and metal ions, combined with spontaneous genipin cross-linking of the protein nanofibrils as well as its induced polyphenol polymerization. The Cryo-TEM images showed metal ions competed with the protein nanofibrils in associating with polyphenols, leading to first increase and then decrease in strength of the amyloid fibril templated Fe3+-ligand-EGCG hydrogels. The Cryo-SEM images indicated that cross-linking of the protein nanofibrils with a natural bioactive molecule genipin made the microstructure network become denser, which accounted for the elevation of gel stiffness for more than one order of magnitude. Furthermore, it is interesting that cross-linking of the protein nanofibrils with genipin unexpectedly caused oxidization and polymerization of tea polyphenols, resulting in microstructure that became denser with decreased mesh size. Gel strength of the genipin cross-linked amyloid fibril templated EGCG-Fe3+ hydrogels was increased for more than two orders of magnitude. Therefore, the system studied provides a concept-to-practice of investigating the in-teractions among various ingredients in foods at multi-length scales, which could be applicable in further design of foods with different properties.