Development of a synergistic antimicrobial hydrogel coating by lysozyme amyloid fibrils and silver-glutathione bio-coordination nanofibrils for long-term preservation of perishable fruits

Lysozyme amyloid fibrils (LAFs) hydrogels exhibit an enhanced antibacterial activity in food preservation compared to pristine lysozyme molecule. However, intrinsic limitations of low gel strength, insufficient coverage and rapid antibacterial effectiveness decay of LAFs restrict their large-scale applications in long-term food preservation. Herein, the co-assembly strategy was proposed to construct a supramolecular nanofibrils hydrogel coating using LAFs and GSH-Ag nanofibrils as building blocks. As expected, intermolecular hydrogen bonding and electrostatic interactions between these two nanofibrils were principally responsible for the co-assembly behavior and silver nanoparticles were found in the co-assembly networks. The co-assembly hydrogel demonstrated around 8.5 folds enhanced gel strength, favorable sprayable property and improved biocompatibility. GSH molecules imparted the imperative antioxidant activity to the co-assembly hydrogel. Sustained release of silver species and LAFs from the hydrogel synergistically exerted bactericidal activity against both Gram-positive and Gram-negative bacteria. Moreover, the co-assembly hydrogel exhibited an improved long-term preservation effect on two types of grapes (Shine Muscat and Red Globe), which could maintain freshness and nutrients of these perishable samples at least 25 days.