Skin-inspired all-natural ionic biogel

Abstract Natural material-based hydrogels are considered ideal candidates for building robust bio-interfaces due to their environmentally sustainable nature and biocompatibility. However, these hydrogels often suffer from limitations such as weak mechanical strength, low water resistance, and poor ionic conductivity. Here, inspired by the role of natural moisturizing factor (NMF) in skin, we propose a simple yet versatile strategy to fabricate all-natural ionic biogel that is highly resilient, ionically conductive, anti-dehydrated, and fully degradable, without requiring any chemical modification. A well-balanced combination of gelatin and NMF gives rise to a significant enhancement in the mechanical strength, ionic conductivity, and water retention capacity of the biogel than pure gelatin hydrogel. The biogel manifests temperature-controlled reversible fluid-gel transition properties due to the triple-helix junctions of gelatin, which enables in situ gelation on various substrates, resulting in conformal contact and dynamic compliance with curved surfaces. Due to its salutary properties, the biogel can serve as an effective and biocompatible interface for high-quality and long-term electrophysiological signal recording. These findings provide a general and scalable strategy for the design of natural material-based hydrogels with tailored functionalities to meet diverse application needs.