Arabinoxylan Hydrogels as a Novel Encapsulation System with Triggered Release by Gut Bacterial Enzymes

Abstract Arabinoxylans are ubiquitous plant biopolymers present in large amounts in cereal bran, a major underutilized side stream of the agrifood industry. Their unique structural properties make them promising matrices for the design of hydrogels for nutritional and pharmacological applications. We report the controlled production of laccase-crosslinked arabinoxylan hydrogels derived from wheat (WAX) and rye (RAX) bran with tuned porous properties via the modulation of freeze-drying temperature, with implications for biostimulatory encapsulation and release. Freezing in liquid nitrogen generated smaller pore sizes in both systems, while RAX hydrogels consistently displayed higher porosity and elastic moduli than WAX hydrogels, reflecting differences in chemical cross-linking density, solid content, and physical network organization. Rheological analyses revealed a correlation between solid content and porosity with enhanced elastic properties, highlighting the poroelastic contributions to hydrogel mechanics. The hydrogels exhibited varying encapsulation and retention ability of the target biomolecules (glucose, tryptophan, and green fluorescent protein), reflecting differences in molecular size and chemistry. Retention of small molecules was dictated primarily by matrix affinity, whereas larger proteins were retained predominantly based on pore size and porosity. Enzymatic degradation by a gut bacteria β-xylanase-triggered cargo release, demonstrating the potential of arabinoxylan hydrogels, as targeted gastrointestinal delivery platforms.