A sulfated arabinose-rich polysaccharide hydrogel from Chaetomorpha valida: preparation, properties and mechanisms

Marine polysaccharides such as alginate, agar, and carrageenan are widely used as commercially hydrocolloids for hydrogels fabrication. In this study, we report the development of a novel sulfated arabinose-rich heteropolysaccharide (CVP) hydrogel from the edible green alga Chaetomorpha valida. CVP is a high-molecular-weight polysaccharide that spontaneously forms hydrogels (CVG) at room temperature and exhibits thermal reversibility. Rheological and textural analyses confirm the viscoelastic properties of CVG, while three-interval thixotropy (3ITT) and gel fracture tests reveal remarkable structural recovery and self-healing capabilities. Congo red assays indicate the presence of a three-dimensional helical conformation, and microscopic observations suggest that gelation is driven by molecular entanglement and hydrogen bonding. Further crosslinking of CVG with sodium tetraborate produces a borate-modified hydrogel (CVBG) with enhanced mechanical strength and brittleness, tunable by borate concentration. Fourier-transform infrared (FT-IR) spectroscopy indicates that borate crosslinking occurs via boron‑oxygen bond formation. This thermally reversible, self-healing hydrogel demonstrates excellent biocompatibility and water retention, highlighting its potential for applications in food additives, preservation systems, and biomedical engineering.