Sustainable collagen-xanthan gum hydrogel scaffolds with super-swelling behavior and biostimulatory activity for agricultural applications.

Semi-interpenetrating hydrogel scaffolds based on collagen and xanthan gum (XG) were developed as fully bio-based, superabsorbent materials aimed at agricultural applications under limited water availability. Hydrogels containing increasing XG fractions (30-70 wt%) were synthesized and systematically characterized in terms of physicochemical properties, hydrolytic, redox, and enzymatic degradation behavior, nutrient release, and biological response using tomato (Solanum lycopersicum) cells, seedlings, and plants. The resulting semi-IPNs exhibited a fibrillar-granular microstructure, with porosity (2.18-6.03 μm) and granule size (2.88-8.62 μm) increasing as a function of XG content. The formulation with the highest XG content (GX70) displayed a maximum swelling capacity of ∼3585%, enhanced thermal resistance (∼70%), and a pronounced increase in mechanical strength (≈2568% increase in storage modulus), together with sustained structural integrity over 30 days under biodegradation conditions. XG-containing hydrogels enabled the gradual release of plant-relevant compounds, reaching total protein concentrations up to ∼19.5 mg/L and phosphorus levels of ∼1.7 mg/L. Biological assays demonstrated excellent biocompatibility, as direct contact between hydrogels and tomato-derived cells supported adhesion, migration, and proliferation and was associated with increased metabolic activity. At the whole-plant level, hydrogel application did not induce adverse effects and supported normal growth during 60 days of cultivation under low-input conditions. These results demonstrate that collagen-XG semi-IPN hydrogels constitute multifunctional biomaterial platforms with tunable hydration, degradation, and nutrient-release properties. By integrating material-level characterization with cellular and early plant evaluations, this study provides a structure-function framework supporting their potential for sustainable water and resource management in agriculture.