Engineering Lignin-Based Tubular Hydrogel Scaffolds for Load-Bearing Biomedical Applications.

The development of mechanically robust, biocompatible, and biodegradable hydrogels remains a significant challenge for biomedical applications involving load-bearing soft tissues. Herein, a tubular lignin-derived hydrogel is engineered to assess its physicochemical, mechanical, and biological properties. Kraft and organosolv lignin are systematically compared at varying crosslinker concentrations to determine their effect on pore morphology, swelling behavior, and mechanical performance. Organosolv lignin formulations at 5% crosslinker concentration demonstrate an optimal balance between strength (ultimate tensile strength: 83.14 ± 0.16 kPa), flexibility (elongation: up to 176%), and hydration (swelling capacity: 261%), and are further fabricated into tubular geometries, with and without polypropylene mesh reinforcement. The reinforced tubular constructs exhibit superior mechanical strength, sustained performance over 100 fatigue cycles, and cytocompatibility with fibroblast cultures (cell viability: 85.5-86.5% after 96 h). These findings highlight the potential of lignin-based hydrogel scaffolds as sustainable, tunable platforms for a broad range of biomedical applications requiring soft, mechanically resilient, and tubular structures, such as tendon repair, vascular conduits, and nerve regeneration.