Mussel-inspired adhesive and tough hydrogel for drug release based on lignin-containing cellulose nanofiber

Lignin-containing cellulose nanofiber (LCNF)-based hydrogels are promising eco-friendly biomaterials, yet the role of lignin in enhancing their adhesion and mechanics remains to be explored. Herein, quaternized lignin-containing cellulose nanofibers (QALCNFs) with varying lignin contents were synthesized from bagasse using a deep eutectic solvent (DES). The relationship between lignin content and the adhesion and mechanical properties of QALCNF hydrogels was systematically investigated. Results demonstrated that lignin in QALCNFs enhanced the hydrogel's gelation time, adhesion and mechanical properties through the provision of quinone/catechol groups, which undergo reversible free radical transformations. As the lignin content decreased, the nanofiber bundles gradually transitioned into more uniform nanofibers, forming a hydrogel with a hierarchical porous structure, superior adhesion, and mechanical properties. Conversely, insufficient lignin content weakened the hydrogel's performance by reducing the quinone/catechol content and decreasing hydrogel porosity. Consequently, QAMLCNF-H exhibited outstanding toughness (2400 J/m²), adhesion strength (114.6 kPa), and high porosity (∼86 %), along with sustained drug release performance, effective antibacterial properties, and excellent cytocompatibility. This study provides a comprehensive understanding of how lignin content in QALCNFs influences hydrogel adhesion, mechanical properties, and drug release behavior, offering valuable insights for the development of high-performance LCNF-based hydrogel biomaterials.