Preparation and characterization of a highly porous, rigid cellulose-based hydrogel for biomedical and biotechnological applications

This study introduces a novel approach for preparing rigid, porous cellulose hydrogels using cellulose acetate as the starting material. The method relies on the slow hydrolysis of acetyl groups directly in an acetone/aqueous ammonia solution. The gradual pace of the process creates conditions favourable for reconstructing of inter- and intramolecular hydrogen bonding networks between the newly formed hydroxyl groups in the cellulose, resulting in a rigid three-dimensional structure. The hydrogels demonstrated excellent mechanical properties, with a compressive (Young's) modulus of up to 43 MPa and an elastic modulus of up to 0.23 MPa. X-ray analysis indicated that the cellulose hydrogels are semi-crystalline, with a crystallinity index of 43–45% and an average crystallite size of 4.3–4.5 nm. Wide-angle X-ray diffraction, along with FT-IR and Raman spectroscopy, confirmed that the gels belong to the cellulose II structural modification. The porous structure of the hydrogels was characterized using inverse size exclusion chromatography, revealing exclusion limits for linear polymers of up to 4 × 10⁶ Da. Thanks to their enhanced mechanical properties and high porosity, crushed hydrogels show potential applications in column technologies for protein chromatography and heterogeneous biocatalysis processes with immobilized enzymes. In film form, the gels' elasticity makes them promising candidates for biomedical applications, such as wound dressings or artificial skin. Furthermore, the lyophilized gels create porous structures suitable for vascularization and bone tissue ingrowth, positioning them as ideal scaffolds for bone tissue engineering.