Sustainable Cellulose-Based Gels: Synthesis, Chemical Modification, and Biomedical Application

The growing demand for sustainable, biocompatible, and non-toxic biomaterials has driven significant advancements in biobased gels for biomedical applications. Among these, cellulose-the most abundant renewable biopolymer-presents an ideal platform due to its inherent hydrophilicity, structural tunability, and biodegradability. This review reports the recent advancements in the processing and engineering of cellulose-based hydrogels for drug delivery systems. We systematically explore the primary synthesis routes, including physical, chemical, and hybrid cross-linking strategies. Special emphasis is placed on chemical modifications (e.g., sulfation, carboxylation, etherification, and polymer grafting) that allow precise tuning of the gel's mechanical strength, swelling kinetics, and stimuli-responsiveness (such as pH, temperature, or enzyme sensitivity). Furthermore, the review highlights essential characterization techniques-spanning structural, morphological, and rheological evaluations-used to relate cross-link density to the water-holding capacity and network homogeneity. By leveraging their highly hydrated and porous 3D architectures, these modified cellulosic networks demonstrate exceptional efficiency in drug loading, controlled release, and targeted localized therapy. Finally, we discuss current challenges, including industrial scalability and mechanical stability, and provide future perspectives on integrating nanoparticles and bioactive moieties to develop "smart" drug-eluting matrices and wound care dressings. Ultimately, this review underscores the immense potential of cellulose-based gels in advancing both clinical outcomes and circular economy goals.