Hydrogels from Renewable Resources: Advances in 3D Networks Based on Cellulose and Hemicellulose

In recent years, natural polymers have gained significant attention due to their abundance, biodegradability and versatility, offering a promising alternative to conventional synthetic polymers. Among natural polymers, cellulose and hemicellulose hold a special place, being the most abundant plant polysaccharides in nature, which serve as key structural materials in the synthesis of hydrogels. Cellulose has attracted significant attention in the development of hydrogels due to the fact that it confers desirable mechanical properties, high water absorption and biocompatibility. Hemicellulose, although with a more amorphous structure than cellulose, contains various functional groups that facilitate its chemical modification. With an environmentally friendly nature and low cost, these polysaccharides have gained major interest and are highly appreciated by both the academic and industrial communities. This review comprehensively presents recent advances in the design and development of hydrogels made from renewable biopolymers—cellulose and hemicellulose—providing an in-depth exploration of the information recorded over the past five years. The latest strategies for the synthesis of hydrogels, their formation mechanisms and their most important properties are analyzed and summarized in detail from the perspective of physical and chemical crosslinking. A comparative analysis is performed between these hydrogels, highlighting not only the advantages and disadvantages of each type of hydrogel but also the main challenges associated with the balance between mechanical strength, swelling capacity, biodegradability and cost-effectiveness. Finally, the advanced biomedical applications of these hydrogels in areas such as drug delivery, wound dressings and tissue engineering are presented in detail.