Recent advances in three-dimensional bioprinted nanocellulose-based hydrogel scaffolds for biomedical applications

Cellulose is the most abundant biopolymer on earth. Due to its excellent physical and biological traits, particularly its biocompatibility, biodegradability, and low cytotoxicity, it has become promising material for biomedical applications. Moreover, cellulose-based hydrogels are the best-suited for biomedical applications due to their biocompatibility and ability to be controllably molded into different shapes. Therefore, in recent years, a significant amount of research has been focused on preparing cellulose-based materials such as cellulose hydrogels with different morphologies and functional groups. Among the various methods used to prepare cellulose-based hydrogels, three-dimensional (3D) bioprinting has been used to generate these materials for drug delivery, tissue engineering, and scaffolds due to the customizability of their complex morphology. To date, many studies have been published on the important aspects of the bioprinting of cellulose-based hydrogels; however, despite an increasing amount of research in this area, various issues still exist that prevent their advanced applications. In addition, cellulose exists in various forms and, depending on its type, exhibits unique physical and rheological properties. It is, therefore, meaningful to fabricate advanced cellulose-based hydrogels only when the properties of the cellulose derivatives are well understood. In this review, the emerging approaches of the design and fabrication of advanced cellulose-based biomaterials (i.e., cellulose nanocrystals, cellulose nanofibrils, and bacterial nanocellulose) are discussed, as well as their roles in traditional and emerging (3D bioprinting) biomedical fields, mainly in drug delivery, wound dressings, tissue engineering, and scaffold applications.