Bio-printed cellulose nanocrystal: Processing, fabrication, and biomedical applications

Background Cellulose nanocrystals (CNCs) are sustainable high-strength nanomaterials for cutting-edge biomedical 3D bioprinting and implantable devices. Aim This review summarizes the aspects of CNC synthesis, printing strategies, biomedical applications, challenges, and prospects. Method The review was carried out from the literature search of Scopus/Web of Science using keywords cellulose nanocrystals (CNC), 3D bioprinting, bioink, rheology, alignment, and hydrogel (2018-2025). Discussion on novelty This review condenses the mechanistic understanding of relationships between the CNC surface chemistry, aspect ratio of particulate, and flow-induced alignment of particles and their connection to bioink printability rheology and anisotropic biofunctionality. These highlights innovations targeting the methacrylation, TEMPO-mediated carboxylation, and hybrid processing, which will enable the covalent crosslinking, tunable degradation, and enhanced thermal stability. New contributions are suggestions for accessible concentration windows for printability in CNC applications; definition of the alignment thresholds in conditions of nozzle sheathing; and proposals for cohesive and standard reporting of rheological data. This also finds a gap in translational aspects of sterilization compatibility, batch reproducibility, and in vivo degradation studies that need prioritization of research and regulatory validation pathways. Conclusion CNC-based 3D bioprinting provides a sustainable and versatile platform for creating mechanically tough, shear-responsive, and anisotropic biomedical constructs. With the recent breakthroughs in surface modification, alignment control, and the use of hybrid bioinks, there is great potential for employing CNC-enabled systems in applications that require personalized medicine, controlled drug delivery, and next-generation tissue engineering applications.