Nanocellulose polymorphs for biomedical applications: Recent advances, prospects and challenges - A review

In the modern era, biodegradable and eco-friendly products are crucial for ensuring a sustainable future. Nanocellulose, derived from cellulose, is widely adopted for modern applications due to its versatility, sustainability, and biodegradability. Nanocellulose polymorphs, such as Cellulose Nanocrystals (CNC), Cellulose Nanofibrils (CNF), and Bacterial Nanocellulose (BNC), have found successful utilization in biomedicine due to their high strength and rigidity (CNC), toughness and flexibility (CNF), and superior biocompatibility and water retention (BNC); all while being lightweight, sustainable, and outperforming synthetic polymers, metals, and traditional cellulose in specialized applications. Nanocellulose excels in biomedicine due to its anisotropic strength, customizable porosity, and biocompatibility, which presents challenges, such as balancing surface functionalization with immunogenicity, optimizing enzymatic biodegradation kinetics, and navigating ISO-compliant manufacturing protocols for clinical-grade reproducibility. This paper encompasses literature published from 2006 to 2025, focusing on the applications of nanocellulose in the medical sector, including drug delivery systems, tissue engineering, wound healing, biosensors, medical implants, and dialysis membranes. This review also highlights the challenges of commercializing and utilizing nanocellulose in clinical settings. Some key issues include scaling up production processes, ensuring reproducibility, meeting regulatory and safety standards, assessing its environmental impact, potential cytotoxicity, and the lack of standardized protocols for characterization and testing.