Isolation and Surface Modification of Nanocellulose: Necessity of Enzymes over Chemicals

Nanocellulose is an emerging sustainable biomaterial with exceptional physicochemical properties. It can be isolated from inexpensive renewable cellulosic biomass. Wood cellulose is the most extensively used biomass for the isolation of nanocellulose. Yet, owing to their hydrophilic nature, their utilization is restricted to applications involving hydrophilic or polar media, which limits their exploitation. With the presence of a large number of chemical functionalities within their structure, these building blocks provide a unique platform for significant surface modification through various methods. On the other hand, significantly used hazardous chemicals make the process environmentally unfriendly. Furthermore, recovery of used chemicals and toxicity of final products are the biggest challenges. To overcome these problems, the enzymatic approach is an emerging trend for isolation and surface modification of nanocellulose. This review assembles current knowledge in the research and development of nanocelluloses from cellulosic biomass and emphasizes the enzymatic routes developed so far for isolation, production, and functionalization.