Nano-biocatalytic Systems for Cellulose de-polymerization: A Drive from Design to Applications

Cellulases are robust biocatalysts that offer applications in industrial bioprocesses, such as catalytic hydrolysis, biopolishing, enhancing the softness of the fabric, increasing the digestibility of cereal-based food, bioconversion, and biotransformation of cellulosic materials to fermentable sugars, enzymatic deinking, bio-pulping, clarification of fruit juices, etc. However, like many other enzymes, cellulases also encounter instability, low recovery, thermal denaturation, and recyclability. To address these concerns, immobilization has become a robust approach to retain the enzyme's activity and lessen production costs. Nanobiocatalysts have been used as potential nano-carriers both in single and multienzyme complexes. With the contribution of nanotechnology, several precisely advanced polymers have been designed that serve as perfect support carriers/matrices for immobilizing enzymes. These nano-supported catalysts exhibit exclusive physicochemical, mechanical, and practical features which depolymerize the cellulose and reinforce its efficiency for varied applications. The nanoparticles can be linked to the enzyme in multiple ways, including direct conjugation to the NPs surface, electrostatic adsorption, coupling using the specific affinity of proteins, and covalent attachment to surface-modified NPs. The work emphasizes the characteristics and applications of chitosan, alginates, silica gel, cross-linking enzyme aggregates, magnetic nanoparticles, carbon nanotubes, and hybrid nanosupports as excellent materials for cellulase immobilization. The work further provides an insight into industrially related potential applications of immobilized cellulases.