Cellulose Nanocrystals: A Versatile Immobilization Matrix for Lipase Enzyme, Driving Self and Accelerated Degradation of Cellulose Acetate Films

Abstract

Cellulose acetate (CA) is an established commercial material based on an inherently biodegradable biobased resource, cellulose. However, chemical modification through acetylation to obtain thermoplastic properties significantly limits the biodegradation rate, making deacetylation the rate-determining step for subsequent biodegradation. We developed an innovative approach by immobilizing lipase (IL) enzymes on cellulose nanocrystals (CNCs), and embedding the resulting CNC-IL into CA films to accelerate the biodegradation of CA. This offers a platform for controlling and accelerating the degradation of CA, as demonstrated by significantly enhanced degradation rates under self-degradation and enzymatic degradation in aqueous medium, including artificial seawater, and under simulated industrial composting conditions. We also explored the underlying mechanisms by detailed characterization of the degradation process in different degradation environments, demonstrating that the enzyme-embedded approach and utilization of CNCs as an immobilization matrix holds significant promise for catalyzing the biodegradation process by initiating self-degradation from inside the polymer material. This approach thus holds promise in accelerating the degradation process and ensuring degradation even under less favorable environmental conditions.