Fabrication of Thermo-Responsive Polymer-MOF@cellulase Composites with Improved Catalytic Performance for Hydrolysis of Cellulose.

Metal-organic frameworks (MOFs) are considered as an ideal enzyme support because of their porous structural superiority. However, MOFs@enzyme composites have usually compromised their hydrolysis efficiency due to the narrow space inducing unfavourable enzyme conformations. Herein, a thermo-responsive poly(N,N-dimethylacrylamide) (PD) was fixed onto the surface of UiO-66-NH₂ (UiO) through a post-synthetic modification protocol. Using poly(2-vinyl-4,4 dimethylazlactone) (V) as a linker, PVD-UiO@cellulase composites were fabricated after cellulase was immobilized onto the UiO surface through covalent bonding. The composites conferred favorable cellulase conformations, boosting hydrolysis efficiency and stability, which relied on the soft PVD shell and confinement effect yielded by the curled PVD chains at high temperatures. Compared with free cellulase, the proposed composites exhibited a 33.1-fold enhancement of the K_cat values at 50 °C. The PVD-UiO@cellulase composites were applied to the hydrolysis of cellulose in the stalks and leaves of Epipremnum aureum. The results highlight the potential of smart PVD-UiO@cellulase composites in the hydrolysis of cellulose, affording a valuable platform for the preparation of unique MOFs@enzyme composites and their industrial applications.