A method of preparing mesoporous Zr-based MOF and application in enhancing immobilization of cellulase on carrier surface

Abstract

In this work, a mesoporous Zr-based MOF (MP-UIO-66) was first synthesized by biomineralization method using dextran as template and the resultant particles were applied in the immobilization of cellulase. Compared with conventional UIO-66, MP-UIO-66 has more mesoporous channels (4.6 nm) that allow cellulase (3.4 * 12.4 nm) to be entrapped into the channels, improving loading capacity and stability of immobilized enzyme. Specifically, the results showed that MP-UIO-66 had an excellent loading capacity (265 mg g−1) for cellulase, and the residual enzyme activity of PVP-cellulase@MP-UIO-66 (PCMU) was still about 83% after 6 cycles. Moreover, the suitable pore structure exposes the active center of cellulase to the external environment, which facilitates the mass transfer of the substrate. Based on Michaelis-Menten constant analysis, the substrate affinity (13.355 mg mL−1) and catalytic efficiency (1.311 mL mg−1 min−1) of PCMU were better than those of free cellulase (14.525 mg mL−1, 0.732 mL mg−1 min−1).