Hierarchical porous iron-based MOFs via defect-induced pore engineering: Efficient co-immobilization of glucose oxidase and horseradish peroxidase for butyl xanthate degradation

Defect-induced hierarchical HP-Fe-MOF enables efficient dual-enzyme immobilization. • The interaction of substrates with Dual-En@HP-Fe-MOF was studied by microcalorimetry. • Dual-En@HP-Fe-MOF exhibits high catalytic activity and enhanced substrate affinity. • Efficient degradation of butyl xanthate was achieved using Dual-En@HP-Fe-MOF. Metal-organic frameworks (MOFs) have emerged as highly promising platforms for enzyme immobilization owing to their tunable porosity, large specific surface area, and outstanding stability. However, enzyme leakage and increased substrate mass transfer resistance have seriously hindered their practical applications. Herein, based on defect-induced pore engineering, we developed a facile and universal approach for dual-enzyme co-immobilization (glucose oxidase, GOx, and horseradish peroxidase, HRP) using hierarchical porous iron-based MOFs (denoted as HP-Fe-MOF). Precise modulation of crystal defects endows HP-Fe-MOF with hierarchical structure, which effectively addresses the issues of high mass transfer resistance and enzyme leaching, and further enhances catalytic efficiency. The intrinsic hierarchical porous features of HP-Fe-MOF facilitate strong enzyme-carrier interactions, achieving a maximum enzyme loading capacity of 169.6 mg/g and high substrate conversion efficiency (∼95%). The biocomposite, Dual-En@HP-Fe-MOF, integrated the structural merits of HP-Fe-MOF and the catalytic properties of dual-enzymes, thereby exhibiting superior catalytic activity, exceptional stability, as well as enhanced binding affinity for substrates. This affinity enhancement stems from optimized enzyme-substrate interactions, which was elucidated via enzyme kinetic and thermodynamic analyses to clarify the structure-function relationship underlying its enhanced catalytic efficiency. Notably, the biocomposite maintained more than 12 times higher relative activity than the free enzyme after incubation at 70 °C for 1 h, and above 70% enzyme activity after 15 cycles. Based on these advantages, Dual-En@HP-Fe-MOF was successfully applied to the efficient degradation of butyl xanthate, underscoring the great potential of MOF-immobilized dual-enzyme composites as advanced biological macromolecular materials for environmental remediation. Download: Download high-res image (199KB) Download: Download full-size image