Biomimetic mineralization of chemically modified glucose oxidase from Aspergillus niger in ZIF-8.

Abstract

Chemical surface modification of enzymes represents a powerful strategy to improve immobilization and catalytic performance. In this study, glucose oxidase (GOx) from Aspergillus niger was chemically modified via periodate oxidation and reductive amination to incorporate L-aspartate (D-GOx) and L-histidine (H-GOx) residues. These modifications enhanced electrostatic and coordinative interactions with Zn²⁺ and 2-methylimidazole during biomimetic mineralization, leading to efficient encapsulation in ZIF-8 frameworks. The resulting D-GOx@ZIF-8 and H-GOx@ZIF-8 biocomposites showed significantly improved activity and stability compared to native GOx. H-GOx@ZIF-8 achieved a specific activity of 4551 IU/g, representing a sixfold increase over previously reported systems. Both modified biocomposites also demonstrated greater resistance to detergent washing and retained higher activity after exposure to 65 °C, indicating stronger incorporation into the ZIF-8 matrix. These results highlight the dual advantage of introducing negatively charged and imidazole-functional groups for promoting biomineralization and improving biocatalyst robustness. This strategy provides a mild, scalable route for preparing enzyme@MOF composites with enhanced operational stability, offering direct potential for industrial bioprocesses, continuous-flow catalysis, and biosensing applications.