Construction of enzyme-MOFs composite with carbon dots: A strategy to enhance the activity and increase the growth rate of the enzyme-ZIF-8 composite.

Encapsulating enzymes in metal-organic frameworks (MOFs) enhances enzyme protection and improves the accuracy of inhibitor recognition and screening. Zeolitic imidazolate framework-8 (ZIF-8) has been widely used as a host matrix for enzyme immobilization. However, challenges such as the microporous structure and hydrophobicity of ZIF-8, along with the protonation of 2-methylimidazole, hinder the maintenance of activity and the rapid formation of composite. Herein, a new strategy to synthesize novel enzyme-MOFs composite by encapsulating carbon dots (CDs)-modified enzyme and FeO nanoparticles within ZIF-8 is presented for the first time. The contribution of CDs in enzyme-MOFs composite was investigated. Characterizations reveal that the CDs-modified enzymes compete with imidazole for Zn ions, inducing mesoporous structures that alleviate diffusion limitations. Modification of enzyme with CDs also modulates enzyme-MOFs interfacial interactions, accelerating the formation of composite. Activity evaluation shows that enzyme-MOFs composite (THR@CDs/FeO@ZIF-8) retains 81.76 % enzyme activity under harsh conditions and maintains 66.0 % of the initial enzyme activity after 10 reuse cycles. This synthesis strategy for the novel enzyme-MOFs composite was proven to be universal. The Km value of THR@CDs/FeO@ZIF-8 (19.32 μM) is lower than that of THR/FeO@ZIF-8, indicating that modification with CDs significantly increases the affinity of enzyme. Furthermore, THR@CDs/FeO@ZIF-8 was effectively utilized for enzyme inhibitor recognition and screening. These results demonstrate that the proposed method is a universal approach for rapidly and controllably fabricating enzyme-ZIF-8 composite with elevated activity and exceptional stability, offering promising potential for advanced drug recognition and screening platforms.