| dc.description.abstract | Metal-organic frameworks (MOFs) are porous material that have emerged in recent years. Because of its high surface area, superior thermal stability and chemical stability, it has been extensively researched and published. Zeolitic imidazolate frameworks-8 (ZIF-8) is a class of MOFs, which is a three-dimensional structure composed of zinc ions and 2-methylimidazole. Because of its high gas storage capacity, superior thermal and chemical stability, this material has been widely used and reported.
A recent literature indicates that the Catalase(CAT)@ZIF-8 biocomposite synthesized by de novo approach, water-based and mild condition, showed undetectable biological activity which majorly resulted from the hydrophobic surface of ZIF-8. Interestingly, one report addressed that the enzyme will be denatured and lost its bioactivity when it was incubated at pH 12 or higher. Thus, we develop a new concept that catalases with no bioactivity due to under strong basic synthetic condition which created by the 2-methylimidazole dissociation under water solvent. The proof-of-concept design is demonstrated by embedding catalase molecules into uniformly sized ZIF-8 crystals via a mechanochemical approach because of water unnecessary during this synthesis.
Several synthetic methods are for obtaining MOF material, such as convectional heating, mechanochemistry, sonochemistry, microwave-assisted heating and electrochemistry etc. Importantly, in this study, we focused on harvesting ZIF-8 particles with morphology and less aggregation phenomenon by use of optimal grinding conditions as well as compared the biological activity of enzyme biocomposites which are synthesized by mechanochemistry and de novo approach, respectively. In addition to the factor of basicity, we also investigated other factors, i.e., ligand effect, to deactivate enzymes.
Finally, the biocomposite of CAT@ZIF-8 with good morphology and less aggregation has been synthesized via mechanochemical method. It is worth noting here that CAT@ZIF-8 sample prepared by mechanochemical method shows an observed rate constant (kobs) of 1.3×10-3 s-1. The low activity (1.0×10-5 s-1) is observed for the sample prepared using de novo. The future studies will continue to optimize synthetic condition for preparing this catalase biocomposite with better bioactivity and then extend this concept to other MOFs materials or enzymes, expanding the applications for enzyme immobilization. | en_US |