| dc.description.abstract | Metal-organic frameworks (MOFs) have been quite popular in the recent years. They are composed of metal ions or metal oxides with organic linkers. Because of their internal cavity structure, high surface area, extraordinary adsorption property and the specific aperture size, they have been used in many fields. Among these fields, we are interested in the application of enzyme immobilized platforms.
However, most of the methods for synthesizing MOF materials are still based on conventional heating, which often requires a large amount of organic solvents, time-consuming, and high temperature synthetic environment. The harsh synthetic conditions place a limitation on applications of encapsulating enzymes into the MOF materials. In our previous report in 2015, we demonstrated a novel approach, so called de novo, for synthesizing the biocomposites of CAT@ZIF-90 by encapsulating enzymes inside MOFs, ZIF-90, under mild aqueous solution. The MOFs could endow enzymes with size selectivity to promote the catalytic reaction of the substrate, prohibiting protease larger than the designed aperture from reaching the catalyst to protect the catalase. In 2017, our group published a report that an eco-friendly and rapid chemical synthesis of UiO-66 analog, UiO-66-F4, was demonstrated at room temperature by the mechanochemistry. Thus, we use this concept of mechanochemical approach to immobilize enzymes inside of MOFs in order to expand the applications of enzyme immobilizations to other MOFs.
Herein, we demonstrated the mechanochemical strategy for the synthesis of biocomposites by embedding catalase, enzymes for hydrogen peroxide hydrolysis, in Zn-MOF-74 via a ball milling process and maintained the enzymatic biological activity. In addition, this synthetic approach is different from the conventional method of enzyme immobilization in which it provides a milder synthetic environment and minimizes the use of organic solvents during synthesis. It is worth noting that the embedded CAT could not only be protected in proteinase K solution by the aperture size selectivity but also reduce unfolding in urea, a denature reagent by spatial confinement of the MOF structure. To demonstrate the generality of the method, chymotrypsin was encapsulating in Zn-MOF-74 via the mechanochemical approach as well as maintaining biological activity. We expect that the developed method can be generally applied to encapsulate enzymes of various sizes into MOFs with varied structures. | en_US |