| dc.description.abstract | There are two parts in this thesis.
Part I: Syntheses of hollow zeolitic imidazolate frameworks:
In 2017, we published a JACS paper regrading an additional strength of the de novo approach by demonstrating that enzymes embedded in met-al-organic frameworks (MOFs) via de novo approach remain functional under a wider range of reaction conditions. The enhanced stability arises from the confinement of the enzyme molecules. We also revealed the mechanism by exposing the embedded enzymes to chemical agents that specifically denature or inhibit free enzymes and examining their resulting catalytic activity for reactions relevant to biological functions etc. Herein, in order to further investigate the influence of spatial confinement on the en-zymatic functionality, we loaded catalase enzymes in crystalline ZIF-8, a subgroup of MOFs, nanoparticles with void to mimic enzymes encapsulated in a less restricted environment. However, those MOF materials, i.e., ZIF-67 and ZIF-8, for preparing hollow MOFs may influence enzymatic function or activity detection. Thus, we explored new materials for avoiding inferences on biological activity. The palladium nanoparticle was utilized as a marker for confirming that a new material of Pd@ZIF-8@ZIF-90 denoted as Pd@8@90 has been successfully prepared. Finally, the new hollow compo-site of Pd@8@void-90 and its derivatives were obtained by using a modified approach based on a recent report. Accordingly, this part work may con-tribute to investigate the influence of spatial confinement on the enzymatic functionality.
Part II: Study on immobilization of enzymes by mechanochemical meth-od:
Recently, we developed a new approach for rapidly encapsulating a glycosidase such as β-glucosidase, disaccharides as substrates, in the robust MOFs of Zr-based UiO-66-NH2 with aperture size about 0.6 nm. This method represents the first report of mechanochemical encapsulation of bi-ocatalysts into MOFs, including the first overall encapsulation method for enzymes into UiO-66 type MOFs, and can be extended to generate robust and recyclable MOF biocomposites, especially MOFs not be given in aqueous, for use in a number of industrial applications. Nonetheless, there were still some questions behind this beautiful story and needed to be further studied. Thus, in this work, we provided FIB-SEM images to show the in-tegrity of internal UiO-66-NH2 where enzymes embedded. We also studied the effect of various milling times during mechanochemical approach toward enzymatic activity. Finally, the optimal condition using 8 Hz and two-step 2.5 min milling for preparing enzyme@UiO-66-NH2 biocomposites show-ing the best biological function. | en_US |