| dc.description.abstract | The catalase (CAT) was embedded into sodalite (SOD) zeolitic imidazolate
frameworks (ZIF-8 and ZIF-90) via a water-based mild de novo approach
previously reported by our group in 2015. The de novo approach provided
shielding confinement properties, allowing the enzymes to maintain their
biological activity without being affected by external factors like inhibitors.
However, there are challenges for alleviating negative effects attributed by
interactions between the material and the enzyme during enzyme immobilization
process resulting in the decrease in activity. Building upon this, we developed a
new technique for rapid synthesis of hollow Metal-Organic Frameworks (HMOFs)
for encapsulation of enzyme, in which hollow MOFs reduces the interfacial
interactions between the material and enzymes. The hollow structure not only
mitigates the issue of decreased activity, but also retains the porous selectivity of
MOFs. However, the bioactivity of enzyme was not fully recovered comparing it
of free enzyme.
In this study, our aim was to explore the potential of HMOFs to not only
enhance activity but also integrate the porous selectivity of MOFs and the internal
space of hollow materials. Our hypothesis was that HMOFs could exhibit
characteristics resembling those of a semi-permeable membrane. To test this, we
employed the enzyme@HZIF-8 material in conjunction with urea as a protein
denaturing agent, aiming to assess its suitability for application in nanoscale semipermeable membranes. During our experimentation, we observed changes in
enzyme activity by manipulating the thickness of the shell layer and adjusting the
denaturation time. However, despite these efforts, we did not observe any
significant recovery in enzyme activity.
iv
To further enhance the enzyme activity in the hollow MOF system, we have
developed a novel approach to obtain the biocomposite of enzyme@HMOF.
Firstly, we selected UiO-66 particles of different sizes for enzyme adsorption onto
the surface. And then, we synthesized a double-layered material known as
enzyme-on-UiO-66@ZIF-90, following the methodology described in our
previous report from 2015. Moreover, taking advantage of the distinct acid and
alkaline tolerances of MOFs, we dissolved the inner layer of UiO-66, resulting in
the formation of enzyme@HZIF-90. The reason why we use the different sizes of
UiO-66 and it is expected that the activity of enzyme can be enhanced by
increasing the size of the cavity of hollow MOF.
In this study, besides maintaining a rapid etching step, enzyme@HZIF-90 not
only tripled the enzyme activity compared to enzyme-on-UiO-66@ZIF-90, with
a kobs reaching 5.87*10-2, but also demonstrated promising performance in semipermeable membrane applications, achieving a maximum activity recovery of
34.9%. | en_US |