Facile
Method To Prepare Microcapsules Inspired by Polyphenol Chemistry for
Efficient Enzyme Immobilization
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Abstract
In
this study, a method inspired by polyphenol chemistry is developed
for the facile preparation of microcapsules under mild conditions.
Specifically, the preparation process includes four steps: formation
of the sacrificial template, generation of the polyphenol coating
on the template surface, cross-linking of the polyphenol coating by
cationic polymers, and removal of the template. Tannic acid (TA) is
chosen as a representative polyphenol coating precursor for the preparation
of microcapsules. The strong interfacial affinity of TA contributes
to the formation of polyphenol coating through oxidative oligomerization,
while the high reactivity of TA is in charge of reacting/cross-linking
with cationic polymer polyethylenimine (PEI) through Schiff base/Michael
addition reaction. The chemical/topological structures of the resultant
microcapsules are simultaneously characterized by scanning electron
microscopy (SEM), transmission electron microscopy (TEM), Fourier
Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy
(XPS), <i>etc.</i> The wall thickness of the microcapsules
could be tailored from 257 ± 20 nm to 486 ± 46 nm through
changing the TA concentration. The microcapsules are then utilized
for encapsulating glucose oxidase (GOD), and the immobilized enzyme
exhibits desired catalytic activity and enhanced pH and thermal stabilities.
Owing to the structural diversity and functional versatility of polyphenols,
this study may offer a facile and generic method to prepare microcapsules
and other kinds of functional porous materials