Exploring a suitable
immobilization strategy to improve catalytic
efficiency and reusability of cellulase is of great importance to
lowering the cost and promoting the industrialization of cellulose-derived
bioethanol. In this work, a layered structure with a thin PEG hydrogel
as the inner layer and sodium polyacrylate (PAANa) brush as the outer
layer was fabricated on low density polyethylene (LDPE) film by visible-light-induced
graft polymerization. Two enzymes, β-glucosidase (BG) and cellulase,
were separately coimmobilized onto this hierarchical film. As supplementary
to cellulase for improving catalytic efficiency, BG was in situ entrapped
into the inner PEG hydrogel layer during the graft polymerization
from the LDPE surface. After graft polymerization of sodium acrylate
on the PEG hydrogel layer was reinitiated, cellulase was covalently
attached on the outer PAANa brush layer. Owing to the mild reaction
condition (visible-light irradiation and room temperature), the immobilized
BG could retain a high activity after the graft polymerization. The
immobilization did not alter the optimal pH and temperature of BG
or the optimal temperature of cellulase. However, the optimal pH of
cellulase shifts to 5.0 after immobilization. Compared with the original
activity of single cellulase system and isolated BG/cellulase immobilization
system, the dual-enzyme system exhibited 82% and 20% increase in catalytic
activity, respectively. The dual-enzyme system could maintain 93%
of carboxymethylcellulose sodium salt (CMC) activity after repeating
10 cycles of hydrolysis and 89% of filter paper activity after 6 cycles
relative to original activity, exhibiting excellent reusability. This
layer coimmobilization system of BG and cellulase on the polymer film
displays tremendous potential for practical application in a biorefinery.
Synthesis and industrial production of functional monodisperse microspheres still face enormous challenges like precise size control and process simplification. Herein, a strategy to prepare monodisperse styrene-maleic anhydride-isoprene terpolymer microspheres via self-stabilized precipitation polymerization was reported. The prepared microspheres with different isoprene proportions have uniform particle sizes (623−1156 nm) and narrow size distributions. The structure analysis showed that the copolymerization proceeded in an alternating way between the electron donor (styrene and isoprene) and electron acceptor (maleic anhydride) monomer, and isoprene was incorporated into the polymer chain through 1, 4 addition. The gel fraction of microspheres varies from 0 to 99% along with an increasing isoprene feeding ratio. The Diels−Alder (D−A) reaction between maleic anhydride and isoprene can be effectively inhibited by increasing the amount of initiator or decreasing the polymerization temperature. The resultant uniform microspheres contain reactive anhydride groups and unsaturated C�C bonds derived from isoprene, which can be used to covalently attach functional moieties and have great potential in fields of adsorption and separation, drug delivery, biodetection, and enzyme immobilization.
Owing to the frequent occurrence of diclofenac sodium (DS) in fresh aquatic environments and its potential toxicity towards living organisms, the effective removal of DS has attracted worldwide concern. Herein,...
Polymerization induced self-assembly (PISA) pioneers a promising route to prepare nanoparticles with various morphologies at high solid content and has attracted intensive attentions in the past decades. In this study,...
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