1 research outputs found
A Spring in Performance: Silica Nanosprings Boost Enzyme Immobilization in Microfluidic Channels
Enzyme microreactors
are important tools of miniaturized analytics and have promising applications
in continuous biomanufacturing. A fundamental problem of their design
is that plain microchannels without extensive static internals, or
packings, offer limited exposed surface area for immobilizing the
enzyme. To boost the immobilization in a manner broadly applicable
to enzymes, we coated borosilicate microchannels with silica nanosprings
and attached the enzyme, sucrose phosphorylase, via a silica-binding
module genetically fused to it. We showed with confocal fluorescence
microscopy that the enzyme was able to penetrate the ∼70 μm-thick
nanospring layer and became distributed uniformly in it. Compared
with the plain surface, the activity of immobilized enzyme was enhanced
4.5-fold upon surface coating with nanosprings and further increased
up to 10-fold by modifying the surface of the nanosprings with sulfonate
groups. Operational stability during continuous-flow biocatalytic
synthesis of α-glucose 1-phosphate was improved by a factor
of 11 when the microreactor coated with nanosprings was used. More
than 85% of the initial conversion rate was retained after 840 reactor
cycles performed with a single loading of enzyme. By varying the substrate
flow rate, the microreactor performance was conveniently switched
between steady states of quantitative product yield (50 mM) and optimum
productivity (19 mM min<sup>–1</sup>) at a lower product yield
of 40%. Surface coating with silica nanosprings thus extends the possibilities
for enzyme immobilization in microchannels. It effectively boosts
the biocatalytic function of a microstructured reactor limited otherwise
by the solid surface available for immobilizing the enzyme