Precipitation-Based Nanoscale Enzyme Reactor with Improved Loading, Stability, and Mass Transfer for Enzymatic CO2 Conversion and Utilization

Abstract

Enzymatic CO2 conversion has gathered a growing attention due to its fast kinetics in converting CO2 to bicarbonate, but the carbonic anhydrase enzymes easily lose their activities in CO2 conversion processes. Here, we propose a “precipitation-based nanoscale enzyme reactor (p-NER)” approach, which stabilizes the activity of carbonic anhydrase, prepared via the two steps of enzyme adsorption into magnetic mesoporous silica and simultaneous enzyme precipitation/cross-linking. The simple addition of enzyme precipitation during cross-linking step resulted in the formation of cross-linked enzyme aggregates (CLEAs) not only inside the mesopores but also on the surface of mesoporous silica. External CLEAs of p-NER contributed to the improvement of enzyme loading (32.9% (w/w)) and mass transfer (KM = 3.68 mM) compared to those of NER (20.1% (w/w) and 4.29 mM, respectively), prepared without enzyme precipitation step and showing no external CLEAs. p-NER was stable under vigorous shaking (200 rpm) with no activity...