(621k) Crosslinked Chitosan Coating on Magnetic Mesoporous Silica with Pre-Adsorbed Enzymes

The approach of carbon conversion and utilization (CCU) is gathering a great attention because CCU utilizes CO₂ to produce various chemicals and products. Especially, Carbonic anhydrase (CA) which can catalyze the conversion of CO₂ to bicarbonate without external energy input, in mild reaction conditions is gathering a growing attention. However, it is a challenging task to develop a protocol of enzyme immobilization for the achievement of high loading and stability in order to improve the economy of biocatalytic conversion of CO_2. In this work, we used magnetically-separable spherical mesocellular siliceous foam (Mag-S-MCF) for the immobilization and stabilization of carbonic anhydrase by using a protocol of crosslinked chitosan (CS) coating. CA was adsorbed into Mag-S-MCF. Then, chitosan was adsorbed onto the surface of Mag-S-MCF with pre-adsorbed enzymes, and further crosslinked via the glutaraldehyde treatment. The resulting composite materials, the crosslinked chitosan coating on Mag-S-MCF with pre-adsorbed CA (ADS-CA/CS-GA), could effectively prevent leaching of enzymes, showing no decrease of enzyme activity under shaking (200 rpm) for 85 days. ADS-CA/CS-GA also showed no activity decrease under recycled uses via facile magnetic separation, and could be successfully used for the biocatalytic CO₂ conversion to bicarbonate, which was further utilized to generate calcium carbonate in the second batch reactor.