(676c) Magnetic Carbonic Anhydrase Nanogel for Enhanced CO2 Sequestration

Carbonic anhydrase (CA) is promising for CO₂ sequestration because of its high turnover rate of 10⁶/s in the hydration of CO₂ to HCO₃^-. The practical application of CA is, however, hindered by its poor stability, i.e., CA is denatured at 63 ℃ and prone to aggregate. The operation and recycle of CA is also of practical concern.

Here we propose a method for synthesizing magnetic nanogel encapsulating CA (MNP-CA nanogel) and examine its effects on CO2 stripping using mono ethanol amine.

During a run, magnetic nanoparticle was grafted with amino and vinyl group via sequential reactions with 3-aminopropyl triethoxysilane (APTES) and N-acryloxysuccinimide (NAS). Then CA was applied and attached onto the surface of MNP via crosslinking triggered by glutaraldehyde. Finally, in situ polymerization was initiated using acrylamide as monomer, yielding magnetic nanogel encapsulating CA. The activity of MNP-CA nanogel was determined in both the CO₂ hydration and hydrolyzing 4-nitrophenylacetate (4-NPA).

We first determined the thermal stability of CA at 65°C, in which free CA was fully denatured in 20 min whereas the CA nanogel appeared 52% of its initial activity after 80min. The magnetic CA nanogel retained 85 % of its initial activity after 10 cycles. The encapsulation led to a 30 % increase in Km while a 48 % decrease in kcat, as compared to the free CA in solution. Nonetheless the greatly enhanced stability and ease of operation and recycle make MNP-CA nanogel attractive for intensified CO₂ sequestration.