Biomaterials obtained by gelation of silica precursor with CO2 saturated water containing a carbonic anhydrase enzyme

Abstract

As part of an effort to develop biomaterials for the capture of CO2 catalyzed by a carbonic anhydrase enzyme, the effects of an aqueous CO2 saturated solution and a carbonic anhydrase on the gelation and texture of SiO2 gels derived from tetramethoxysilane (TMOS), were studied. Both aqueous CO2 and the enzyme were found to accelerate the gelation of silica, with a stronger effect when both the enzyme and CO2 saturated aqueous water, were used. According to the gel texture data, aqueous CO2 acted as an acid type catalyst, while the carbonic anhydrase acted as a weak base type catalyst. Moreover, a gel with a more granular visual aspect was obtained when both the enzyme and CO2 saturated water were used. The latter characteristic was consistent with a double action of the enzyme, first as a gelation catalyst on the silica precursor, secondly as a reverse protonation catalyst which accelerated the back nucleation of CO2 gas bubbles from aqueous HCO3 − anions.