LAUSR

AbstractSilica aerogels have in common with silica glass to present a random 3-dimensional network of Si(-O-)4 molecular tetrahedrons. The main difference stands on the presence of a high volume ratio of macropores and mesopores, which may exceed 90% by volume in aerogels. By comparison, silica glass is a dense material. Consequently, an aerogel can entrap relatively big macromolecules in its pores. In the present article, the work done to observe the random network structure of oxide aerogels during the last thirty years, by the present author and his co-workers, is reviewed. As an application, the entrapment of two types of enzymes in silica aerogels is summarized. The first one comprises two types of lipases, used as biocatalysts of esterification reactions in organic solvents. The second one is carbonic anhydrase, applicable in the capture of CO2 in aqueous un-dried wet gels. The influence of the gel network on the enzyme activity and of the enzymes on the aerogels network structure, are both discussed. Overall, these investigations were independent from to the work by Phalippou and co-workers, but they largely beneficiated from cross synergy with them. The work done by the author and his co-workers on the structure of oxide aerogels and their use to entrap enzymes, is reviewedHighlightsThe porous network structures of silica, boehmite and montmorillonite aerogels is described.The pore volume may exceed 90% and comprise micropores, mesopores and macropores.The pores can be efficiently used to entrap enzymes and make efficient biocatalysts.The case of two types of enzyme: a lipase and a carbonic anhydrase are summarized.Proteins such as enzymes are also shown to influence the aerogel network formation.