Biocatalysis on porous materials

Edited by Vincent Blay, Luis F. Bobadilla, Alejandro Cabrera-García.
Enzyme-based processes are gaining ground in applied industrial catalysis. The exploitation of the biocatalytic activity of enzymes in a massive context ineludibly implies their heterogeneization and/or immobilization on solid supports whereas their catalytic efficiency is maintained at some extent. Since the catalytic role of enzymes is directly related to their quaternary/tertiary structure, the non-covalent immobilization strategies normally become more effective. This Chapter deals with several methods for encapsulating enzymes within porous materials developed by our group in the last decade. Apart from the non-covalent nature of the enzyme-support interaction, the encapsulation of enzymes provides some extra key advantages: (i) the resultant solid biocatalysts can take advantage of the size sieving of the reactants and products provided by the supports; (ii) the both kinds of studied supports, i.e. SiO2- or organosilica-based ordered mesoporous materials (OMM) and metal-organic framework (MOF) materials, can be easily and controllably functionalized by organic groups favoring the immobilization efficiency and preventing the enzyme leaching; (iii) the pore arrangement of the supports can be tailored to the enzyme requirements, such as the use of cage/window mesoporous system allowing the in-situ encapsulation of enzymes with no subsequent leaching at all. All these strategies have been widely and successfully developed for OMMs materials, although it is recommendable to optimize the physicochemical properties of the OMM support for any particular enzyme. On the contrary, the use of MOFs as supports of enzymes is relatively new, especially the universal approaches in which the MOF materials do not need to have pore larger than the enzyme to be immobilized. The very rich compositional, structural and functionalization versatility of these porous supports entails a very promising future for the enzyme immobilization.