Building multifunctional hybrid materials that integrate both bio- and chemo-catalytic functionalities is a promising way to carry out multistep chemical reactions in a more sustainable fashion. Yet, the combination of an enzyme and a heterogeneous catalyst is not straightforward, for example in the case of zeolite catalysts: the enzyme cannot be inserted in the microporosity of the carrier, and a grafting on the external surface is not satisfactory.
To overcome this issue, Valentin Smeets (during his PhD in the group of Damien Debecker) has developed a method to immobilize enzymes inside spherical structures made of zeolite nano-crystals. The zeolite microspheres are obtained by a spray drying technique and feature a central cavity which is used to load and entrap the enzyme. This controlled design – where the structured zeolite material is used both as a nest for the enzyme and as an active inorganic catalyst – allows combining all the decisive features of the zeolite with a high enzyme loading. This is a change in paradigm with respect to the classical approach for the preparation of heterogeneous biocatalysts where the enzyme is immobilized onto a support.
The strategy is validated by performing a chemo-enzymatic reaction: entrapped glucose oxidase catalyzes the in situ production of H2O2 subsequently utilized by the TS-1 zeolite to catalyze the epoxidation of allylic alcohol toward glycidol. The strategy was also used to entrap other enzymes and combinations of enzymes which can be put at work simultaneously in cascade reactions.
It is anticipated that this strategy will open up new perspectives for the fabrication of multifunctional hybrid microstructures: leveraging on the spray drying technique, it will be possible to shape microparticles made of various nano-objects and to use them as vessels to entrap different types of biological macromolecules.
Valentin Smeets, Walid Baaziz, Ovidiu Ersen, Eric M. Gaigneaux, Cédric Boissière, Clément Sanchez, Damien P. Debecker
Chemical Science – In press DOI: 10.1039/C9SC04615A