Wiring step-wise reactions with immobilized multi-enzyme systems

The immobilization of multi-enzyme systems on advanced materials is an emerging technology inspired by the spatial localization found in Nature. These systems harness the high chemo-, regio- and stereoselectivity of the enzymes and the heterogeneous nature of the resulting biocatalyst. This synergy allows more efficient and selective synthetic schemes which reduce waste production and simplify downstream processing. The revolution of the nanotechnology has contributed to design advanced materials that allow precisely controlling the spatial distribution of the different catalytic modules forming a multi-enzyme system. Outstandingly, this fact has boosted the development and the improvement of more complex cascade reactions catalyzed in vitro by heterogeneous multi-functional biocatalysts. In this review, we have discussed the different challenges that must be faced during the immobilization of multi-enzyme systems; from the carrier surface to the incorporation of cofactors into the solid-phase. We have analyzed how the physico-chemical properties of the solid materials affect the efficiency of the multi-enzyme systems and how enzymes can be co-immobilized to optimize their performance as a cascade. We have also discussed the effect of the architecture and spatial organization of the enzymes on the productivity of the system. Furthermore, we have given some clues to coordinate both activity and stability of individual enzymes to orchestrate their performance towards the necessities of the reaction cascade. Finally, we have summarized the last advances for the incorporation of biological cofactors into the solid-phase to fabricate self-sufficient heterogeneous biocatalyst that do not require the exogenous addition of those expensive cofactors. Therefore, the main goal of this review is presenting to the biocatalysis community the available tools to implement immobilized enzymatic cascades into synthetic, analytical, medical and environmental chemistry.