Development of heterogeneous enzymatic cascades with a case study for a separable and recyclable system using a combination of magnetic and nonmagnetic supports

In recent years, energy and environmental issues have become more topical as the public have become more conscious about the fragility of the planet we live in. Biocatalysis can have a strong impact on these issues as most enzymes are operated at low energy and solvent-free environments with often high conversion, activity and selectivity. Enzymatic cascades are multistep reactions that can produce more complex chemical products and mimic in vivo reactions in nature. Therefore, they can provide valuable solutions for many environmental problems. However, enzymes can be expensive, difficult to recycle and wasteful, as seen in other homogeneous systems. For heterogenized biocatalytic systems, enzyme immobilization has been considered to enhance reuse and recycling of enzymes but immobilized enzymes are still underdeveloped for use in cascade systems. Hence, there is an opportunity for advancement. The difficulties for implementing immobilized enzymes in cascades mainly concern enzyme compatibility, compartmentalization and optimization. In this perspective, we have highlighted key examples in using enzymatic cascades using immobilized enzymes, in particular those systems related to the energy and environment sectors. We also demonstrate use of a combination of a magnetic and a nonmagnetic support for enhancing enzyme reuse and recycling in a cascade system, and more importantly, separation of enzymes from each other postreaction. We can foresee that, with significant effort spent on the development, enzyme immobilization could play a significant role in cascades for the green synthesis of fine chemicals.