Enzyme-Decorated Covalent Organic Frameworks as Nanoporous Platforms for Heterogeneous Biocatalysis.

Sustainability in chemistry heavily relies on heterogeneous catalysis. Enzymes, the main catalyst for biochemical reactions in nature, are an elegant choice to catalyze reactions due to their high activity and selectivity, although they usually suffer from lack of robustness. To overcome this drawback, enzyme-decorated nanoporous heterogeneous catalysts were developed. Three different approaches for Candida antarctica lipase B (CAL-B) immobilization on a covalent organic framework (PPF-2) were employed: physical adsorption on the surface, covalent attachment of the enzyme in functional groups on the surface and covalent attachment into a linker added post-synthesis. The influence of the immobilization strategy on the enzyme uptake, specific activity, thermal stability, and the possibility of its use through multiple cycles was explored. High specific activities were observed for PPF-2-supported CAL-B in the esterification of oleic acid with ethanol, ranging from 58 to 283 U mg-1 , which was 2.6 to 12.7 times greater than the observed for the commercial Novozyme 435.

Enzyme Immobilization in Covalent Organic Frameworks: Strategies and Applications in Biocatalysis.

The development of efficient catalytic systems is a fundamental aspect for the straightforward production of chemicals. During the last years, covalent organic frameworks (COFs) emerged as an exciting class of organic nanoporous materials. Due to their pre-designable structure, they can be prepared with distinct physicochemical characteristics, specific pore sizes, and tunable functional groups. Moreover, associated with their stability in different media, these materials are considered promising supports for enzyme immobilization. Herein, it is highlighted the recent literature of enzyme immobilization in COFs, the main immobilization strategies, and the catalytic applications of these composites.