Immobilization of Enzymes for Use in Supercritical Fluids

Supercritical fluids (SCFs) are environmentally benign solvents that enable efficient ability to dissolve and/or transport many hydrophobic compounds. Because the solvent properties of SCFs can be adjusted by changing either the pressure or the temperature, they are widely used in a industrial extractive clean processes. For enzymatic biotransformation, several criteria must be considered to select an SCF as the reaction medium, such as the critical parameters or the safety and cost advantages. The importance of strategies for stabilizing enzymes toward SCFs, as well as the appropriate design of reactors is also discussed. Four different high-pressure reactors (i.e., stirred tank, packed bed, cross-flow membrane, and membrane with recirculation) used for enzymatic synthetic processes utilizing SCFs are described in detail. Protocols for operation with these reactors to carry out butyl butyrate synthesis or the kinetic resolution or rac-1-phenylethanol are described in detail, including procedures to obtain membranes with immobilized enzymes and a list of notes of special interest for researchers.