Sustainable Chemistry for the Environment (Dec 2023)
Nature of support system and enzyme as key factors in immobilized biocatalyzed processes
Abstract
Enzymes reign over inorganic and organometallic catalysts in aspects of conversion and product selectivity. Natural products are always produced in small quantities and to mimic such biological setups for large-scale production requires harsh solvent systems and elevated temperatures to promote the reaction rates, conditions known to denature most enzymes. Immobilization of enzymes has been used to surpass such challenges in addition to allowing single and multiple enzyme reactions in contrasting reaction media. This review addresses the different techniques used to support and stabilize biocatalysts. Silica is the oldest support material used to encapsulate/immobilize enzymes and like all immobilization techniques, it significantly increases the thermal stability, extreme pH tolerance, recyclability and lifespan of biocatalysts. Immobilization supports with reactive functional groups such as metal salts, metal-, covalent- and hydrogen-bonded organic frameworks work well with enzymes that exhibit hydrophobic tolerance. Bienzymatic immobilization by one support system or the use of multiple supports for a single enzyme and further enhancement of immobilized enzymes to increase activity is possible. Some immobilization support systems such as silica and enzyme hybrid nanoflowers work well with both hydrophilic/hydrophobic and metal-free/metal-containing enzymes. Solid supports such as natural fibers and metal salts, for example, polyoxometalate hybrids stretch the enzyme’s thermal stability further (>60 °C) and also accommodate more enzyme particles.
