Immobilization of enzymes is every technique and method that enables insolubilization of native enzyme while maintaining its activity. There are numerous ways to achieve this, of which main ones are entrapment in hydrogels (alginate, chitosan, carrageenan, polyacrylamide), adsorption (celite, active charcoal, hydroxyapatite) and covalent attachment (epoxy resins, glutaraldehyde for glycosylated proteins, carbodiimide, etc).
Main reasons for immobilizing enzyme are stabilization (thermostability and stability to solvents are often increased), multiple reuse, easy control of process, easy downstream processing of product etc. Drawbacks are often attributed to diffusion limitations, loss of enzyme activity during immobilization procedure, complicated procedures and use of reactive chemicals.