Enzymes are natural biocatalysts and they are used in many industrial applications. The use on an industrial scale strongly depends on the immobilization of the enzymes, as those are more robust than free enzymes and much easier to recover for further use. The covalent immobilization of enzymes includes the activation of the enzyme (e.g., via an amine), the binding to a linker, and the subsequent coupling to the inorganic support material. These consecutive steps are very time-consuming.

In organic synthesis the applicability of microwaves (MWs) is known since the 1980s, but enzymes are generally considered to be too sensitive to MW irradiation to be suitable for this fast coupling method. Udo Kragel, University of Rostock, Germany, and colleagues tested three different commercially available enzymes (two laccases and a glucose oxidase) for their sensitivity towards MW-irradiation during the coupling process. The MW irradiation can be used for an improved immobilization protocol, reducing the coupling time from 40 h for the conventional method to 4 h with MW irradiation. Stability and activity tests show that enzymatic deactivation under MW irradiation is very slight, with glucose oxidase showing the highest resistance to MW irradiation.

• Microwave-assisted covalent immobilization of enzymes on inorganic surfaces,
  Regina Plagemann, Jan von Langermann, Udo Kragl,
  Eng. Life Sci. 2014.
  DOI: 10.1002/elsc.201300115