Enzyme immobilization using chitosan systems

The use of enzymes to synthesize chemical products of industrial importance or for biotechnological applications is quickly developing. However, free enzymes are thermal and chemically unstable. Immobilization on solid supports enhances their stability and allows their reuse while facilitating the purification of products. The performance of the enzyme depends largely on the selected support and strategy of immobilization. Chitosan is a natural biopolymer containing reactive amino and hydroxyl functional groups in its structure that can be used for covalent binding or, if charged, electrostatic interactions with the enzyme. Here, we review the most frequently used immobilization techniques employing different geometrical configurations of chitosan. We chose horseradish peroxidase, glucose oxidase, and β–galactosidase to exemplify more recently designed systems for their use as bioreactors or biosensors.