Carrier-Binding

The carrier-binding method is the oldest immobilization technique for enzymes. In this method, the amount of enzyme bound to the carrier and the activity after immobilization depend on the nature of the carrier. The following picture shows how the enzyme is bound to the carrier:

The selection of the carrier depends on the nature of the enzyme itself, as well as the:

Particle size
Surface area
Molar ratio of hydrophilic to hydrophobic groups
Chemical composition

In general, an increase in the ratio of hydrophilic groups and in the concentration of bound enzymes, results in a higher activity of the immobilized enzymes. Some of the most commonly used carriers for enzyme immobilization are polysaccharide derivatives such as cellulose, dextran, agarose, and polyacrylamide gel.

According to the binding mode of the enzyme, the carrier-binding method can be further sub-classified into:

Physical Adsorption
Ionic Binding
Covalent Binding

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