Enzyme critical binding reagents

Despite these improvements, there are other important biosensor limitations related to stability and reproducibility that have to be addressed. In this context, enzyme immobilisation is a critical factor for optimal biosensor design. Typical immobilisation methods are direct adsorption of the catalytic protein on the electrode surface, or covalent binding. The first method leads to unstable sensors, and the second one presents the drawback of reducing enzyme activity to a great extent. A commonly used procedure, due to its simplicity and easy implementation, is the immobilisation of the enzyme on a membrane. The simplest way is to sandwich the enzyme between the membrane and the electrode. Higher activity and greater stability can be achieved if the enzyme is previously cross-linked with a bi-functional reagent. 

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