The incorporation of enzymes in hydrogels, adsorbed to electrode surfaces, is a promising research line in the field of bioelectrochemistry. In this work, gelatin is selected as hydrogel for the encapsulation of different redox enzymes [1-2]. Gelatin is a water soluble protein, composed of a variety of amino acids, via amide bonds form a linear polymer with a molecular weight between 15000 and 250000 Da [3]. Due to the hydrophilic groups or domains, the hydration and native configuration of the encapsulated biomolecules is ensured. The entrapment of enzymes in a hydrogel without a membrane results in a faster response or a faster diffusion of analyte to the enzyme. In addition, an increased enzyme stability is obtained next to a better resistance to dehydratation/rehydratation which has his benefits concerning the storage of the biosensor.

In the present work, we compare different strategies to immobilize gelatin layers on electrode surfaces: drop dried and spincoated layers. Within the gelatin matrix, we can encapsulate different enzymes such as horse heart cytochrome c [3], cytochrome c peroxidase, catalase, … Depending on the selected immobilization method, we observe different electrochemical behaviour of the immobilized enzymes. Additionally, the electrocatalytic behaviour of the enzymes towards their target molecules is investigated. Our strategy is to create an open hydrogel for the predictable response of quasi-freely diffusing enzyme, mediator and substrate (analyte). This method is now a model system for new biosensor applications in industry.

[1] K. De Wael, S. De Belder, S. Van Vlierberghe, G. Van Steenberge, P. Dubruel, A. Adriaens, Talanta 82(5) (2010) 1980-1985.

[2] K. De Wael, B. Qamar, S. Van Vlierberghe, P. Dubruel, H. Heering, A. Adriaens, Bioelectrochemistry, in press

[3] J.E. Eastoe, A. A. Leach, in ‘The science and technology of gelatin’, (Eds. Ward  A.G., Courts A.), Academic Press, New York (1977) Chapter 3.

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