Enzyme microencapsulation platform for bioelectrocatalytic systems

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Redox enzymes are very powerful catalysts to circumvent the fundamental limitations of electrochemical processes which are the lack of selectivity and low catalytic properties of most bare electrodes. In order to use such enzymes as efficient electrocatalysts, one must place the enzyme on the surface of an electrode. Enzymes were designed by Nature to work in specific environments such as living cells and biological fluids rather than on the surface of an electrode Immobilizing enzymes in a way that preserves their activity while allowing efficient electron transfer with the electrode represents a challenge that has stimulated research in this field for over forty years (since the first reported enzyme electrode by Clark and Lyons in 1962). Our research proposes the use of microencapsulation as a way to immobilize enzymes on the surface of electrodes for the development of bioelectrocatalytic systems. Microencapsulation consists in the confinement of a delicate agent in a hollow, semi-permeable sphere of variable size in the microns range. The hollow core of microcapsules contains the enzyme in an aqueous environment which is therefore very favorable to retain enzymatic activity and stability. The microcapsules can be made from a large array of materials, the nature of which depends on the targeted application; a biocompatible polymer can be used for in-vivo application of enzyme electrodes. The microcapsules can be covalently bound to the surface of electrodes to achieve immobilization. That way, the enzymes (contained in the capsules) are physically retained on the surface without decreasing their activity. The enzyme immobilization platform described here will find application in many high-technology sectors through the development of biosensors (monitoring in environmental and biomedical fields) and bio-fuel cells (portable power sources for micro and nanoelectronic devices and sensors).