FIBEROPTIC GLUCOSE BIOSENSOR USING ENZYME MEMBRANES WITH 2-D CRYSTALLINE-STRUCTURE

Two-dimensional crystalline bacterial surface layers (S-layers) compos ed of identical (glyco)protein subunits turned out to be ideal matrice s for immobilizing monolayers of functional macromolecules. Due to the ir crystalline character, S-layers exhibit a characteristic topography with a defined arrangement and orientation of functionalities, which is a prerequisite for a reproducible and geometrically defined binding of biomolecules. The proteinic nature of S-layers provides an adequat e microenvironment for immobilized biomolecules, frequently along with the effect of a high retention of biological activity and enhanced st ability towards drying. For the development of a fibre-optic glucose b iosensor, monomolecular layers of glucose oxidase were covalently immo bilized on the surface of S-layer ultrafiltration membranes. During gl ucose measurements, the enzyme monolayer was attached to the transduce r, an oxygen optode containing a ruthenium(II) complex whose fluoresce nce is dynamically quenched by molecular oxygen. The performance of th e sensor, in terms of response time, linear range and stability, is co mparable to existing optodes. Given its minute size, the system presen ted is considered to hold great promise for the development of micro-i ntegrated optical biosensors.