Comparative study of polymeric supports as the base of immobilisation of chemically modified enzymes

One of the difficulties in using optical biosensors based on enzymatic reactions is the immobilisation of the enzyme involved in the determination. A detailed study has been carried out of the various polymeric supports which could provide a potential alternative for the immobilisation of chemically modified enzymes. Before immobilisation, the enzyme is attached by means of a covalent bond to a fluorescent probe, which is optically active in the visible region. The main advantage of this covalent bond is that it is possible to follow the enzymatic reaction by fluorescence without the need for immobilising any further reagent (reagentless biosensors). The results indicate that the most stable and reproducible polymeric supports are derived from polyacrylamide obtained by UV photopolymerisation. The experiments have been carried out using chemically modified glucose oxidase as the model enzyme. The films thus obtained have a lifetime of at least two months, an RSD of 9.2%, and a linear range of 300 to 2000mg L-1 of glucose. They are completely reversible by regeneration in an appropriate buffer solution.