BETA-CYCLODEXTRIN CATION-EXCHANGE POLYMER MEMBRANE FOR IMPROVED 2ND-GENERATION GLUCOSE BIOSENSORS

Both condensation beta-cyclodextrin polymer (beta-CDP) and condensatio n carboxymethylated beta-cyclodextrin polymer (beta-CDPA) were used fo r preparation of membranes for amperometric glucose biosensors. Glucos e oxidase (GOD) was covalently immobilized in the membranes and the te trathiafulvalenium/tetrathiafulvalene (TTF+/TTF) mediating couple was retained in the beta-CDP membrane due to supramolecular complex format ion while in the beta-CDPA one due to supramolecular complex formation as well as ion exchange (by the pending carboxymethyl groups). In the latter case, retention of the mediator was greatly improved, leading to a superior biosensor performance. This performance was tested in ph osphate buffer pH 7.4 with respect to the optimum GOD and TTF loadings as well as the membrane thickness. Under the optimum conditions, i.e. , at the 90 units GOD and 0.1 mg TTF loadings and ca. 45 mu m membrane thickness, the electrode detectability, sensitivity and response time towards glucose were 0.2 mM, 2.54 mu A ml(-1) and 25.5 s, respectivel y. The (beta-CDPA)-GOD-TTF biosensor displays excellent selectivity to wards glucose in the presence of commonly interfering substances, such as ascorbic acid, uric acid and acetaminophen. The (beta-CDPA)-GOD-TT F preparation strategy was employed for fabrication of glucose biosens ors based on a disposable screen-printed Ag-carbon strip two-electrode transducer.