The widest linear range of glucose test strips based on various mediators and membranes for whole blood analysis

Abstract

We present a novel approach to increasing the upper limit of linearity in the calibration range of glucose test strips. Instead of using a diffusion membrane over an enzyme-containing layer, we propose membrane-forming mixtures for co-immobilization of enzymes and mediators in polymer matrices for a single-step electrode modification. Additionally, membrane components may be mixed into carbon paste and deposited on electrode supports in the course of screen-printing. We have shown that the transport of water-soluble mediators is controlled by the density of the immobilizing membrane as well as by electrostatic interactions between mediator and membrane-forming polymer. The resulting biosensor calibration range exceeds glucose concentrations in blood, due to prolongation of the linear range up to 50 mM. Furthermore, test strips, which are made via co-immobilization of mediator and enzyme in chitosan retain linear response in a wide range and 90% of the sensitivity, when tested in blood.