DEVELOPMENT OF NEEDLE-TYPE GLUCOSE SENSOR WITH HIGH SELECTIVITY

An amperometric needle-type glucose biosensor employing rhodium as ele ctrocatalyst for hydrogen peroxide detection is described. A novel tra nsducer design is based on electrodeposition of rhodium particles on t he external wall of the needle which serves as the working electrode a nd an external Ag/AgCl reference/counter electrode. Electropolymerized 1,3-diaminobenezene (1,3-phenylenediamine) is employed as a protectiv e layer for the rhodium particles as well as an interference eliminati ng layer. This configuration uses the rhodium electrocatalyst in its m ost active dispersed form and ensure good mechanical rigidity. At the same time, because of the large working surface area, it provides a la rge sensitivity for the sensor response. The use of rhodium electrocat alyst allows detection of H2O2 at low working potential of + 0.25 V. E lectrophoretic deposition of enzyme on the needle surface followed by cross-linking with glutaraldehyde was chosen for the immobilization of glucose oxidase (GOD) on the needle surface. Nafion was used as exter nal diffusion control and additional interference eliminating layer, w hich extend the linear range of the sensor response to over 25 mM gluc ose concentration. These biosensors demonstrated diminished response t o interference from oxidizable compounds present in body fluids and a life time of at least 3 months. (C) 1998 Elsevier Science S.A. All rig hts reserved.