AMPEROMETRIC NEEDLE-TYPE GLUCOSE SENSOR BASED ON A MODIFIED PLATINUM-ELECTRODE WITH DIMINISHED RESPONSE TO INTERFERING MATERIALS

A needle-type glucose sensor that can be used to determine glucose in serum and whole blood samples was developed. Platinum wire was used as the working electrode and a disposable hypodermic stainless-steel needle electroplated with platinum was used as the counter and reference electrode. A method involving both photocross-linking of PVA-SbQ and cross-linking with glutaraldehyde was used to immobilize the enzyme [PVA-SbQ is a poly(vinyl alcohol) bearing stilbazolium groups]. Nafion and cellulose triacetate membranes were used to prevent inaccuracy from interfering materials and to increase the dynamic range of the sensor, respectively. The response, reproducibility and long-term stability of the sensor and the effects of temperature, pH and metal ions on the response were investigated. Owing to the effective method for enzyme immobilization, the large surface area of the counter electrode and the relative inactivity of the counter electrode to chemical reactions, the sensor showed good response, stability and reproducibility. The sensor did not respond to ascorbate and urate at the concentrations normally found in blood. Data obtained from the sensor for glucose in serum and whole blood samples showed a good correlation (r > 0.95) with a clinical laboratory automated analyser.