Enzyme electrode for determining glucose in whole blood

In this sensor for glucose in whole blood, glucose oxidase (EC 1.1.3.4) is directly coupled to a platinum electrode by a silane coupling agent and glutaraldehyde. This very thin catalytic layer is then coated with a thin rubber membrane. The response to glucose in whole blood varies linearly with glucose concentration to at least 6000 mg/L with a small positive intercept. The response time is a few minutes. The key factor in the success of this sensor is the unitized construction, with both membrane and enzyme chemibonded to the electrode. The compatibility with whole blood and the high oxygen permeability of the membrane also contribute to the good performance. The coefficient of variation in replication (glucose concentration 1 g/L, n = 13) is about 3%. The sensor is insensitive to hematocrit and has a lifetime of several days after initial use.