Invited Paper BP-SuA5
Bioelectrocatalysis in Diabetes Management

Sunday, October 19, 2008, 4:20 pm, Room 202

FreeStyle NavigatorTM, introduced this year by Abbott Diabetes Care, accurately monitors minute by minute the glucose concentration in the subcutaneous fluid. The system alerts the diabetic user to actual and impending high and low glucose levels. It is intended to eliminate the constant worry of diabetic people about their having or not having the desired level of glucose. The system was approved for use in the 27 countries of the European Union in 2007 and by the FDA in 2008. The sensor of Navigator, implanted in the fat under the skin at 5 mm depth, is the first and only one having a bioelectrocatalyst at which glucose is directly electrooxidized. The bioelectrocatalyst is a thick-film of a water-swollen redox polymer, which 3-dimensionally envelopes and penetrates the glycoprotein of the enzyme glucose oxidase, forming a unique crosslinked hydrated network in which electrons, glucose, and ions diffuse. Electrons cascade across small potential gradients from glucose to the reaction centers of the enzyme; from the enzyme to the hydrated redox polymer; and through the hydrated polymer to the anode of a miniature electrochemical cell. Navigator follows FreeStyle, the first mass manufactured sub-microliter fluidic device, introduced in 2000 and available worldwide, which made the monitoring of glucose in withdrawn blood samples painless. Its core is a 300 nL thin-layer microcoulometer, in which glucose is electrooxidized in a two-step process diffusionally mediated by PQQ-glucose dehydrogenase and a complex of osmium.