title: Accuracy of the one-point in vivo calibration of "wired" glucose oxidase electrodes implanted in jugular veins of rats in periods of rapid rise and decline of the glucose concentration.
abstract: The hypothesis of the feasibility of one-point in vivo calibration of intravenously implanted glucose sensors during periods of rapid rise and decline of venous blood glucose concentration was tested. Miniature (5 x 10(-4) cm2 mass transporting area) glucose electrodes with 10-90% response times < 2 min, that did not consume oxygen, were implanted in jugular veins of systemically heparinized rats and used in 4-h experiments, during which the blood glucose concentration was amperometrically monitored. The glucose electrodes were made by electrically connecting ("wiring") reaction centers of glucose oxidase through an electron-conducting redox hydrogel to gold electrode surfaces. The redox polymer and enzyme constituting the electrode sensing layer were immobilized by cross-linking, and thus the electrodes had no diffusional and readily leached redox mediator. One hour after their implantation, the electrodes accurately tracked the blood glucose concentration when calibrated in vivo by a one-point calibration, when the glucose concentration was steady, when rising rapidly, and when declining steeply. For an assumed 2-min lag time, the sensor readings were well correlated with the true blood glucose concentrations, with linear regression analysis yielding a slope of 0.97 +/- 0.07 and an intercept (bias) of 0.3 +/- 0.3 mM. The correlation coefficient, r2, was 0.949 +/- 0.020, and the percent difference through the 2-22 mM range was 1.9 +/- 1.0%. The results suggest that, in combination with understanding and modeling of transient physiological differences between the subcutaneous and the blood glucose concentrations, it will be possible to calibrate by one-point in vivo calibration subcutaneously implanted sensors, even while the glucose concentration changes rapidly.
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin 78712-1062, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Schmidtke
authors.forename: A
authors.initials: A
authors.lastname: Heller
mesh_terms: D000818:Animals; D000933:Antifibrinolytic Agents / Q000008:administration & dosage; D015374:Biosensing Techniques; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism; D002138:Calibration; D004567:Electrodes, Implanted; D005240:Feasibility Studies; D005782:Gels; D005949:Glucose Oxidase / Q000737:chemistry*; D006046:Gold; D006493:Heparin / Q000008:administration & dosage; D066298:In Vitro Techniques; D007601:Jugular Veins / Q000502:physiology; D016014:Linear Models; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity
chemical_list: D000933:Antifibrinolytic Agents; D001786:Blood Glucose; D005782:Gels; D006046:Gold; D006493:Heparin; D005949:Glucose Oxidase