Measurement of Glucose Concentration in the Presence of Coreactants with a Platinum Electrode

Abstract

An implantable glucose sensor is being developed that is based on the use of a high-area platinum electrode. The sensor is operated in a controlled potential mode, in which the potential of the platinum working electrode versus an unpolarized reference electrode is periodically varied according to a preselected voltage-time regimen. The change in potential is accompanied by a flow of current between the platinum working electrode and a counter-electrode. This current serves to periodically rejuvenate the electrode surface and to provide a signal that is proportional to the glucose concentration. A method for analyzing this signal has been developed, the compensated net charge (CNC) method, that involves integration of the current over one complete potential cycle. This method significantly improves both the sensitivity and selectivity for determining glucose in the presence of the normal physiologic coreactants. For a solution containing glucose, amino acids, and urea, a change in glucose concentration from 50 to 150 mg/dl gives about a 50% change in the net charge. A change in the urea concentration from 20 to 40 mg/dl has no effect on the net charge. A change in the amino acids concentration from 35 to 65 mg/dl has little effect on the net charge above a glucose concentration of about 100 mg/dl. Negligible effects on the net charge have also been found for creatinine (0-1.5 mg/dl) and uric acid (0-4 mg/dl).

Fluorometric Determination of Hydrogen Peroxide in Natural Water Samples by Flow Injection Analysis with a Reaction Column of Peroxidase Immobilized onto Chitosan Beads

“…The peak height was constant over 0.3 to 0.8 cm 3 . Therefore, the injection volume was set at 0.3 cm 3 .…”

“…The preserving solution of the immobilized enzyme was prepared by dissolving 1.0 g of bovine serum albumin (BSA), 0.88 g of sodium chloride and 1.2 g of Tris in 100 cm 3 of water. All other chemicals used were of analytical reagent grade (Wako Pure Chemical Ind.…”

“…2 The biosensors have been classified into two typical types. One involves the direct detection of electrons which move in an enzyme membrane; 3,4 the other type involves the indirect detection of some redox substances which are produced by a chain reaction of some enzymes. 5 Some studies have also developed methods to utilize enzymatic reactions for non-separated analyses which involve some selective reactions.…”

Raney-platinum film electrodes for potentially implantable glucose fuel cells. Part 1: Nickel-free glucose oxidation anodes

“…Furthermore, in separate experiments (data not shown) the observed degradation could not be reversed by exchange of the testing solution against freshly prepared PBS with 3.0 mM glucose. Also in previous investigations such a degradation of platinum-based anodes upon glucose electro-oxidation has been observed, and attributed to electrode poisoning due to adsorbed reaction products, in particular gluconic acid [2,39,40].…”

Continuous Glucose Monitoring: An Overview of Its Development

“…So, picking up our historical review of this, the early 1980s saw the appearance of an important symposium on potentially implantable glucose sensors in Diabetes Care in 1982, 27 which included several important contributions from many of the leaders in the field, including Clark, Updike, Soeldner, Clemens, and Gough. [28][29][30][31] The same year saw important contributions from Fischer's group in East Germany 33 and Shichiri's group in Japan. 34 In the next 2 decades, much progress was made in the development of potentially viable continuous glucose sensing.…”