Electrochemical Glucose Sensors and Their Applications in Diabetes Management

Abstract

About 6,000 peer reviewed articles have been published on electrochemical glucose assays and sensors, of which 700 were published in the 2005-2006 two-year period. Their number makes a full review of the literature, or even of the most recent advances, impossible. Nevertheless, this review should acquaint the reader with the fundamentals of the electrochemistry of glucose and provide a perspective of the evolution of the electrochemical glucose assays and monitors helping diabetic people, who constitute about 5% of the world's population. Because of the large number of diabetic people, no assay is performed more frequently than that of glucose. Most of these assays are electrochemical. The reader interested also in nonelectrochemical assays used in, or proposed for, the management of diabetes is referred to a 2007 review of Kondepati and Heise. 1 Adam Heller was born in 1933. Surviving the Holocaust, he arrived in Israel in 1945. He received his M.Sc. in Chemistry and Physics in 1957, then his PhD in Organic Chemistry in 1961 from Ernst David Bergman at the Hebrew University in Jerusalem. He postdoced at UC Berkeley (1962-3) and at Bell Laboratories . At GTE Labs (1964-1975 he built the first Nd 3+ liquid laser and, with J. J. Auborn, the still worldwide used Li/SOCl 2 battery. At Bell Labs (1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988) he designed the first >10% efficient electrochemical solar cells and the first >10% efficient hydrogengenerating solar-powered photoelectrode. He also headed Bell Labs' Electronic Materials Research Department (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988), which developed part of the high density chip interconnection technology underlying the miniaturization of portable electronic devices. He was appointed to the Ernest Cockrell Sr. Chair in Engineering of the University of Texas at Austin in 1988, and in 2001 became one of UT's first Research Professors. At UT he pioneered the electrical wiring of enzymes. In 1996 he cofounded with his son Ephraim Heller TheraSense Inc., now part of Abbott Diabetes Care, to improve the lives of diabetic people. The company introduced in 2000 the blood sugar monitor FreeStyle, a thin-layer microcoulometer utilizing only 300 nL of blood, so little that it was, for the first time, painlessly obtained. In 2007 it provided for more than 1 billion painless glucose assays. After alleviating the pain of diabetes monitoring, FreeStyle Navigator, based on the electrical wiring of glucose oxidase, introduced in 2007 in Europe and Israel and in 2008 in the U.S., removed the worry of diabetic people by continuously monitoring their glucose levels. Heller aims his work at alleviating suffering through bioelectrochemistry.

Flow Cytometry-Assisted Detection of Adenosine in Serum with an Immobilized Aptamer Sensor

“…3 While protein enzymes and antibodies are the traditional molecules of choice for making biosensors, aptamers are emerging as a promising alternative due to their small sizes, high stability (especially DNA aptamers), ease of modification and immobilization, and excellent target recognition properties. [4][5][6][7][8][9][10][11][12][13][14][15][16] Aptamers are single-stranded nucleic acids that can selectively bind to target molecules.…”

Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases

“…Siloxane gels with co-immobilised enzyme and mediator were deposited onto screenprinted graphite electrodes and optimised with respect to concentrations of all components to provide both the highest stability and response (Table 1) range from 0.6 to 32 mM, which covers the physiological level of glucose in blood (Heller and Feldman 2008). The detection limit calculated as the standard deviation of the baseline current multiplied by three was estimated to be 1.2 μM, which is among the lowest recorded for mediated enzyme biosensors.…”

Properties and Customization of Sensor Materials for Biomedical Applications

“…The major mechanism of failure is the biodegradation of the sensing layer and the changing diffusional barrier that arises from the host's response toward the implanted sensor (12). Current devices cannot be used for prolonged periods of measurement because of endogenous interferences, fouling, and so on (13)(14)(15). However, there are few examples of commercially available sensors that are suitable for short-term continuous monitoring of clinical relevant markers.…”

“…The barcode contains ionogels that are doped with several pH chromogenic dyes (having different pK a ) such that the device is capable of monitoring the pH in the range 4.5-7.5. The authors reported that the pNIPAAm/[P 6,6,6,14 ][dca] ionogel provides a convenient matrix to immobilize the pH responsive dyes, as it reduces leaching of the dyes through electrostatic interactions within the IL. The device was integrated into a commercially available plaster, and was successfully used for measuring the pH of an athlete during a 50-min training session.…”

“…One of the most effective biosensor configurations reported thus far is an enzymatic glucose sensor developed by Heller et al in collaboration with Abbott Diabetes Care. In this configuration, an osmium hydrogel entraps the glucose dehydrogenase at one electrode (14,16). The sensor is functional over the range 20-500 mg dl À1 , with a correlation coefficient of R 2 ¼ 0.99 against the Yellow Spring (YSI) glucose analyzer (326).…”