In Vivo Brain Glucose Measurements: Differential Normal Pulse Voltammetry with Enzyme-Modified Carbon Fiber Microelectrodes

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• 作者：Larissa I. Netchiporouk ; Nataliya F. Shram ; Nicole Jaffrezic-Renault ; Claude Martelet ; and Raymond Cespuglio
• 刊名：Analytical Chemistry
• 出版年：1996
• 出版时间：December 15, 1996
• 年：1996
• 卷：68
• 期：24
• 页码：4358 - 4364
• 全文大小：260K
• 年卷期：v.68,no.24(December 15, 1996)
• ISSN：1520-6882

文摘

The enzyme glucose oxidase was immobilized on thesurface of carbon fiber microelectrodes (CFMEs) eitherby cross-linking in glutaraldehyde vapor or by enzymeentrapment in electropolymerized films ofm-phenylenediamine or resorcinol. The cross-linked enzymaticlayerwas, in the given conditions, covered with an additionalmembrane of Nafion or cellulose acetate. The preparedglucose sensors were tested using differential normalpulse voltammetry (DNPV, in which the scan comprisessuccessive double pulses ("prepulse and pulse"), theprepulses are of increasing amplitude, and the currentmeasured is the differential of the current existing between each prepulse and pulse). With properly chosenDNPV parameters, the response to glucose presented apeak at a potential of about 1 V versus an Ag/AgClreference, owing to the oxidation of enzymatically produced hydrogen peroxide. The calibration curves obtained (peak height/glucose concentration) were linearfrom 0.3-0.5 up to 1.5-6.5 mM and showed a sensitivityranging from 1.4 up to 34.5 mA M^-1cm^-2, dependingon the sensor type. The DNPV response to glucoseexhibited an essential insensitivity toward easilyoxidizableinterfering substances such as ascorbic acid and acetaminophen present at physiological concentrations. Peptides, the interfering species typical of the cerebralmedium, were effectively retained by the above additionalmembranes. Concentration values of glucose in plasmaand cerebrospinal fluid, determined in vitro from theDNPV peak height, agreed well with those measured bystandard procedures. In the anesthetized rat,extracellular brain concentration of glucose was also monitoredduring administration of either insulin or glucagon.Under such pharmacological conditions, the changesobserved in the peak height were in perfect agreementwith the known effects induced by both substances.