Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor

Hu, Yaozhong; Mitchell, Kim; Albahadily, F. N.; Michaelis, Elias K.; Wilson, George S.

doi:10.1016/0006-8993(94)90870-2

Cited by 256 publications

(268 citation statements)

References 45 publications

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“…16,17,20 These basic sensors exhibited Michaelis-Menten kinetics with a V max of 6.2 ± 0.9 nA and a K m of 0.25 ± 0.10 mmol l 21 , n = 4, the latter value being the same as that observed for GluOx in solution. 21 Considering the sensitivity of Pt to AA, 40 bare cylinders of the dimensions used here would be expected to give about 400 nA for 500 mmol l 21 AA.…”

Section: Pt/ppd/gluox Electrodesmentioning

confidence: 53%

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Biosensor for Neurotransmitter L-Glutamic Acid Designed for Efficient Use of L-Glutamate Oxidase and Effective Rejection of Interference

Ryan

Lowry²,

O’Neill³

1997

Analyst

124

179

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An amperometric biosensor for l-glutamic acid (Glu) was constructed by the adsorption and dip coating of l-glutamate oxidase (GluOx, 200 U ml 21 phosphate buffer, pH 7.4) onto 60-mm radius Teflon-coated Pt wire (1 mm exposed length). The enzyme was then trapped on the surface by electropolymerisation of o-phenylenediamine that also served to block electroactive interference. This procedure afforded electrodes with similar substrate sensitivity compared with the classical approach of immobilising enzyme from a solution of monomer, and represents an approximately 10 000-fold increase in the yield of biosensors from a batch of enzyme. A number of strategies were examined to enhance the sensitivity and selectivity of the Pt/PPD/GluOx sensors operating at 0.7 V versus SCE. Pre-coating the Pt with lipid and incorporation of the protein bovine serum albumin into the polymer matrix were found to improve the performance of the electrode. The sensors had a fast response time, high sensitivity to Glu, with an LOD of about 0.3 mmol l 21 , and possessed selectivity characteristics suggesting that monitoring Glu in biological tissues in vivo may be feasible.

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Section: Pt/ppd/gluox Electrodesmentioning

confidence: 53%

“…These properties compare favourably with those of other GluOx-based sensors in the literature. 16,17,20 Fig . 2 (inset) shows a typical response of a Pt/PEA/PPD/ BSA/ GluOx electrode to 500 mmol l 21 AA.…”

Section: Other Characteristics Of the Pt/pea/ppd/bsa/gluox Sensormentioning

confidence: 99%

Biosensor for Neurotransmitter L-Glutamic Acid Designed for Efficient Use of L-Glutamate Oxidase and Effective Rejection of Interference

Ryan

Lowry²,

O’Neill³

1997

Analyst

124

179

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“…See Section 3.5. 50% and occurs over several hours exposure to brain tissue (Garguilo and Michael, 1994;Hu et al, 1994). Although previous in vitro studies have shown that Pt/PPD/GOx sensors are virtually free from both protein and lipid fouling (Lowry and O'Neill, 1994) we carried out an additional in vitro conditioning of the sensors prior to implantation (see Section 2.4), similar to the preconditioning procedure used by Hill and coworkers to improve the stability of ferrocene-mediated glucose biosensors (Cass et al, 1984).…”

Section: Stability Of Biosensor In 6i6omentioning

confidence: 99%

“…This is because of the importance of glucose monitoring in the disease diabetes mellitus and the fact that glucose determination in various body fluids, such as blood, plasma and urine, remains one of the most common analysis carried out in clinical laboratories. However, only a few such devices have been used in vivo in neurochemical studies.With the exception of a report by Boutelle et al (1986) these have all been carried out in anaesthetized animals and have all involved amperometric enzyme-modified electrodes, predominantly for glucose (Lowry et al, 1994a;Silver and Ereciñ ska, 1994;Netchiporouk et al, 1996;, with some recent reports for glutamate (Albery et al, 1992;Hu et al, 1994;Asai et al, 1996) and choline (Garguilo and Michael, 1993;Garguilo and Michael 1994). The small number of such reports reflects the numerous difficulties associated with performing direct neurochemical measurements in such a hostile and complex environment as brain extracellular fluid (ECF).…”

Section: Introductionmentioning

confidence: 99%

An amperometric glucose-oxidase/poly(o-phenylenediamine) biosensor for monitoring brain extracellular glucose: in vivo characterisation in the striatum of freely-moving rats

Lowry

Miele

O’Neill

et al. 1998

Journal of Neuroscience Methods

100

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Amperometric glucose biosensors based on the immobilization of glucose oxidase (GOx) on Pt electrodes with electropolymerized o-phenylenediamine (PPD) were implanted in the right striatum of freely-moving rats. Carbon paste electrodes for the simultaneous monitoring of ascorbic acid (AA) and/or tissue O 2 were implanted in the left striatum. A detailed in vivo characterization of the Pt/PPD/GOx signal was carried out using various pharmacological manipulations. Confirmation that the biosensor responded to changing glucose levels in brain extracellular fluid (ECF) was obtained by intraperitoneal (i.p.) injection of insulin that caused a decrease in the Pt/PPD/GOx current, and local administion of glucose (1 mM) via an adjacent microdialysis probe that resulted in an increase in the biosensor current. An insulin induced increase in tissue O 2 in the brain was also observed. Interference studies involved administering AA and subanaesthetic doses of ketamine i.p. Both resulted in increased extracellular AA levels with ketamine also causing an increase in O 2 . No significant change in the Pt/PPD/GOx current was observed in either case indicating that changes in O 2 and AA, the principal endogenous interferents, have minimal effect on the response of these first generation biosensors. Stability tests over a successive 5-day period revealed no significant change in sensitivity. These in vivo results suggest reliable glucose monitoring in brain ECF.

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“…This has been achieved through the use of 'first generation' hydrogen peroxide-detecting microelectrochemical biosensors prepared by immobilizing a sensitive and selective oxidoreductase enzyme on, or within close proximity of, an amperometric electrode. Extracelluw x w x w x lar levels of glucose 2-5 , lactate 6-8 , choline 9-12 w x Ž and glutamate [13][14][15][16] have been measured in 'acute' i.e.…”

Section: Introductionmentioning

confidence: 99%

Real-time monitoring of brain energy metabolism in vivo using microelectrochemical sensors: the effects of anesthesia

Lowry

Fillenz

2001

Bioelectrochemistry

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Ž. Ž Rats were implanted in the striatum with a PtrIr electrode for measurement of regional cerebral blood flow rCBF H clearance 2 . technique , a carbon paste electrode for monitoring tissue oxygen and a glucose biosensor for monitoring extracellular glucose. Changes Ž . Ž in all three parameters were recorded in response to the intraperitoneal i.p. administration of the anesthetics chloral hydrate 350 . Ž . Ž . mgrkg , sodium pentobarbitone 60 mgrkg and ketamine 200 mgrkg . An i.p. injection of normal saline, given as a control for the injection of the anesthetics, produced a parallel increase in rCBF and tissue oxygen accompanied by a brief decrease in extracellular glucose. Changes in tissue oxygen reflected the changes in rCBF; there was a decrease in both after sodium pentobarbitone, a decrease followed by a rebound after ketamine and a transient increase after chloral hydrate. All three anesthetics produced a decrease in extracellular glucose. The disparity between the changes in glucose and the changes in rCBF and oxygen suggests that during anesthesia, the reduction in extracellular glucose is not due to a reduction in the direct delivery of glucose from the blood vascular system. These results also indicate that levels of enzymatic substrates and mediators, which are intrinsic to the design and operation of amperometric biosensors, are clearly altered in a complex manner by anesthesia and suggest that caution should be exercised in extrapolating data from acute anesthetized experiments to normal physiology. q

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Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor

Cited by 256 publications

References 45 publications

Biosensor for Neurotransmitter L-Glutamic Acid Designed for Efficient Use of L-Glutamate Oxidase and Effective Rejection of Interference

Biosensor for Neurotransmitter L-Glutamic Acid Designed for Efficient Use of L-Glutamate Oxidase and Effective Rejection of Interference

An amperometric glucose-oxidase/poly(o-phenylenediamine) biosensor for monitoring brain extracellular glucose: in vivo characterisation in the striatum of freely-moving rats

Real-time monitoring of brain energy metabolism in vivo using microelectrochemical sensors: the effects of anesthesia

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