Microelectrodes, glutamate

Mikeladze E, Schulte A, Mosbach M, Blochl A, Csoiegi E, Solomonia R, Schumann W (2002) Redox hydrogel-hased bienzyme microelectrodes for amper-ometric monitoring of L-glutamate. fElectroanalysis 14 393-399... 

Biosensors (glutamate only) Microelectrodes or microelectrode arrays Various enzyme modifications available Measures current or luminescence Rapid in-vivo monitoring of glutamate only <1 sec 10-<1 uM [134-136,138]... 

Burmeister JJ, Pomerleau F, Palmer M, Day BK, Huettl P, Gerhardt GA. Improved ceramic-based multisite microelectrode for rapid measurements of L-glutamate in the CNS. J Neurosci Meth 2002 119 163-71. 

Figure 2. Schematic diagram the electrophysiological assay used to test for biological activity of spider venom components. Lx>ngitudinal ventrolateral muscles of Musca domestica were impaled with an intracellular microelectrode, which recorded excitatory junctional potentials (EJP) in response to nerve stimulation or ionophoretic junctional potentials (IP) in response to glutamate application by ionophoresis.

Day BK, Pomerleau F, Burmeister JJ (2006) Microelectrode array studies of basal and potassium-evoked release of l-glutamate in the anesthetized rat brain. Journal of Neurochemistry 96 1626-1635. 

Pomerleau F, Day BK, Huetd P (2003) Real Time in vivo Measures of 1-Glutamate in the Rat Central Nervous System Using Ceramic-Based Multisite Microelectrode Arrays. Annals of the New York Academy of Sciences 1003 454 57. 

An amperometric sensor for amino acids based on flow injection analysis (FIA) and using microelectrodes (10 pm diameter) primarily of P(Py) doped with sulfonate dopants such as tosylate and 3-sulfobenzoate was demonstrated by Akhtar et al. [823, 824]. Linear response was demonstrated for analytes such as aspartic acid and glutamic acid over the concentration range 7.5 X 10 to lO" with sensitivities in the region of 1.5 nC-M and detection limits of ca. 10 M. These authors also showed the use of a pattern recognition technique using the responses of six detector electrodes. Fig. 17-11 shows typical response of one of their sensors. 

In a similar experiment, Shinohara et al. [1024] loaded glutamate onto a 50 jum-diameter Pt microelectrode and a controlled, pulsed release, resembling that occurring at neuronal synapses, was attempted. Fig. 24-2 shows the result of this experiment. The response time of the release indicated chronoamperometrically was ca. 1 ms. The ultimate application envisioned for both the Zinger et al. and Shinohara et al. work was controlled release of important chemicals such as neurotransmitters in vivo for the treatment of disease. 

A recent report of an in vivo flexible strip microelectrode sensor array for glutamate and lactate monitoring in tissue represents an advance [44], The polyimide substrate was patterned with platinum microelectrodes in addition to epoxy and dry film insulations to produce amperometric, enzyme-based sensors. An on-chip reference electrode and a perm-selective layer, with hydrogel membranes or direct cross-hnking for enzyme immobihzation, provided stable devices with good performance and allowed a demonstration of in vivo application to glutamate monitoring in rat brain. 

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