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Continuous Monitoring of L ‐Glutamate Released from Cultured Rat Nerve Cells with a Microfabricated On‐Line Sensor at a Slow Flow Rate
Author(s) -
Niwa Osamu,
Kurita Ryoji,
Horiuchi Tsutomu,
Torimitsu Keiichi
Publication year - 1999
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199905)11:5<356::aid-elan356>3.0.co;2-8
Subject(s) - capillary action , horseradish peroxidase , volumetric flow rate , electrode , materials science , syringe driver , analytical chemistry (journal) , chromatography , chemistry , syringe , composite material , biochemistry , psychology , physics , quantum mechanics , psychiatry , enzyme
A microfabricated online L ‐glutamate sensor was developed to monitor changes in the local concentration of L ‐glutamate released from cultured nerve cells. The sensor consists of two glass plates and a fused silica sampling capillary. One of the glass plates has rectanglar flow channels cut into it with a dicing saw and the other has three carbon film based electrodes. One of the electrodes was modified with an Os‐polyvinylpyrridine‐based polymer layer containing horseradish peroxidase. A GluOx enzyme layer was immobilized upstream of the working electrode. A syringe pump in the suction mode was used to sample extracellular fluid continuously via a glass capillary with a pointed end. The sensor sensitivity did not decrease with decreasing flow rate when the flow rate was reduced to about 200 Nl/min. This is because the increase in the conversion efficiency compensated for the decrease in the analyte flow into the sensor. As a result, a low detection limit (6.4 nM) was obtained at a slow flow rate. In an in vitro experiment, the extracellular fluid near a particular nerve cell was sampled through a capillary and continuously introduced into the sensor via the suction provided by a syringe pump. The nerve cells were stimulated by KCl and a transient L ‐glutamate release with a sharp peak was monitored with a slow flow rate of 500 nL/min to 2 μL/min.