Continuous monitoring of L-glutamate released from cultured nerve cells by an online sensor coupled with micro-capillary sampling.
A small volume L-glutamate online sensor was developed in order to monitor changes in the local concentration of L-glutamate released from cultured nerve cells. Syringe pump in the suction mode is used to sample extracellular fluid continuously from a glass micro-capillary and the concentration of L-glutamate can be determined by using a glassy carbon (GC) electrode modified with an Os-polyvinylpyridine mediator bottom film containing horseradish peroxidase and a bovine serum albumin top layer containing L-glutamate oxidase. The overall efficiency of L-glutamate detection with a sensor is 71% under optimum conditions due to an efficient enzymatic reaction at the modified electrode in the thin layer radial flow cell. As a result, we achieved a detection limit of 7-15 nM and a linear range of 50 nM to 10 microM. In an in vitro experiment, the extracellular fluid near a particular nerve cell can be sampled with this micro-pipet and continuously introduced into the modified GC electrode in the radial flow cell via suction provided by a syringe pump. The nerve cells are stimulated by the KCl in a glass capillary and the L-glutamate concentration change can be monitored by changing the distance between the sampling pipet and the nerve cells.
Niwa
O
O
NTT Basic Research Laboratories, Atsugi, Japan.
Horiuchi
T
T
Torimitsu
K
K
D000818:Animals; D015374:Biosensing Techniques; D002138:Calibration; D002478:Cells, Cultured; D003584:Cytological Techniques; D004558:Electric Stimulation; D018698:Glutamic Acid / Q000378:metabolism*; D016014:Linear Models; D008846:Micromanipulation / Q000379:methods*; D009474:Neurons / Q000378:metabolism*; D009862:Online Systems; D051381:Rats; D017208:Rats, Wistar; D013396:Suction; D013594:Syringes
D018698:Glutamic Acid