Farhang Ebrahimifar - Department of Biochemistry and Biophysics, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad.
Jamshidkhan Chamani - Department of Biochemistry and Biophysics, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad.
Hassan Tavakoli - Neuroscience Research Center, Bagiyatallah University of Medical Sciences, Tehran, Iran.

Introduction: Glutamate is an excitatory neurotransmitter in the mammalian central nervous system, playing a major role in a wide variety of brain functions. For this reason, detection of glutamate is of importance in both clinical and food samples. Thus, there is a need for rapid and sensitive methods to detect it in a variety of samples. In this study, for monitoring of glutamate, an electrochemical biosensor is constructed using immobilization of glutamate oxidase and polycathionic chains of nano chitosan at the surface of platinum electrode. Since temperature has a great effect on glutamate oxidase activity and biosensor responses, in this study, the effect of temperature on the responses of fabricated biosensor is investigated.Material and methods: The temperature effect on the response of fabricated biosensor was evaluated between 25±1 °C and 75±1 °C at pH 7.4 and scan rate 10 mv/s using cyclic voltametry method. Cyclic voltammograms were considered as biosensor response. All experiments were performed in buffer phosphate (0.1 M), pH 7.4 containing 0.5 × 10-3 M glutamate. Results and conclusion: The results indicated that the biosensor’s response increased with temperature augmentation. In fact, the responses gradually increased up to 45±1 ºC, afterwards, the sensor lost its activity. This phenomenon may be due to thermal inactivation of glutamate oxidase. Also, the results showed that the best response was happened at 25 °C, so that, this temperature was chosen as working temperature for all further experiments.

Electrochemical Biosensor, Glutamate Neurotransmitter, Glutamate Oxidase, Cyclic Voltammetry