Graphene and tricobalt tetraoxide nanoparticles based biosensor for electrochemical glutamate sensing.

An amperometric biosensor based on tricobalt tetraoxide nanoparticles (Co3O4), graphene (GR), and chitosan (CS) nanocomposite modified glassy carbon electrode (GCE) for sensitive determination of glutamate was fabricated. Scanning electron microscopy was implemented to characterize morphology of the nanocomposite. The biosensor showed optimum response within 25 s at pH 7.5 and 37 °C, at +0.70 V. The linear working range of biosensor for glutamate was from 4.0 × 10-6 to 6.0 × 10-4 M with a detection limit of 2.0 × 10-6 M and sensitivity of 0.73 μA/mM or 7.37 μA/mMcm2. The relatively low Michaelis-Menten constant (1.09 mM) suggested enhanced enzyme affinity to glutamate. The glutamate biosensor lost 45% of its initial activity after three weeks.