Ultra-sensitive electrochemical detection of glutamate based on reduced graphene oxide/Ni foam nanocomposite film fabricated via electrochemical exfoliation technique using waste batteries graphite rods

Glutamate (Glut) is the most abundant excitatory neurotransmitter in our brain and central nervous system (CNS) that is essential for the proper functioning of the brain. The uneven concentration of glutamate causes cell's overstimulation which leads to many severe diseases, including brain cancer, and brain cell damage. Further, the overexcitation of neuronal cells which is involved in the neurotoxic processes induces many neurodegenerative diseases such as amyotrophic lateral sclerosis, motor neuron, Huntington's, Alzheimer's, and Parkinson's diseases. Thus, real-time quantitative analysis is of utmost importance for its prevention. In the present study, we report an enzymatic electrochemical biosensor based on reduced graphene oxide-modified nickel foam (rGO/NiF) for glutamate detection. Graphene has been successfully synthesized via electrochemical exfoliation technique using waste batteries graphite rods as a cheap, waste recycling, and environmentally friendly approach. Using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the rGO-modified NiF electrode demonstrates improved electrocatalytic activities compared to the bare Ni foam electrode. Under the optimal conditions, the fabricated enzyme-based rGO/NiF biosensor shows a linear response in the physiological range of 5-300 mu M (normal value 30-80 mu M), revealing a sensitivity of -4.8 mu A/(mu M & sdot;cm2) with a correlation coefficient of -0.997, the limit of detection (LOD) -0.1 mu M and shelf-life of about ten weeks. Thus, we believe that the fabrication of this sensitive and selective responding biosensor will also enable us to measure the dynamic processes associated with Glut neurotransmission in the CNS.