Interactions of graphene derivatives with glutamate-neurotransmitter: A parallel first principles - Docking investigation.

Glutamate plays an important role in excitatory neurotransmission, learning, and memory processes, and under pathological conditions it is directly associated with several chronic neurological disorders, such as depression, epilepsy, schizophrenia, and Parkinson's. Therefore, the detection and quantification of Glutamate is important for the rapid diagnosis of these diseases. Using first principles and molecular docking simulations we have evaluated the energetic, structural, and binding properties of graphene derivatives, such as pristine graphene (pristine-Gr) and oxidized graphene with carboxylic (Gr-COOH), carbonyl (Gr-COH), hydroxyl (Gr-OH), and epoxy (-O-) groups interacting with the glutamate neurotransmitter. The calculated binding affinity free energies from the docking complexes (glutamate-graphene family) suggest higher oxidized graphene-based glutamate molecular recognition than the pristine-Gr, with the following order of oxidized graphene derivatives according to ab initio results: (Gr-O∼Gr-COOH ∼ Gr-COH > Gr-OH)>pristine-Gr. Herein, the ab initio binding energies found for the glutamate-graphene family complexes are in the range of 0.24-0.80 eV. The configurations studied showed a biophysical adsorption regime without significant changes in the physico-chemical properties of the adsorbed glutamate neurotransmitter, in accordance with the general acceptance criteria of the detection systems.