Investigation of the effects of L-glutamine stress on B35 cell line on graphene oxide sheets

Graphene, a monolayer of sp2-bonded carbon atoms, is a quasi–two-dimensional (2D) material with unique electrical and chemical properties. In terms of biomedical applications of graphene and graphene oxide (GO), nervous system would be an ideal breakthrough model, because neural cells are electro-active. Glutamine (Gln) is found abundantly in the central nervous system (CNS) where it participates in a variety of metabolic pathways. Its major role in the brain is being a precursor of the neurotransmitter amino acids: the excitatory amino acids, glutamate (Glu) and aspartate (Asp), and inhibitory amino acid, γ-amino butyric acid (GABA). Glutamine is synthesized from glutamate with ammonia added at the carboxyl group by glutamine synthetase, forming the CH2CH2CONH2 side chain R group. The aim of this work is to investigate whether culture of CNS neurons on GO has any neuroprotective effect against L-glutamine stress. Graphene oxide powder was coated onto glass slides as a thin film and B35 cells were cultured on graphene oxide (GO) sheets. Cultivated cells on glass slides were used as the control group. After 24 hours of cell culture, L-glutamine induced excitotoxicity was applied on B35 cells on both surfaces. After 24 hours of post-stress culture, morphologies of cells were examined by scanning electron microscopy (SEM). Cell viability was measured by MTT assay. The effects of L-glutamine stress on cell viability were visible as early as 1 hour on both surfaces. The cell viability of B35 cells on GO sheets was higher than on glass slides, and cells recovered from the stress within 6 hours on GO surfaces while viability on glass surfaces was lower than 54% after 24 hours. Cell morphology and toxicity measurements also supported this observation. We demonstrated that glutamate is toxic to B35 cells above the concentration of 100mM. The culture on GO increases the resistance to L-glutamine stress on B35 cells, and helps fast recovery. Based on the findings of this study, it is concluded that GO may have a potential for biomedical applications with further studies in the field.