Positive biocompatibility of several graphene derivatives with dopaminergic cells at long term culture

The emerging carbon nanomaterial graphene (G) and its oxidized derivative graphene oxide (GO) have recently gained considerable attention in biomedical applications such as cancer therapy or biosensors. It has for example been demonstrated that G has an efficient bioconjugation with common biomolecules and activates cell differentiation of neuronal stem cells (Li et al., 2013). This way, G could acts as a physical support or scaffold to promote axonal sprout as a “deceleration” support for the DA cells derived from neural stem cells. Since GO in its multilayer form and with multiples carboxilate and epoxy groups seems to shows interesting biological properties (Yang et al., 2013) the aim of the present work has been to test different graphene derivatives searching for the best scaffold to be used in stem cell differentiation. For this purpose we have tested the cytotoxicity of GO and reduced GO, and specifically its biocompatibility with SN4741, a dopaminergic cells line derived from mouse substance nigra, measuring the effect in the cells at long term culture. The cells were cultured in Dulbecco’s modified Eagle’s medium 10% FCS (Gibco) to about 80% confluence. Cells were incubated applying 1.000 cells in 96-well microliter plates with graphene using three chemically different types of GO as powders and films: 1) GO, which is hydrophilic; 2) partially reduced GO (PRGO) which is hydrophobic and 3) fully reduced GO (FRGO), also hydrophobic, in five concentrations: 1 mg/ml; 0.1 mg/ml; 0.05 mg/ml; 0.02 mg/ml and 0.01 mg/ml, in each type of graphene. Cells were cultured with GO and cell viability was determined after 24 hours, 1 week and 2 weeks using the MTT assay (Roche) and cytotoxicitity was determined by the lactate dehydrogenase (LDH) (Roche) assay measured at 560nm. The results demonstrated positive biocompatibility between the G-derivatives and SN4741 cells. We conclude that the use of our G-derivative scaffolds can enhance the neural differentiation towards neurons (TH positive) providing a cell growth microenvironments and appropriate synergistic cell guidance cues. This findings demonstrated that biocompatibility of scaffolds is a pre-requisite for generation of successful clinical application of graphene. It could offer a platform for neural stem cells and a promising approach for neural regeneration in the research of neurological diseases like PD. Long-term studies on the biological effects of graphene will now be performed for the development of therapeutic treatment as the goal. (Refs: Li N., Zhang Q, Gao S. et a., 2013, Nature/Sci Rep. 3:1604. doi: 10.1038/srep01604; Yan K., Li Y., Tan X., et al., 2013, Small., 9(9-10): 1492-1503)1. Universidad de Malaga. Campus de Excelencia Internacional Andalucia Tech, España. 2. The Norwegian Research Council (grant nº 215086, Oslo, Noruega. 3. Karolinska Institute Reasearch Fund, Estocolmo, Suecia