Graphene oxide-based substrate: physical and surface characterization, cytocompatibility and differentiation potential of dental pulp stem cells

Objective. The aim of this study was to evaluate the cytotoxicity and differentiation potential of a graphene oxide (GO)-based substrate using dental pulp stem cell (DPSC). Methods. GO was obtained via chemical exfoliation of graphite using the modified Hummer's method and dispersed in water-methanol solution. 250 mu L of 1.5 mg/mL solution were added to a cover slip and allowed to dry (25 degrees C, 24 h). GO-based substrate was characterized by Raman spectroscopy, AFM and contact angle. DPSC were seeded on GO and glass (control). Cell attachment and proliferation were evaluated by polymeric F-actin staining, SEM and MTS assay for five days. mRNA expression of MSX-1, PAX-9, RUNX2, COL I, DMP-1 and DSPP were evaluated by qPCR (7 and 14 days). Statistical analyses were performed by either Mann-Whitney, one or two-way Anova followed by and Tukey's post hoc analysis (alpha = 0.05). Results. Peaks at 1587 cm(-1) and 1340 cm(-1) (G and D band) and ID/IG of 0.83 were observed for GO with Raman. AFM showed that GO was randomly deposited and created a rougher surface comparing to the control. Cells successfully adhered on both substrates. There was no difference in cell proliferation after 5 days. Cells on GO presented higher expression for all genes tested except MSX-1 and RUNX2 for 7 days. Significance. GO-based substrate allowed DPSC attachment, proliferation and increased the expression of several genes that are upregulated in mineral-producing cells. These findings open opportunities to the use of GO alone or in combination with dental materials to improve their bioactivity and beyond. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.