▎ 摘　　要

Graphene is a novel carbon-based material widely studied in bio-electrochemical fields because of its high electrical conductivity and excellent electrocatalytic activity. However, its biological applications have been limited due to the lack of understanding of its compatibility with numerous biological entities. In this paper, cytoxicities of MDA-MB-231 breast cancer cells (MDA cells) on carbon paste (CP) and graphene-carbon paste (GCP) substrates are assessed. GCP was prepared by mixing graphene powder into carbon paste with different graphene contents. Cytotoxic effect was evaluated from cell viability, cell adhesion, ROS production and fluorescence staining studies. Cell viability on GCP substrate was found to initially increase as graphene content increases from 0 to 2.5 wt% but then decrease as the content increases further. In addition, the viability decreases with time for all substrates. Similarly, graphene concentration affected the number of adherent cells in the same manner as the cell viability. Likewise, reactive oxygen species (ROS) induced by carbon substrate increased with time and decreased with small graphene inclusion, confirming that low graphene content led to lower cytotoxicity. Moreover, confluence of MDA cells on substrate evaluated using Hoechst 33342 fluorescence staining was also found to be enhanced at low graphene concentration. Therefore, low-content graphene incorporation can effectively improve biocompatibility of carbon-based materials with MDA-MB-231 breast cancer cells, enabling potential applications such as electrochemical electrode for cell study. (C) 2013 Elsevier B.V. All rights reserved.