a b s t r a c tGraphene has been demonstrated in many biomedical applications and its potentials for neural interfacing. Emerging concerns on graphene, as a biomedical material, are its biocompatibility and how biologically targeted tissue/cells respond to it. Relatively few studies attempted to address the interactions of graphene or its derivatives with the tissues/cells, while very few reports on neural system. In this study, we tried to explore how neurites, one of the key structures for neural functions, are affected by graphene during the development until maturation in a mouse hippocampal culture model. The results reveal that graphene substrates exhibited excellent biocompatibility, as cell viability and morphology were not affected. Meanwhile, neurite numbers and average neurite length on graphene were significantly enhanced during 2e7 days after cell seeding compared with tissue culture polystyrene (TCPS) substrates. Especially on Day 2 of the neural development period, graphene substrates efficiently promoted neurite sprouting and outgrowth to the maximal extent. Additionally, expression of growthassociate protein-43 (GAP-43) was examined in both graphene and TCPS groups. Western blot analysis showed that GAP-43 expression was greatly enhanced in graphene group compared to TCPS group, which might result in the boost of neurite sprouting and outgrowth. This study suggests the potential of graphene as a material for neural interfacing and provides insight into the future biomedical applications of graphene.

Gold nanoparticles (GNPs) and modified GNPs having two kinds of functional molecules, cysteamine (AET) and thioglucose (Glu), are synthesized. Cell uptake and radiation cytotoxicity enhancement in a breast-cancer cell line (MCF-7) versus a nonmalignant breast-cell line (MCF-10A) are studied. Transmission electron microscopy (TEM) results show that cancer cells take up functional Glu-GNPs significantly more than naked GNPs. The TEM results also indicate that AET-capped GNPs are mostly bound to the MCF-7 cell membrane, while Glu-GNPs enter the cells and are distributed in the cytoplasm. After MCF-7 cell uptake of Glu-GNPs, or binding of AET-GNPs, the in vitro cytotoxicity effects are observed at 24, 48, and 72 hours. The results show that these functional GNPs have little or no toxicity to these cells. To validate the enhanced killing effect on cancer cells, various forms of radiation are applied such as 200 kVp X-rays and gamma-rays, to the cells, both with and without functional GNPs. By comparison with irradiation alone, the results show that GNPs significantly enhance cancer killing.