A simple synthetic route for the preparation of functional nanoscale graphene oxide (NGO), a novel nanocarrier for the loading and targeted delivery of anticancer drugs, is reported. The NGO is functionalized with sulfonic acid groups, which render it stable in physiological solution, followed by covalent binding of folic acid (FA) molecules to the NGO, thus allowing it to specifically target MCF-7 cells, human breast cancer cells with FA receptors. Furthermore, controlled loading of two anticancer drugs, doxorubicin (DOX) and camptothecin (CPT), onto the FA-conjugated NGO (FA-NGO) via pi-pi stacking and hydrophobic interactions is investigated. It is demonstrated that FA-NGO loaded with the two anticancer drugs shows specific targeting to MCF-7 cells, and remarkably high cytotoxicity compared to NGO loaded with either DOX or CPT only. Considering that the combined use of two or more drugs, a widely adopted clinical practice, often displays much better therapeutic efficacy than that of a single drug, the controlled loading and targeted delivery of mixed anticancer drugs using these graphene-based nanocarriers may find widespread application in biomedicine.

Neural stem cell (NSC) based therapy provides a promising approach for neural regeneration. For the success of NSC clinical application, a scaffold is required to provide three-dimensional (3D) cell growth microenvironments and appropriate synergistic cell guidance cues. Here, we report the first utilization of graphene foam, a 3D porous structure, as a novel scaffold for NSCs in vitro. It was found that three-dimensional graphene foams (3D-GFs) can not only support NSC growth, but also keep cell at an active proliferation state with upregulation of Ki67 expression than that of two-dimensional graphene films. Meanwhile, phenotypic analysis indicated that 3D-GFs can enhance the NSC differentiation towards astrocytes and especially neurons. Furthermore, a good electrical coupling of 3D-GFs with differentiated NSCs for efficient electrical stimulation was observed. Our findings implicate 3D-GFs could offer a powerful platform for NSC research, neural tissue engineering and neural prostheses.

Tremendous research efforts have been devoted to fabricating high quality quantum dots (QDs) for applications in biology and medicine. Much of this research was pursued with an ultimate goal of using QDs in clinical applications. However, a great deal of concern has been voiced about the potential hazards of QDs due to their heavy-metal content. Many studies have demonstrated toxicity of various QDs in cell culture studies. However, in a smaller number of studies using small animal models (mice and rats), no abnormal behaviour or tissue damage was noticed over periods of months after the systemic administration of QDs. Nevertheless, the correlation of these results with the potential for negative effects of QD on humans remains unclear. Many urgent questions must be answered before the QDs community moves into the clinical research phase. This review provides an overview of the toxicity assessment of QDs, ranging from cell culture studies to animal models and discusses their findings. Guidelines for using various nonhuman primate models for QD toxicity studies are highlighted. This review article is intended to promote the awareness of current developments of QD applications in biology, the potential toxicity of QDs, and approaches to minimizing toxicity.