Endocytic carboxylated nanodiamond for the labeling and tracking of cell division and differentiation in cancer and stem cells.

Nanodiamond (ND) is carbon nanomaterial developing for biological applications in recent years. In this study, we investigated the location and distribution of 100 nm carboxylated ND particles in cell division and differentiation. ND particles were taken into cells by macropinocytosis and clathrin-mediated endocytosis pathways. However, the cell growth ability was not altered by endocytic ND particles after long-term cell culture for 10 days in both A549 lung cancer cells and 3T3-L1 embryonic fibroblasts. ND particles were equal separating into two daughter cells of cell division approximately. Finally, the cell retained a single ND's cluster in cytoplasm after sub-cultured for several generations. Interestingly, ND's clusters were carried inside of cell but without inducing damages after long-term cell culture. Moreover, ND particles did not interfere with the gene or protein expressions on the regulation of cell cycle progression and adipogenic differentiation. Together, these findings provide that endocytic ND particles are non-cytotoxic in cell division and differentiation, which can be applied for the labeling and tracking of cancer and stem cells.