A diamond nanocone array for improved osteoblastic differentiation

Efficient delivery of biomolecules to cells is of great importance in biology and medicine. To achieve this, we designed a novel type of densely packed diamond nanocone array to conveniently transport molecules to the cytoplasm of a great number of cells. The nanocone array was fabricated by depositing a thin layer of diamond film on a silicon substrate followed by bias-assisted reactive ion etching. The height of the diamond nanocones varied from 200 nm to 1 μm with tip radii of approximately 10 nm. Our fluorescein and propidium iodide staining results clearly demonstrated that dramatically enhanced delivery of fluorescein into cells was realized without leading to noticeable cell death with the aid of nanocone treatment. As a test case of the drug delivery application of the device, MC-3T3 cells in differentiation medium were applied to the nanocone array for enhanced intracellular delivery of the medium. This was confirmed by the fact that nanocone treated cells experienced much higher differentiation ability at an early stage in comparison with untreated cells. Overall, the results indicate that the diamond nanocone array provides a very simple but yet very effective approach to achieve delivery of molecules to a large number of cells.