Evaluation of the enhancement of osteogenesis by Zn-releasing diamond-like carbon film

Diamond-like carbon (DLC) has a wide range of commercial applications and some types are known to be biologically stable. Zinc (Zn) has received attention because it enhances the production of alkaline phosphatase (ALP), which promotes bone calcification. Therefore, we manufactured a DLC that contains Zn (Zn-DLC) and can supply Zn to biological systems, as a potential biomaterial to enhance osteogenesis. The present study compared the characteristics of DLC films manufactured using different amounts of Zn, which was introduced using the reactive sputtering method, and compared these with normal DLC, which does not contain Zn. We evaluated film crystallinity using Raman spectroscopy and measured the amount of released Zn using inductively coupled plasma mass spectrometry (ICP-MS). In addition, we evaluated the effects of Zn-DLC on osteogenesis in vitro. Raman spectroscopy verified that Zn-DLC had an increased D peak compared to normal DLC. ICP-MS measurement of the concentration of Zn released from Zn-DLC into the cell culture medium showed that small amounts of Zn were released from this film. Osteoblasts cultured on Zn-DLC tended to show a greater area of calcification than those cultured on DLC, although no significant differences in ALP activity were observed. These results suggested the possibility that osteogenesis could be enhanced by the Zn that is released from Zn-DLC.