Osteogenic cell differentiation on H-terminated and O-terminated nanocrystalline diamond films

Abstract

Nanocrystalline diamond (NCD) films are promising materials for bone implant coatings because of their biocompatibility, chemical resistance, and mechanical hardness. Moreover, NCD wettability can be tailored by grafting specific atoms. The NCD films used in this study were grown on silicon substrates by microwave plasma-enhanced chemical vapor deposition and grafted by hydrogen atoms (H-termination) or oxygen atoms (O-termination). Human osteoblast-like Saos-2 cells were used for biological studies on H-terminated and O-terminated NCD films. The adhesion, growth, and subsequent differentiation of the osteoblasts on NCD films were examined, and the extracellular matrix production and composition were quantified. The osteoblasts that had been cultivated on the O-terminated NCD films exhibited a higher growth rate than those grown on the H-terminated NCD films. The mature collagen fibers were detected in Saos-2 cells on both the H-terminated and O-terminated NCD films; however, the quantity of total collagen in the extracellular matrix was higher on the O-terminated NCD films, as were the amounts of calcium deposition and alkaline phosphatase activity. Nevertheless, the expression of genes for osteogenic markers – type I collagen, alkaline phosphatase, and osteocalcin – was either comparable on the H-terminated and O-terminated films or even lower on the O-terminated films. In conclusion, the higher wettability of the O-terminated NCD films is promising for adhesion and growth of osteoblasts. In addition, the O-terminated surface also seems to support the deposition of extracellular matrix proteins and extracellular matrix mineralization, and this is promising for better osteoconductivity of potential bone implant coatings.

Keywords:

• nanocrystalline diamond film
• osteoblast
• Saos-2
• collagen
• SHG

Acknowledgments

Jana Liskova acknowledges the Centre of Biomedical Research (project CZ.1.07/2.3.00/30.0025) for financial support. This project is cofunded by the European Social Fund and the state budget of the Czech Republic. Further support has been provided by the Grant Agency of the Czech Republic (“Center of Excellence”; grant number P108/12/G108). Mr Robin Healey (Czech Technical University, Prague) is gratefully acknowledged for his language revision of the manuscript. The abstract of this paper was presented at the 8th Combined Meeting of Orthopaedic Research Societies (CORS), Venice, Italy, October 13–16, 2013, as a poster presentation with interim findings. The poster’s abstract was published in “Poster Abstracts” in Bone Joint J 2014, vol. 96-B: (SUPP 11) 250. This work can be found at this Website: http://www.bjjprocs.boneandjoint.org.uk/content/96-B/SUPP_11/250.abstr.

Disclosure

The authors report no conflicts of interest in this work.