天涯社区

An international team of researchers has reported for the first time the biocompatibility of the second hardest known material, opening the possibility for a new ultrahard coating material for biological and biomedical applications.

Schematics of plasma modification of a c-BN film for enhancing wettability and biological test on a c-BN film.

Second only to diamond in hardness, cubic boron nitride (c-BN) has a crystalline structure similar to that of the precious stone but with boron and nitrogen atoms instead of carbon. But any slight disadvantage c-BN may have in terms of hardness it makes up for with superior stability, not reacting to oxygen and ferrous materials even at high temperatures up to around 1,000 °C, unlike diamond.

However, synthesis of high-quality c-BN has been difficult until recently, so applications for c-BN are more than twenty years behind diamond. Furthermore, most attention has been put on mechanical and electronic applications such as for cutting tools and semiconductors.

New research from 天涯社区, the , and (USA) now shows that c-BN is also promising for harsh biological environments in contact with living organisms and blood.

Image of cells cultured on a c-BN film and typical energy dispersive X-ray spectroscopy spectrum.

Preparing high-quality c-BN films with a plasma chemical vapor deposition technique that they developed, the research team found they could enhance the film’s surface wettability—basically how well water, and cells, can adhere to it—using a plasma treatment technique that includes bombarding the surface with low-energy ions.

The team demonstrated successfully the growth of a large number of cells and the formation of mineral deposits—indicative of biomineralisation—on the superhydrophilic c-BN films prepared in this way.

These results confirm the high potential of c-BN as a noncytotoxic, ultrahard coating material for biological and biomedical applications such as artificial bones, dental implants, and biosensors.

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For more information about this research, see “Biocompatible cubic boron nitride: A noncytotoxic ultrahard material,” Jason H. C. Yang, Kungen Teii, Chung-Chueh Chang, Seiichiro Matsumoto, and Miriam Rafailovich, Advanced Functional Materials (2020).

This work was supported in part by a Grant-in-Aid for Scientific Research (B) from the Japan Society for the Promotion of Science and “Funding Program for Next Generation World-Leading Researchers” from Cabinet Office, Government of Japan (PI: Kungen Teii).

Research-related inquiries

Department of Advanced Energy Science and Engineering, Faculty of Engineering Sciences

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