Fluorescent Nanodiamonds

5Biocompatibility of Nanodiamonds

“A diamond is forever,” De Beers’ diamond campaign launched on the New York Times, September 1948, is the same slogan still used today [1]. Funny as it may sound, if asked, scientists working on nanodiamonds (NDs) would say the same. Scientifically, the slogan vividly depicts the exceptionally high physical and chemical stability of the gemstone under ambient conditions. However, some may be wondering: Stable, yes, but is it safe to use? How to tell if it is safe for humans? Can we measure safety in a quantitative way and, if so, how? These are some questions that we try to answer in this chapter.

Diamond, categorized as an inorganic material, is considered both chemically inert and biologically compatible because it is composed of pure sp³‐hybridized carbon atoms, except those on the surface. According to International Union of Pure and Applied Chemistry (IUPAC), the term “biological compatibility” or “biocompatibility” in short is defined in a general context as “the ability to be in contact with a living system without producing an adverse effect” or, in the context of medical therapy, “the ability of a material to perform with an appropriate host response in a specific application” [2]. The exceptionally low chemical reactivity of diamond is well in line with the first definition. This characteristic, together with the facts that diamond can be synthesized by chemical vapor deposition methods for coating of biomedical devices and the surface ...