Diamond as Functional Material for Bioelectronics and Biotechnology

Understanding the interaction between the biological environment (tissues, cells, proteins, electrolytes, etc.) and a solid surface is crucial for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and the optimization of implant materials. Cells, the cornerstones of living tissue, perceive their surroundings and subsequently modify it by producing extracellular matrix (ECM), which serves as a basis to simplify their adhesion, spreading and differentiation (Shakenraad & Busscher, 1989). This process is considerably complex, flexible and strongly depends on the cell cultivation conditions including the type of the substrate. Surface roughness of the substrate plays an important role (Babchenko et al., 2009; Kalbacova et al., 2009; Kromka et al., 2009; Zhao et al., 2006), other influential factors include both the porosity (Tanaka et al., 2007) and the wettability of the substrate, the latter influencing protein conformation (Browne et al., 2004; Rezek, Ukraintsev, Michalíková, Kromka, Zemek & Kalbacova, 2009) as well as the adsorption and viability of cells (Grausova et al., 2009; Kalbacova, Kalbac, Dunsch, Kromka, Vanecek, Rezek, Hempel & Kmoch, 2007). Materials which are commonly employed as substrates for in vitro testing are polystyrene and glass. In this context, diamond as a technological material can provide a relatively unique combination of excellent semiconducting, mechanical, chemical as well as biological properties (Nebel et al., 2007). Diamond also meets the basic requirements for large-scale industrial application, most notably, it can be prepared synthetically. Diamond can be synthesized either as a bulk material under high-pressure and high-temperature conditions, or in the form of thin films by chemical vapor deposition of methane and hydrogen on various substrates including glass and metal (Kromka et al., 2008; Potocky et al., 2007). Moreover, the application of selective nucleation makes it possible to directly grow conductive diamond microstructures, which operate e.g. as transistors or pH sensors (Kozak et al., 2010). Nowadays, it is possible to deposit diamond even on large areas (600 cm2 or more) using linear antennas (Kromka et al., 2011; Tsugawa et al., 2010). The excellent compatibility of diamond with biological materials and environment (Bajaj et al., 2007; Grausova et al., 2009; Diamond as Functional Material for Bioelectronics and Biotechnology