Diamond Seeding and Growth of Hierarchically Structured Films for Tissue Engineering

Abstract

The growth of nanocrystalline diamond (NCD) has attracted many researchers because of the combination of advanced intrinsic properties such as their smooth surface, excellent optical, mechanical, and thermal properties, biocompatibility, high affinity for covalent bonding with specific organic molecules, and chemical inertness. [1][2][3] Low-cost insulating (nominally undoped) and semiconducting (boron-doped) nanocrystalline diamond films can be deposited on large areas [4] and thus new fields for their bioelectronic and biosensor applications are opened. [5][6][7][8][9] Moreover, in vivo studies of diamond-based implants (TiAl6V4 probes covered with NCD) in a rabbit femur showed very high bonding strength to the metal base and also to the surrounding bone tissue, without any problems of corrosion. [10] The large-area deposition of NCD films is still not a trivial technological task because of the low reproducibility over large areas and low nucleation yield. The main drawback of the low nucleation yield is the prolonged deposition time required for getting fully closed and uniform NCD layers.Common minimum film thickness is at least several hundred nanometers. There are several factors that can positively enhance the diamond growth, such as surface defects (scratching lines), the tendency of the substrate to form a carbide layer, the resistance of the substrate to carbon bulk diffusion, and the surface energy of substrate. [11] In comparison with several nucleation procedures, [12] the ultrasonic seeding technique with ultradispersed detonation diamond (UDD) powder seems to be the most promising technique to achieve extremely high nucleation yields. [13][14][15] However, detailed studies on ultrasonic seeding are mostly restricted to ''after'' growth study. [16][17] No details of the surface morphology of ''just seeded'' substrate or technological data (such as the UDD type and seeding time) have yet been published.Well-defined uniformity and controllable morphology of NCD films is of utmost importance for their biological applications in tissue engineering. Generally, the biological performance of a biomaterial is strongly dependent on its surface properties. [18] Surface energy, charge, wettability, chemistry, and topography influence the biological response of cells and tissues to an implant device. The first contact of cells with the implant surfaces is a multistep event. Firstly, serum/plasma proteins adsorb on the material surface, then cells attach to this protein layer, and integrins (specific cellular receptors), recognizing the presented extracellular ligands, mediate the first interaction of cells with the material. The attachment/adhesion process of the cells is accompanied by rearrangement of cytoskeleton proteins, formation of tight focal adhesion contacts, activation of focal adhesion kinase, and induction of several intracellular signal transduction pathways leading to cell proliferation and differentiation. [19] In that way the material surface indirectly determines cellular fate, finally the o...

Characterization of Optical and Electrical Properties of Transparent Conductive Boron-Doped Diamond thin Films Grown on Fused Silica

“…The substrates had been washed for 5 minutes in an ultrasonic bath using acetone and 2-isopropanol. Next, they had been seeded for 1 hour by sonication in a commercially available diamond suspension with a grain size of 5-20 nm (Blue-seeds, ITC, USA) [31,32]. Then the substrates were washed again in 2-isopropanol and dried in a stream of nitrogen.…”

Investigation of residual stress in structured diamond films grown on silicon

“…The structured films are required for applications like protective layers on transistors [7] or advanced hybrid MEMS devices [8]. The micro-structured diamond films are also used for tissue engineering [9][10][11].…”

Diamond nucleation and seeding techniques for tissue regeneration

“…In recent years, ultrasonic treatment using ultradispersed detonation diamond represents the most perspective pretreatment method that is easily applied to substrates with a complex geometry and shape (Williams et al , 2007;Kromka et al , 2009a). From the broad range of bombardment and irradiation pretreatments, ion bombardment is the most promising alternative allowing the heteroepitaxial growth of diamond fi lms on iridium substrates (Schreck et al , 1997).…”