Amorphous Carbon Coatings for Biological Applications - Biological and Biomedical Coatings - page 91

FIGURE 2.37
Transcortical implants in lateral femoral cortex of sheep. One (silver) uncoated CoCr alloy and two (black) a-C:H
coated implants are shown in this intraoperative photograph. (Reprinted with permission from Allen et al., J.
Biomed. Mater. Res. B , 58, 319, 2001.)
indicated that a-C:H followed the set pattern of response to an inert biocompatible material.
At the end of 6 months, a-C:H/titanium implants were encapsulated by a 5- to 20- μ m-thick
layer of fibrous tissue, which reduced in thickness to 5-l0 μ m by 1 year. The surrounding
muscle appeared to be normal. There was also no evidence of delamination of the coating
or release of a-C:H particles into the surrounding tissue.
Tetrahedral amorphous carbon films (ta-C) coated Si die were implanted into male
SV129 mice for in vivo tissue response [138]. The ta-C films were produced by pulsed laser
deposition to be rich in either three- or four-fold (i.e., sp 2 - or sp 3 -bonded C) content. Tissue
reaction to these materials over a period of 6 months was assessed following subcutane-
ous implantation of ta-C-coated silicon die. The reaction to ta-C particles injected near the
sciatic nerve was studied as well. These particles were used as a simple analog to small,
free-floating ta-C devices that might be used in vivo and as a well-characterized system to
study tissue reaction to possible μ m scale debris from a ta-C coated device.
The ta-C-coated die implants were easily removed with surrounding tissues and then
processed for histologic evaluation of the tissue response at 4, 15, 23, and 56 days, and
at 6 months after implantation. A typical ta-C-coated die is shown in Figure 2.38. This
FIGURE 2.38
ta-C coated Si die in situ at the time of dissection. Implant dimensions are 5 × 5 × 0.5 mm 3 . (Reprinted with
permission from LaVan et al., Biomaterials , 26, 465, 2005.)