No abstract

Plasma activation of polyetheretherketone (PEEK) surfaces and the influence on coating formation in a supersaturated calcium phosphate solution was investigated in this study. It was observed that plasma treatment in a N2/O2 plasma had a significant effect on the wettability of the PEEK surface. The contact angle decreased from 85 degrees to 25 degrees after plasma treatment. Cell culture testing with osteoblastic cell lines showed plasma activation not to be disadvantageous to cell viability. X-ray photoelectron spectroscopy (XPS) analysis was performed to characterize the chemical composition of the PEEK surfaces. It was observed that the O1s intensity increased with plasma activation time. At the C1s peak the appearance of a shoulder at higher binding energies was observed. Coating of PEEK was performed in a supersaturated calcium phosphate solution. Coating thicknesses of up to 50 microm were achieved after 24 days of immersion. Plasma activation followed by nucleation in a highly saturated hydroxyapatite solution had a positive effect on the growth rate of the layer on PEEK. Chemical analysis revealed that the coating consists of a carbonate-containing calcium phosphate.

The purpose of this investigation was to study the behavior of vacuum-plasma-sprayed hydroxyapatite (VPS-HA) coatings in a defined simulated physiological environment that mimics the conditions that the material experiences after implantation in the human body. Commercially available and clinically used HA coatings on titanium alloy substrates were immersed in an inorganic simulated body fluid (SBF) with ion concentrations that were almost equal to those of human blood plasma and in fetal calf serum (FCS) for time periods of 1, 3, 7, 14, and 28 days. At each time interval, the VPS-HA coatings were analyzed using scanning electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy, and inductively coupled plasmaatomic emission spectroscopy. The as-received VPS coatings consisted of HA as the main phase component; in addition, small concentrations of tricalciumphosphate (TCP) were determined to be present. During immersion in SBF, transformation of the peripheral area of the VPS coating to a regular spherical shape was observed. Concentration measurements of the immersion solution indicated that dissolution of the more-soluble TCP started within the first day. At the same time, precipitation of a carbonatecontaining, marginally crystalline calcium phosphate with very small coherently scattering domains was observed. In FCS, the dissolution of calcium and phosphorus was observed; however, the precipitation of the new calcium phosphate layer was retarded by the presence of proteins, which indicates their important role in the ion-exchange mechanisms. In both solutions, the coating integrity was not adversely affected, which indicates the high stability of VPS-HA coatings in a simulated physiological environment.

Biomaterials and related process engineering in order to obtain optimal surface and structural biocompatibility of implants and devices are presented. Vital-avital composites for tissue engineering, cell culture models, porous ceramics and degradable polymers are introduced as examples. Emphasis is laid on the conversion of basic research results into clinical applications and on the exchange of technologies from the non-medical into the medical field and vice versa.