Papers by Author: Jürgen Schmidt

Abstract: Surface biofunctionalization is a common strategy to improve the material-tissue interface of inert implant surfaces. In this context we coated alumina-toughened zirconia (ATZ) ceramics after titanium plasma spraying with two different porous calcium phosphate layers and subsequently functionalized the obtained surfaces either with an RGD containing cell adhesion peptide sequence or a bone morphogenetic protein (BMP)-glycosaminoglycan complex. We studied initial cell adhesion densities, integrin expression, and alkaline phosphatase activity as an osteogenic marker of the coatings in vitro in comparison to the non-functionalized ATZ ceramics to evaluate the bone ingrowth potential of these biofunctionalized implant coatings.

Abstract: Anodization of aluminum (Al) is a well-known process for the production of oxidized Al surfaces. Within the scope of the present work, three different Al-oxide layers, produced with different electrochemical methods, were investigated in view of their layer morphology and tribological properties. For this purpose, a newly developed PCO layer (Innovent e.V.), and two commercially available layers, Ematal and a CERANOD®, were compared. Al-oxide layers produced on flat samples were tested against cylindrical DIN 100Cr6 rings under dry sliding conditions. It was observed that under the selected conditions, the frictional behavior of the Al-oxide layers can be influenced by their structural composition and their surface topography, i.e. is different when their structure is amorphous or crystalline. The newly developed Al-oxide layer, which possesses the lowest surface roughness and a very uniform porosity, provided the longest lasting low friction period. Since γ-Al₂O₃ was also observed in this layer, it is believed that the structural composition of the Al-oxide layer has additionally influenced the frictional response of these samples.

Abstract: As bio-absorbable implant material the magnesium alloy Mg-1Ca is able to degrade in-vivo. The mechanical properties of this alloy are similar to those of human bone; both Mg and Ca are essential elements in human body. The main problem is the high corrosion rate of this alloy. Two coating systems based on plasma-chemical oxidation and an organic dip coating are applied onto MgCa1.0 magnesium alloy in order to slow down the corrosion rate. The corrosion behaviour of the coated alloys was investigated with electrochemical noise measurements. The influence of hydrogen evolution and increasing pH-value on the cytotoxicity was examined. The results of these investigations suggest that a combination of both coating systems leads to promising degradation properties.