Martina Feldmann

The effects of copper additives on the quantity and cell viability of adherent Staphylococcus epidermidis in silicone implants.

This in vitro study evaluated the antibacterial effect of copper additives in silicone implants. Specimens of a standard silicone material used in breast augmentation and modified copper-loaded silicone specimens were prepared and incubated in a Staphylococcus epidermidis suspension (2 h, 37°C). After the quantification of adhering staphylococci using a biofluorescence assay (Resazurin), the viability of the adhering bacterial cells was quantified by live or dead cell labeling in combination with fluorescence microscopy. In the Resazurin fluorometric quantification, a higher amount of adhering S. epidermidis cells was detected on pure silicone (4612 [2319/7540] relative fluorescence units [rfu]) than on silicone with copper additives (2701 [2158/4153] rfu). Additionally, a significantly higher amount of adhering bacterial cells (5.07% [2.03%/8.93%]) was found for pure silicone than for silicone with copper additives (1.72% [1.26%/2.32%]); (p < 0.001). Calculations from live or dead staining showed that the percentage of dead S. epidermidis cells adhered on pure silicone (52.1%) was significantly lower than on silicone with copper additives (79.7%); (p < 0.001). In vitro, silicone material with copper additives showed antibacterial effects against S. epidermidis. Copper-loaded silicone may prevent bacterial colonization, resulting in lower infection rates of silicone implants.

Sol–gel and precursor-derived coatings with cover function on medical alloys

Various studies have reported detectable urine and serum levels of metal ions or their accumulation in organs or tissues of patients with metal implants. The concentrations of these ions are considerably higher in the tissue surrounding the implants. These ions may lead to systematic toxicity, carcinogenesis or allergic reactions, and influence the osseointegration and stability of the implants. Developments in the field of orthopaedic implants are in progress which involve covering the metal implants with a layer, which may limit the leakage of metal ions and reduce problems with loosening of the implants. In this study it is shown that sol–gel coatings (TiO2) and precursor-derived coatings in the system Si–C–N(–Ti) enhance the in vitro cytocompatibility of medically relevant alloys and also hinder the diffusion of toxic ions like vanadium, cobalt and chromium ions out of Ti6Al4V and a cast Co28Cr6Mo alloy, respectively.