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Implant-associated infections remain a challenge in biomedical engineering and prevention of such complications is a topical subject. For that, local drug delivery is associated with a number of advantages over systemic antibiosis. In this context, incorporation of antibiotic drugs into fibrous nonwovens is a promising approach for the generation of antiinfective implant envelopes or wrappings. Such materials can be manufactured in large scale and electrospinning process is suitable for a wide range of drugs to be incorporated. With regard to increasing numbers of pacemaker implantations and associated risk factors for infections, biodegradable ceftriaxone loaded poly(L-lactide)-co-poly(ethylene glycol) (PLLA-co-PEG) nonwovens have been characterised concerning the influence of the drug on morphology, thermal and mechanical properties and drug release behaviour. Our results show that the chosen material combination is promising for further approaches towards an antiinfective nonwoven pacemaker envelope.

Various manufacturing techniques are available for polymer stent fabrication. Polymer semi-finished products can be prepared using solvent based methods, e.g. dip coating, as well as thermal processes, e.g. extrusion. These different methods may lead to an altered polymer crystal structure, resulting in a different deformation mechanism during mechanical stress. For the material property characterization needed for implant development, the test specimens usually are prepared using laser-cut or die-cut methods. Due to these different preparation protocols, a change in polymer microstructure, causing a material property variation, may also result. For this purpose, comparison of laser-cut versus die-cut of PLLA films has been performed. PLLA films have been prepared by dip-coating and were evaluated with respect to structural, thermal, and mechanical properties. In this study, a combination of uniaxial tensile tests, SEM and DSC studies was used. The results of the mechanical tests showed drastic differences in the elongations at break of die-cut specimens compared to laser-cut ones. The results point out formation of complex crystal structures during the manufacturing process. By the use of SEM imaging and DSC measurements, we were able to attribute these changes to the different plastic deformation mechanisms.

For applications in the cardiovascular field, the production of tailored biomaterials such as those required for insulations or patches is a key technology. In this work we were able to manufacture thermoplastic silicone polycarbonate elastomer scaffolds with a porous external surface. The samples were produced using the dip coating process. Pores were created using the salt leaching technique. The complete removal of the salt was verified by Raman microscopy. The absence of solvents was demonstrated by biocompatibility tests using an endothelial cell line. The potential functionality of the system was thus demonstrated. The next step will focus on promoting the adhesion of suitable cells for specific applications. [ABSTRACT FROM AUTHOR]

Cast polyurethane films made of an aliphatic polycarbonate-based thermoplastic polyurethane (Carbothane PC) and poly(ether urethane) (Pellethane) were manufactured and their biostability under a static strain rate was investigated in vitroin comparison to unloaded samples. The PU films were stretched to an elongation of 300% and exposed to hydrogen peroxide/cobalt chloride (H2O2/CoCl2) solution for specific periods of time (up to 63 days). Unstrained PU samples were treated in the same way for comparison. The samples were observed for surface degradation via scanning electron microscopy and the bulk erosion by measuring the weight difference. The surface roughness greatly increased in strained Pellethane with scanning electron microscopy (SEM) evidence of deep cracks and holes or ragged and stretched fractures perpendicular to the direction of stress. Carbothane showed a lower degradation compared with Pellethane under mechanical constraint. [ABSTRACT FROM AUTHOR]