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Biomaterial research efforts focus on the development of biomaterials that mimic the natural extracellular environment. In addition, different strategies are applied to render materials for blood-contacting devices nonthrombogenic through surface modifications that would suppress activation of platelets, coagulation and the complement system. A confluent thin layer of endothelial cells lines all blood vessels and produces factors responsible for inhibition of coagulation, thrombosis and neointimal hyperplasia. Thus, the ability to rapidly form a healthy endothelium upon implantation represents a desired property of biomaterials used for cardiovascular devices. In this study we used advanced in vitro methods to investigate the biocompatibility of a biodegradable and a permanent electrospun nanofiber fabric, poly-L-lactic acid and polycarbonate-based silicone elastomer respectively, with the focus on endothelialization and hemocompatibility.

Electrospinning (ES) is a suitable and cost effective method to mimic the chemical composition, morphology, and functional surface of natural tissues, for example of the nervous, dermal, vascular, and musculoskeletal systems. This technique is a versatile tool to obtain tailored fibrous scaffolds from various polymer materials. By varying the diameter, porosity, orientation, layering, surface structuring, mechanical properties and biodegradability of the fibers the properties can be adapted for specific applications ranging from implantable medical devices to wound repair and protective clothing. Especially the combination of different polymer types offers a high potential. In this study electrospun two-component nonwoven structures of thermoplastic copolyester elastomer (TPC-ET) and bioresorbable polylactide (PLLA) were fabricated, using different ES setups. A comparative evaluation in terms of porosity, thermal and mechanical properties as well as required fabrication effort, was performed. Nonwovens made from polymer blends and coaxial spun core-sheath fibers showed similar tensile strength, which was higher than dual electrospun fabrics. Porosity was found to be in the range of 80 - 90%. By modifying the polymer solution and process parameters multicomponent nonwoven structures with tailored properties and drug release profiles can be manufactured.

Implant-associated infections still must be considered as a major risk factor and represent a significant threat to the well-being of patients. The detection of such complications is often late, making therapy at this stage difficult. However, the common route of systemic antibiotic prophylaxis can be associated with numerous side effects on the patient or even lead to resistant strains of bacteria. In this context, local antibiotic drug load is a promising way to protect implants against pathogen adhesion and biofilm formation. This work addresses the incorporation of the antibiotic Doxycycline into a biodegradable nonwoven matrix as potential implant coating. While the nonwoven matrix itself displayed already inhibitory effects on Staphylococcus aureus (S. aureus) biofilm formation in vitro, this effect was even more pronounced by the incorporation of Doxycycline. Antibiotic loaded nonwovens display the possibility for local inhibition of biofilm formation. In the shape of an implant coating, this may further help to avoid implantassociated infections. Nevertheless, as pathogens vary in shape and type, further adjustments have to be performed to improve wide-ranging protective effects