It is particularly important to consider the biocompatibility of material interfaces. For example, implant materials with a surface composition that favours cell growth have a decisive advantage. However there are other cases where biophobic material characteristics might be more suitable. For example, specifically modifying the surface of surgical metals might prevent pathogens from attaching and could also make the cleaning and deactivation of surgical instruments more effective. We investigated the adhesion ability of prions on differently coated surfaces.
Prions, which are considered to be the cause of bovine spongiform encephalopathy (BSE) and the new variant of Creutzfeld-Jacob disease (vCJD) in humans, are known to have a strong ability to adhere to metal surfaces and are very difficult to remove. This makes the effective cleaning and sterilisation of contaminated surgical instruments according to the criteria published by the Robert Koch Institute very time-consuming and costly. Therefore, major efforts are made to prevent the adhesion of prions and other potential pathogens to medical instruments.
In a project funded by the German Federal Ministry of Economics (PRO INNO II; project management organisation: AiF, Berlin), the company NTTF (Rheinbreitbach), in cooperation with the ILM, developed novel biocompatible layer structures whose surface morphology considerably reduces the adhesion of pathogens such as prions and which have also been developed to resist aggressive cleaning and disinfection methods. As part of the same project, ILM researchers developed a detection system that enables the optical detection of adhering prion protein (PrP) by using specific antibodies in combination with novel fluorescence markers (Qdots). The system was used to investigate whether the surface coatings used effectively protected the surface of medical instruments against the adhesion of prions, hence preventing the iatrogenic transmission of infectious particles. Under the fluorescence microscope, the PrP-contaminated areas revealed an extensive red fluorescence (Figure, left). The project also led to the identification of coatings with the sought-after repellent effect. At the material's interface, these coatings revealed a strongly reduced prion-Qdot fluorescence on the coated side (Figure, right) which was caused by a reduced amount of PrP. The next steps will focus on the stability of these surface coatings.
Further investigations on the bioactivity and compatibility of surface modifications will soon complement previous findings in this field of research. Cell growth experiments will be undertaken to improve the biocompatibility of surface-modified implant materials, which is a crucial aspect of the permanent transplantation of an implant in the human body.