Surface functionalization of poly(ε-caprolactone) improves its biocompatibility as scaffold material for...

Within this study, chemically modified polymer surfaces were to be developed, which should enhance the subsequent immobilization of various bioactive substances. To improve the hemocompatibility and endothelialization of poly(ε-caprolactone) (PCL) intended as scaffold material for bioartificial vessel prostheses, terminal amino groups via ammonia (NH₃) plasma, oxygen (O₂) plasma/aminopropyltriethoxysilane (APTES), and 4,4'-methylenebis(phenyl isocyanate) (MDI)/water were provided. Then, immobilization of the anti-inflammatory and antithrombogenic model drug acetylsalicylic acid (ASA) and vascular endothelial growth factor (VEGF) were performed by employing N,N-disuccinimidyl carbonate (DSC) as crosslinker. Contact angle and fluorescence measurements, X-ray photoelectron spectroscopy and infrared spectroscopy confirmed the surface modification. Here the highest functionalization was observed for the O₂ plasma/APTES modification. Furthermore, biocompatibility studies demonstrated that the surface reactions have no negative influence, neither on the viability of L929 mouse fibroblasts, nor on primary or secondary hemostasis. Release studies showed that the immobilization of ASA and VEGF on the modified PCL surface via DSC is greatly improved compared to the adsorption-only reference. The advantage of DSC is that it immobilizes both bioactive substances via non-hydrolyzable and/or hydrolyzable covalent bonding. The highest ASA loading and cumulative release was detected using NH₃ plasma-activated PCL samples. For VEGF, the O₂ plasma/APTES-modified PCL samples were most efficient with regard to loading and cumulative release. In conclusion, both modifications are promising methods to optimize PCL as scaffold material for bioartificial vessel prostheses.