Amino acid functionalized polyvinylidene fluoride thin films

Abstract The remarkable properties of fluorinated polymers are the reason for their use in medicine, such as vascular grafts, surgical meshes, or sutures. However, their use as vascular grafts can be accompanied by drawbacks, in particular thrombosis leading to limited patency of the graft in the long term. To reduce thrombosis and protein adsorption, coatings imitating the layers found on the surface of vascular endothelial cells could potentially be used. For any covalent permanent surface functionalization to be possible, otherwise almost inert fluorinated polymers must be activated. For that purpose, a protocol is described in this work that allows for the activation of spin-coated polyvinylidene fluoride (PVDF) thin films with an ammonia plasma, introducing amino groups at the surface. The amino groups can be used to covalently attach N-protected glycine and thus modify the polymer surface via conventional solid phase peptide synthesis. The morphological features of the films are investigated by atomic force microscopy and the hydrophilicity quantified by water contact angle measurements. The chemical composition of the films is characterized by X-ray photoelectron spectroscopy. This work contributes to the understanding of fluoropolymer plasma activation and subsequent grafting of amino acids and, therefore, lays the foundation for a subsequent tuning of PVDF as a medical material. Graphical abstract