Post-plasma grafting of AEMA as a versatile tool to biofunctionalise polyesters for tissue engineering

In the last decade, substantial research in the field of post-plasma grafting surface modification has focussed on the introduction of carboxylic acids on surfaces by grafting acrylic acid (AAc). In the present work, we report on an alternative approach for biomaterial surface functionalisation. Thin poly-ε-caprolactone (PCL) films were subjected to a dielectric barrier discharge Ar-plasma followed by the grafting of 2-aminoethyl methacrylate (AEMA) under UV-irradiation. X-ray photoelectron spectroscopy (XPS) confirmed the presence of nitrogen. The ninhydrin assay demonstrated, both quantitatively and qualitatively, the presence of free amines on the surface. Confocal fluorescence microscopy (CFM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to visualise the grafted surfaces, indicating the presence of pAEMA. Static contact angle (SCA) measurements indicated a permanent increase in hydrophilicity. Furthermore, the AEMA grafted surfaces were applied for comparing the physisorption and covalent immobilisation of gelatin. CFM demonstrated that only the covalent immobilisation lead to a complete coverage of the surface. Those gelatin-coated surfaces obtained were further coated using fibronectin. Osteosarcoma cells demonstrated better cell-adhesion and cell-viability on the modified surfaces, compared to the pure PCL films.