Surface modification of a synthetic polyurethane by plasma glow discharge: Preparation and characterization of bioactive monolayers

In the present study, a surface functionalization of a synthetic polyurethane was carried out by using biofunctional moieties to obtain a material with the appropriate mechanical properties and processing conditions and, at the same time, the advantages of a bioactive material. The polyurethane (PU) was synthesised from poly(e-caprolactone) diol, 1,6-diisocyanatohexane and 1,4-cyclohexane dimethanol as chain extender. PU films were grafted with acrylic acid using argon plasma. The carboxyl groups formed were used to covalently bind model biomimetic/bioactive macromolecules (gelatine and poly (L-lysine). All characterizations (attenuated total reflection Fourier transform infrared spectroscopy, ATR-FTIR; X-ray photoelectron spectroscopy, XPS; atomic force microscopy, AFM; scanning electron microscopy, SEM) confirmed the surface changes at each stage of treatment, both in morphology and in chemical composition. Besides, achieved treatment allowed to obtain a very thin layer of both PAA and macromolecules. Moreover, preliminary in vitro tests were performed using NIH-3T3 fibroblasts as cell model. Both materials showed to support cell adhesion and growth, with poly (Llysine) performing better in activating cellular processes, as it can be seen by cell shape, which appears elongated on poly (L-lysine) coating, whereas on gelatine, cells are more spherical and not uniformly distributed on the polymer surface.