Conductive electrospun polyurethane-polyaniline scaffolds coated with poly (vinyl alcohol)-GPTMS under oxygen plasma surface modification

Polyurethane is an important synthetic polymer which considered promising for bone tissue engineering. Besides, presence of conductive polymer such as could play a crucial role in efficient reconstruction of injured tissue. In the present study, the polyurethane-polyaniline scaffolds were fabricated by electrospinning technology. The electrospun fibers were modified by oxygen plasma treatment technique for immobilization of polyvinyl alcohol and 3-Glycidoxypropyl-trimethoxysilane. Eventually, the prepared constructs were characterized using proper analysis including morphology and roughness observation, chemical characterization, water-scaffolds interaction and biomineralization potential, cellular adhesion and proliferation, and finally osteogenic expression. According to microscopy results, bead-free, uniform, and nano-sized fibers were obtained; after coating, the surface was covered homogeneously with polyvinyl alcohol and 3-glycidoxypropyl-trimethoxysilane. The electrospun scaffolds showed highly porous structures, and their large surface-to-volume ratio made them suitable for tissue engineering applications. The degree of roughness and the mean height were increased from 96.59 nm to 144.4 and 267-429 nm, respectively, after the oxygen plasma surface treatment. Additionally, the modified fibers showed improved hydrophilicity and swelling capacity compared with pure polyurethane-polyaniline constructs. The contact angle of the polyurethane-polyaniline, oxygen plasma modified polyurethane-polyaniline, oxygen plasma modified polyurethane-polyaniline coated with polyvinyl alcohol, and oxygen plasma modified polyurethane-polyaniline coated with polyvinyl alcohol-3-glycidoxypropyl-trimethoxysilane scaffolds was 116.33 degrees, 65.64 degrees, 60.17 degrees, and 62.50 degrees, respectively. Although the addition of 3-glycidoxypropyl-trimethoxysilane led to a slight reduction in absorption potential, it could induce mineralization of hydroxyapatite-like layers which was proved by microscopy images and crystalline peaks in X-ray diffraction spectra. Ameliorating the cell attachment and the viability of a higher number of the cells after the surface treatment and coating process confirmed the biocompatible nature of the scaffolds. Also, in the alkaline phosphatase activity, all groups showed significant (p < 0.0001) increases compared with the control group. Expression of alkaline phosphatase proved the initial potential of the constructs for further pre-clinical and clinical analyses in order to reconstruct the injured bones.