Production of biodegredable and biocompatible polymeric tissue scaffolds with different surface charges and evaluation of cell-scaffold interactions

The aim of this thesis study is to produce biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofiber mats with different surface charges for tissue engineering applications. It is important for a scaffold to mimic fibrous form of the natural extracellular matrix (ECM). In the present study, nanofiber materials with morphologies similar to the native ECM were produced by electrospinning technique. Most polymeric materials are hydrophobic in nature, therefore their surfaces are not favorable for cellular adhesion. In this sense, modification of the hydrophobic surfaces of polymers with plasma surface modification technique is proposed. In this study, hydrophobic PHBV polymer was used as the main matrix. In order to increase the surface hydrophilicity of the PHBV and also improve cell adhesion and proliferation, radio-frequency (RF) plasma surface modification technique was used. The nitrogen and oxygen gases were used as plasma atmosphere to create positive and negative surface charges, respectively. The hydrophilicity of the electrospun PHBV nanofiber mats was significantly increased by the plasma treatment, as confirmed by contact angle measurements. But, the sustainability of surface hydrophilicity of plasma-treated polymeric mats is the main problem for the fabrication of tissue scaffold due to hydrophobic recovery. This problem was minimized by silk fibroin (SF) modification via preventing the reorientation of polar groups. Biomineralization results showed that incorporation of SF as well as oxygen plasma strongly activates the precipitation rate of the Ca-P minerals. Obtained nanofiber mats especially nitrogen plasma-treated and silk fibroin modified (PS/N2) ones provide the most favorable environment for SaOS-2 osteoblastic cell attachment and growth. In addition, the mats showed no noticeable cytotoxic effect on SaOS-2 cell and L929 mouse fibroblast-like cells.These results indicate that the plasma treated and silk fibroin modified PHBV nanofiber mats have great potential in the development of novel polymeric scaffolds for bone tissue engineering applications.