Preparation and characterization of chitosan-gelatin/hydroxyapatite scaffolds for hard tissue engineering approaches

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2010

Öğrenci: CANSEL IŞIKLI

Danışman: VASIF NEJAT HASIRCI

Özet:

Hard tissue engineering holds the promise of restoring the function of failed hard tissues and involves growing specific cells on extracellular matrix (ECM) to develop „„tissue-like” structures or organoids. Chitosan is a linear amino polysaccharide that can provide a convenient physical and biological environment in tissue regeneration attempt. To improve chitosan‟s mechanical and biological properties, it was blended with another polymer gelatin. 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) were used to crosslink the chitosan-gelatin matrix to produce stable structures. These natural polymers are mechanically weak especially to serve as a bone substitude and therefore, an inorganic calcium phosphate ceramic, hydroxyapatite, was incorporated to improve this aspect. The objective of this study was to develop chitosan-gelatin/hydroxyapatite scaffolds for a successful hard tissue engineering approach. For this reason, two types of hydroxyapatite, as-precipitated non-sintered (nsHA) and highly crystalline sintered (sHA) were synthesized and blended into mixtures of chitosan (C) and gelatin (G) v to produce 2-D (film) and 3-D (sponge) structures. The physicochemical properties of the structures were evaluated by scanning electron microscopy, X-Ray Diffraction (XRD), Fourier Transform Infrared-Attenuated Total Reflectance spectrometer (FTIR-ATR), differential scanning calorimetry, contact angle and surface free energy measurements and swelling tests. Mechanical properties were determined through tensile and compression tests. In vitro cell affinity studies were carried out with SaOs-2 cells. MTS assays were carried out to study cell attachment and proliferation on the 2-D and 3-D scaffolds. Several methods such as confocal, fluorescence and scanning electron microscopy were used to examine the cell response towards the scaffolds. Cell affinities of the samples were observed to change with changing chitosan-gelatin ratio and hydroxyapatite addition into the matrices. XRD and FTIR results confirmed the purity of the hydroxyapatite synthesized. Mechanical test results showed that 2-D and 3-D chitosan-gelatin/hydroxyapatite constructs have similar properties as bones, and in vitro studies demonstrated that the prepared matrices have the potential to serve as scaffold materials in hard tissue engineering applications.