Development of a new electrospinning setup for reinforced composite nanopolymer scaffolds for orthopedic applications

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Δουλγκέρογλου, Μελέτιος-Νικόλαος
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During this thesis, we managed to install and establish a functional electrospinning unit in the Laboratory of Biomechanics and Biomedical Engineering in order to test polymers and substances that may be suitable for cellular scaffolds. More specifically, polycaprolactone (PCL) was used as the main polymer either dissolved in acetone or acetic acid 99%. The parameters that affect electrospinning were tested, such as concentration of polymer, distance between the collector and the needle etc and mixtures of polycaprolactone with chitosan and carbon nanotubes were electrospun successfully. For the qualitative evaluation of results, a scanning electron microscopy unit was used with which the architecture of the electrospun materials may be viewed and the diameter size of fibers can be calculated. Polycaprolactone electrospun samples along with samples that contained a blend of polycaprolactone with carbon nanaotubes, were mechanically tested. More specifically, tensile was applied in the specimens and the modulus of elasticity was estimated. Three methods were used for the estimation of the modulus of elasticity while statistical tests were performed in order to examine whether the different methods may be considered equivalent in a confidence level. The three methods contained the estimation of the modulus of elasticity by a regression line in the proportional limit of the specimens in the respective stress-strain curve, by the estimation of a tangent line in a specific point of the linear region and by the secant line that initiates from the start of axis and ends at the end of the linear region. Furthermore, since scaffolds may be considered two dimensional in the macrolevel, a novel method was implemented to create a porous three dimensional scaffold. A new type of a porous collector was designed and implemented based on the design of a commercial screen. Layers of polycaprolactone were electrospun and they were binded with a polymeric glue, leading to the creation of the three dimensional scaffold. The final part of this thesis, included cell cultures in selected materials. The main purpose was to evaluate proliferation and differentiation of the mesenchymal stem cells derived from umbilicar cord. The amount of total protein produced is an indicator of proliferation while the expression of the alkaline phosphatase is an indicator of differentiation of cells into osteoblasts. Cell cultures were observed during the third and seventh day while staining of cell nuclei was performed for visualization of their proliferation.
Electrospinning, Scaffold, Biomedical nanometers