[dipl] Teknillinen korkeakoulu / TKK

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Browsing [dipl] Teknillinen korkeakoulu / TKK by Degree programme/Major subject "Bioinformaatioteknologia"

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  • Metabolic characterisation of mild cognitive impairment by 1H NMR spectroscopy and self-organising maps
    (2008) Tukiainen, Taru
     Helsinki University of Technology | Master's thesis
  • Preparation of polycaprolactone based tissue engineering scaffolds by stereolithography
    (2009) Elomaa, Laura
     Helsinki University of Technology | Master's thesis
    A novel photocrosslinkable and biodegradable resin was prepared for the use in a stereo lithography apparatus (SLA). Three-branched poly(epsilon-caprolactone) (PCL) oligomers of five molecular weights were synthesized. As the molecular weight of the oligomer increased, the melting point approached that of linear high molecular weight PCL (~ 60 C°). To prepare photocrosslinkable polyester macromers , hydroxyl-terminated oligomers were methacrylated with methacrylic anhydride. Photocrosslinkable poly(ester-anhydride) macromers were prepared by functionalizing hydroxyl-terminated oligomers with succinic anhydride and then methacrylating them with methacrylic anhydride. The polyester macromers were photocrosslinked using ultraviolet light and Irgacure 2959 photoinitiator. The crosslinking density increased as the molecular weigh of the macromer decreased. The gel content was between 98,2 and 89,8 %. Crosslinking increased the glass transition temperature by restricting the molecular mobility of polymer. Young's modulus of the networks was between 15,4 and 6,7 MPa and the elongation at break between 19,3 and 78,5 %. Cytotoxicity test showed good biocompatibility of the crosslinked networks. Three-dimensional tissue engineering scaffolds were built by SLA using the molten polyester macromer, blue light and Irgacure 369 photoinitiator. The scaffolds resembled the structures modeled by computer-aided design closely. Any solvent was not used in SLA, and due to that, no material shrinkage was observed. The average porosity was 70,5 % ± 0,8 %, when the designed porosity was 70 %. More than 90 % of the pores were in the range of 350 to 550 µm in diameter, and the average pore size was 465 µm. The pores were highly interconnected. Low cytotoxicity of the crosslinked material along with the optimal pore architecture of the scaffolds indicates good applicability of the prepared PCL resin in a SLA building process.