Preparation and characterization of cartilage mimicked structures

In this thesis, micro-environment of cartilage tissue was mimicked by adjusting the surface topography, stiffness and chemistry of polydimethylsiloxane (PDMS) which is a biocompatible synthetic elastomeric polymer. PDMS substrates were synthesized with different stiffness between 2.13±0.150 MPa and 0.56±0.06 MPa which were in the range of healthy human articular cartilage's stiffness (0.45-0.80 MPa) and measured by nanoindendation. A template mimicking the collagen type II bundle alignment, geometry and size of healthy human cartilage tissue were prepared (A= 100, 150, 200 µm; B = 30, 40, 50 µm; C= 30, 40, 50 µm) by photolithography. PDMS substrates with desired patterns were prepared by soft lithography. In order to mimic the chemistry of the cartilage tissue micro-environment, PDMS substrates were modified with amino acid conjugated self-assembled molecules (Histidine, Leucine and Tryptophan) and also with type II collagen. Stiffness of PDMS substrates were analyzed with nanoindentation measurements and chemical modifications of substrates were confirmed by using X-ray Photoelectron Spectroscopy and contact angle measurements. According to the characterization results, prepared substrates with cartilage like stiffness, chemistry and topography are possible cell substrates for cartilage tissue engineering. Keywords: Cartilage-mimicked structures, Polydimethylsiloxane (PDMS), Stiffness, Amino acids, Self-assembled Molecules (SAMs)