Microfabricated polydimethylsiloxane (PDMS) scaffolds for bone tissue engineering.

摘要

This dissertation presents the development of textured scaffolds to provide osteoconductive stimuli to CTPs (Connective Tissue Progenitor Cells) for bone regeneration applications. First, the effect of surface topography on bone cell adhesion was validated through experiments using roughned surfaces and an osteoblastic cell line. Second, microfabrication and soft lithographic techniques were used to develop two dimensional substrates with various surface micro-textures from Polydimethylsiloxane (PDMS). Human CTPs were then cultured on these substrates and analyzed to reveal enhanced cell growth on 10 mum post textures. Third, mechanical and chemical properties of various PDMS formulations were analyzed to investigate the effects of common biomedical and microfabrication processes including spin coating, chemical immersion, sterilization, and exposure to oxygen plasma and tissue culture media. The PDMS formulations were analyzed by gravimetry, goniometry, tensile testing, nano-indentation, SEM, XPS, and FTIR. Fourth, equipment and protocols were developed to enable the construction of scaffolds comprising precise three dimensional (3D) micro-architectures along with surface micro-textures. A multi-layer process was developed to create SU-8 structures of up to six-levels using a single developing step. The SU-8 structures acted as molds in a custom mechanical jig that permitted precise alignment for dual-sided molding of PDMS layers. The combination of SU-8 molds, custom mechanical jig, and subsequent PDMS stacking enabled the fabrication of 3D scaffolds (3D PDMS Texture) with both precise micro-architecture and surface micro-textures. The 3D PDMS Texture scaffolds were 1.5 mm high and 1 cm in diameter, and exhibited 66% porosity by volume with 300 mum diameter meandering vertical pores, 200 mum x 400 mum horizontal pores, and 71% surface coverage with 10 mum diameter and 10 mum high posts. Another set of scaffolds were fabricated with the same micro-architecture, but with smooth rather than micro-textured surfaces (3D PDMS Smooth). Finally, the 3D scaffolds were used as substrates for in vitro culture of human CTPs. A preliminary investigation into CTP growth characteristics revealed that colonies on the 3D PDMS Texture scaffolds extended in both vertical and horizontal directions and were significantly (p 0.05) bigger (499 cells/colony) compared to those on 3D PDMS Smooth (188 cells/colony) scaffolds.