| Summary: | 碩士 === 國立高雄大學 === 生物科技研究所 === 97 === The study focused on a combination of magnetic nanoparticles and bioactive polymers to develop a magnet-induced gel-forming system. The magnetic gel was able to form a gel by physical crosslink and precipitation, as well as by external magnetic field induction. Thus, we can accessibly transfer particles to desired spots under well control and induction in order to fabricate a scaffold for cell growth and tissue reparation. In the design of materials, iron oxide nanoparticles played an important role because of their superparamagneticity and biocompatibility. On the other hand, the cell growth and attachment was able to be enhanced using natural polyelectrolytes as the outer coating. Experimentally, the well-dispersed magnetic Fe3O4 nanoparticals were prepared by a chemical coprecipitation method. The particle surfaces were passivated and protected using polyelectrolyte surfactants, and then were coated by the opposite-charged biodegradable polyelectrolyte (i.e., chitosan, alginate). As mixing different ratios of chitosan-coated to alginate-coated particles, we were able to control the morphology of gel forming on a substrate with a suitable interaction with the external magnet. The substrates were then contacted with Schwann cells in a certain time to observe the cell attachment and growth. The magnetic nanoparticles were analyzed and characterized by XRD, TEM, zeta potential meter, XPS, and so on. Fe3O4 structure and crystalline was proved by the XRD analysis as literatures reported. TEM photographs illustrated the nanoparticles sizing as 10-20 nm in diameter. And also the size was increased as being encapsulated by natural polymers. Zeta potential analysis showed the CS-coated particles displayed a highly positive potential as +31.7 mV, while the AA-coated particles as -40.3 mV, demonstrating their well-dispersion and highly attractive interaction between each other. XPS analysis on the composition changes for the particle surfaces also provided an evidence of successful polymer coating. As injecting and mixing the equivalent ratio between the two opposite-charged nanoparticle suspensions, we were able to find the nanoparticles gel-forming to a homogeneous thin film on a substrate under control by an external magnetic field. As changing the magnetic direction and quantity, a fiber-like microstructure was specified. Preliminary cell attachment tests on the fiber-like films, Schwann cells tended to attach and grow along the fiber orientation. All the results demonstrated the gel to be a potential template for repairing peripheral nerve system.
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