| Summary: | 博士 === 國立中正大學 === 化學工程所 === 97 === A novel method named as “a swelling and penetration process” is proposed for the preparation of polymer-based, magnetic microspheres. According to the proposed method, pre-made, Polystyrene-based polymer particles of micron or sub-micron size were swollen in an aqueous solution of N-methyl-2-pyrrolidone (NMP) and then mixed with superparamagnetic iron oxide nanoparticles (SPIONs). The magnetic nanoparticles were able to diffuse into polymer particles and were entrapped within the polymer microspheres. The saturation magnetization of resultant magnetic polymer microspheres increased with increasing magnetic nanoparticle concentrations. A higher ratio of NMP-to-water led to a greater swelling but a larger loss of polymer mass due to polymer chain dissolution in the NMP solution. Sodium dodecyl sulfate (SDS) in the NMP aqueous solution significantly enhanced the swelling and penetration process. The use of SDS could not only shorten the process time but also lower the required NMP concentration.
Applications of prepared magnetic polymer microspheres were also demonstrated. These magnetic poly(styrene-glycidyl methacrylate) (PS-GMA) microspheres were chemically modified and then coupled with single-stranded oligonucleotides as probes for DNA hybridization. The immobilized probes showed repeatable capture of target oligonucleotides. Also, magnetic PS–GMA microspheres were modified on their surface and coupled with Sca-1 antibody for the selection of Sca-1 positive cells from mononuclear cells in murine bone marrow.
In addition, a novel methodology for seeding of mesenchymal stem cells (MSCs) onto the scaffold through the transfection of Notch 1 proteins with superparamegantic iron oxide nanoparticles was proposed for the application in tissue engineering. Mediated by the pulsed magnetic field, the SPION-containing MSCs were applied to seed onto the scaffold by the aid of an external magnet to yield a tissue of high cell density. Internalization of SPIONs coupled with Notch 1 family protein, MSCs could be seeded with a high density and could have a high growth rate, providing a potential for clinical applications.
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