| Summary: | 碩士 === 國立高雄應用科技大學 === 化學工程與材料工程系 === 99 === The dual functional particles with luminescent and magnetic properties are of particular importance because of their broad range of potential applications, e.g., biochemical sensing, biological imaging and cell tracking. Typically, the dual functional particles were prepared by incorporating emission centers, such as organic fluorophores, lanthanides or quantum dots. However, the preparation involved multiple processing steps and the incorporated luminescent materials are expensive and environmentally toxic. In view of this, a novel luminescent magnetic silica particle without incorporating fluorophores was developed in this study. Since the calcinated organosilica synthesized by mixing tetraethyl orthosilicate (TEOS) and 3-aminopropyl triethoxysilane (APTES) is able to emit fluorescence after calcinating at 600C, the magnetic core of Fe3O4 nanoparticles were coated with the organosilica as an emission layer. The results showed that the direct attachment of the fluorophore-free emission layer on Fe3O4 core would quench the fluorescence of the organosilica, indicating that an insulating layer between Fe3O4 core and emission shell was necessary. Accordingly, the luminescent magnetic particles were fabricated by first coating a silica layer on Fe3O4 nanoparticles, following by covering the fluorophore-free emission layer. The fluorescent intensity of the particles was affected by the thickness of the insulation silica layer as well as the preparation condition of the organosilica. An optimum thickness of insulated silica could prevent the quench by magnetic cores. The optimum condition for prepare the emission layer was employing TEOS and APTES at the molar ratio of 1:1 and calcining at 600C for 2 h. From XPS and TGA analysis, the mechanism for the emission of calcinated organosilica is though due to the defect centers in the silica forming by the impurities of carbon and oxygen rather than nitrogen centered effects. Since the quantum yield of the as-synthesized particles could be up to 0.25, the novel luminescent magnetic material free of fluorophore is expected to be promising for biosensing applications.
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