奈米科技乃廿一世紀之新產業革命動力，奈米新材料與量子理論對於催化、光吸收、醫藥與國防科技等方面具前瞻之應用前景。故奈米材料之研發，已然成為銳不可擋之世界潮流，其中磁性奈米微粒因展現與塊材相異之磁性質，能廣泛應用於磁流體、磁紀錄、藥物磁性載體、隱形塗料與感測器等領域，已成為眾多研究團隊之主要研究方向。
有鑒於此，本研究乃針對奈米四氧化三鐵(Fe3O4)磁性粒子之合成與應用進行探討，依應用領域區細分成以下三部分。
第一部分主要研究以化學共沉澱法合成單一粒徑分布之奈米Fe3O4粉體，藉以比較奈米Fe3O4粉體與微米塊材Fe3O4，於結構、磁性與價數等之相異性。
第二部分乃發展，利用化學共沉澱法所合成單一粒徑分布之奈米Fe3O4粉體，藉由表面改質技術，批覆不同之矽氧化合物，防止所合成之磁性奈米粒子再度聚集，進而改善奈米Fe3O4粒子於有機溶液中之分散性，期能將改質後之奈米Fe3O4粉體應用於隱形塗料之研發。
第三部分乃將奈米Fe3O4磁性粒子與卵白素(Avdin)及生物素(Biotin)相結合。有鑑於商用抗體皆附著於Biotin上，且於室溫下Avdin與Biotin共價鍵結特性相當良好。故本研究期望能發展一簡單且方便應用於生物醫學檢測之技術。
本研究所採用之分析技術涵括：以X-光粉末繞射儀(X-ray powder diffraction; XRD)與Rietveld精算法鑑定材料之純度與晶體結構；以穿透式電子顯微鏡(transmission electron microscope; TEM)鑑定奈米Fe3O4粉體之粒徑與表面型態；利用傑塔電位儀(zeta potential)量測粉體之表面電位，藉由同步輻射光源之X 光吸收近邊緣結構 (X-ray absorption near-edge structure; XANES)光譜與X-光磁圓偏振二向性(X-ray magnetic circular dichrosim)可分別得知樣品之氧化價數及磁矩，以酵素連結免疫吸附分析技術(enzyme-link immunosorbent assay；ELISA)觀察磁性粒子與卵白素及生物素鍵結時，所產生之呈色反應，藉由上述之量測分析技術，得以探討奈米磁性粒子之相關特性。
In this dissertation, the study of synthesize and application of Fe3O4 nano particle the main purpose, divide the application into three following parts.
In the first part, nanometer-sized magnetic materials have attracted the attention of many researchers, because magnetic nanoparticles exhibit unusual chemical and physical properties such as superparamagnetism and quantum tunneling of magnetization. A number of techniques, both chemical and physical, have been used to make magnetic particles. In this dissertation, ferrite nanoparticles [magnetite (Fe3O4)] were prepared using a simple chemical coprecipitation method. Oleic acid was added to protect nanoparticles from aggregation. The characteristics of nano-magnetic Fe3O4 particles were determined by various techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray absorption near edge structure spectroscopy (XANES) and X-ray magnetic circular dichroism (XMCD)
In the second part, A method for manufacturing ferrous ferric oxide powder is disclosed, The method includes mixing ferrous ferric oxide powder with a coupling agent having a silane functional group in an organic solution for improving its quality. The ferrous ferric oxide powder with improved surface quality manufactured by the present invention can be dispersed and mixed steadily and uniformly in a nonpolur solvent . In addition to that, it has longer dispersion time and is hardly to precipitate, so it has relatively high production value and can be widely used in manufacturing all kinds of ferrous ferric oxide - containing stealth paint.
In the third part, we study the preparation and properties of bio-compatible magnetic nanoparticles for immunoassay detection. The magnetite (Fe3O4) nanoparticles were prepared by a chemical co-precipitation method and dextran is selected as the surfactant to suspend the nanoparticles. Suspended particles associated with avidin followed by biotin were qualitatively analyzed by enzyme-linked immunosorbent assay (ELISA) method. We found further the ethylenediamine blocked activated residual groups efficiently, hence enhancing the attachment of biotin for probing the avidin.
