The synthesis of water-soluble nanoparticles is a well-developed field for ferrite-based nanoparticles with the majority consisting of iron oxide or mixed metal iron oxide nanoparticles. However, the synthesis of non-agglomerated non-ferrite metal/metal oxide NPs is not as well established. The synthesis and characterization of uniform 20 nm, biologically compatible cobalt oxide (CoO) nanoparticles (NPs) is described. These nanoparticles have two principle components: 1) a CoO core of suitable size to contain enough cobalt atoms to be visualized by X-ray fluorescence microscopy (XFM) and 2) a robust coating that inhibits NP aggregation as well as renders them water-soluble and biocompatible (i.e. stealth coatings). Stable cobalt oxide NPs are obtained with octadecyl amine coatings as reported by Bhattacharjee. Two strategies for solubilizing these NPs in water were investigated with varying degrees of success. Exchanging the octadecyl amine coating for a nitrodopamine anchored PEG coating yielded the desired water-soluble NPs but in very low yield. Alternately, leaving the octadecyl amine coating on the NP and interdigitating this with a maleic anhydride-vinyl copolymer with different hydrophobic sidechains followed by opening the maleic anhydride ring with amine substituted PEG polymers (the water solubilizing component), yielded the desired water soluble NPS were obtained in good yield. Characterization data for the nanoparticles and the components of the coatings required for bioorthogonal reactions to ligate them with biotargeting agents are also described.

中文翻译：

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用于 X 射线荧光显微镜的生物相容性氧化钴纳米颗粒

水溶性纳米粒子的合成是铁氧体基纳米粒子的一个成熟领域，其中大部分由氧化铁或混合金属氧化铁纳米粒子组成。然而，非团聚非铁氧体金属/金属氧化物纳米粒子的合成尚未成熟。描述了均匀 20 nm、生物相容性氧化钴 (CoO) 纳米颗粒 (NP) 的合成和表征。这些纳米颗粒有两个主要组成部分：1) 尺寸合适的 CoO 核心，包含足够的钴原子，可通过 X 射线荧光显微镜 (XFM) 观察到；2) 坚固的涂层，可抑制纳米颗粒聚集并使其水溶性和生物相容性（即隐形涂层）。据 Bhattacharjee 报道，稳定的氧化钴纳米颗粒是通过十八烷基胺涂层获得的。研究了两种将这些纳米颗粒溶解在水中的策略，并取得了不同程度的成功。将十八烷基胺涂层替换为硝基多巴胺锚定的 PEG 涂层，得到了所需的水溶性纳米颗粒，但产率非常低。或者，在 NP 上保留十八烷基胺涂层，并将其与具有不同疏水性侧链的马来酸酐-乙烯基共聚物交指，然后用胺取代的 PEG 聚合物（水溶性组分）打开马来酸酐环，得到所需的水溶性 NPS获得良好的收率。还描述了纳米颗粒和生物正交反应所需的涂层成分的表征数据，以将它们与生物靶向剂连接。