Silica encapsulation and magnetic properties of FePt nanoparticles
Silica encapsulation and magnetic properties of FePt nanoparticles
复制标题
DOI：
10.1016/j.jcis.2005.04.050
复制
发表时间：
2005-10-15
影响因子：
9.9
通讯作者：
Dravid, VP
中科院分区：
文献类型：
--
作者：
Aslam, M;Fu, L;Dravid, VP
核-壳纳米粒子已成为一类重要的功能纳米结构，在许多不同的领域，特别是在健康科学中具有潜在的应用。我们使用了一种改进的水溶胶-凝胶法合成了具有尺寸选择性的FePt@SiO2核壳纳米粒子。在这种方法中，油酸和油酸胺稳定的FePt纳米颗粒首先通过氨基丙氧基硅烷（APS）单层封装，然后在FePt颗粒表面上缩合三乙氧基硅烷（TEOS）。这些具有窄尺寸分布的定义明确的FePt@SiO2核-壳纳米颗粒在水性介质中变成胶体，因此可以用作生物分子复合物的载体流体。相比之下，FePt颗粒表面上的油酸单层的稀缺亲水性产生了边缘部分涂层的二氧化硅时，只有TEOS被施加用于表面改性。通过高分辨透射电子显微镜（HRTEM），EDS的直接技术和间接通过紫外-可见吸收和FTIR研究，合成的核-壳纳米粒子进行了表征。的FePt@SiO2纳米粒子表现出超顺磁性行为的基本特征，通过SQUID磁强计调查。利用零场冷却（ZFC）/场冷却（FC）曲线研究了FePt和FePt@SiO2（135和80 K）的阻塞温度（T-B）。(c)2005年爱思唯尔公司All rights reserved.
Core-shell nanoparticles have emerged as an important class of functional nanostructures with potential applications in many diverse fields, especially in health sciences. We have used a modified aqueous sol-gel route for the synthesis of size-selective FePt@SiO2 core-shell nanoparticles. In this approach, oleic acid and olyel amine stabilized FePt nanoparticles are first encapsulated through an aminopropoxysilane (APS) monolayer and then subsequent condensation of triethoxysilane (TEOS) on FePt particle surface. These well-defined FePt@SiO2 core-shell nanoparticles with narrow size distribution become colloidal in aqueous media, and can thus be used as carrier fluid for biomolecular complexes. In comparison, the scarce hydrophilic nature of oleic acid monolayers on FePt particle surface yields an edgy partial coating of silica when only TEOS is applied for the surface modification. The synthesized core-shell nanoparticles were characterized by direct techniques of high resolution transmission electron microscopy (HRTEM), EDS and indirectly via UV-vis absorption and FTIR studies. The FePt@SiO2 nanoparticles exhibit essential characteristics of superparamagnetic behavior, as investigated by SQUID magnetometry. The blocking temperatures (T-B) of FePt and FePt@SiO2 (135 and 80 K) were studied using zero field cooled (ZFC)/field cooled (FC) curves. (c) 2005 Elsevier Inc. All rights reserved.