Magnetic nanocomposite particles and hollow spheres constructed by a sequential layering approach
Magnetic nanocomposite particles and hollow spheres constructed by a sequential layering approach
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DOI：
10.1021/cm001164h
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发表时间：
2001-01-01
影响因子：
8.6
通讯作者：
Caruso, RA
中科院分区：
文献类型：
--
作者：
Caruso, F;Spasova, M;Caruso, RA
磁性复合核壳粒子和空心球的制备是通过多步(逐层)策略完成的。将磁性氧化铁(Fe3O4)纳米层与聚电解质交替吸附于水溶液中，包覆亚微米级阴离子聚苯乙烯(PS)胶乳，制得复合粒子。沉积的多层膜的厚度可以通过选择执行的吸附循环次数或通过在每个纳米粒子层(即层间)之间沉积的聚电解质层数来以纳米级的精度进行精细调节。透射电子显微镜显示，当聚电解质夹层的数量从1个[(聚二烯丙基二甲基氯化铵)(PDADMAC)]增加到3个[(PDADMAC/聚(苯乙烯磺酸)(PSS)/PDADMAC)]时，复合多层膜的生长、均匀性和规律性都得到了显著的改善。通过高温焙烧得到了中空的、完整的磁球。在此基础上，采用焙烧法制备了包覆多层二氧化硅和Fe3O4纳米粒子的PS复合中空球。这些纳米工程的胶体颗粒可能会被用作输送系统，或用于诊断，在诊断中，颗粒可以通过施加外部磁场来引导。
The fabrication of magnetic composite core-shell particles and hollow spheres with tailored dimensions and compositions has been accomplished by a multistep (layer-by-layer) strategy. Composite particles were prepared by coating submicrometer-sized anionic polystyrene (PS) latices with magnetite (Fe3O4) nanoparticle layers alternately adsorbed with polyelectrolyte from aqueous solution. The thickness of the deposited multilayers could be finely tuned with nanoscale precision, either by selection of the number of adsorption cycles performed or by the number of polyelectrolyte layers deposited between each nanoparticle layer (i.e., interlayer). As demonstrated by transmission electron microscopy, a marked improvement in the growth, uniformity, and regularity of the composite multilayers was achieved when the number of polyelectrolyte interlayers was increased from one [(poly(diallyldimethylammonium chloride) (PDADMAC)] to three [(PDADMAC/poly(styrenesulfonate) (PSS)/PDADMAC)]. Hollow, intact magnetic spheres were obtained by calcination of the core-shell particles at elevated temperature. Furthermore, composite hollow spheres were prepared by calcination of PS latices coated with multilayers of silica and Fe3O4 nanoparticles. These nanoengineered colloidal particles may potentially find applications as delivery systems, or in diagnostics, where the particles can be directed by application of an external magnetic field.