Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core–Shell Structures upon Nanoemulsion Fusion,Langmuir

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Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core–Shell Structures upon Nanoemulsion Fusion
Langmuir ( IF 3.7 ) Pub Date : 2017-09-22 00:00:00 , DOI: 10.1021/acs.langmuir.7b02743
Ahmet Kertmen _{1,

2,

3} , Pau Torruella ₄ , Emerson Coy ₂ , Luis Yate ₅ , Grzegorz Nowaczyk ₂ , Jacek Gapiński ₂ , Carmen Vogt ₃ , Muhammet Toprak ₃ , Sonia Estradé ₄ , Francesca Peiró ₄ , Sławomir Milewski ₁ , Stefan Jurga ₂ , Ryszard Andruszkiewicz ₁

Affiliation

It has been long known that the physical encapsulation of oleic acid-capped iron oxide nanoparticles (OA–IONPs) with the cetyltrimethylammonium (CTA⁺) surfactant induces the formation of spherical iron oxide nanoparticle clusters (IONPCs). However, the behavior and functional properties of IONPCs in chemical reactions have been largely neglected and are still not well-understood. Herein, we report an unconventional ligand-exchange function of IONPCs activated when dispersed in an ethyl acetate/acetate buffer system. The ligand exchange can successfully transform hydrophobic OA–IONP building blocks of IONPCs into highly hydrophilic, acetate-capped iron oxide nanoparticles (Ac–IONPs). More importantly, we demonstrate that the addition of silica precursors (tetraethyl orthosilicate and 3-aminopropyltriethoxysilane) to the acetate/oleate ligand-exchange reaction of the IONPs induces the disassembly of the IONPCs into monodispersed iron oxide–acetate–silica core–shell–shell (IONPs@acetate@SiO₂) nanoparticles. Our observations evidence that the formation of IONPs@acetate@SiO₂ nanoparticles is initiated by a unique micellar fusion mechanism between the Pickering-type emulsions of IONPCs and nanoemulsions of silica precursors formed under ethyl acetate buffered conditions. A dynamic rearrangement of the CTA⁺–oleate bilayer on the IONPC surfaces is proposed to be responsible for the templating process of the silica shells around the individual IONPs. In comparison to previously reported methods in the literature, our work provides a much more detailed experimental evidence of the silica-coating mechanism in a nanoemulsion system. Overall, ethyl acetate is proven to be a very efficient agent for an effortless preparation of monodispersed IONPs@acetate@SiO₂ and hydrophilic Ac–IONPs from IONPCs.

中文翻译：

醋酸盐诱导的纳米乳液融合将球形氧化铁纳米颗粒簇解聚为单分散的核-壳结构

众所周知，油酸封端的氧化铁纳米粒子（OA–IONPs）与十六烷基三甲基铵（CTA ⁺表面活性剂诱导球形氧化铁纳米粒子簇（IONPCs）的形成。但是，在化学反应中IONPC的行为和功能特性已被大大忽略，并且仍未被很好地理解。在本文中，我们报告了分散在乙酸乙酯/乙酸盐缓冲液系统中时激活的IONPC的非常规配体交换功能。配体交换可以成功地将IONPC的疏水性OA-IONP结构单元转变为高度亲水的，乙酸盐封端的氧化铁纳米颗粒（Ac-IONPs）。更重要的是，我们证明了在IONP的乙酸盐/油酸酯配体交换反应中添加二氧化硅前体（原硅酸四乙酯和3-氨基丙基三乙氧基硅烷）会导致IONPC分解成单分散的氧化铁-乙酸盐-二氧化硅核-壳-壳（IONPs @醋酸盐@SiO₂）纳米粒子。我们的观察证据表明，IONPs @ acetate @ SiO ₂纳米粒子的形成是由IONPC的Pickering型乳液与在乙酸乙酯缓冲条件下形成的二氧化硅前体的纳米乳液之间的独特胶束融合机制引发的。提议在IONPC表面上动态重新排列CTA ^+-油酸酯双层，以负责围绕各个IONP的二氧化硅壳的模板化过程。与文献中先前报道的方法相比，我们的工作提供了纳米乳液系统中二氧化硅涂层机理的更详细的实验证据。总体而言，已证明乙酸乙酯是轻松制备单分散IONPs @ acetate @ SiO的非常有效的试剂₂和IONPC的亲水性Ac–IONP。

更新日期：2017-09-23

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