Ultra-Small Fatty Acid-Stabilized Magnetite Nanocolloids Synthesized byIn SituHydrolytic Precipitation

Kheireddine El-Boubbou,Muhanna K Al-Muhanna,Nadim Darwish,Khaled O Al-Saad,Salem D Al-Suwaidan,Hassan M Bahhari,Rabih O Al-Kaysi,Abdulaziz I Al-Romaeh

doi:10.1155/2015/620672

Abstract

Simple, fast, large-scale, and cost-effective preparation of uniform controlled magnetic nanoparticles remains a major hurdle on the way towards magnetically targeted applications at realistic technical conditions. Herein, we present a unique one-pot approach that relies on simple basic hydrolyticin situcoprecipitation of inexpensive metal salts (Fe2+and Fe3+) compartmentalized by stabilizing fatty acids and aided by the presence of alkylamines. The synthesis was performed at relatively low temperatures (~80°C) without the use of high-boiling point solvents and elevated temperatures. This method allowed for the production of ultra-small, colloidal, and hydrophobically stabilized magnetite metal oxide nanoparticles readily dispersed in organic solvents. The results reveal that the obtained magnetite nanoparticles exhibit narrow size distributions, good monodispersities, high saturation magnetizations, and excellent colloidal stabilities. When the [fatty acid] : [Fe] ratio was varied, control over nanoparticle diameters within the range of 2–10 nm was achieved. The amount of fatty acid and alkylamine used during the reaction proved critical in governing morphology, dispersity, uniformity, and colloidal stability. Upon exchange with water-soluble polymers, the ultra-small sized particles become biologically relevant, with great promise for theranostic applications as imaging and magnetically targeted delivery vehicles.

Highlights

The continuous trials to produce controlled monodisperse magnetic metal oxide nanoparticles (M3NPs) for both in vitro and in vivo endpoints have sky-rocketed [1]
The major difficulty for the production of colloidal M3NPs lies in designing simple, practical, economical, and safe approach to produce large quantities of monodisperse magnetite nanoprobes that are stable for months and do not precipitate from their dispersions
The so-called “Ko-precipitation Hydrolytic Basic (KHB)” method described consists of the following components: inexpensive metallic ions dissolved in aqueous media, long-chain fatty acid surfactants, cosurfactants, and a base

Summary

Introduction

The continuous trials to produce controlled monodisperse magnetic metal oxide nanoparticles (M3NPs) for both in vitro and in vivo endpoints have sky-rocketed [1]. Various synthetic methods have been reported to produce M3NPs, which include nonaqueous and aqueous sol-gel, microemulsion, sonochemical, and the most popular hydrothermal/solvothermal techniques [3]. Of the many available approaches, two main synthetic solutionbased routes [4] have been popularized: (a) basic aqueous coprecipitation [5] of iron salts (as demonstrated by Massart) in the presence or absence of surfactants/polymers [6], (b) high-temperature thermal decomposition [7] of organometallic precursors (Fe(acac)3 [8], Fe-oleate [9], Fe-carboxylate [10], Fe-pivalate [11], or heterodoped ferrite pivalate [12, 13]) in high-boiling solvents at elevated temperatures (∼200– 360∘C).

Methods

Results

Conclusion