Molecules · 2013 · 796 citations · 38 references
NanoparticlesMagnetic PropertiesEngineeringMetal NanoparticlesFe₃o₄ NanoparticlesMagnetic ResonanceBiomedical EngineeringChemistryMagnetic MaterialsMagnetismChemical EngineeringTherapeutic NanomaterialsBioimagingContrast EnhancementNanoparticle CharacterizationNanomanufacturingSurface ModificationMagnetic MaterialMagnetic NanoparticlesObtained NanoparticlesNanomaterialsDrug Delivery SystemsMedicineFunctional MaterialsBiomedical ApplicationsNanomagnetism
Superparamagnetic iron oxide nanoparticles with tailored surface chemistry enable diverse biomedical uses such as MRI contrast, hyperthermia, drug delivery, and cell separation, but require high magnetization and sub‑100‑nm sizes. This paper reports the experimental details for preparing monodisperse oleic‑acid‑coated Fe₃O₄ nanoparticles by chemical co‑precipitation, optimizing pH, initial temperature, and stirring speed to achieve the desired small size and narrow distribution. The authors synthesized the OA‑coated Fe₃O₄ MNPs under the optimized conditions and characterized them with FTIR, TEM, SEM, EDXRF, TGA, XRD, and VSM. The results showed that particle size and magnetization depended on pH, temperature, and stirring speed, with optimal conditions (pH 11, 45 °C, 800 rpm) producing 7.8 ± 1.9 nm monodisperse particles that exhibited chemisorbed oleic acid, improved dispersibility, superparamagnetic behavior, and a size‑dependent increase in saturation magnetization.
Superparamagnetic iron oxide nanoparticles (MNPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. These applications required that the MNPs such as iron oxide Fe₃O₄ magnetic nanoparticles (Fe₃O₄ MNPs) having high magnetization values and particle size smaller than 100 nm. This paper reports the experimental detail for preparation of monodisperse oleic acid (OA)-coated Fe₃O₄ MNPs by chemical co-precipitation method to determine the optimum pH, initial temperature and stirring speed in order to obtain the MNPs with small particle size and size distribution that is needed for biomedical applications. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). The results show that the particle size as well as the magnetization of the MNPs was very much dependent on pH, initial temperature of Fe²⁺ and Fe³⁺ solutions and steering speed. The monodisperse Fe₃O₄ MNPs coated with oleic acid with size of 7.8 ± 1.9 nm were successfully prepared at optimum pH 11, initial temperature of 45°C and at stirring rate of 800 rpm. FTIR and XRD data reveal that the oleic acid molecules were adsorbed on the magnetic nanoparticles by chemisorption. Analyses of TEM show the oleic acid provided the Fe₃O₄ particles with better dispersibility. The synthesized Fe₃O₄ nanoparticles exhibited superparamagnetic behavior and the saturation magnetization of the Fe₃O₄ nanoparticles increased with the particle size.
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