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Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

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ABSTRACT

This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed.

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Typical SEM images of the polyacrylic acid-Fe3O4 hybrid nanostructure synthesized using different initial iron amounts of 0.7 mmol (A), 1.5 mmol (B), 3.0 mmol (C), and 5.0 mmol (D). All of the scale bars are 2 μm. Magnetization curves of the hybrid nanostructure with different sizes at a temperature of 300 K and 1.8 K. Insets show the data around zero field with an expanded scale ranging from −1000 to 1000 Oe (E), (F). Photographs of a solution of the hybrid nanostructure with the diameter of 400 nm in the absence and presence of a magnet (G). (Reprinted with permission from S Liu et al 2011 CrystEngComm13 2425. Copyright 2011 Royal Society of Chemistry.)
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Figure 9: Typical SEM images of the polyacrylic acid-Fe3O4 hybrid nanostructure synthesized using different initial iron amounts of 0.7 mmol (A), 1.5 mmol (B), 3.0 mmol (C), and 5.0 mmol (D). All of the scale bars are 2 μm. Magnetization curves of the hybrid nanostructure with different sizes at a temperature of 300 K and 1.8 K. Insets show the data around zero field with an expanded scale ranging from −1000 to 1000 Oe (E), (F). Photographs of a solution of the hybrid nanostructure with the diameter of 400 nm in the absence and presence of a magnet (G). (Reprinted with permission from S Liu et al 2011 CrystEngComm13 2425. Copyright 2011 Royal Society of Chemistry.)

Mentions: The microwave-assisted synthesis method has been widely used to prepare magnetic IONPs with controllable size and shapes recently [89–92]. For example, Sreeja and Joy reported the fabrication of superparamagnetic γ-Fe2O3 NPs with an average diameter of 10 nm using the microwave-assisted method at 150 °C, in a short time-duration of 25 min. Their work showed that lower temperature and less reaction time were required to obtain comparable results by microwave heating [93]. Jiang et al have reported cubic IONPs that were prepared via the microwave-assisted method followed by Ostwald ripening procedures. The results illustrated the phase and magnetic properties of IONPs would change by varying the experimental conditions [94]. Indeed, the phase of IONPs by the microwave-assisted synthesis could be slightly different depending on the experimental conditions. For instance, Hu et al synthesized three major iron oxide phases: magnetite, maghemite and hematite, under microwave treatment in an autoclave, from alcohol/water solutions of chloride salts in the presence of NaOH. The results revealed that the pure hematite phase can be obtained in the presence of single precursor FeCl3. When FeCl2 was used as the single precursor, magnetite or maghemite NPs were produced depending on the drying process used [95]. Additionally, the microwave-assisted synthesis method is often employed to prepare biocompatible magnetic IONPs. Recently, Osborne reported a rapid and straightforward microwave-assisted synthesis of superparamagnetic dextran-coated IONPs. The NPs were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic process. The IONPs are found to be superparamagnetic and exhibit properties consistently in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization [96]. As shown in figure 9, Zhu et al reported polyacid-conjugated Fe3O4 superparamagnetic hybrid nanostructures that were conveniently fabricated by the introduction of a microwave-assisted method. The hybrid nanostructure was composed of superparamagnetic magnetite nanograins and presented a cluster-like structure; and its size range can be tuned from about 100–400 nm by varying the amount of FeCl3 in the system. The hybrid nanostructure exhibits excellent magnetic responsibility and good biocompatibility, which offers advantageous functionality due to the preferential exposure of uncoordinated carboxylate groups on its surface [97]. Compared to the thermal decomposition method, the stabilization of the IONPs prepared by the microwave-assisted synthesis route in organic solvents can be easily dispersed in water without laborious ligand exchange or purification steps. Such characteristics can be considered as attractive for fabrication of large-scale IONPs [98].


Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications
Typical SEM images of the polyacrylic acid-Fe3O4 hybrid nanostructure synthesized using different initial iron amounts of 0.7 mmol (A), 1.5 mmol (B), 3.0 mmol (C), and 5.0 mmol (D). All of the scale bars are 2 μm. Magnetization curves of the hybrid nanostructure with different sizes at a temperature of 300 K and 1.8 K. Insets show the data around zero field with an expanded scale ranging from −1000 to 1000 Oe (E), (F). Photographs of a solution of the hybrid nanostructure with the diameter of 400 nm in the absence and presence of a magnet (G). (Reprinted with permission from S Liu et al 2011 CrystEngComm13 2425. Copyright 2011 Royal Society of Chemistry.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036481&req=5

Figure 9: Typical SEM images of the polyacrylic acid-Fe3O4 hybrid nanostructure synthesized using different initial iron amounts of 0.7 mmol (A), 1.5 mmol (B), 3.0 mmol (C), and 5.0 mmol (D). All of the scale bars are 2 μm. Magnetization curves of the hybrid nanostructure with different sizes at a temperature of 300 K and 1.8 K. Insets show the data around zero field with an expanded scale ranging from −1000 to 1000 Oe (E), (F). Photographs of a solution of the hybrid nanostructure with the diameter of 400 nm in the absence and presence of a magnet (G). (Reprinted with permission from S Liu et al 2011 CrystEngComm13 2425. Copyright 2011 Royal Society of Chemistry.)
Mentions: The microwave-assisted synthesis method has been widely used to prepare magnetic IONPs with controllable size and shapes recently [89–92]. For example, Sreeja and Joy reported the fabrication of superparamagnetic γ-Fe2O3 NPs with an average diameter of 10 nm using the microwave-assisted method at 150 °C, in a short time-duration of 25 min. Their work showed that lower temperature and less reaction time were required to obtain comparable results by microwave heating [93]. Jiang et al have reported cubic IONPs that were prepared via the microwave-assisted method followed by Ostwald ripening procedures. The results illustrated the phase and magnetic properties of IONPs would change by varying the experimental conditions [94]. Indeed, the phase of IONPs by the microwave-assisted synthesis could be slightly different depending on the experimental conditions. For instance, Hu et al synthesized three major iron oxide phases: magnetite, maghemite and hematite, under microwave treatment in an autoclave, from alcohol/water solutions of chloride salts in the presence of NaOH. The results revealed that the pure hematite phase can be obtained in the presence of single precursor FeCl3. When FeCl2 was used as the single precursor, magnetite or maghemite NPs were produced depending on the drying process used [95]. Additionally, the microwave-assisted synthesis method is often employed to prepare biocompatible magnetic IONPs. Recently, Osborne reported a rapid and straightforward microwave-assisted synthesis of superparamagnetic dextran-coated IONPs. The NPs were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic process. The IONPs are found to be superparamagnetic and exhibit properties consistently in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization [96]. As shown in figure 9, Zhu et al reported polyacid-conjugated Fe3O4 superparamagnetic hybrid nanostructures that were conveniently fabricated by the introduction of a microwave-assisted method. The hybrid nanostructure was composed of superparamagnetic magnetite nanograins and presented a cluster-like structure; and its size range can be tuned from about 100–400 nm by varying the amount of FeCl3 in the system. The hybrid nanostructure exhibits excellent magnetic responsibility and good biocompatibility, which offers advantageous functionality due to the preferential exposure of uncoordinated carboxylate groups on its surface [97]. Compared to the thermal decomposition method, the stabilization of the IONPs prepared by the microwave-assisted synthesis route in organic solvents can be easily dispersed in water without laborious ligand exchange or purification steps. Such characteristics can be considered as attractive for fabrication of large-scale IONPs [98].

View Article: PubMed Central - PubMed

ABSTRACT

This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed.

No MeSH data available.


Related in: MedlinePlus