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

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.


Schematic presentation of the typical hysteresis loops of IONPs (a); the ZFC/FC curves of γ-Fe2O3 at the different applied field (b).
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Figure 3: Schematic presentation of the typical hysteresis loops of IONPs (a); the ZFC/FC curves of γ-Fe2O3 at the different applied field (b).

Mentions: There are a number of magnetic properties for characterization of IONPs. The most decisive properties are the response type to the magnetic field (including ferromagnetic, paramagnetic, antiferromagnetic and ferrimagnetic) and magnetization, which can be measured from the hysteresis loops (M–H) and zero-field cooled/field cooled (ZFC/FC, M–T) curves. As shown in figure 3(a), the saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (HC) can be obtained from the hysteresis loops. When the IONPs are superparamagnetic, the M–H curve should show no hysteresis, and the forward and backward magnetization curves overlap completely and are almost negligible [17, 18]. As shown in figure 3(b), in ZFC measurements, the samples were cooled from 300 to 10 K without applying an external field. After reaching 10 K, an external field was applied, and the magnetic moments were recorded as the increased temperature. Conversely, for FC measurements, the samples were cooled from 300 K under an applied external field, and then the magnetic moments were recorded as the increased temperature. When the IONPs are cooled to the zero magnetic field temperature, the total magnetization of the IONPs will be zero since the magnetization of the individual IONPs is randomly oriented. An external magnetic field energetically favors the reorientation of the moments of the individual particle along the applied field at low temperatures. Thus, upon increasing the temperature, all ZFC magnetic moments increase and reach a maximum, where the temperature is referred to as the blocking temperature (TB). TB is defined as the temperature at which NPs’ moments do not relax (known as blocked) during the time scale of the measurement [19, 20]. The high field can lower the energy barriers between the two easy axis orientations, therefore, lowering the blocking temperature. Moreover, if the applied field reaches a critical value, the blocking temperature will disappear [13].


Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications
Schematic presentation of the typical hysteresis loops of IONPs (a); the ZFC/FC curves of γ-Fe2O3 at the different applied field (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Schematic presentation of the typical hysteresis loops of IONPs (a); the ZFC/FC curves of γ-Fe2O3 at the different applied field (b).
Mentions: There are a number of magnetic properties for characterization of IONPs. The most decisive properties are the response type to the magnetic field (including ferromagnetic, paramagnetic, antiferromagnetic and ferrimagnetic) and magnetization, which can be measured from the hysteresis loops (M–H) and zero-field cooled/field cooled (ZFC/FC, M–T) curves. As shown in figure 3(a), the saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (HC) can be obtained from the hysteresis loops. When the IONPs are superparamagnetic, the M–H curve should show no hysteresis, and the forward and backward magnetization curves overlap completely and are almost negligible [17, 18]. As shown in figure 3(b), in ZFC measurements, the samples were cooled from 300 to 10 K without applying an external field. After reaching 10 K, an external field was applied, and the magnetic moments were recorded as the increased temperature. Conversely, for FC measurements, the samples were cooled from 300 K under an applied external field, and then the magnetic moments were recorded as the increased temperature. When the IONPs are cooled to the zero magnetic field temperature, the total magnetization of the IONPs will be zero since the magnetization of the individual IONPs is randomly oriented. An external magnetic field energetically favors the reorientation of the moments of the individual particle along the applied field at low temperatures. Thus, upon increasing the temperature, all ZFC magnetic moments increase and reach a maximum, where the temperature is referred to as the blocking temperature (TB). TB is defined as the temperature at which NPs’ moments do not relax (known as blocked) during the time scale of the measurement [19, 20]. The high field can lower the energy barriers between the two easy axis orientations, therefore, lowering the blocking temperature. Moreover, if the applied field reaches a critical value, the blocking temperature will disappear [13].

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.