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Tunable magnetic nanowires for biomedical and harsh environment applications.

Ivanov YP, Alfadhel A, Alnassar M, Perez JE, Vazquez M, Chuvilin A, Kosel J - Sci Rep (2016)

Bottom Line: The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations.This property renders these core-shell nanowires attractive materials for application to harsh environments.A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

View Article: PubMed Central - PubMed

Affiliation: Computer, Electrical and Mathematical Sciences and Engineering Division (CEMSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.

ABSTRACT
We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

No MeSH data available.


Shell to core ratio for different annealing times of polycrystalline and single-crystal NWs, showing that after 24 hours, the polycrystalline NWs are fully oxidized, while the maximum shell thickness for single-crystal NWs is 12 nm, even after 72 hours.
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f5: Shell to core ratio for different annealing times of polycrystalline and single-crystal NWs, showing that after 24 hours, the polycrystalline NWs are fully oxidized, while the maximum shell thickness for single-crystal NWs is 12 nm, even after 72 hours.

Mentions: Shell thicknesses following annealing times are summarized in Fig. 5. Shell thickness of polycrystalline NWs increases linearly with annealing time until pure Fe3O4 NWs are obtained after 24 hours (Fig. 4b). Single-crystal NWs oxidize slower such that shell thickness saturates at around 12 nm (Fig. 4d). This can be attributed to the absence of grain boundaries that are required for heat-assisted oxygen diffusion. The ability of single-crystal core-shell NWs to resist complete oxidation is a great advantage for applications that require high-temperature operations, while they maintain the magnetic properties of the Fe core.


Tunable magnetic nanowires for biomedical and harsh environment applications.

Ivanov YP, Alfadhel A, Alnassar M, Perez JE, Vazquez M, Chuvilin A, Kosel J - Sci Rep (2016)

Shell to core ratio for different annealing times of polycrystalline and single-crystal NWs, showing that after 24 hours, the polycrystalline NWs are fully oxidized, while the maximum shell thickness for single-crystal NWs is 12 nm, even after 72 hours.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829833&req=5

f5: Shell to core ratio for different annealing times of polycrystalline and single-crystal NWs, showing that after 24 hours, the polycrystalline NWs are fully oxidized, while the maximum shell thickness for single-crystal NWs is 12 nm, even after 72 hours.
Mentions: Shell thicknesses following annealing times are summarized in Fig. 5. Shell thickness of polycrystalline NWs increases linearly with annealing time until pure Fe3O4 NWs are obtained after 24 hours (Fig. 4b). Single-crystal NWs oxidize slower such that shell thickness saturates at around 12 nm (Fig. 4d). This can be attributed to the absence of grain boundaries that are required for heat-assisted oxygen diffusion. The ability of single-crystal core-shell NWs to resist complete oxidation is a great advantage for applications that require high-temperature operations, while they maintain the magnetic properties of the Fe core.

Bottom Line: The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations.This property renders these core-shell nanowires attractive materials for application to harsh environments.A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

View Article: PubMed Central - PubMed

Affiliation: Computer, Electrical and Mathematical Sciences and Engineering Division (CEMSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.

ABSTRACT
We have synthesized nanowires with an iron core and an iron oxide (magnetite) shell by a facile low-cost fabrication process. The magnetic properties of the nanowires can be tuned by changing shell thicknesses to yield remarkable new properties and multi-functionality. A multi-domain state at remanence can be obtained, which is an attractive feature for biomedical applications, where a low remanence is desirable. The nanowires can also be encoded with different remanence values. Notably, the oxidation process of single-crystal iron nanowires halts at a shell thickness of 10 nm. The oxide shell of these nanowires acts as a passivation layer, retaining the magnetic properties of the iron core even during high-temperature operations. This property renders these core-shell nanowires attractive materials for application to harsh environments. A cell viability study reveals a high degree of biocompatibility of the core-shell nanowires.

No MeSH data available.