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Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core – Shell Particle for Protein Adsorption and pH-Controlled Release

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ABSTRACT

Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.

No MeSH data available.


Hysteresis loops obtained from a VSM measured operating at room temperature for CoFe2O4, and apatite (Ap)-coated citric acid–stabilized cobalt ferrite (CFCA-Ap) particles.
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Figure 5: Hysteresis loops obtained from a VSM measured operating at room temperature for CoFe2O4, and apatite (Ap)-coated citric acid–stabilized cobalt ferrite (CFCA-Ap) particles.

Mentions: The room temperature magnetic properties of CF and CFCA-Ap were recorded under an applied field of 10 kOe. The samples exhibit hysteresis loops typical of magnetic materials having an ordered magnetic structure (Figure 5). The saturation magnetizations (Ms) derived from the hysteresis loops of cobalt ferrite particles are higher than those of apatite-coated cobalt ferrite particles. The coercivity (Hc) of the CoFe2O4 is slightly lower after coated by apatite. The values of the Hc are 1896.9 and 1808.5 Oe for the CF and CFCA-Ap particles, respectively. The lower value of magnetization for CFCA-Ap compared with that CF is due the lower amount of the magnetic particles in the coated composites. Another interpretation is that the non-magnetic coating layer (apatite) forms a magnetic dead layer on the surface. This will affect the magnitude of the magnetization by quenching the surface moment that contributes to surface anisotropy.


Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core – Shell Particle for Protein Adsorption and pH-Controlled Release
Hysteresis loops obtained from a VSM measured operating at room temperature for CoFe2O4, and apatite (Ap)-coated citric acid–stabilized cobalt ferrite (CFCA-Ap) particles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211243&req=5

Figure 5: Hysteresis loops obtained from a VSM measured operating at room temperature for CoFe2O4, and apatite (Ap)-coated citric acid–stabilized cobalt ferrite (CFCA-Ap) particles.
Mentions: The room temperature magnetic properties of CF and CFCA-Ap were recorded under an applied field of 10 kOe. The samples exhibit hysteresis loops typical of magnetic materials having an ordered magnetic structure (Figure 5). The saturation magnetizations (Ms) derived from the hysteresis loops of cobalt ferrite particles are higher than those of apatite-coated cobalt ferrite particles. The coercivity (Hc) of the CoFe2O4 is slightly lower after coated by apatite. The values of the Hc are 1896.9 and 1808.5 Oe for the CF and CFCA-Ap particles, respectively. The lower value of magnetization for CFCA-Ap compared with that CF is due the lower amount of the magnetic particles in the coated composites. Another interpretation is that the non-magnetic coating layer (apatite) forms a magnetic dead layer on the surface. This will affect the magnitude of the magnetization by quenching the surface moment that contributes to surface anisotropy.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.

No MeSH data available.