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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.

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Fit of the release data to ktn (a) and Fit of the release data to φo(1 - exp(-kbt)) (b). The observed values and the fitted values to ktn when the pH values of the buffer solution are 4.0, 6.5, and 7.4. The values of the k and n are (67.215 h-1,0.25) for pH 4.0, (35.031 h-1, 0.40) for pH 6.5 and (22.184 h-1, 0.30) for pH 7.4, respectively. For the observed values and the fitted values to φo(1 - exp(-kbt)) of the φo and kb, which lead to the best fits are (100.00, 0.805 h-1), (70.430, 0.659 h-1) and (35.417, 0.605 h-1), respectively, for the three pH values of 4.0, 6.5, and 7.4.
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Figure 10: Fit of the release data to ktn (a) and Fit of the release data to φo(1 - exp(-kbt)) (b). The observed values and the fitted values to ktn when the pH values of the buffer solution are 4.0, 6.5, and 7.4. The values of the k and n are (67.215 h-1,0.25) for pH 4.0, (35.031 h-1, 0.40) for pH 6.5 and (22.184 h-1, 0.30) for pH 7.4, respectively. For the observed values and the fitted values to φo(1 - exp(-kbt)) of the φo and kb, which lead to the best fits are (100.00, 0.805 h-1), (70.430, 0.659 h-1) and (35.417, 0.605 h-1), respectively, for the three pH values of 4.0, 6.5, and 7.4.

Mentions: where Mt and M0 are the concentrations of the protein (part of the biomolecule which in the present case is BSA) released into a medium up to time t and the initial concentration of protein on the particles. Mt/M0 is the fractional concentration of the released protein. The Peppas's model was developed for water-soluble release from a polymeric device. It has been applied to porous ceramic materials even though the mechanism of release is unknown. It is in good agreement with the release kinetics of biomolecules from devices that have a fast dissolution rate compared to the diffusion times. We have applied a regression analysis to fit Peppas's model, Eq. 4, to the data given on Figure 8. The results of these fits for the different pH environments are shown in Figure 10a. The correlation coefficients, Rc, are 0.957, 0.883, and 0.868 for the pH 4.0, 6.5, and 7.4 data, respectively. While the fits to the data for the first five-hour period are quite good, the fits after the first 5 h are poor, especially the release of BSA in a mild acidic medium (pH 6.5) and in the physiological pH level (pH 7.4).


Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core – Shell Particle for Protein Adsorption and pH-Controlled Release
Fit of the release data to ktn (a) and Fit of the release data to φo(1 - exp(-kbt)) (b). The observed values and the fitted values to ktn when the pH values of the buffer solution are 4.0, 6.5, and 7.4. The values of the k and n are (67.215 h-1,0.25) for pH 4.0, (35.031 h-1, 0.40) for pH 6.5 and (22.184 h-1, 0.30) for pH 7.4, respectively. For the observed values and the fitted values to φo(1 - exp(-kbt)) of the φo and kb, which lead to the best fits are (100.00, 0.805 h-1), (70.430, 0.659 h-1) and (35.417, 0.605 h-1), respectively, for the three pH values of 4.0, 6.5, and 7.4.
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Related In: Results  -  Collection

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Figure 10: Fit of the release data to ktn (a) and Fit of the release data to φo(1 - exp(-kbt)) (b). The observed values and the fitted values to ktn when the pH values of the buffer solution are 4.0, 6.5, and 7.4. The values of the k and n are (67.215 h-1,0.25) for pH 4.0, (35.031 h-1, 0.40) for pH 6.5 and (22.184 h-1, 0.30) for pH 7.4, respectively. For the observed values and the fitted values to φo(1 - exp(-kbt)) of the φo and kb, which lead to the best fits are (100.00, 0.805 h-1), (70.430, 0.659 h-1) and (35.417, 0.605 h-1), respectively, for the three pH values of 4.0, 6.5, and 7.4.
Mentions: where Mt and M0 are the concentrations of the protein (part of the biomolecule which in the present case is BSA) released into a medium up to time t and the initial concentration of protein on the particles. Mt/M0 is the fractional concentration of the released protein. The Peppas's model was developed for water-soluble release from a polymeric device. It has been applied to porous ceramic materials even though the mechanism of release is unknown. It is in good agreement with the release kinetics of biomolecules from devices that have a fast dissolution rate compared to the diffusion times. We have applied a regression analysis to fit Peppas's model, Eq. 4, to the data given on Figure 8. The results of these fits for the different pH environments are shown in Figure 10a. The correlation coefficients, Rc, are 0.957, 0.883, and 0.868 for the pH 4.0, 6.5, and 7.4 data, respectively. While the fits to the data for the first five-hour period are quite good, the fits after the first 5 h are poor, especially the release of BSA in a mild acidic medium (pH 6.5) and in the physiological pH level (pH 7.4).

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.