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

I-Ming Tang13, Nateetip Krishnamra24, Narattaphol Charoenphandhu24, Rassmidara Hoonsawat15 and Weeraphat Pon-On1*

Author Affiliations

1 ThEP Center, Commission of Higher Education, 328 Si Ayuthaya Rd., Bangkok 10400, Thailand

2 Consortium for Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

3 Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

4 Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

5 Mahidol University International College, Salaya Campus, Mahidol University, Salaya 73720, Thailand

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Nanoscale Res Lett 2011, 6:19  doi:10.1007/s11671-010-9761-4

Published: 31 August 2010


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.

Protein release; Cobalt ferrite; Apatite; Bovine serum albumin (BSA)