Non-aqueous synthesis of water-dispersible Fe3O4-Ca-3( PO4)(2) core-shell nanoparticles

Abstract

The Fe3O4-Ca-3(PO4)(2) core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe3O4 and the bioactive functions of Ca-3(PO4)(2) into single entities. The Fe3O4 nanoparticles were pre-formed first by thermal reduction of Fe(acac)(3) and then the Ca-3(PO4)(2) layer was coated by simultaneous deposition of Ca2+ and PO43-. The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca-3(PO4)(2) shell forms an hcp phase (a = 7.490 angstrom, c = 9.534 angstrom) on the Fe3O4 surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca-3(PO4)(2) and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe3O4 and Ca-3(PO4)(2) in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.