Gold-loading magnetic core-shell organic/inorganic nanocomposites: Facile preparation and multiple properties

Abstract

Magnetic composite nanospheres (MCS) were first prepared via mini-emulsion polymerization. Subsequently, the hybrid core-shell nanospheres were used as carriers to support gold nanoparticles. The as-prepared gold-loading magnetic composite nanospheres (Au-MCS) had a hydrophobic core embed with γ-Fe3O4 and a hydrophilic shell loaded by gold nanoparticles. Both the content of γ-Fe3O4 and the size of gold nanoparticles could be controlled in our experiments, which resulted in fabricating various materials. On one hand, the Au-MCS could be used as a T2 contrast agent with a relaxivity coefficient of 362mg-1mlS-1 for magnetic resonance imaging. On the other hand, the Au-MCS exhibited tunable optical-absorption property over a wavelength range from 530nm to 800nm, which attributed to a secondary growth of gold nanoparticles. In addition, dynamic light scattering results of particle sizing and Zeta potential measurements revealed that Au-MCS had a good stability in an aqueous solution, which would be helpful for further applications. Finally, it showed that the Au-MCS were efficient catalysts for reductions of hydrophobic nitrobenzene and hydrophilic 4-nitrophenol that could be reused by a magnetic separation process. ? 2014 John Wiley & Sons, Ltd