Ferrofluids of magnetic multicore nanoparticles for biomedical applications

Abstract For a variety of magnetically based biomedical applications, it is advantageous to use sedimentation stable suspensions of relatively large ( d >20 nm) magnetic core–shell nanoparticles. Water-based suspensions of multicore nanoparticles were prepared by coating of the particles (synthesized by means of a modified alkaline precipitation method) with a carboxymethyldextran shell. The resulting ferrofluids were structurally and magnetically characterized. It was found that these fluids show a specific heating power of about 60 W/g ( f =400 kHz, H =10 kA/m). This value was increased up to 330 W/g by a simple fractionation method based on centrifugation. Finally, the cellular uptake of the multicore nanoparticles was demonstrated.