Superparamagnetic Fe2O3 Beads−CdSe/ZnS Quantum Dots Core−Shell Nanocomposite Particles for Cell Separation

Abstract

This paper describes the synthesis of new nanocomposite nanoparticles that consist of polymer coated γ-Fe2O3 superparamagnetic cores and CdSe/ZnS quantum dots (QDs) shell. A single layer of QDs was bound to the surface of thiol-modified magnetic beads through the formation of thiol−metal bonds to form luminescent/magnetic nanocomposite particles. Transmission electron microscopy (TEM) and energy disperse spectroscopy (EDS) were used to characterize the size, size distribution, and composition of the luminescent/magnetic nanoparticles. Their average diameter was 30 nm with a size variation of ±15%. The nanoparticles were modified with carboxylic groups to increase their miscibility in aqueous solution. A 3-fold decrease in the luminescence quantum yield of the luminescent/magnetic particles and a slight blue shift in their emission peaks compared to individual luminescent QDs were observed. However, the particles were bright and were easily observed using a conventional fluorescence microscope. Additionall...