Core-shell magneto-luminescent nanocomposites

Magneto-luminescent materials that do not exist in nature, can find a wide application in biomedical and environmental fields. Here we describe magneto-optical properties of core-shell-shell nanocomposites consisting of a Fe3O4 superparamagnetic iron oxide nanoparticle (SPION) covered with quantum-sized brightly luminescent CdSe layer surrounded by ZnS passivating shell. The synthesized nanocomposites demonstrate excitonic bands in their absorption and photoluminescent (PL) spectra centered at 585 nm and 603 nm, respectively. The PL quantum yield of nanocomposites has been increased by 5 times due to their passivation with ZnS shell. The analysis of magneto-optical properties of the synthesized Fe3O4/CdSe/ZnS nanocomposites has shown that their magnetic circular dichroism (MCD) spectrum is characterized with the bands centered at 430 nm, 350 nm and 303 nm corresponding to (6)A(1) -> E-4, (4)A(1)((4)G); (6)A(1) -> E-4(D-4) and (6)A(1) -> T-4(1) (P-4) electronic transitions, respectively. It has been found that the synthesized core-shell SPIONs demonstrate excellent colloidal stability, magneto-optical properties typical for SPIONs and bright photoluminescence.