LAUSR

Abstract Magnetic-optical nanocomposites, which consist of iron oxide nanoparticles and quantum dots, have aroused considerable research interest owing to their unique magnetic and luminescent properties. However, the luminescence of quantum dots tends to be quenched by the magnetic component. Resonant Raman scattering (RRS) of semiconductor nanocrystals, which originates from a strong electron-phonon interaction, provides a new candidate property to be exploited as an analytical tool. Herein, Fe3O4/ZnS nanocomposites were prepared with the seed-mediated growth approach. The nanocomposites exhibited superparamagnetism and characteristic multi-order phonon resonant Raman lines. By using biofunctionalized Fe3O4/ZnS nanocomposites as RRS probes, a femtomolar immunoassay of a model protein, human IgG, was realized with the assistance of an external magnetic field. The results provide guidance for the broad applications of magnetic-optical nanocomposites.