Preparation and characterization of Fe3O4/CdTe magnetic/fluorescent nanocomposites and their applications in immuno-labeling and fluorescent imaging of cancer cells.

The synthesis of a new kind of magnetic, fluorescent multifunctional nanoparticles (approximately 30 nm in diameter) was demonstrated, where multiple fluorescent CdTe quantum dots (QDs) are covalently linked to and assembled around individual silica-coated superparamagnetic Fe(3)O(4) nanoparticles and active carboxylic groups are presented on the surface for easy bioconjugation with biomolecules. The Fe(3)O(4) nanoparticles were first functionalized with thiol groups, followed by chemical conjugation with multiple thioglycolic acid modified CdTe QDs to form water-soluble Fe(3)O(4)/CdTe magnetic/fluorescent nanocomposites. X-ray diffraction, infrared spectroscopy, transmission electron microscopy, absorption and fluorescence spectroscopy, and magnetometry were applied to fully characterize the multifunctional nanocomposites. The nanocomposites were found to exhibit magnetic and fluorescent properties favorable for their applications in magnetic separation and guiding as well as fluorescent imaging. The carboxyl groups on the nanocomposite surface were proved to be chemically active and readily available for further bioconjugation with biomolecules such as bovine serum albumin and antibodies, enabling the applications of the nanocomposites for specific recognition of biological targets. The Fe(3)O(4)/CdTe magnetic/fluorescent nanocomposites conjugated with anti-CEACAM8 antibody were successfully employed for immuno-labeling and fluorescent imaging of HeLa cells.