Magnetic-Encoded Fluorescent Multifunctional Nanospheres for Simultaneous Multicomponent Analysis

In this study, magnetic-encoded fluorescent (CdTe/Fe3O4)@SiO2 multifunctional nanospheres were constructed by adjusting the initial concentration of Fe3O4 in a fabrication process based on reverse microemulsion. The resultant multifunctional nanospheres were characterized by transmission electron microscopy, X-ray diffraction measurements, fluorescence spectrophotometry, and vibrating sample magnetometry. They showed good fluorescence properties, gradient magnetic susceptibility (weak, moderate, and strong), and easy biofunctionalization for biomolecules, such as immunoglobulin G (IgG), protein, and antibody. Then the capture efficiency of the (CdTe/Fe3O4)@SiO2 nanospheres were investigated by using the fluorophore-labeled IgG-conjugated nanospheres as a model. Further studies demonstrated the ability of these (CdTe/Fe3O4)@SiO2 multifunctional nanospheres to accomplish sequentially magnetic separation, capture, and fluorescent detection for each corresponding antigen of CA125, AFP, and CEA with a detection limit of 20 KU/L, 10 ng/mL, and 5 ng/mL, respectively, from a mixed sample under a certain external magnetic field within a few minutes. The strategy of combining magnetic-encoding-based separation and fluorescence-based detection proposed in this study shows great potential to achieve easy, rapid, economical, and near-simultaneous multicomponent separation and analysis for a variety of targets such as drugs, biomarkers, pathogens, and so on.