Preparation And Characterization Of Chimeric Magnetic Encoded Fluorescent Nanocomposites

Nanomaterials known as "new materials in the21st century" had attracted the interests of more and more researchers. Especially, fluorescent quantum dots and magnetic nanoparticles became two kinds of popular representative nanomaterials. Fluorescent quantum dots had unique optical properties, such as broad excitation spectra, narrow and symmetric emission spectra, tunable emission spectra, improved brightness, superior photostability, and simultaneous excitation of multiple fluorescence colors, which displayed a wide range of application prospects in the field of bio-medicine. Because of their good magnetic manipulation and separating function, magnetic nanoparticles had been widely used in capture and separation of targets in the complex system, magnetically induced targeted delivery and hyperthermia. However, in the actual biological applications, it often required the synergy of variety of nanoparticles with different functions to achieve the simultaneous analysis of multiplex targets due to the complexity of the biological objects.Fluorescent labeling and magnetic separation were two kinds of important technologies applied in biomedical field. If these two technologies could be combined together to accomplish the simultaneous detection and separation of targets, it would greatly improve the efficiency of the related work. In this study, multifunctional nanocomposites with fluorescence properties and magnetic properties were constructed using fluorescent quantum dots and magnetic nanoparticles through layer-by-layer self-assembly method. By controlling their assembling layers of magnetic nanoparticles, the magnetic encoded fluorescent nanocomposites with different magnetic response were obtained. And then these nanocomposites were biofunctionalized with different fluorescent materials-labeled IgG biomolecules as models, which were subsequently separated and captured under the external magnetic field. Study results showed the as-prepared magnetic encoded fluorescent nanocomposites were with excellent fluorescence and magnetic properties, and high separation capture efficiency for target substances, and could be biofunctionalized. The successful constructions of the magnetic encoding fluorescent-magnetic multifunctional nanocomposites would be expected to provide new opportunities for the analysis of complex samples in the important areas of disease diagnosis and food safety monitoring. The main contents of this paper were as follows:(1) Use thioglycolic acid modified CdTe quantum dots made with hydrothermal method as a raw material to prepare CdTe@SiO2nanoparticles by reverse microemulsion method, and their particle size, morphology and fluorescence properties were characterized.(2) Based on the electrostatic interaction, fluorescent-magnetic multifunctional nanocomposites was fabricated by Layer-by-Layer self-assembly method which alternately assembled a positively charged polyelectrolyte and negatively charged supermagnetic nanoparticles onto the surface of CdTe@SiO2nanoparticles. The fluorescent magnetic multifunctional nanocomposites with different magnetic response were obtained by adjusting the assembly layers of the supermagnetic nanoparticles. Then the structure, morphology and performance of nanocomposites were characterized.(3) Three kinds of fluorescent materials-labelled IgG biomolecules were coupled with three kinds of fluorescent magnetic nanocomposites with different magnetic susceptibilities respectively by covalent coupling to construct bioprobes, each of which then had been successfully separated and captured under external magnetic field, and subsequently obtained the capture efficiencies through fluorescence analysis.