A new class of highly fluorescent, photostable, and magnetic core/shell nanoparticles has been synthesized from a reverse microemulsion method. The obtained bifunctional nanocomposites were characterized by transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) spectrometry, photoluminescence (PL) spectrometry, and fluorescence microscopy in a magnetic field. To further improve their biocompatibility, the silica-coated nanoparticles were functionalized with amino groups. The fluorescent magnetic composite nanoparticles (FMCNPs) had a typical diameter of 50 ± 5 nm and a saturation magnetization of 3.21 emu g−1 at room temperature, and exhibited strong excitonic photoluminescence. Through activation with glutaraldehyde, the FMCNPs were successfully conjugated with goat anti-mouse immunoglobin G (GM IgG), and the bioactivity and binding specificity of the as-prepared FMCNPs-GM IgG were confirmed via immunofluorescence assays, commonly used in bioanalysis. So they are potentially useful for many applications in biolabelling, imaging, drug targeting, bioseparation and bioassays.

Many sensing/catalytic applications in nanotechnology require a programmed assembly of nanospheres/nanorods onto surfaces. The gold nanorods, formed by a seed-mediated, surfactant-assisted synthesis protocol, are stabilized in solution due to surface modification by the surfactant cetyltrimethylammonium bromide. DNAtemplated self-assembly of gold nanorods with different aspect ratios at different DNA concentration values has been studied using transmission electron microscopy. Under appropriate conditions such as aspect ratio and DNA concentration, gold nanorods assemble into one-and two-dimensional structures. A stable phase of side-by-side supramolecular assemblies was formed, and some of the double-layer assemblies extend to superlattices of nanorods. The resulting guide for designing statistically patterned arrays of nanoparticles suggests the possibility of fabricating spontaneously organized nanoscale devices.

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In this study, hydrophilic high-luminescent magnetic nanocomposites (LMNCs) composed of both fluorescent clusters (quantum dots, QDs) and magnetic nanoparticles were synthesized. The nanocomposites exhibited high luminescence and were easily separated in an external magnetic field. The LMNCs were capped with streptavidin (SA), and the SA on the surface of LMNC-SA composites was confirmed to be bioactive by competitive inhibition analytic methods. The fabricated LMNC-SA composites have potential application in biolabelling, bioseparation, immunoassay and pathogenic diagnosis.