Core-ShellStructureofNaYF4@SiO2@AuNanocompositeofSynthesisandCharacterizationwithMechanismsResearch

A facile method for preparing monodisperse NaYF4@SiO2@Au core-shell nanocomposite was developed. Transmission electron microscopy（TEM） as well as EDX（energy dispersive X-ray） was used to characterize the samples. The TEM showed the composite was a core-shell structure, spherical,with the uniform size of about 100 nm. TEM and EDX revealed that the NPs were coated with a layer of SiO2 and Au shell. The core shell structure of NaYF4@SiO2@Au nanocomposite could dispersed in water easily. More importantly,after being coated with SiO2 and Au, it was feasible for function by-SH and-NH2 groups, respectively. The forming process of the Au shell was monitored with TEM. The mechanism of coating Au shell was discussed in detail. It is expected that the core shell nanoparticle will act as multifunctional molecular imaging probes, such as positron emission tomography（PET）, magnetic resonance imaging（MRI）, optical imaging（OI）, or contrast agent for sensing and detection.