Synthesis Of Multifunctional Magnetic-rare Earth Luminescent Nanoparticles For Cell Imaging Application

Nowadays, cancer has become the leading cause to human death. The combination ofnanotechnology and biomedicine has many incomparable advantages in contrast totraditional cancer treatments, which is expected to make breakthrough in the diagnosis andtreatment of cancer, and has caused widespread attention.The design and application of high performance multifunctional probe is the key toachieve this goal and the hot topic of nanomedicine. Though some progreses have beenachieved in the diagnosis and treatment of cancer with nanomedicine, there is still a longroad to realize its clinical application. The main issue are lacking of appropriate probes forin vivo imaging and the cytotoxicity of as-prepared probes. Thus it is desirable to developthe novel multifunctional probes with smaller size, good chemical stability, betterbiocompatibility and low cytotocixity.In this paper, two kinds of multifunctional magnetic-luminescent nanoparticles havebeen synthesized, taking advantages of the unique superparamagnetic properties of ironoxide nanoparticles and special fluorescent properties of rare-earth nanoparticles. Themain contents are as follows:（1） Magnetic-down conversion rare-earth luminescent nanparticles have beensynthesized by polyol method. First, hydrophilic magnetite nanoparticles have beensynthesized through thermal decomposition of Fe（acac）3precursor in triethylene glycol.Then, a CeF₃:Tb shell was directly precipitated on the Fe₃O₄core in diethylene glycol toform multifunctional nanoparticles. The structure and morphology of the nanoparticleswere characterized using TEM （Transmission electron microscope）, XRD （X-raydiffraction）, PL （Photoluminescence） and the results showed that the resultantnanoparticles are less than20nm and have very good superparamagnetic and luminescentproperties.（2） Multifunctional magnetic-up conversion rare-earth luminescent nanoprobes withbright yellow-green light were prepared through two different methods. Magnetitenanoparticles were synthesized by thermal decomposition of an ironoleate complexprecursor firstly. Then the first kind of core-shell structured Fe₃O₄@NaYF₄:Yb,Er nanoparticles were prepared by a seeded-growth process. Another kind nanoparticles withmagnetic cores and up conversion fluorescent shells were synthesized by assemblingNaYF₄:Yb,Er nanoparticles onto the surface of Fe₃O₄@SiO₂nano-composites which wereformed with a reverse microemulsion method.（3） After surface modification with critic acid, folic acid as a targeting ligand wasbioconjugated onto the surface of the above probes and was applied for the cell imaging invitro. The experiments demonstrated that the probes showed low cytotoxicity even at ahigh concentration of450μg/mL, and exhibited strong green luminescence and high MRIrelaxation rate. Therefore, this novel magnetic-luminescent nanoparticles might havegreat potential in MRI and fluorescence imaging.