| Rare earth doped luminescent nanomaterials possess many advantages, such as narrow emission peak, long fluorescence lifetime, high photochemical stability, large stokes shift and low toxicity. As a new type of marker, rare earth doped luminescent nanomaterials have attracted wide interest. In the past decades, great efforts have been dedicated to the synthesis of rare earth doped luminescent nanomaterials. Although the present methods have been quite mature, but there still exist some deficiencies, so that to develop a new method which can fabricate the high quality luminescent nanomaterials with shorten time and high efficiency is still important. In addition, preparation of magnetic-luminescent bifunctional nanoparticles is aiso the hotspot in bio-analysis area. The magnetic-luminescent bifunctional nanoparticles can be used to realize enrichment of trace sample during bio-analytical detection and achieve the targeted labeling of living organisms simultaneously. It not only improves the detection sensitivity, but also expands applications of the materials. Based on the background, the aim of the present work is to establish rapid methods for the preparation of rare earth doped luminescent nanomaterials and magnetic/luminescent nanocomposites, and then use them for labeling of tumor cells and detection of biomolecules. The main contents are outlined as below:1. Microwave-assisted method was used for the preparation of LaF3:Ce,Tb and LaF3:Eu down-conversion luminescent nanoparticles. During the synthesis procedure of the nanoparticles, effects of reaction conditions on the optical properties of as-prepared nanoparticles were investigated, and the optimal synthetic conditions were obtained. Through the change of doped rare earth ions and their molecular ratio, a four color system of luminescent nanoparticles with green, yellow, orange and red emissions was obtained. 2. Microwave-assisted method was used for the preparation of NaYF4:Yb,Er up-conversion nanoparticles. The effect of precursor was first investigated. Among the three nanoparticles prepared with rare earth acetate, rare earth stearate and rare earth thioglyco llate as precursor separately, the luminescent intensity of nanoparticles prepared with rare earth acetate was strongest, which was nearly10and30times more than the other two nanoparticles. And then, effect of fluorine source was investigated through four different fluorides (NH4F, NaF, NH4HF2and BmimBF4). The results showed that luminescent intensity of nanoparticles prepared with NH4F was strongest, which was nearly100times more than others. In addition, the proportion of luminescence intensity at543nm and653nm is obviously different in nanoparticles synthesized with this four fluorine source, based on this phenomenon, the nanoparticles with green, orange, yellow and green emission were obtained separately.3. A new kind of magnetic/luminescent bifunctional nanocomposites was synthesized by covalently linking multiple carboxyl-functionalized superparamagnetic Fe3O4nanoparticles with individual amino-functionalized silica-coated NaYF4:Yb,Er up-conversion nanoparticles. Effects of various factors on the luminescent intensity of the nanocomposites were investigated. The as-prepared nanocomposites possess superparamagnetic and excellent green up-conversion luminescent properties, which can realize the detection and separation of biological samples at the same time. In addition, there are carboxyl and amino groups on the surface of the nanocomposites, which can directly conjugate with biological molecules for subsequent application.4. The NaYF4:Yb,Er upconversion nanoparticles synthesized through microwave-assisted solvothermal method and magnetic-luminescent bifunctional Fe3O4/NaYF4:Yb,Er nanocomposite synthesized via covalent binding method were used for the labeling and imaging of HeLa cells, with CEA8antibodies and transferrin as markers, respectively. The results showed that both of these two methods can perfectly realize specific labeling of HeLa cells, and the near infrared excitation can avoid effectively auto-fluorescence of sample.5. The LaF3:Ce,Tb nanoparticles synthesized by microwave-assisted method was first combined with Fe3O4magnetic nanoparticles through specific reaction between chitosan and concanavalin. Under the use of synthesized nanocomposites, a new method for the detection of glucose was established, based on the competition between glucose and chitosan on the surface of LaF3:Ce,Tb. The linear relationship of this detection was I=4.59×102-4.79C (R=0.9993) in the range of2.5-18.5μmol·L-1, and the detection limit of glucose was0.65μmol·mL-1(3σt) with relative standard deviation (RSD) of1.3%(16.5μmol·L-1, n=11).6. A new method for the rapid detection of ascorbic acid was developed based on the luminescence quenching of ascorbic acid to LaF3:Ce,Tb nanoparticles, which were synthesized through microwave-assisted solvothermal method with ionic liquid and citric acid. Under optimum conditions, a linear relationship was obtained in the range of0-1.0×10-4mol·L-1, according to I=402.10-1.21×106C, R=0.9995, with the detection limit of2.4×10-6mol·L-1and a RSD of0.5%(5.331×10-5mol·L-1, n=11). The method was applied for the determination of ascorbic acid in vitamin C injection, and the results was in good consistent with those obtained through standard redox titration method.7. NaYF4:Yb,Tm nanoparticles possess blue upconversion emission were prepared by microwave-assisted solvothermal method, and used as the donor to set up a luminescence resonance energy transfer system with doxorubicin for rapid detection of doxorubicin. There was a linear relationship of I=4.98×102-9.92C (R=0.9995) between luminescent intensity and concentration of doxorubicin in the range of0-66.23μmol·L-1. A detection limit of0.69μmol·L-1(3a) was obtained by the LRET system with a RSD of1.6%(60μmol·L-1, n=11). This approach is expected to be used for the clinical detection of doxorubicin in medicine. |
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