Novel Multicolor Fluorescence Markers And Fluorescence Imaging Nano-labeis

In recent years, with the fluorescent nanoparticles as probes of bioluminescence imaging is currently a hot research topic in the field of biophotonics. Much focus has been given to thedevelopment of efficient optical agents and fluorescence imaging systems. The ideal luminescentlabels should possess some characteristics such as small particles, high fluorescence quantumefficiency, well light stability, resistance to light bleaching and little effect on biomolecule, etc.In order to obtain these goals, We intend to seeking a new luminescent label and detectionmethods, which can improve the luminous intensity and avoiding background interference. Myresearch focuses on multicolor fluorescence materials doped with rare-earth ions, the nearinfrared nano luminescent materials doped with rare-earth ions and electron trapping infrared tovisible light photoconversion material. The main research work includes the following:Monoclinic Gd2O3:Bi phosphors were prepared with combustion method using glycine as afuel and PEG4000(10%) as a dispersant. The samples were characterized by X-ray diffraction,photoluminescence spectroscopy and transmission electron microscope. XRD indicated that bothmonoclinic and cubic Gd2O3:Bi3+could be achieved with combustion method. Variation of themolar ratios of glycine-to-NO3-(G/N) was found to play key roles in the formation of the twodifferent crystalline structures. Unlike the cubic Gd2O3:Bi3+, which gave broad-bandbluish-green fluorescence, the monoclinic Gd2O3:Bi3+gave bright blue fluorescence whenexposed to UV lamp. The monoclinic Gd2O3:Bi3+nano-spher could be achieved with at anignition temperature as low as240-300℃for1h. PL intensity of monoclinic Gd2O3:Bi3+phosphors could be greatly improved by calcining it at1100℃for1h and adding0.2mL ofPEG4000(10%). The optimized Bi3+doping concentration is3.0%. TEM images show theproduct consist of aggregate of nanospheres with50-200nm in size. The particle is promising inthe application of fluorescence immunoassay.Monoclinic Gd2O3:Bi3+,Eu3+/Sm3+phosphors were prepared with combustion method usingglycine as a fuel. The samples under different experimental conditions were characterized byX-ray diffraction, photoluminescence spectroscopy and transmission electron microscope. Theresults show that the efficient energy-transfer from Bi3+to Eu3+/Sm3+. In this work, theluminescence colours of Gd2O3:Bi3+,Eu3+/Sm3+nanophosphors can be easily tuned from blue tored and white by changing the concentration of Bi3+, Eu3+and Sm3+. They lay a good foundationfor the further development of fluorescent probe in multi-labeling technology.Monoclinic Gd2O3:Bi3+,Yb3+/Nd3+phosphors were prepared with combustion method using glycine as a fuel. The structure of the phosphor was characterized by X-ray diffraction and TEM.The influences of Bi3+and Yb3+/Nd3+concentration on the spectrum shape, fluorescence intensityand fluorescence lifetimes were investigated. The results show that the efficient energy transferfrom Bi3+to Yb3+/Nd3+ions happened. With optimized Bi3+content of6.0%and Yb3+content of4.0%; Bi3+content of6.0%and Nd3+content of2.0%, the monoclinic Gd2O3:Bi3+,Yb3+/Nd3+phosphor has the strongest near-infrared luminescence intensity, which stronger than that ofsample with absence of Bi3+.Ca2SnO4:Gd3+,Sm3+phosphor was synthesized by high solid-state method. The X-raydiffraction were conducted to characterize of the samples; Excitation and emission spectrum, thedecay curves of the afterglow, photostimulated luminescence and thermoluminescence curveswere analyzed to study their optical properties. According to the results, the Ca2SnO4:Gd3+,Sm3+phosphor exhibits obvious a orange-red afterglow emission in the dark after UV irradiation. It isinteresting to note that photostimulated luminescence lasted for a few seconds when stimulatedby980nm laser light. The decay curve of photostimulated luminescence consists of a very fastand a slow component. The slow rising and falling edge is atrributed to the result ofelectron(hole) retrapping by shallow traps. The energy stored in Ca2SnO4:Gd3+,Sm3+can besaved for more than20hours and only needs a charged can be markers for monitoring for manytimes. Effect on of Gd3+and Sm3+molar concentration on optical properties of theCa2SnO4:Gd3+,Sm3+phosphor. To understand the trap properties and storage mechanism of PSL,we studied the TL curves. The results illustrate the large potential of this new class of materialfor photonic applications involving fluorescence immunoassay.