Preparation And Properties Of Novel Near-infrared Luminescence Materials Involving Quantum Cutting And Energy Transfer

Near infrared （NIR）light-emitting properties can be used in biological analysis, due toNIR light has many advantages, such as no damage to the tested substances, deep tissueimaging, small background interference and high sensitivity. In recent years, detection ofbiological molecules had important development, due to the combination of nano-materials andbio-detection technology. The near-infrared luminescence nanoparticles have greater stabilityand better light-emitting properties with doped rare earth. Thus they are promisingluminescence probe used for immunoassay, and have broad prospects development. Weresearch the near-infrared light-emitting materials with the maximum luminous intensity, whichcan be used in biological analysis.The Na₂SrSiO₄:Ce³⁺,Tb³⁺,Yb³⁺phosphors were synthesized by solid-state reaction in areductive atmosphere. It was found that Ce³⁺can sensitize the NIR luminescence of Tb³⁺â†'Yb³⁺by Quantum Cutting. The structures of the phosphors were characterized by X-ray diffraction.The influences of Ce³⁺/Tb³⁺/Yb³⁺concentration on the spectrum shape, fluorescence intensityand fluorescence lifetimes were systemically investigated. The results show that the efficientenergy-transfer from Ce³⁺to Tb³⁺is due to good overlap between Ce³⁺emission band andTb³⁺excitation bands, and the characteristic near-infrared luminescence of Tb³⁺is remarkablysensitized by co-doping of Ce³⁺. The phosphors sintered at750°C for2h give the strongestnear-infrared luminescence intensity with optimized Ce³⁺, Tb³⁺and Yb³⁺content of2%，13%and16%. The mechanism of the energy transfer from Tb³⁺â†'Yb³⁺in Na₂SrSiO₄: Ce³⁺, Tb³⁺,Yb³⁺phosphors is also discussed briefly.NIR luminescence material Ca₂Al₂SiO₇:Ce³⁺,Yb³⁺was synthesized by high temperaturesolid state method. The result showed that the doping of Ce³⁺can improve the NIRluminescence through enhancing the intensity of Yb³⁺luminescence. The phosphor whichsintered at1100℃for2h and doped with2%Ce³⁺and10%Yb³⁺give the strongest NIRluminescence intensity.Gd₂O₃:Bi³⁺,Nd³⁺powders were prepared by high temperature solid state method. It wasfound that near-infrared luminescence of Nd³⁺in Gd₂O₃:Bi³⁺,Nd³⁺could be very efficientlysensitized with co-doped Bi³⁺. When excited with a347nm of diode argon laser, it gives strong near-infrared fluorescence at810nm,890nm and1060nm. The influences of sinteredtemperature and the dopant concentration were investigated, and the strongest NIR emissionwas achieved for samples sintered at1100oC for2h and doped with0.01Bi³⁺and0.04Nd³⁺.Gd₂O₃:Bi³⁺,Nd³⁺near-infrared light-emitting nanoparticles are prepared by combustionmethod. The nanoparticles can be used for biological analysis. Studies have shown that thecrystalline phase of Gd₂O₃:Bi³⁺,Nd³⁺near infrared nano-powder is related to the ignitiontemperature. When the ignition temperatures are240°C and205°C, we get the monoclinicphase and cubic phase respectively. We also found the crystalline type have the relationship toG/N ratio. Comparing to the Preparation conditions of Gd₂O₃:Bi³⁺,Nd³⁺luminescence materialsby high-temperature solid-phase method and combustion, we fond the reaction temperature bycombustion is lower, more energy-efficient and less doping ions, more uniform distribution ofdoping ions in the lattice. So Gd₂O₃:Bi³⁺,Nd³⁺near-infrared light-emitting nanoparticles arePotential nano-markers for immunofluorescence analysis.