Preparation Of Photostimulatd Materials And Their Applications In Bioimaging

Cr³⁺-doped near-infrared photostimulated material possess superior merits such as wide response range,high quantum conversion efficiency,no background fluorescence,and high signal-to-noise ratio,and so on.Therefore,it is widely used in information storage,biological imaging,and infrared detection.In this thesis,Tb³⁺,Cr³⁺: ZnGa₂O₄,Tb³⁺,Cr³⁺: La3Ga5 Ge O14,and Cr³⁺,Er³⁺: Ca₂YGa₃Ge₂O₁₂ near-infrared phosphors were prepared,and the phase and morphology of the phosphors were analyzed in detail.The effects of doped ion content and temperature on the luminescence properties of phosphors were investigated,the possible energy transfer mechanism between doped ions was explored.The synthesized phosphors have near-infrared afterglow emission,which has potential application prospects in biological tissue imaging.Nano-scale Tb³⁺,Cr³⁺: ZnGa₂O₄ samples were synthesized by hydrothermal synthesis method.X-ray diffraction analysis demonstrated that the prepared phosphor was a pure phase.Transmission electron microscopy tests showed that 0.03Tb³⁺,0.03Cr³⁺: Zn Ga1.94O4 sample display good dispersibility,the average particle size was estimate to be about 20 nm,and the interplanar spacing corresponding to the 311 plane was 0.246 nm.At room temperature,the optimal emission of this phosphors appeared at 0.03Tb³⁺,0.03Cr³⁺: Zn Ga1.94O4.The fluorescence attenuation curve manifested that the energy transfer efficiency from Tb³⁺ to Cr³⁺ reaches 85.56%.The quadrupole-quadrupole interaction can responsible for the energy transfer between Tb³⁺ and Cr³⁺.The activation energy obtained from the temperature-dependent spectrum was calculated to be 0.17 e V.At 423 K,the integrated intensity of the sample can remain 59.64% of its intensity at room temperature.The afterglow spectrum revealed that the afterglow time exceeds 15 minutes.FT-IR and Zeta potential tests proved that-OH,-NH2 and bovine serum albumin?BSA?successfully modified the surface of 0.03Tb³⁺,0.03Cr³⁺: Zn Ga1.94O4.The low toxicity of 0.03Tb³⁺,0.03Cr³⁺: Zn Ga1.94O4 sample was confirmed by in vitro cytotoxicity experiments and in vivo biological safety analysis.Tb³⁺,Cr³⁺: La3Ga5 Ge O14 near-infrared phosphor was prepared by high-temperature solid-state reaction technology.The phase purity of the prepared phosphor was characterized by X-ray diffraction and Rietveld refinement.For 0.06Tb³⁺,0.07Cr³⁺: La2.94Ga4.93 Ge O14 sample,the energy band gap obtained through the diffuse reflection spectrum is 4.95 e V.At room temperature,the 0.06Tb³⁺,0.07Cr³⁺: La2.94Ga4.93 Ge O14 shows the optimal emission,and the full width at half maximum of the Cr³⁺ emission spectrum reaches 264 nm.Furthermore,the energy transfer efficiency from Tb³⁺ to Cr³⁺ can reach 99.20%.The temperature-dependent spectra of 0.06Tb³⁺,0.07Cr³⁺: La2.94Ga4.93 Ge O14 display two thermal processes.The activation energy of 0.06Tb³⁺,0.07Cr³⁺: La2.94Ga4.93 Ge O14 at low-temperature process and the high-temperature process are 0.05 e V and 0.57 e V,respectively.The afterglow spectrum declared that the afterglow time is more than 25 minutes.Cr³⁺,Er³⁺: Ca₂YGa₃Ge₂O₁₂ near-infrared emitting phosphors were manufactured by high temperature solid-state reaction.X-ray diffraction and refinement results indicated that the synthesized phosphors were pure phases.The calculated band gap of 0.06Cr³⁺,0.10Er³⁺: Ca2Y0.90Ga2.94Ge2O12 is 4.97 e V.When the molar ratios of Cr³⁺ and Er³⁺ are 0.02 and 0.10,respectively,the photoluminescence spectrum display optimal emission intensity.According to the fluorescence decay curve display that the energy transfer efficiency between Cr³⁺ and Er³⁺ is 27.02% and the energy transfer mechanism from Cr³⁺ to Er³⁺ is dipole-dipole interaction.Moreover,the good thermal stability of the 0.06Cr³⁺,0.10Er³⁺: Ca2Y0.90Ga2.94Ge2O12 sample can be proved by temperature-dependent photoluminescence spectrum.The afterglow emission spectrum suggested that the Cr³⁺ and Er³⁺ afterglow time exceeds 40 minutes and 3 minutes,respectively.