| Up-conversion luminescence nanomaterial is a special kind of anti-Stokes luminescence materials,which could emit high-energy shorter wavelength light being excited by long wavelength light.Rare earth up-conversion luminescence nanomaterials are usually excited by infrared radiation,which could penetrate into biological tissue deeper and have no autofluorescence interference.In addition,it also has several advantages,such as good optical stability,high luminous intensity,luminous long life,low toxicity.Nowadays,rare earth up-conversion luminescence nanomaterials have been widely applied in biomedical fields,such as biological imaging,biological detection,immune analysis and so on.In this paper,NaLuF4:Yb,Ho up-conversion nanoparticles(UCNPs)were synthesized and their applications were studied.NaLuF4:Yb,Ho UCNPs were synthesized by solvothermal method with water-ethanol as the solvent.Based on the luminescence intensity,the maximum emission peak wavelength of the as prepared UCNPs was at 541 nm,giving out bright green light.the optimal conditions to synthesize the UCNPs were determined.The nanoparticles were characterized by transmission electron microscopy(TEM),X-ray diffraction(XRD)and infrared spectrometer(FL-IR).The resault showed that the particles were spherical with the size of 10?30 nm and they were hexagonal crystals with good crystallinity,in addition,the nanoparticles coated with the PEG on the surface.Using as-prepared NaLuF4:Yb,Ho nanoparticles as energy donor,rhodamine B(RhB)as acceptor,we built a new luminescent resonance energy transfer system,making the luminescence being quenched.Then Fenton reagent was added to generate hydroxyl radical(·OH),which could initiate oxidative cleavage of RhB,and then the luminescence of the nanoparticles recorvered.based on this phenomenon,a simple and sensitive method for the quantitative detection of-OH was developed.Under the optimum conditions,the luminescence intensity is proportional to the concentration of ·OH in the range of 1.00×10-6?2.00×10-4 mol/L,the linear regression equation was I=145.9+1.217c(the unit of c is 10-6 mol/L)with a correlation coefficient of 0.9986 and the detection limit was 2.4×10-7 mol/L.This method was used to detect ·OH in the tap water with recorveries in the range of 94.1%?103%,the results proved that the method was accurate and reliable.In addition,we used this method to study ·OH-scavenging abilities of common antioxidants such as tannic acid,ascorbic acid,glutathione(reduced)and oxalic acid.The results showed that the scavenging efficiency decreased in this sequence:tannic acid>glutathione(reduced)>ascorbic acid>oxalic acid.And then the antioxidant capability of vitamin C tablets,grape seed capsule,green tea were evaluated in this method,the results showed that the antioxidant capability of water extract of these substances decreased in this sequence:grape seed>vitamin C tablets>green tea. |
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