Synthesis Of Upconversion Nanoparticles Fluorescence Probe And Selective Detection Of Perfluorooctane Sulfonste

As one of the final organic products of various perfluorinated compounds（PFCs）in the environment,Perfluorooctane sulfonate（PFOS）has the characteristics of environmental persistence,bioaccumulation and long-distance migration.It is easy to enrich in the environment and cause potential harm to humans.Therefore,it is especially important to establish a simple,fast,and highly sensitive method for the detection of PFOS.Based on the advantages of rare earth up-conversion particles with good optical stability,low background fluorescence and low toxicity,as a luminescent material,molecular imprinting technique was introduced to construct a fluorescent probe and used to detect PFOS in water.The mechanism of the interaction between the probe and PFOS is discussed,and the method is applied to the analysis and determination of PFOS in environmental water samples and serum matrices.The main work contents are as follows:（1）An upconversion fluorescent method for rapid detection of PFOS based on fluorine-fluorine interaction.In this study Na YF₄:Yb,Er upconversion luminescence particle which had high photostability and good water dispersibility were prepared by solvothermal method,and then a simple surface-coated N,O-bis（trimethylsilyl）trifluoroacetamide was used as a fluorescent probe to interact with PFOS,and a new fluorescence analysis method for detecting PFOS was established.In Britton-Robinson buffer solution at p H=6.30,PFOS and the probe rapidly bind through the fluorine-fluorine interaction,which causes the fluorescence of Na YF₄:Yb,Er@Si O₂-BSTFA to quench.Study shows that the decreased fluorescence intensity at 545 nm are linear with the PFOS concentration in the range of 3 to 100 nmol/L,and the detection limit（3σ）of2.43 nmol/L.This fluorescent probe has a good selective response to PFOS.（2）Preparation of upconversion based molecularly imprinted fluorescent probe and application for detection of PFOS.This work used NH₂-UCNPs as a core support and a fluorescent signal source,N,O-bis（trimethylsilyl）trifluoroacetamide as a functional monomer,cetyltrimethylammonium bromide as a porogen,PFOS as a template molecule and ethyl silicate as a cross-linker.Then,an ultrathin imprinted shell was formed on the NH₂-UCNPs surface by sol-gel process.After removing PFOS,the molecularly imprinted fluorescent probe NH₂-UCNPs@MIPs with mesoporous structure was obtained.In the buffer solution system,PFOS can specifically binds to the amino groups and fluorine-containing groups on the surface of the NH₂-UCNPs@MIPs,which caused the fluorescence of NH₂-UCNPs@MIPs at 545 nm under 980 nm irradiation to be significantly quenched.According to this,efficient identification and rapid and sensitive detection of PFOS under acidic to alkaline p H conditions are achieved.The standard curve ranges from 0.01 to 15 nmol/L and the detection limit is 0.01 nmol/L.（3）The two fluorescent probes were used to detect PFOS in tap water,lake water,river water and human serum samples.The recovery range of Na YF₄:Yb,Er@Si O₂-BSTFA for PFOS in environmental and simulated water samples was 85.8%～118.6%,RSD≤9.8%.As a result,it was found that Na YF₄:Yb,Er@Si O₂-BSTFA can still accurately determine PFOS in water samples.In addition,NH₂-UCNPs@MIPs probes were used to perform spiked and recovered PFOS in lake water,river water and human serum samples under acidic and neutral p H conditions.The results found that both conditions can be used to detect PFOS in environmental water samples and serum samples,and the recovery rate of the standard addition ranged from 89.0%to 117.9%,with RSD≤8.31%.The constructed NH₂-UCNPS@MIPs probe can detect PFOS in a wide p H range,and has certain potential application value in the detection of complex matrix samples.