Preparation Of Functionalized Rare Earth Nanomaterials And Application In The Detection Of Environmental Pollutants

Rare earth elements（except scandium and yttrium）are widely used in the fields of optics,biosensors,and catalysis due to their partially unfilled 4f orbitals and rich electronic energy level structures.With the rapid development of nanomaterials,rare earth nanoparticles usually exhibit good optical properties and excellent stability in the construction of electrochemiluminescence（ECL）and fluorescence（FL）probes in research.In this paper,several ECL and FL sensors had been designed and constructed to identify and determine several potential pollutants in the environment based on rare earth nanomaterials with high sensitivity.The specific research contents are as follows:Chapter Ⅰ:This chapter gave an overview of rare earth nanomaterials,including the application of rare earth nanomaterials in ECL and FL analysis technology,and briefly described these two technologies.Chapter Ⅱ:As an efficient and easily available pesticide,imidacloprid（IM）has been widely used in agriculture to cure pests.However,ecological environment threats are becoming increasingly prominent due to abuse and pesticide residues.This chapter designed a sensitive ECL sensor based on zeolite imidazolate framework-coated upconverting nanoparticles（UCNPs@ZIF-8）nanocomposites combined with molecularly imprinted polymers（MIPs）to successfully achieve quantitative detection of IM.The composites exhibited a certain multi-faceted prismatic structure and the effective binding of UCNPs was demonstrated by characterization technology.In addition,the sensor exhibited outstanding ECL performance including a strong and stable signal and excellent selectivity with the UCNPs@ZIF-8 as the ECL material under optimal conditions.This sensor displayed a good linear response to IM in a wide concentration range(0.1 ng·L^-1～1 mg·L^-1),with the limit of detection as low as 0.01 ng·L^-1.The ECL sensor was used for the analysis of IM residues in environmental samples,with a recovery of 95.0%～105.2%and a relative standard deviation of 1.3%～5.1%,the results were satisfactory.Chapter Ⅲ:The release of hydrogen sulfide（H₂S）gas can cause serious pollution to the natural environment,and excessive inhalation of H₂S by humans will cause strong stimulation and toxicity.To realize rapid identification and sensitive monitoring of potential H₂S in the circumstance,an eco-friendly and rapid dual-mode detection method is proposed.In this chapter,the carbon dots doped with europium oxide（Eu₂O₃@CDs）nanocomposites with excellent ECL and photoluminescence properties were applied to construct the ECL and ratio type FL dual-mode sensor platform.It successfully realized the precise quantitative detection of H₂S due to the destructive influence of S^2-to Eu₂O₃.The experimental results showed a good linear equation between the concentration of S^2-and the response signal in the concentration range of 1 p M to 10 m M,and the detection limits were as low as 0.0537 p M.In addition,both sensors showed excellent selectivity and stability,and the extremely short response time greatly enhances the analysis efficiency.Applied to the detection of spiked recovery of actual environmental samples,the recovery rate was 86.49%～118.6%,and the relative standard deviation was 0.97%～3.2%,which provided a new idea for the development of novel H₂S sensors.Chapter Ⅳ:The excessive concentration of heavy metal mercury ions(Hg²⁺)in the environment seriously affects the ecological environment and even threatens beings’health,so it is essential to design rapid and low-cost detection methods to achieve trace detection of Hg²⁺.Therefore,in this chapter,an ECL sensing platform with functionalized rare earth material cerium oxide（Ce O₂）as the light-emitting unit and aptamer as the capture unit was designed and developed.The change of ECL signal by the“T-Hg-T”structure formed by the specific asymmetric matching between Hg²⁺and thymine（T）base pairs in DNA single-strand was utilized and achieved a direct sensitive response to Hg²⁺further.The experimental results showed a linear relationship between the concentration in the range of Hg²⁺of 10 p M～100μM and the response signal,and the detection limit was as low as 0.35 p M.In addition,this probe exhibited stable ECL performance and excellent specificity for identifying the target Hg²⁺and was used for spike recovery testing of actual samples in the environment to obtain reliable results,the recovery rate was between 82.99%and 105.0%,and the relative standard deviation was between 0.7%and 2.5%.