Design And Application Study Of Nanosensors For Mercury Ions Detection

The harm of heavy metal pollution to human health and the environment cannot be ignored.Among them,the toxicity of mercury ions has attracted much attention due to its non-biodegradability and accumulation in the food chain.Therefore,it is of great significance to develop a sensitive and convenient method for quantitative determination of Hg²⁺in environment,medicine,food and drinking water.In this paper,in order to achieve rapid,sensitive and convenient detection of Hg²⁺,the unique advantages of nanomaterials were used to explore the method of daul-response sensor detection of Hg²⁺.Part one:Design and application of fluorescence and colorimetric dual response sensors based on EMSN@Pt NCs for mercury ions detectionObjective:A rapid and sensitive fluorescence and colorimetric dual response sensor was designed based on reamed-hole mesoporous silicon-loaded platinum cluster（EMSN@Pt NCs）to detect Hg²⁺in actual samples of pueraria powder,providing a solution for the rapid,sensitive and convenient detection of Hg²⁺in Chinese medicinal materials.Methods:The EMSN@Pt NCs nanocomposites were synthesized by the methods mentioned in the literature,and characterized by transmission electron microscopy（TEM）,high resolution transmission electron microscopy（HRTEM）,fourier transform infrared spectroscopy（FT-IR）,nitrogen adsorption-desorption,zeta potential and fluorescence spectroscopy.Firstly,the fluorescence and mimic peroxidase properties of EMSN@Pt NCs were verified,and the reaction factors such as p H value and concentrations of reactants were optimized.Then Hg²⁺was detected under the optimal conditions.The linear fitting equation was obtained and the detection limit was calculated.Finally,the Hg²⁺in pueraria powder was detected by sample recovery method..Results:The results of TEM,HRTEM,FT-IR and Zeta confirmed the successful synthesis of EMSN@Pt NCs composites.In the colorimetric method,EMSN@Pt NCs showed excellent peroxidase activity.In the presence of Hg²⁺,the peroxidase activity of EMSN@Pt NCs was inhibited due to the formation of Pt-Hg alloy.The optimum p H was 4.0;the optimum reaction concentration of EMSN@Pt NCs was 3.0μg/m L;the optimum reaction concentrations of TMB（3,3’,5,5’-Tetramethylbenzidine）and H₂O₂ were 0.45and 12 m M,respectively.The detection range and detection limit of Hg²⁺were 0.25～200 n M and 8.62 n M,respectively.In the fluorescence method,in the presence of Hg²⁺,the fluorescence intensity of EMSN@Pt NCs decreased due to the formation of Pt-Hg alloy.The detection range and detection limit of Hg²⁺were 5～50 n M and 1.51 n M,respectively.Fluorescence and colorimetric methods achieved good recovery of Hg²⁺in pueraria powder.Conclusion:The fluorescence and colorimetric dual response sensor based on EMSN@Pt NCs realized the sensitive detection of Hg²⁺.Compared with other literatures,the linear range broadened and the detection limit reduced.The Hg²⁺in the Chinese medicinal materials pueraria powder was detected sensitively.This method provided a reference for the design and application of other biosensors,and provided a solution for the rapid and sensitive detection of Hg²⁺in Chinese medicinal materials.Part two:Design and application of fluorescence/SERS dual response sensors based on AgNPs for mercury ions detectionObjective:Based on silver nanoparticles（AgNPs）,a fast,simple and sensitive SERS/UV dual response sensor was designed to detect Hg²⁺.The designed sensor was used to detect Hg²⁺in actual samples of Chinese medicinal materials pueraria powder and tap water,providing a solution for the rapid,sensitive and convenient detection of Hg²⁺in actual samples.Methods:AgNP_S were synthesized and characterized by TEM and UV absorption spectra.AgNPs@MBN was synthesized using p-mercaptobenzonitrile（MBN）and AgNPs through Ag-S bond connecting SERS probe.The concentration of AgNPs@MBN was optimized.Then Hg²⁺was detected under the optimal conditions.The linear fitting equation was obtained and the detection limit was calculated.Finally,Hg²⁺in pueraria powder and tap water were detected by sample recovery method.Results:The AgNPs were spherical,and the results of TEM and HRTEM confirmed the successful synthesis of AgNPs.Used MBN as Raman probe,AgNPs@MBN was synthesized by connecting AgNPs and MBN through Ag-S bond.The optimal concentration of AgNPs@MBN was 12p M.In the presence of Hg²⁺,citrate reduced Hg²⁺to Hg⁰ and the silver amalgam was produced on the surface,which reduces the Raman signal strength of AgNPs@MBN.The final detection range and detection limit of Hg²⁺were 1～300 n M and 0.499 n M,respectively.In the ultraviolet method,in the presence of Hg²⁺,the formation of Ag-Hg alloy reduced the UV absorption intensity of AgNPs.The detection range and detection limit of Hg²⁺were0.1～10 n M and 0.75 n M,respectively.SERS and UV methods achieved good recovery of Hg²⁺in pueraria powder and tap water.Conclusion:SERS/UV dual response sensor based on AgNPs realized the sensitive detection of Hg²⁺.Compared with other literatures,the linear range was broadened,the detection limit was reduced.Hg²⁺added to Chinese medicinal materials pueraria powder and tap waterwas detected sensitively.Results of selectivity and practicability showed that structured sensor showed excellent specificity and sensitivity,which provided a method for detection of Hg²⁺in actual samples.