Aptamer Regulating The Doped COF Catalysis Of The Gold Nanoreaction To Determine Environmental Pollutants By RRS/SERS Method

Due to the continuous development of the economy,society and the continuous improvement of the industrial level,the environment’s pollutants level has risen sharply.Organic pollutants and heavy metal pollutants continue to migrate in the environment and accumulate in the human body through the food chain,which endangers human beings’survival and reproduction.Therefore,it is vital to develop environmental analysis methods with high sensitivity,high selectivity,and low price.Covalent Organic Frameworks（COF）have the advantages of high specific surface area,ordered pores,high specific surface area,and easy modification.In recent years,because COF materials are easy to functionalize and have a definite surface electronic structure,researchers have attracted widespread attention.However,COF materials are rarely used in molecular spectroscopy,especially in resonance Rayleigh scattering（RRS）and surface enhanced Raman spectroscopy（SERS）.Therefore,it is of scientific significance to establish an analytical method for detecting trace species based on COF materials’functionalization and applying them to RRS and SERS spectroscopy techniques.In this paper,the catalytic performance of doped COF materials,combined with aptamers,can control the catalytic activity of doped COF and establish a SERS/RRS analysis method for detecting trace pollutants in the environment.The doped COF materials were analyzed by Transmission electron microscope（TEM）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,and molecular spectroscopy,and the catalytic enhancement mechanism was proposed.The specific content is as follows:COF-Tp Pa（Tp Pa）was synthesized by the solvothermal method using trialdehyde phloroglucinol and p-phenylenediamine as the basic building blocks and then reduced Pd Cl₂/Ag NO₃ with CO to prepare Pd Tp Pa/Ag Tp Pa loaded with Pd NP/Ag NP.The experimental results show that compared with Ag Tp Pa,Pd Tp Pa has a strong catalytic effect on the Na H₂PO₂-HAu Cl₄ gold nanometer indicator reaction.When there is an oxytetracycline aptamer(Oxytetracycline Aptamer,Apt _OTC),it can be adsorbed on the surface of Pd Tp Pa by electrostatic interaction to inhibit its catalytic activity.When OTC is added,it can combine with Apt _OTC to form an Apt _OTC-OTC complex so that the catalytic activity of Pd Tp Pa is restored.The reaction rate of Na H₂PO₂-HAu Cl₄ is accelerated,and the concentration of Au NP with RRS signal increases.When the OTC concentration is in the range of 2.5-25 ng/m L,the RRS signal increases linearly with the OTC concentration,and an OTC RRS analysis method can be established.After adding Victoria Blue 4r（VB4r）to the reaction system,Au NP is used as a SERS substrate,and it can generate a strong SERS signal,which changes with the concentration of Au NP.According to the SERS signal changing with OTC concentration,a new SERS method for OTC is established.It has a linear range of 2.5-15 ng/m L and a detection limit of 0.64 ng/m L.By coupling the RRS and SERS analysis methods,the reproducibility and sensitivity of the analysis method can be improved.The SERS-RRS dual-mode analysis method for detecting OTC is established,with the linear range of2.5-15 ng/m L and the detection limit of 0.45 ng/m L.By changing the types of aptamers,we tried to detect glyphosate（GLY）,tetracycline（TEC）,and bisphenol A（BPA）,and found that they still have good applicability.The detection ranges are 0.42-1.7 ng/m L,0.011-0.056 ng/m L and0.57?10^-3-5.7?10^-3 ng/m L,respectively.Through the investigation of interfering ions and the detection of actual samples,it is found that the method is feasible and provides a reference for the analysis method of detecting trace organic pollution in the environment.In third section,the COF-Tp BD（Tp BD）material was prepared by the solvothermal method using trialdehyde phloroglucinol and benzidine as precursors.The surface of Tp BD was doped with precious metals of Pd,Pt,Au,or Ag by the reduction of CO,and the change of its catalytic performance was studied through the Na H₂PO₂-HAu Cl₄ reaction.The study results show that the doped Tp BD’s catalytic performance is mainly affected by the doping element and its particle size.Among them,the particle size of Pd NP loaded on the surface of Tp BD is 0.8-1.5 nm,and the degree of dispersion is high,which can significantly improve the catalytic performance of Tp BD.At the same time,as a transition element,Pd has underfilled d-orbital electrons on the surface,which can couple with theπ-bonded electrons on the surface of Tp BD to increase the electron transfer of the Na H₂PO₂-HAu Cl₄ reaction,thereby accelerating the reaction.Through experiments,cadmium ion aptamers(Cd²⁺Aptamer,Apt _Cd2+)can inhibit the catalytic effect of palladium-doped Tp BD（Pd Tp BD）,thereby inhibit the occurrence of the Na H₂PO₂-HAu Cl₄ reaction.After adding Cd²⁺,it reacted explicitly with Apt _Cd2+to bind to each other,and Apt _Cd2+desorbed from the surface of Pd Tp BD.Then the catalytic activity of Pd Tp BD recovered,and the Na H₂PO₂-HAu Cl₄ reaction accelerated.The Au NP produced in the system increased,and the RRS signal gradually increased.Based on this principle,a linear equation related to Cd²⁺concentration and RRS signal intensity can be established so as to achieve the purpose of detecting Cd²⁺.Because the Au NP generated by the reaction can be used as a SERS substrate,after the addition of VB4r probe molecules,the SERS effect can occur,and the signal will increase as the concentration of Au NP increases.Therefore,when the Cd²⁺concentration is in the range of 0.15-3.0 nmol/L,the system’s SERS signal increases linearly,the detection limit is 0.12 nmol/L,and the correlation coefficient is 0.9718.Good results have been achieved by applying the established RRS and SERS analysis methods to actual environmental water detection.This work provides a new idea for the application of COF to the analysis of environmental pollutants.