Research On The Construction Of The New Chromogenic Systems And The Application Of Environmental Analysis

Colorimetric sensor has the characteristics of simple operation,low cost,short response time and direct observation of the response signal with the naked eye.It not only has a good performance in food safety,medical health and other aspects,but also plays a very important role in the field of environmental analysis.The traditional colorimetric system meets the requirements of real-time and on-site analysis in the detection of environmental pollutants,shortens the qualitative and quantitative process of environmental pollutants,and improves the speed of preliminary judgment.This article first introduces the common analysis methods and construction schemes of environmental pollutants,and summarizes the advantages and disadvantages of these methods.According to the property classification of the constituent materials of the colorimetric sensor（nanomaterials,organic photosensitive molecules and biomolecules）,the color system based on plasma nanoparticles,chromogenic molecules,dyes and other chromogenic agents are introduced in detail,and the traditional colorimetric system has three shortcomings:irreversible color rendering,lack of specificity of the color substrate,and recognition obstacle of single color rendering.This paper designs three new colorimetric systems based on colorimetric sensing.Three different visual sensing platforms not only solve the above problems,but also successfully applied to the analysis and detection of three different environmental pollutants.The specific content is as follows:1.Using the synthesized silver nanoparticles（AgNPs）with localized surface plasmon resonance（LSPR）effect,under the excitation of the blue light corresponding to the absorption wavelength,and then introducing the chromogenic substrate 2,2′-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid）diammonium（ABTS）constitutes a colorimetric sensing system for halogen ions Cl^-and Br^-of detection.In this system,the halogen ion act as cofactor for photocatalysis,and the formed chromogenic system is able to return to the initial state.With the help of transmission electron microscope,ultraviolet-visible spectrophotometer,electron spin resonance spectrometer,etc.,we studied the characteristics and mechanism of the blue light-gated reversible silver nanozyme reaction networks,and explored the significance of the nanozyme reaction networks as self-adaptive as life.2.It was discovered that uranyl ion(UO₂²⁺)has properties similar to peroxidase.ABTS is selected as the chromogenic substrate.In the presence of hydrogen peroxide（H₂O₂）,the solution containing UO₂²⁺generates a signal response,which constitutes a chromogenic system for detecting UO₂²⁺.The mechanism is explored by ultraviolet-visible spectrophotometer,electron spin resonance spectrometer,fluorophotometer,electron spin resonance spectrometer and other instruments,and the substrate selectivity of(UO₂²⁺)is compared through experiments of different chromogenic substrates.Through optimization conditions to achieve the goal of colorimetric detection of UO₂²⁺,which based on electrostatic-driven coordination interaction between ABTS and UO₂²⁺.Finally,the signal response ability of this method in actual water samples was tested.3.MoO_3-x nanosheet dispersions containing oxygen vacancy was prepared by pyrrole reduction of MoO₃ nanosheets,and we found that the LSPR peak of MoO_3-x can be tunable by adjusting the temperature,as a result,nanosheet dispersions with different colors are prepared.The nanoplate dispersions were characterized and tested by transmission electron microscopy,X-ray diffractometer,and ultraviolet-visible spectrophotometer.The blue and blue-green MoO_3-x nanosheet dispersions were selected as the colorimetric sensing platform for detecting H₂O₂,and the condition was optimized by adjusting the p H.Finally,we conducted the experiment of determining natural sample,and assess the performance of the system under the real situation.