Colorimetric Assay For Small Molecules Based On Catalytic Etching Of Metal Nanoparticles

With the rapid development of industry,the environmental pollution problems have seriously affected social sustainable development and human's survival and health.Therefore,developing a sensitive,rapid analytical method for environmental pollutant detection has become a more important role.With excellent performances,nanomaterials powerfully promote the development of the environmental and biological detection.Nanomaterials can be used as the signal transmission in the design of optical sensing methods for environmental pollutants due to its unique optical properties.The chemical reaction between metal nanoparticles or functional nanoparticles and target molecules results in the change of the color of nanoparticles,providing selective method for detection of target molecules.Based on this,the paper focuses on colorimetric assay for small molecules based on catalytic etching of metal nanoparticles.Taking the advantage of the catalytic etching of metal nanoparticles,herein we developed two colorimetric methods for sensitive determination of Mn2+ and ascorbic acid,respectively.The detail contents of this thesis are as follows:1.Colorimetric assay for Mn2+ based on catalytic etching of gold nanorods.With the presence of nitrilotriacetic acid(NTA),bivalent manganese ion Mn(II)first reacted with potassium periodate(KIO4)to generate Mn(III)-NTA complex.The generated Mn(III)-NTA complex in aqueous solutions then oxidized gold nanorods along the longitudinal direction,resulting in the color change of the solution from blue to red.According to the principle,the colorimetric assay was developed for the detection of Mn2+ with high sensitivity and selectivity(LOD = 1.0 nM).In addition,the proposed method was successfully applied to the detection of manganese ion in water samples.2.Colorimetric assay for ascorbic acid based on catalytic etching of manganese dioxide nanoparticles.In this part,ascorbic acid can react with manganese dioxide nanoparticles to produce dehydroascorbic acid and bivalent manganese ion.The generated dehydroascorbic acid can be reduced to ascorbic acid with the presence of TCEP.The progress accompanied by the etching of manganese dioxide nanoparticles and a visible color change from yellow to colorless.The proposed method is simple and rapid and can be applied to visual detection of ascorbic acid in urine.