Colorimetry Method For Detection Of Xanthine In Food Based On Transition Metal Selenides

With the improvement of people's living standards,high purine foods are becoming increasingly popular.These foods are along with potential risks,such as gout,hyperuricemia and other metabolic diseases,which occur frequently.Xanthine(XA)is a purine that is widely distributed in the human body,other biological organs and body fluids.It is eventually converted to uric acid by xanthine oxidase(XAO).Furthermore,hyperuricemia and gout can be induced when XA content in human body is too high and exceeds the body's own metabolic capacity.The intake of purine foods is closely associated with the occurrence of these diseases.And some researchs have confirmed that a low purine diet can significantly help patients with hyperuricemia and gout.Therefore,it is of great significance to establish a rapid,convenient and low-cost detection method for XA content in food to provide scientific guidance for people's diet.The colorimetric method has the advantages of simple operation,good selectivity,visual results and doesn't require expensive equipment.The introduction of nanoenzymes can effectively improve the detection and analysis performance of the colorimetric method.Because of large surface areas and catalytic activity sites of transition metal selenides,the study of regarding it as nanoenzymes has been deepening.Hence,this thesis establishes the colorimetric method,applying it to the content detection of XA in food.The research is divided into the following two parts:In the first part,we prepared WSe₂ nanosheets with the liquid exfoliation method.Discovering the WSe₂ nanosheets possessed peroxidase-like activity.Based on this performance,XAO was used to selectively catalyze XA oxidation to produce H₂O₂.XAO catalyzes XA oxidation and thereby induces H₂O₂ production.WSe₂ nanosheets can effectively catalyze the oxidization of 3,3',5,5'-tetramethylbenzidine(TMB)by H₂O₂ and produce a blue oxidation product of TMB.On this basis,a colorimetric detection method for XA detection was established.Under the optimal conditions,the linear range of XA detection was 0.01-0.5 m M.The limit of detection was 4.37?M.The proposed method is used for the rapid determination of XA content in fish,and the spiked recoveries were 91.2%-102.8%.And the results were consistent with the commercial ELISA kit,proving that the method can be applied to the rapid and sensitive detection of XA in real samples.In the second part,MnSe nanosheets were prepared by hydrothermal synthesis method with manganese acetate and selenium dioxide as raw materials.It was found that MnSe nanosheets possessed good peroxidase-like activity,and can catalyze the reaction of H₂O₂ with chromogenic substrate TMB,which can change the solution from colorless transparent to visible blue.Combined with the ability that XA can produce H₂O₂ under the action of XAO,the colorimetric sensing platform of XA was constructed.Under the optimal conditions,the linear range was 0.008-1.0 m M and the detection limit was 3.04?M.The method was used to rapidly detect XA content in fish and beer.The recoveries were 96.0%-101.5%and 99.5%-102.5%,respectively.Based on solution detection,a simple and portable MnSe-agarose hydrogel was designed,and the collected images were analyzed with image processing software(such as Image J),realizing the on-site semi-quantitative and visual detection of XA in fishs with the recovery rates of 95.57%and96.25%,respectively.The content of XA detected from the portable hydrogel was basically consistent with the result of the solution-based detection.In addition,the experiment proves that hydrogel has good specificity,which can realize the rapid and sensitive detection of XA in food.