| Chemical analysis(CA),thin film chromatography(TLC),gas chromatography(GC)and high performance liquid chromatography(HPLC)have been widely used in food detection and analysis,but complex and time-consuming pretreatment is needed.Compared with low sensitivity CA and TLC,GC and HPLC are more sensitive.However,its expensive equipment makes it highly demanding for users.However,in recent years,with the rapid development of biosensor technology,the performance requirements of biosensors are getting higher and higher.It is of great significance to develop simple,portable,sensitive,accurate and durable new biosensors.Gold nanoparticles are red in dispersion state and blue in cross-linked aggregation state,which provides a convenient method for visual detection.Click reaction has the advantages of readily available raw materials,mild reaction conditions,high yield,good selectivity,strong specificity and easy separation and purification,which provides a feasible theory for rapid and high sensitivity.Therefore,this topic combines the advantages of simple and fast click reaction and the characteristics of visual detection of gold nanoparticles.The spherical gold nanoparticles(AuNPs)were prepared as the carrier.Based on the click chemistry principle,the gold nanoparticles were modified to combine with the reactants to make the gold nanoparticles agglomerate or polymerize to produce color changes.A highly sensitive and selective visual biosensor based on the modified gold nanoparticles was constructed and successfully applied to food analysis and detection.In order to realize the efficient visual detection method of glucose,sodium isoascorbate and glutathione in food.(1)Gold nanoparticles were prepared by green reduction using the orange peel extract of Qingjin.The optimum preparation conditions were as follows:mother liquor concentration 50%,reaction temperature 25℃,reaction time 25 min,stirring speed 1300 rpm.Infrared spectroscopy showed that a variety of active substances were involved in the synthesis of AuNPs,and the mechanism was analyzed:forming a protective layer around the particles to prevent AuNPs aggregation.The prepared AuNPs have good catalytic activity.(2)The simple reaction conditions for the conversion of Cu(II)into Cu(I)were discussed.A simple method for the formation of Cu(Ⅱ)was developed by simplifying the complex product and only considering the amount of Cu(Ⅱ).In this experiment,single factor experiment and orthogonal table design were used to optimize the reaction conditions of glucose for Cu(Ⅱ)conversion into Cu(Ⅰ).The results showed that the optimum conditions were as follows:reaction temperature was 80℃,sodium hydroxide concentration was 50 mmol/L(Cu2+:OH-=1:10),reaction time was 15 min.(3)Functionalization of gold nanoparticles to combine AuNPs with azides(AuNPs-N3).The reaction conditions for the synthesis of AuNPs-N3 were investigated,and the optimal conditions were obtained as follows:the reaction temperature was 25℃,the rotation speed was 430 rpm,and the reaction time was 30 min.The prepared AuNPs-N3 particle size was larger than that of AuNPs.Infrared spectroscopy also indicated the synthesis of AuNPs-N3.AuNPs-N3 are negatively charged.(4)The click reaction between the synthesized AuNPs-N3 and alkyne compounds was discussed,and a colorimetric sensor with high sensitivity and high selectivity for glucose detection was constructed,and the click chemical reaction detection system was optimized.The results showed that under the optimal detection system,the constructed click chemical reaction colorimetric sensor had high sensitivity for glucose detection.In the concentration range of 0.01～0.25μmol/L glucose,the regression equation of the working curve was y=0.0003x+0.311,and the detection limit was 5.7 nmol/L(S/N=3).The colorimetric sensor showed excellent anti-interference to glucose.The detection limit was lower than that of other nanomaterials for glucose detection.It has good recovery rate and precision.In addition,the constructed colorimetric sensor has been successfully applied to the actual sample detection.(5)A colorimetric sensor with high sensitivity and high selectivity for detecting sodium isoascorbate was constructed based on click chemistry reaction,and its detection system was optimized.The results showed that under the optimal detection system,the constructed click chemical reaction colorimetric sensor had a wide range of detection for sodium isoascorbate.In the concentration range of 0.4-6 mmol/L,the regression equation of the working curve wasy=0.007x+0.190,the correlation coefficient was R2=0.998,and the detection limit was 1.33×10-2 mmol/L(S/N=3).The recovery rate of sodium isoascorbate detection system was 99.80%～103.03%,and the constructed colorimetric sensor had high sensitivity and stability for sodium isoascorbate detection.It has good detection performance for canned food and has practical application potential.(6)The click chemistry reaction with AuNPs-N3 participation was discussed to construct a colorimetric sensor with high sensitivity and high selectivity for glutathione detection,and the click chemistry reaction detection system was optimized.The results showed that under the optimal detection system,the constructed click chemical reaction colorimetric sensor had high sensitivity for glutathione detection.In the concentration range of 0.4-4 mmol/L glutathione,the regression equation of the working curve was y=0.019x+0.166,the correlation coefficient was R2=0.992,and the detection limit was 1.79×10-2 μmol/L(S/N=3).The recovery rate is 97.10%～108.10%,and has certain anti-interference ability.This click chemical colorimetric sensor showed excellent selectivity for glutathione.In addition,it has been successfully applied to the detection of glutathione in pig liver with a good recovery rate.Therefore,the constructed colorimetric sensor has great prospects for successful application in actual sample detection. |
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