Research On New Analytical Detection Methods For Food Components Based On Deformation Of Precious Metal Nanoparticles

Food is the most fundamental substance for human survival and development.Food safety and quality control are increasingly important to consumers and food enterprises.Therefore,the development of effective detection technology and tools for rapid detection and analysis of food components（including nutritional and harmful ingredients）is of great significance to ensure food safety and quality control.Traditional detection techniques have problems such as long operating procedures and high costs,making it difficult to meet the requirements for rapid detection.Noble metal nanoparticles such as gold and silver have excellent light scattering signals due to their localized surface plasmon resonance（LSPR）.This paper combines noble metal nanoparticles as optical probes with dark-field microscopy（DFM）technology to achieve high-sensitivity and effective detection of food components,demonstrating a broader application prospect.The specific research contents are as follows:1.Based on the induction of elemental iodine（I₂）,Au@Ag NPs were deformed into Au-AgI NPs heterojunctions,and quantitative detection of glucose was achieved using dark-field imaging technology.When glucose oxidase（GOx）and oxygen are present,glucose is converted to gluconic acid and hydrogen peroxide（H₂O₂）,hydrogen peroxide rapidly oxidizes potassium iodide（KI）to elemental iodine under the catalysis of molybdate,inducing the morphology of Au@Ag NPs to change from spherical to Au-AgI NPs heterojunction,casuing redshift of LSPR peaks of Au@Ag NPs.Under DFM,the scattered light color of Au@Ag NPs changed from green to red.The glucose concentration was in the range of 0.1～25.0 μmol/L,which had a good linear relationship with the red/green ratio（R/G）of Au@Ag NPs.The linear regression equation was R/G=0.0981x+0.1607（R²=0.995）.The detection limit as low as 35 nmol/L.This method was successfully used for glucose detection in beverage samples,with a recovery rate of 96%～102%.2.Based on the induction of nitrite ions（NO₂^-）,Au NCs were deformed into spherical gold nanoparticles,and quantitative detection of nitrite was achieved using dark-field imaging technology.Under acidic conditions,NO₂^-ions induced the deformation of Au NCs,and the morphology of concave gold nanoparticles changed to spherical,which led to the blue shift of LSPR characteristic absorption peaks of Au NCs.Under DFM,the scattered light color of Au NCs changed from red to green.NO₂^- ion concentration showed a good linear relationship with the green/red ratio（G/R）of Au NCs in the range of 0.2～10.0 μmol/L.The linear regression equation was G/R=0.1279x+0.2059（R²=0.995）.The limit of detection was 0.1 μmol/L.This method was applied to the analysis of pickle samples and achieved satisfactory recovery.3.Based on the etching of cyanide ions（CN-）on AgI in the gold-silver iodide nanoparticles（Au-AgI NPs）heterojunction,the morphology of AgI was changed to gold nanoparticles,and quantitative detection of cyanide was achieved using dark-field imaging technology.CN-ions selectively etch AgI in Au-AgI NPs,resulting in a transformation of their morphology to spherical shape,blueshifting of LSPR peaks of Au-AgI NPs.Under DFM,the scattered light color of the probe changes from red to green in real-time.The CN-concentration had a good linear relationship with the green/red（G/R）of Au-AgI NPs in the range of 0.2～4.0 μmol/L.The linear regression equations were G/R=0.0677x+0.3717（R²=0.992）.The CN-concentration had a good linear relationship with the green/red（G/R）of Au-AgI NPs in the range of 4.0～15.0μmol/L.The linear regression equations were G/R=0.2945x+0.4835（R²=0.994）.The limit of detection was 69 nmol/L.This method was applied to the analysis of drinking water samples,achieving a recovery rate of 97%～100%and verifying the practicality of the method.