Preparation Of Silver Nanoparticles And Gold Nanoclusters And Its Application In Food Detection

Food safety is closely related to people's health level.In order to ensure the safety of food,the food analysis and detection play an important role.Noble metal nanomaterials have unique physical and chemical properties with low toxicity,easy synthesis,strong water solubility and easy surface modification,which make them widely used in analysis and detection.By modifying the appropriate ligand on the surface of the nanomaterial,the interaction between the ligand and the target can be used to achieve the purpose of detection.In addition,with the special fluorescence properties of nanoclusters,the fluorescence intensity of the nanoclusters can be changed under the action of the target,so that the quantitative analysis of the substance can be realized.Compared with the traditional methods,the detection method based on noble metal nanomaterials has the advantages of economy,simplicity,rapid response and good selectivity.In this paper,silver nanoparticles and gold nanoclusters were used as research objects,and green and simple methods were used to prepare them.Using surface the plasma resonance effect of nanoparticles and the fluorescence characteristics of nanoclusters,three kinds of sensors were constructed to detect the content of Cr2+,Al3+and phytic acid in food.The main research contents and results are as follows.1.Detection of Cr3+ in water based on gallic acid and p-nitrophenol double ligand functionalized silver nanoparticles.Silver nanoparticles were synthesized by sodium borohydride reduction method,and gallic acid and p-nitrophenol were co-modified on the surface of silver nanoparticles.Based on the fact that Cr3+ can lead to the aggregation of co-modified silver nanoparticles,which can change the UV-Vis spectrum and color of silver nanoparticles,a colorimetric sensor is constructed to quickly detect Cr3+.Under the optimal experimental conditions,there is a good linear relationship between the concentration of Cr3+ and the absorbance ratio of the system(A550/A390).When the concentration of Cr3+ was in the range of 0.04?1.2?M,the linear equation was Y=0.0528C+0.0127(R2=0.9917).When the concentration of Cr3+was in the range of 1.2?2.0?M the linear equation was Y=0.4693C-0.4836(R2=0.9900),and the detection limit was 0.013 ?M.The recovery rate of this method in the range of 97.2%?117.5%.2.Fluorescent sensing of phytic acid based on glutathione-stabilized gold nanoclusters.Glutathione-stabilized gold nanoclusters were synthesized by using glutathione as stabilizer and reductant,and then used as fluorescent probe.Based on the principle that Pb2+ can interact with glutathione on the gold nanoclusters to form aggregates,which enhances the fluorescence of the system and that phytic acid can complex with Pb2+ to reduce the fluorescence of the system after the introduction of phytic acid.a fluorescence analysis method for quantitative detection of phytic acid with the help of Pb2+ was designed.Under the optimal experimental conditions,the phytic acid concentration in the range of 0.5?4.0 was a good linear relationship with the relative fluorescence intensity(F/FA)of the system,and its linear equation is Y=-0.1597C+1.0490(R2=0.9934),The minimum detection limit is 0.3 ?M.This method has good selectivity for common amino acids and ions,and has been successfully used for the analysis and detection of milk powder and glutinous rice samples.The recovery was in the range of 83.2%?112.8%.3.Detection of Al3+ by fluorescence sensor based on histidine-stabilized gold nanoclkS ters and glutathione-stabilized gold nanoclusters.Histidine-stabilized gold nanoclusters with green fluorescence were synthesized using histidine as template,while introducing glutathione-protected gold nanoclusters.The two,gold nanocluster solutions were used as fluorescent probes.Using the phenon11non that Al3+ can react with the mixture of two kinds of gold nanoclusters through electrostatic interaction,which leads to the aggregation of gold nanoclusters and the obvious enhancement of the total fluorescence intensity of the system,a fluorescent sensor is constructed to realize the sensitive detection of A13+.Under the best experimental conditions,when the concentration of Al3+ was in the range of 0.1?8.0 ?M,it was in a positive proportion to the relative fluorescence intensity of the system.The linear equation was Y=0.0805C+0.9981(R2=0.9985),and the detection limit was 0.06 ?M.This method obtained good recovery in the actual water sample,which shows that it has a good application prospect.