Study On Detection Of Hydrogen Peroxide In Food And Sterilization Of Pathogenic Bacteria Based On Ferric Maltol Enzyme Activity

Safeguarding food safety is an important part of ensuring public health and comprehensively promoting the construction of a healthy China.Therefore,it is particularly important to realize the analysis and detection of food and green prevention for the control of food-borne pollutants quickly and effectively.In recent years,with the excellent physical and chemical properties of nanomaterials being continuously explored and their applications in many fields being favored,they have broad prospects in the fields of food analysis and detection and green prevention for control.Ferric Maltol（FM）nanomaterials were prepared based on the coordination between maltol,an intermediate product of the Maillard reaction,and Fe（Ⅲ）ion.The peroxidase-like activity was further studied,and its application in food analysis and food-borne pathogen killing was realized.The main contents and results of this study are as follows:（1）Preparation and catalytic activity development of Ferric Maltol.FM was synthesized based on the chelation of maltol with Fe（Ⅲ）ion,and Fe was used as the active metal center.The microstructure,element composition,functional group,and valence state of the prepared FM were characterized and analyzed by Scanning Electron Microscope（SEM）,Transmission Electron Microscope（TEM）,Energy Dispersive Spectroscopy（EDS）,Fourier Transform Infrared Spectroscopy（FT-IR）and X-ray Photoelectron Spectroscopy（XPS）.The results showed that FM was a particle with a size of about 40 nm,and the elements were uniformly distributed in it.FM could catalyze hydrogen peroxide（H₂O₂）to mimic peroxidase activity by using 3,3’,5,5’tetramethyl-benzidine（TMB）as a chromogenic substrate.Then the catalytic reaction conditions were optimized,and it was found that FM kept a good catalytic effect in weak acid（p H 3～5）environment and high catalytic activity in a certain temperature range（20～60℃）.Kinetic analysis showed that the enzyme had a high affinity and catalytic rate for both TMB and H₂O₂.In addition,its catalytic mechanism was explored,and it was confirmed that its peroxidase activity came from superoxide radicals(O₂^·-).Density Functional Theory（DFT）calculations further revealed the mechanism of stereostructure and high catalytic activity of FM.FM provides a favorable site for the adsorption of H₂O₂,which contributes to enzyme-like catalysis.（2）Construction and application of colorimetric detection system for H₂O₂.Based on the activity of FM nanozymes,a colorimetric detection system for H₂O₂ was established.The sensitivity,selectivity,and stability of the colorimetric sensor were evaluated.The colorimetric detection system was applied to the detection of drinking water samples.According to the experimental results,the linear detection range of H₂O₂ concentration is1～100μM,and the limit of detection（LOD）is 0.45μM.In addition,mineral cations,biomolecules,and amino acids did not affect the colorimetric detection signal,which confirmed the selectivity of the detection system.At room temperature,the catalytic activity of FM did not change more than 6%in the intensity of colorimetric signal value within 70days,confirming its catalytic stability.In addition,the colorimetric detection system was successfully applied to the determination of H₂O₂ in spiked purified drinking water samples,and the recoveries were in the range of 89.35%～102.43%.Based on the activity of FM enzymes,the colorimetric detection and analysis of H₂O₂ in food can be realized.（3）Study on killing methicillin-resistant Staphylococcus aureus（MRSA）based on FM enzyme activity.The bactericidal performance based on the activity of FM-like peroxidase was evaluated in food-borne resistant pathogenic bacteria MRSA.First,the plate counting method was used to quantitatively study its catalytic germicidal efficacy.The bactericidal efficiency was 99.99%of 100μM H₂O₂ when the concentration of 500μg·m L^-1 was used,which greatly reduced the concentration of traditional H₂O₂.In addition,the distribution of images presented by the results of fluorescent live/dead staining and the SEM results of microorganisms observed under the same group of treatments were consistent with the corresponding plate culture.The free radical quenching experiment in the bactericidal system further confirmed that the high catalytic bactericidal effect was derived from the O₂^·-produced by the FM peroxidase activity catalyzing H₂O₂.These results strongly confirmed that based on the FM peroxidase activity could achieve excellent germicidal efficacy against MRSA.Through the application of biological enzyme catalysis sterilization,the efficacy and safety of killing pathogenic bacteria in a complex biological system based on FM were verified.The results showed that FM and low concentration H₂O₂ could decrease the number of bacteria and increase the hydration of skin.The results of visceral tissue sections and other health indicators showed that FM had high biological safety.This research strongly promotes the design and transformation of nanomaterials with high biological safety and is expected to be applied in the field of ensuring food safety.