Development Of Rapid Detection Method And Device Based On The Photothermal Effect Of Gold Nanoparticles

In recent years,the food safety issues have been paid more attention by society.Detection of pathogenic bacteria and veterinary drug residues in food was an important guarantee of food safety.There are many methods for the detection of harmful substances in food.The gold nanoparticles?GNPs?test strip methods which include immunochromatography assay and immunofiltration assay was one of the commonly used detection methods.In this paper,the GNPs immunochromatography detection methods which use GNPs as a chromogenic substance of the immunochromatography assay were studied.It can be divided into double-antibody sandwich and competition methods based on the number of antigen epitopes.The nitrocellulose membrane?NC?and glass can be used as substrate.The immunochromatography assay was widely applied in the food industry,medical diagnostic system and other fields.However,the sentitivity of the traditional GNPs immunochromatographic test strips was low.GNPs can produce a lot of heat when irradiated by 532 nm laser,therefore GNPs have good photothermal effect.In this paper,GNPs immunochromatographic test strips of Salmonella typhimurium were prepared and the quantitative analysis results were obtained by thermal imager based on the photothermal properties of GNPs.However,the price of thermal imager is still higher.Thus infrared sensor was used as a new type of photothermal detection device,and rapid detection method based on thermal effect was established.The contents of this paper were showed as follows:In the first chapter,preparation method,property,the labeling technique and the photothermal mechanism of GNPs and the classification of test strip were summarized.The research progress of GNPs test strip based on visual method,GNPs test strip standard reader,and application of GNPs' photothermal effect were emphasized.In the second chapter,a test strip method for detecting Salmonella typhimurium based on GNPs' photothermal effect was established.GNPs were prepared and the antibody was conjugated with GNPs.The preparation process and the time of laser irradiation were optimized by thermal imager.Detection limits of visualization and thermal imager were determined.The detection limit of thermal imager method and visual method Salmonella typhimurium were 1.57×10⁷ CFU·mL^-1 and 1.7×10⁶ CFU·mL^-1,respectively.The sensitivity of thermal imager method was improved by about 9 times compared with the visual detection method.In the third chapter,a rapid detection method based on GNPs' photothermal effect was established.The commercial Salmonella typhimurium double-antibody sandwich test strips and commercial Clenbuterol hydrochloride competition test strips was used for quantitative detection by thermal imager.The detection limit of Salmonella typhimurium and Clenbuterol hydrochloride by visual method and thermal imager detection method were determined.The detection limits were 1.13×10⁷ CFU·m L-1 and 1.2×10⁶ CFU·mL^-1 respectively.The sensitivity of thermal imager method was improved by about 9 times compared with the visual detection method.Meanwhile,the detection limit of the Clenbuterol hydrochloride test strip was also obtained.The detection limit of thermal imager test was 0.5 ng·mL^-1.The sensitivity of thermal imager method was improved by about 10 times compared with the visual detection method.In the fourth chapter,a small infrared temperature sensor device was developed,the homemade and commercialized Salmonella typhimurium test strips and Clenbuterol hydrochloride test paper tested in the second and third chapter.And the laser irradiation distance,the sensor measurement distance and the laser irradiation time were optimized.The detection limits of Salmonella typhimurium and Clenbuterol hydrochloride was determined by the visual inspection method and the photothermal effect of the infrared sensor.Results showed that the detection limits of homemade Salmonella typhimurium were 1.57×10⁷ CFU·mL^-1 and 1.25 × 10⁶ CFU·m L-1,respectively,and the infrared temperature sensor sensitivity was improved by about 12 times compared with the visual detection method.The detection limits of the visual inspection method and the infrared temperature sensor test were 1.13 × 10⁷ CFU·mL^-1 and 1.0 × 10⁶ CFU·mL^-1,respectively,and the infrared temperature sensor sensitivity was improved by about 11 times compared with the visual detection method.The detection limits of the Clenbuterol hydrochloride test strip and the infrared temperature sensor test were 5 ng·mL^-1 and 0.3 ng·m L-1,respectively,and the infrared temperature sensor sensitivity was improved by about 16 times compared with the visual detection method.The fifth chapter concluded the rapid detection method and the developed detection device based on GNPs thermal effect.The advantages of this method were to realize the rapid detection of the target test object,and improve the detection limit compared with method.This simple and rapid method can be widely used in resource-limited and no need for large instrumentations.