| Aflatoxins(AFT),as one types of difurcoumarin derivatives with similar chemical construction,are mainly produced from the metabolism of Aspergillus flavus and Aspergillus parasiticus.Aflatoxin B1(AFB1)is the most toxic among aflatoxins,which is widely distributed and listed as a class I carcinogen by the World Health Organization.Therefore,it is urgent to develop a rapid detection and analysis method with high sensitivity and selectivity to aflatoxin,so as to monitor aflatoxin contamination in cereals and oil crop products.The lateral flow strip biosensor possesses the advantages of high detection speed,simple pretreatment and high sensitivity,with great potential application values in research and industry.The detection mechanism of lateral flow strip biosensor is based on using a specific antigen or antibody as a recognition element immobilized on the nitrocellulose membrane,and various nanomaterials are applied as labels for qualitative and quantitative detection with simple instrument analysis.In this study,the lateral flow strip biosensor was constructed using nano-gold-silica particles(Au@SiO2)and nano-gold as color labels.The comparison and research study of the analytical performance of three different strip biosensors were accomplished,concentrating on the detection of AFBi concentration in camellia-seed oil samples.The superiority of nano-composite material based strip biosensor for on-site and fast detectioin includes the simplificaiton of pretreatment process,the shortened detection time,and easy operation.It can be used for qualitative analysis with naked eye and quantitative analysis by portable instrument.The main contents of this thesis are as follows:(1)The synthesis of nano-gold-silica particles(Au@SiO2)composite was accomplished,and the nanocomposites based strip biosensor was established.The working conditions of the strip biosensor were optimized,including pH value for binding of Au@SiO2 and antibody,Au@SiO2 and antibody concentation.Meanwhile,the analytical performance of the strip biosensor is studied.Under the optimum test conditions,the optimum pH value for the binding of Au@SiO2 and antibody is 6.0,the optimum Au@SiO2 concentration to antibody amount is 0.2 μg/mL.There is a good linear relationship between the response signal intensity of the strip and the concentration of standard toxin in the range of 0.001～5 ng/mL,and the detection limit is 0.8 pg/mL.After one month stored at room temperature and 4℃,the response signal of the strip to the target toxin remained the same,showing good reproducibility and stability.The strip has no obvious response signal to other non-target toxins(ochratoxin,Okadaic Acid,etc.),showing good specificity.(2)Study and prepare the AuNPs strip biosensor and AuNPs amplification strip biosensor.The working conditions of two different sensors were optimized respectively.The analytical performance of the strip was studied.Under the optimal conditions,the AuNPs based strip biosensor had a good linear relationship in the concentration range of 0.01～10 ng/mL,and the detection limit is 0.019 ng/mL,and the reproducibility and specificity were good,but the stability of one-month store was not good.The AuNPs amplification based strip biosensor had a good linear relationship in the concentration range of 0.005～10 ng/mL.and the detection limit is 0.0046 ng/mL,with good reproducibility,specificity and stability.(3)The analytical performances of the three strip biosensors,and the detection of aflatoxin B1 in the camellia-seed oil samples were investigated and compared.By comparing the calibration curve,sensitivity,detection limit,stability and reproducibility of the three strip biosensors,it is found that the Au@SiO2 based strip biosensor has the best research and analysis performance and the lowest detection limit.For detection of APB1 in camellia-seed oil samples,the intensity of the response signal of the strip biosensor has a good linear relationship with the concentration of the target toxin in the complex matrix in the range of 0.001～5 ng/mL,and the detection limit is 0.97 pg/mL and the calibration curve of real sample is similar to that of the standard sample.The results showed that the strip biosensor still has a good selectivity to the target toxin in the complex matrix environment.The detection results of the real samples were consistent with the results of ELISA kit and commercial strip product,which indicated a high accuracy of Au@SiO2 based strip biosensor. |
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