The Application Of Quantum Dot Fluorescence Immunoassay In Detection Of Salmonella Contamination In Food

Salmonella,an extremely widespread pathogen,can cause severely threat to human health through contaminating food.The traditional detection method of Salmonella is complicated,which has a long detection period.Salmonella can also be rapidly detected by molecular biology methods and immunological methods.Because of the professional technical support and the higher cost,it is difficult to meet the needs of large-scale screening for Salmonella by molecular biology methods.In immunological methods,the application of immunochromatographic assay is the most extensive.Immunological methods are generally labeled with fluorescein or colloidal gold.But both of them are easily disturbed by the environment.And the sensitivity of two methods is also at a low level,which of colloidal gold is only 106?107 cfu/mL.Developing a new type of quantum dot detection kit for the rapid detection of Salmonella in foods is based on protein materials and platform conditions,which is provided by the laboratory of Vazyme Medical Co.,Ltd.The kit uses new water-soluble quantum dots instead of traditional tracer materials.As the tracer material,the quantum dots will not quench easily,which have the advantages of excellent performance in stability and sensitivity.It describes the process of development and optimization of Salmonella quantum dot fluorescent immunoassay kit in the paper.And it also evaluates the basic performance of the kits.Simultaneously,the kit is applied to detect meat and poultry eggs.The main results of the research are as follows:1?The anti-Salmonella O antigen monoclonal antibody,was labeled with quantum dots,which had excellent performance in specificity and sensitivity.2?The optimal concentration of the control line and the test line was determined to be 1.0 mg/mL and 2.0 mg/mL.The optimal dilution ratio of quantum dot dilution solution is 1:10,and the perfect dosage of each aid is:sucrose 4%,BSA 0.5%.In the sample pad blocking solution,the best additive quality of Casein and sucrose were 1%and 5%.3?The limit detection of blank is 1.0×103 cfu/mL,and the linear range which can be accurately detected is 1.0×103 cfu/mL?1.0×108 cfu/mL.The coefficient of variation of the kit was less than 10%.Therefore,the kit has superior performance in precision and specificity.It has no obvious cross reaction with other pathogenic bacteria in the process of specific investigations.Finally,the reagent cards were placed at 37?,and assessed the accelerated stability for 21 days.Compared with 4?,when detecting the high and the low values,the deviation of results were less than 15%,and its stability was excellent.4?The kit is applied to detect the salmonella in food,which includes artificial contamination experiment and 315 random food samples from supermarkets and vegetable markets in Nanjing.The result which is detected by kit is accurate and reliable,and the sensitivity of the kit is no more than 1.0×103 cfu/mL.