Rapid Detection Of Rongalite Via A Sandwich Lateral Flow Strip Assay Using A Pair Of Aptamers

Specificity,high sensitivity and rapid detection of illegal food additives and toxins have great significances for food safety.All additives that are outside the permitted scope of the standard or exceed the standard are called illegal additives.Rongalite is one kind of industrial dyestuff,it can cause allergies,intestinal irritation or other adverse reactions,even poisoning,kidney,liver damage or other diseases.In the national standard "food additives using health standards",hanging rongalite is excluded from the statutory food additives.However,there are still some traders who illegally add and use them in the production process of rice flour,bean curd,tofu and shark fin to achieve the purpose of whitening food.At present,the main detection methods of rongalite are detecting the decomposition products of rongalite.These methods not only operate cumbersome,but also cause large deviation by detecting the decomposition products.Therefore,it is urgent to develop a method for rapid detection of rongalite.The new identification elements,aptamers,screened by SELEX have extremely important applications on food safety,drug research and development,medical diagnosis and other fields.Our research group has screened two aptamers SF-A09 and SF-B09 that can specifically identify rongalite.Literal flow strip assay(LFSA)is a simple rapid and inexpensive analytical method that uses visualization sensors to rapidly detect analytes.Therefore,our group used the LFSA platform,based on SF-A09 and SF-B09 as the identification elements,and then compare and optimize the entire reaction system for the test strip,including the resuspension formulation,the membrane pretreatment solution formulation,the membrane material model,and the optimum concentration of the various solutions.A colloidal gold aptamer test strip was successfully established to detect hanging white pieces,and the test strip was used for on-site rapid detection of hanging white pieces in food.A sandwich lateral flow strip assay(LFSA)using a couple of aptamers functionalized with gold nanoparticles(AuNPs)was designed to assess the presence of rongalite in agrifood products.This system allows the successful and direct detection of rongalite in food samples with concentrations as low as 1 ?g/mL,simply by observing the color change of LFSA control and test line.These results were confirmed by high performance liquid chromatography(HPLC).In addition,food samples from the surrounding market were purchased for testing.The application of LFSA in point-of-care testing(POCT)field was confirmed again.At the same time,the matrix effects of different sample were investigated.The detection limits of noodle,ersi,and skin of tofu is 1 ?g/m L,and the detection limits of dried beancurd sticks is 2 ?g/ m L.In summary,the self-assembled sandwich lateral flow strip assay(LFSA)using a couple of SF-A09 and SF-B09 aptamers functionalized with gold nanoparticles(AuNPs)can be used for on-site rapid detection of rongalite in rice noodle and other food samples,which provides new technical means to ensure the safety of the food market.