Development Of Magnetic Lateral Flow Immunoassays For Rapid Detection Of Chloramphenicol Residues

Along with the frequent food safety incidents happening today, the food safety hasbecome one emergent problem which more and more people concern about. Undoubtedly,this brings more challenges for the modern analytic techniques.Chloramphenicol, a broad-spectrum antibiotic, because of its good cost-effectiveratio, was widely used for the bacterial disease in human beings and animals. Furthermore,the drug is also used as a feed additive in animal aquaculture. However, it has been provedthat chloramphenicol would result in lots of side effects. Many countries prohibited theuse of chloramphenicol in any edible species. The European Union reduces the detectionlimit from10μg/kg to0.1μg/kg,100times stringent than the original standard; the USFDA also changed the detection limit from5μg/kg to0.3μg/kg. Thus, in order to controlthe prevalence of chloramphenicol, it is necessary to develop an efficient, sensitive andeconomic analysis method for chloramphenicol residues.The magnetic lateral flow immunoassays (MLFIAs), as a new analysis method, hasreplace the traditional marker colloidal gold to the magnetic bead (MB). MLFIAs canaccomplish the quantitative detection by a material with special magnetic character.This paper intends to test several kinds of MBs, screen out the suitable MB for theMLFIAs and to optimize the conditions, establishing a new test system of MLFIAs. In thispaper, we use both immunomagnetic separation and MLFIAs.The main works include:1. Screening out the magnetic nanoparticles for the MLFIAs: select suitable MB A andMB D for MLFIAs through comparing the8kinds of MB;2. Optimizing the conditions for MLFIAs: Comparing the different performance of MBA and MB D in different salt concentration and pH; analyzing the influence on theMBs with different buffer and finding that the surfactant and high concentration ofproteins obviously promote the movement of MB on the NC membrane. MB A cantotally spread in Tween20with above0.05%concentration, and partly spread in BSAwith above5%concentration. So we used0.01M PBS with5%BSA and1%Tween20to be the sample buffer. We analyzed the influence of dryness on MB spreadingconditions and found out that MBs after drying out are prone to aggregate. Because of the aggregation of MB D-IgG, we performed the experiment with MB A.3. Testing CAP residues with MLFIAs. Optimizing the test of CAP according to couplingcondition of MB and IgG, blocking condition of T line and C line, and sample dealingcondition. With CB as the blocking buffer, the best blocking concentration for GAMin C is1:100, and for T is1:5. The best AbCAPcoupling is under1:100concentration.Compared with1:25concentration, the test limit for CAP drops from10ng/mL to4ng/mL. The test limit could further drop if using MLFIAs to deal with large volumesamples.