Rapid detection of melamine based on immunoassay using portable surface plasmon resonance biosensor

Melamine is an illegal adulteration in milk, infant formula and pet food. Its misuse is toxic to human and animals. Rapid and reliable screening methods for melamine detection are essential to allow faster decisions to be made with respect to food contamination. A portable miniaturized surface plasmon resonance (mini-SPR) biosensor has been developed and used to rapidly detect and quantify melamine through immunoassay based on binding between melamine and anti-melamine antibody (anti-MEL). The assays show high selectivity to melamine. Three types of immunoassays, namely direct assay, displacement assay and competitive assay are employed. Compared to direct assay, the displacement assay and competitive assay using bovine serum albumin conjugated melamine (BSA-MEL) enhance the sensitivity by about 14 times and 60 times, respectively. The competitive assay can be finished in 15 min with detection limit of 0.02 μg/mL. The feasibility of testing real samples is proven good for infant formula after simple pretreatment. The SPR biosensor with proposed analysis assays is rapid, convenient and low-cost for effective detection of melamine.