A sensitive colorimetric immunoassay based on poly(dopamine) modified magnetic nanoparticles for meat authentication

Magnetic nanoparticles as solid substrate and polydopamine as coating polymer were combined for the construction of a sensitive colorimetric immunoassay aimed at the quantification of pork associated with meat fraud. In this study, a competitive assay was conducted between purified IgGs and porcine IgGs covalently immobilized on magnetic nanoparticles, for the binding sites of peroxidase-labelled antibody. The recognition of porcine IgG was monitored by a simple colorimetric method in the presence of peroxidase substrate. The performed immunoassay was successfully employed for the screening of pork in adulterated meat, allowing low level of 0.01% to be detected in short time of analysis. The specificity of the immunoassay was tested against five different meat species (pork, lamb, turkey, chicken and beef) and it was found to be highly specific towards pork. Furthermore, the used magnetic probe has maintained a satisfactory stability enabling sensitive detection of pork within 20 days of storage. With the versatility and facile-preparation of polydopamine modified magnetic nanoparticles as well as the easy handling of the whole assay, this colorimetric method provides a specific and sensitive in-field-test for the detection of pork in adulterated meat and thus verifying halal meat authenticity.