Rapid detection of Salmonella in milk with a nuclear magnetic resonance biosensor based on a streptavidin–biotin system and a polyamidoaminedendrimer- targeted gadolinium probe

摘要

Rapid and sensitive detection technology is the key topreventing food-borne disease outbreaks. In this study,a low-field nuclear magnetic resonance (NMR) biosensorbased on polyamidoamine dendrimers was preparedfor the rapid detection of Salmonella in milk. Thepolyamidoamine dendrimer was biotinylated by amidereaction and chelated to diethylene triamine pentacetateacid and gadolinium to form magnetic complexes.The antibody and magnetic complexes were combinedthrough a streptavidin–biotin system using streptavidinas an intermediate bridge to obtain the immunoprobe.Salmonella was captured by the immunoprobe via antigen–antibody interaction and then separated fromthe mixture by membrane filtration. Finally, the longitudinalrelaxation signal of the filtrate was obtainedby NMR. The biosensor had excellent anti-interferencecapability and could detect Salmonella within 1.5 h at asensitivity of 103 cfu mL–1. This method based on NMRcan realize detection in complex samples and has thepotential to be a quick and nondestructive method fordetecting target bacteria.