A novel electrochemical aptasensor based on layer-by-layer assembly of DNA-Au@Ag conjugates for rapid detection of aflatoxin M1 in milk samples

ABSTRACT Aflatoxin M 1 (AFM 1 ) is a common toxin in dairy products that causes acute and chronic human health disorders. Thus, the development of a rapid and accurate AFM 1 detection method is of vital importance for food safety monitoring. This work was to develop a novel electrochemical aptasensor for sensitive and specific determination of AFM 1. The dendritic-like nanostructure was formed on the gold electrode surface by layer-by-layer assembly of gold-silver core-shell nanoparticles modified with DNA conjugates. In the presence of AFM 1 , the specific recognition between AFM 1 and Apt caused the disassociation of the DNA controlled dual [email protected] conjugates from the surface of the electrode, causing less methylene blue to bind to the surface and weakening the electrochemical signal. The more AFM 1 there is, the weaker the electrochemical signal. Transmission electron microscope results showed that the successfully synthesized [email protected] nanoparticles exhibited a core-shell structure with Au as core and Ag as shell, and their average diameter was about 30 nm. Under optimal conditions, the electrochemical aptasensor showed a wide detection ranging from 0.05 ng mL −1 to 200 ng mL −1 , and a low detection limit of 0.02 ng mL −1 . Moreover, the proposed strategy has been successfully applied to the detection of AFM 1 in cow, goat, and sheep milk samples with satisfactory recoveries ranging from 91.10% to 104.05%. This work can provide a novel rapid detection method for AFM 1 , and also provide a new sensing platform for the detection of other toxins.