An optical aptasensor for aflatoxin M1 detection based on target-induced protection of gold nanoparticles against salt-induced aggregation and silica nanoparticles.

Not only intoxications of aflatoxins are significant risk for human beings, but also; the contamination with these toxins affect the economy. Therefore, developing a rapid, precise and inexpensive determination method is vitally important. Here, a colorimetric aptasensor is introduced for the detection of aflatoxin M1 (AFM1) based on the preservation of gold nanoparticles (AuNPs) against NaCl-induced aggregation by detaching of complementary strand of aptamer (CS) from the aptamer-modified streptavidin coated silica nanoparticles (SNPs) following the addition of target. So, the color of sample remains red. While, in the lack of AFM1, salt-induced aggregation of AuNPs occurs and the color of sample becomes purple as the aptamer/CS (dsDNA)-modified SNPs is stable and CS cannot bind to AuNPs. The proposed aptasensor could detect AFM1 in a linear dynamic range, 300-75,000 ng/L, with a detection limit of 30 ng/L. Also, the sensing method was effectively applied for AFM1 recognition in milk samples.