Optical and Electrochemical Aptasensors for Sensitive Detection of Aflatoxin B and Aflatoxin M in Blood Serum, Grape Juice, and Milk Samples.

Aflatoxin food contamination with toxic and carcinogenic impacts on human health is a global concern. We have developed aptasensors for the detection of Aflatoxin M (AFM) and B (AFB) using electrochemical and optical methods. In the first method, an electrochemical aptasensor was designed for the detection of AFM based on complementary strand of AFM aptamer that was attached onto the gold nanoparticles and a hairpin-shaped AFM aptamer. The designed electrochemical aptasensor showed high selectivity toward AFM with a limit of detection (LOD) as low as 0.9 nM. Moreover, the developed aptasensor was successfully used to detect AFM in milk and serum with LODs of 1.8 and 1.2 nM, respectively. In the second method, a novel electrochemical aptasensor was developed based on the π-shape structure of AFB aptamer. The detection limit was found to be 2 pg/mL in buffer. Also, the developed aptasensor was used to analyze AFB spiked human serum and grape juice samples, and the recoveries were 95.4-108.1%. In another method, a fluorescent sensing scheme was developed for AFB detection based on a hairpin structure of G-quadruplex oligonucleotide-aptamer chimera, streptavidin-coated silica nanoparticles (SNP-streptavidin) and N-methyl mesoporphyrin IX (NMM). The LOD was reported as 8 pg/mL with a linear range of 30-900 pg/mL. Moreover, the developed sensor could detect AFB in serum and grape juice with the LOD of 9.8 and 11.2 pg/mL, respectively.