Highly sensitive aflatoxin B1 sensor based on DNA-guided assembly of fluorescent probe and TdT-assisted DNA polymerization

A novel aptasensor, based on a perylene probe (PAPDI; N,N′-bis(propylenetrimethylammonium)-3,4,9,10-perylenediimide), was developed for the detection of aflatoxin B1 (AFB1) in maize samples. AuNPs/DNA composites were synthesized and integrated with aptamers-modified magnetic nanoparticles (MNPs) via DNA hybridization. For AFB1 determination, AuNPs/DNA composites were released from MNPs through specific binding of AFB1 with the aptamer and used for assembly of the PAPDI probe. To enhance the method sensitivity, terminal deoxynucleotidyl transferase (TdT)-catalyzed DNA polymerization was performed to elongate DNA on AuNPs/DNA composites. As a result, more PAPDI probes were assembled on the AuNPs/DNA composites. Through a multiple signal amplification strategy, the proposed method exhibited high sensitivity towards AFB1, with a detection limit of 0.01 nM (3.1 pg/mL). In summary, the proposed method has great potential to be a universal strategy for monitoring AFB1 in food samples.