Development of a colorimetric aptasensor for aflatoxin B1 detection based on silver nanoparticle aggregation induced by positively charged perylene diimide

Abstract

A sensitive colorimetric aptasensor for rapid quantification of aflatoxin B1 (AfB1) has been successfully developed. The sensing strategy is based on the aggregation and localized surface plasmon resonance (LSPR) of silver nanoparticles (AgNPs) that involves interactions of a specific aptamer, positively charged perylene diimide (PCPD), and AgNPs nanoprobes. The aptamer can explicitly bind to AfB1, resulting in a conformational change of the aptamer, leading to a dissociation of the PCPD-aptamer complex. Eventually, the released PCPD induces aggregation of AgNPs, producing a new color tone derived from the surface plasmon wavelength shift of AgNPs. The absorbance ratio between 520 nm and 393 nm (A520/393 nm) of AgNPs aggregation has been applied to calculate AfB1 concentration in the sample. A high concentration of AfB1 displays the increasing A520/393 nm. Inversely, a low concentration of AfB1 exhibits the decreasing A520/393 nm. A calibration graph of the aptasensor exhibits excellent linear response to the AfB1 amount in the range of 0.2–6.0 ng/mL. A detection limit for AfB1 determination is 0.09 ng/mL with very low cross-reactivity from other mycotoxins, signifying high selectivity. Furthermore, the proposed method has been successfully applied to determine AfB1 in peanut, corn, and chicken feed samples. Obtained recoveries are more significant than 80%, with RSD lower than 10%. Hence, an innovative aptasensor can be used as an alternative method for quantifying AfB1 in real samples.