Detection of aflatoxin B1 with a new label-free fluorescent aptasensor based on exonuclease I and SYBR Gold

Abstract

This paper describes a new label-free fluorescent aptasensor for the detection of aflatoxin B₁ (AFB₁) based upon exonuclease I (Exo I) and SYBR Gold, in which SYBR Gold, aptamer, AFB₁, and Exo I were used. Specific combinations of aptamer and AFB₁ occurred in the presence of AFB₁ and consequently altered the spatial structure of the aptamer, thereby preventing its digestion by Exo I. When SYBR Gold was added, intense fluorescence was observed. Additionally, a good linear relationship was observed under optimized conditions between the fluorescence intensities and the AFB₁ concentrations (R² = 0.993). The established aptamer sensor was highly sensitive and exhibited a low limit of detection of 1.82 ng mL⁻¹, with superior specificity for AFB₁. It was also used in the quantification of AFB₁ levels in soybean sauce samples and demonstrated satisfactory recoveries in the scope of 94.8–108.9%. The proposed sensor is highly sensitive, low cost, and capable of rapid detection and can thus be used to determine mycotoxin levels in a wide range of feeds and food products in a high-throughput and quantitative means.