Abstract: In this paper, we aimed to develop a sensitive and rapid method to detect aflatoxin B1 (AFB1). Based on the fact that graphene oxide (GO) can efficiently adsorb single-strand oligonucleotides (ssDNA) through π-π conjugation, but hardly adsorb ssDNAs bound to the targets, a scheme for screening aptamers for AFB1 was designed and performed. After 10 rounds of screening, a total of 45 ssDNA sequences were obtained. Secondly, six representative sequences were selected for further affinity analysis, whose dissociation constants (Kd) were 16.29, 27.88, 18.54, 23.11, 47.94, and 22.31 nmol/L, respectively. Subsequently, the specificity of the ssDNAs AFB-5 and AFB-8, with higher affinity, were determined. The results revealed that the selected aptamers could bind to AFB1 with high specificity. Finally, AFB-8 was used as recognition element to construct a gold nanoparticles (AuNPs)-based colorimetric assay for AFB1。Under the optimized detection conditions, AFB1 concentration (x) showed a good linear relationship with A520 nm (y), which was expressed by the following equation: y = ?0.007 09x + 0.461 42 (R2 = 0.997 9). The linear range and the detection limit were 0.025–10 ng/mL and 0.025 ng/mL, respectively. The specificity of this method was evaluated and the recoveries for spiked rice samples were in the range of 83.36%–105.74%. The results obtained proved the feasibility of the method.

Key words: aflatoxin B1; aptamer; systematic evolution of ligands by exponential enrichment; colorimetric detection; gold nanoparticles