Two Birds with One Stone: A Fluorescent/Colorimetric Dual-Mode Aptasensor Based on Au/Mof Nanocomposite for Accurate and Convenient Detection of Aflatoxin B1

Accurate and convenient detection of aflatoxin B1 (AFB1) is crucial for food safety and agricultural economy. Herein, a fluorescent/colorimetric dual-mode aptasensor for simple and accurate detection of AFB1 has been constructed based on Au/metal–organic frameworks (Au/MOF) composite. Au/Fe3O4 composites modified with aptamers (Apt/Au/Fe3O4) are employed as recognition elements. Au/MOF composites modified with complementary chains and 3,3′,5,5′-tetramethylbenzidine (cDNA/TMB/Au/MOF) serve as fluorescent probes and colorimetric probes. These two composites are coupled with each other to generate conjugations, enabling the detection of AFB1 by dual-mode method. In the presence of AFB1, it competes with cDNA for aptamers and preferentially bonded to aptamers, resulting in colorimetric signal increasing and fluorescence intensity weakening. Due to the correlation between the detection results of the two modes, the efficiency and accuracy have been further improved. Moreover, this dual-mode aptasensor can achieve simultaneous fluorescence and colorimetric detection of AFB1 without the material and reagent replacement. The fluorescent/colorimetric aptasensor is able to detect AFB1 with LODs of 0.04 ng mL-1 and 0.06 ng mL-1, respectively. It is also used for AFB1 quantification in real samples successfully, exhibiting a great potential in the field of food safety testing.