A Novel Colorimetric Nano Aptasensor for Ultrasensitive Detection of Aflatoxin B1 Based on the Exonuclease III-Assisted Signal Amplification Approach

Abstract

The detection of aflatoxin B1 (AFB1) has recently garnered much attention on the issue of food safety. In this study, a novel and sensitive aptasensor towards AFB1 is proposed using an Exonuclease III (Exo III)-integrated signal amplification strategy. This reported sensing strategy is regulated by aptamer-functionalized nanobeads that can target AFB1; furthermore, complementary DNA (cDNA) strands can lock the immobilized aptamer strands, preventing the signal amplification function of Exo III in the absence of AFB1. The presence of AFB1 triggers the displacement of cDNA, which will then activate the Exo III-integrated signal amplification procedure, resulting in the generation of a guanine (G)-rich sequence to form a G-4/hemin DNAzyme, which can catalyze the substrate of ABTS to produce a green color. Using this method, a practical detection limit of 0.0032 ng/mL and a dynamic range of detection from 0.0032 to 50 ng/mL were obtained. Additionally, the practical application of the established sensing method for AFB1 in complex matrices was demonstrated through recovery experiments. The recovery rate and relative standard deviations (RSD) in three kinds of cereal samples ranged from 93.83% to 111.58%, and 0.82% to 7.20%, respectively, which were comparable with or better than previously reported methods.

Magnetic nanoparticle‐based immunosensors and aptasensors for mycotoxin detection in foodstuffs: An update

“…Enzyme‐free catalytic hairpin assembly (CHA) reaction or enzyme‐driven oligonucleotides cycling seems to be a promising technique to achieve signal amplification (Chen, Zhang et al., 2021; Wu et al., 2023; Yan, Zhao et al., 2022; Yang, Wu et al., 2022; Zhang, Wang et al., 2020; Zhao et al., 2023). In the work of Chen et al., the immunocomplexes of OTA antigen‐MNPs/mAb‐barcode DNA‐AuNPs can be dissociated by the addition of dithiothreitol; consequently, the disassembled barcode DNAs triggered the CHA reaction, thereby substantially enhancing the signal amplification (Figure 6e) (Chen et al., 2020).…”

A Novel Fluorescent Aptamer Sensor with DNAzyme Signal Amplification for the Detection of CEA in Blood

“…However, the sensitivity of conventional fluorescent aptamer sensors is generally low because the nucleic acid aptamer-to-target molecule binding ratio is generally 1:1, and each molecule of target can only trigger a change in the fluorescence signal of one molecule of probe. In order to improve the detection sensitivity of fluorescent aptamer sensors, a series of nucleic acid signal amplification strategies have been proposed by national and international researchers in recent years, such as enzyme cycle cutting reactions [ 4 , 5 ], cyclic chain substitution reaction [ 6 ], rolling loop amplification reaction, hybrid chain reaction [ 7 ] and DNA cyclic self-assembly reactions [ 8 ], etc. With the introduction of these nucleic acid signal amplification strategies, the detection sensitivity of fluorescent aptamer sensor has been greatly improved, but it still can’t meet the needs of the detection of some ultra-low content substances, especially disease markers.…”

Single-Walled Carbon Nanohorn-Based Fluorescence Energy Resonance Transfer Aptasensor Platform for the Detection of Aflatoxin B1

“…Among them, instrumental analytical methods include thin layer chromatography (TLC) [8], liquid chromatography-tandem mass spectrometry (LC-MS) [9], and high-performance liquid chromatography (HPLC) [10]. However, these methods and need complicated pre-processing, expensive instrumentation, specialized operators, and long time, which limit their application in rapid detection at the field level [11,12]. In addition, antibody-based immunoassays, such as the enzyme-linked immunosorbent assay (ELISA) [13], immunoaffinity column (IAC) [14], and immunochromatographic strip (ICS) [15], enable the rapid detection of AFB1 with some sensitivity.…”