Min Wei

A dual‐emission fluorescent aptasensor was developed for the rapid and simultaneous determination of aflatoxin B1 (AFB1) and ochratoxin A (OTA) in food samples. The platform integration relies on a MXene‐Ti ₃ C ₂ T _X /MoS ₂ composite quencher paired with two aptamer‐functionalized gold nanoclusters (AuNCs‐Apt) emitting at 525 and 630 nm. The MXene‐Ti ₃ C ₂ T _X /MoS ₂ composite exhibited higher quenching performance than either individual component. Furthermore, the introduction of Mn ²⁺ substantially enhanced the ΔF/F ₀ from 3.45 and 4.35 to 7.00 and 10.68, which was attributed to the reduced electrostatic repulsion and facilitated probe adsorption. Under the optimized conditions, the proposed aptasensor exhibited linear detection ranges of 0.05–200 ng/mL for both OTA and AFB1, with limits of detection of 15.7 pg/mL and 8.6 pg/mL, respectively. The assay could be completed within 40 min without complicated separation procedures. In addition, the sensor demonstrated high selectivity, repeatability, and reproducibility. In individual target assays, recoveries of 94.1%–108.0% were obtained in spiked red wine and corn flour samples, and the analytical results agreed well with certified reference values. Furthermore, analysis of mixed OTA/AFB1 samples with varying target ratios yielded acceptable recoveries of 94.5%–111.0%, confirming independent and interference‐free dual‐target quantification. Compared with previously reported methods, the developed platform combines simultaneous dual‐target detection, a broad linear range, low detection limits, and a relatively short assay time within a single assay. These results indicate that the proposed aptasensor is a useful tool for rapid multiplex mycotoxin monitoring and food safety analysis.

In this work, MB-loaded DNA nanoflowers were prepared as signal probes, and a high-sensitivity electrochemical aptasensor for acrylamide detection was successfully constructed with excellent analytical performance.

A self-calibrated ratiometric electrochemical aptasensor was developed for the detection of ochratoxin A. This sensor is based on DNA-mediated gold/prussian blue nanoflowers (Au/PB NFs), methylene blue/platinum/zinc-cobalt metal-organic framework (MB/Pt/ZnCo MOF), and an exonuclease III (Exo III)–driven bipedal DNA walker cyclic amplification strategy. The self-calibration mechanism of this sensor relies on the ratio between the response signal of MB/Pt/ZnCo MOF (I_MB) and the internal reference signal of Au/PB NFs (I_PB). This ratio can effectively resist external interference factors. DNA-mediated Au/PB NFs with a flower-like structure provide stable internal reference signals and promote electron transfer. MB/Pt/ZnCo MOF, leveraging ZnCo MOF with a porous structure and bimetallic synergistic effects, and Pt with electrocatalytic activity, serve as response signals. An Exo III–driven biped DNA walker was used to realize the cyclic amplification strategy. The sensor showed a wide linear range of 0.001~500 ng/mL, with a low limit of detection of 0.17 pg/mL. The detection capability of spiked corn flour, wine, and coffee powder samples was satisfactory, and the detection results for the quality control samples of coarse rice flour and wheat flour were not significantly different from those of high-performance liquid chromatography (HPLC), showing the potential for practical application.

Cobalt, a rare element in the Earth’s crust, is widely used in industries due to its hardness and antioxidant properties. It also plays a vital role in physiological functions, being a key component of vitamin B₁₂. However, excessive cobalt intake can cause health issues. Detecting cobalt ions, especially Co²⁺, in food is crucial due to potential contamination from various sources. Fluorescent probes offer high sensitivity, selectivity, a rapid response, and ease of use, making them ideal for the accurate and efficient recognition of Co²⁺ in complex samples. In this context, a highly selective fluorescent probe, 2,2′-((3-(1H-benzo[d]imidazol-2-yl)-1,2-phenylene) bis(oxy)) bis(N-(quinolin-8-yl) acetamide) (DQBM-B), was synthesized using chloroacetyl chloride, 8-aminoquinoline, 2,3-dihydroxybenzaldehyde, and benzidine as raw materials for the recognition of Co²⁺. Probe DQBM-B can exhibit fluorescence alone in DMF. However, as the concentration of Co²⁺ increased, Photoinduced Electron Transfer (PET) occurred, which quenched the original fluorescence of the probe. Probe DQBM-B shows better selectivity for Co²⁺ than other ions with high sensitivity (detection limit: 3.56 μmol L⁻¹), and the reaction reaches equilibrium within 30 min.

Current detection methods for trace mycotoxins in the environment suffer from false negatives, false positives, or low accuracy. Therefore, it is important to establish a sensitive and efficient mycotoxin detection method for food safety. In this study, a novel fluorescent aptamer sensor is proposed by interacting layered MoSe₂ nanosheets (MoSe₂ NSs) with a zearalenone (ZEN) aptamer‐functionalised FAM probe (Apt‐FAM) that specifically binds to ZEN. The proximity of the fluorescent moiety FAM to MoSe₂ NSs resulted in fluorescence quenching. With the presence of ZEN, Apt‐FAM can specifically bind ZEN. Using ribonucleic acid exonuclease III (Exo III) as an auxiliary signal amplification and triggering surface desorption of MoSe₂ NSs allows fluorescence signals to be recovered. Under optimal conditions, the sensor had a detection range of 0.05–100 ng/mL. The limit of detection (LOD) for ZEN in the range of 0.05–1 ng/mL was 6.4 pg/mL and the LOD for ZEN in the range of 5–100 ng/mL was 4.4 pg/mL. Furthermore, the aptasensor successfully measured ZEN levels in commercially bought corn and beer with satisfactory results.

Mercury(II) ions (Hg²⁺) are heavy metal ions that can cause human poisoning and can lead to death in severe cases. Therefore, establishing a rapid quantitative detection method for Hg²⁺ is important for protecting human health. In this study, a portable hydrogel-based fluorescent aptasensor was developed for the rapid and quantitative detection of Hg²⁺. A type of RCA/G-quadruplex product was designed during the rolling circle amplification (RCA) process. By combining it with the thioflavin T (ThT) fluorescent dye, a highly efficient RCA-ThT fluorescent probe was obtained, which could sensitively and efficiently recognise Hg²⁺. Furthermore, the RCA-ThT fluorescent probe was physically combined with a hydrogel to construct a novel hydrogel-based fluorescent sensor. The hydrogel combined with the RCA-ThT fluorescent probe was dropped onto the lid of a centrifuge tube. The solution containing Hg²⁺ was added to the same centrifuge tube. The centrifuge tube was inverted so that the solution will come into contact with the sensor. This enabled portable rapid detection, which fully complies with the basic requirements of Point-of-Care Testing (POCT). Additionally, the RGB values were obtained through photo capture, and colorimetric analysis was performed to determine the exact content of Hg²⁺ using the WeChat App. The portable hydrogel-based fluorescent aptamer sensor offered a detection limit of 0.044 μmol L⁻¹ for Hg²⁺ and a detection range of 1–100 μmol L⁻¹. The sensor exhibited good stability and immediate detection capabilities, showing promising application prospects in food safety monitoring.