Hongshuo Chen

Food safety is crucial for human health, and the development of rapid and sensitive detection technologies is of great significance for pollutant monitoring. The integration of electrochemical and optical approaches in dual‐mode aptamer (APT) sensors has been shown to enhance detection reliability via complementary signal verification. While current implementations focus mainly on single‐target detection, the modularity of APT recognition elements and the multiplexing capability of optical readouts such as surface‐enhanced Raman spectroscopy (SERS) and fluorescence, provide a clear route toward simultaneous ultratrace monitoring of multiple contaminants in future developments. This review comprehensively evaluated the working principles and analytical performance of dual‐mode sensors, including electrochemical‐colorimetric, electrochemical‐fluorescent, and electrochemical‐SERS, among others, as well as focused on the impact of their integrated signal amplification strategies on sensitivity and detection range. Studies have shown that dual‐mode sensors perform well in the laboratory, but still face some challenges such as insufficient stability of nanomaterials, limited multi‐target detection capability of APTs and high cost of equipment. In order to further promote its practical application in the field of food safety, this paper also provided theoretical framework on the optimization and innovation of dual‐modal sensing technology, to facilitate the construction of an efficient food contaminant monitoring system.

Developing a reliable detection method for aflatoxin B ₁ (AFB ₁ ) is urgent due to its potent hepatocarcinogenic effects. An electrochemical aptamer sensor based on competitive binding was prepared for the rapid detection of AFB ₁ in this study. Poly(amideamine) dendrimers were electrodeposited onto a screen‐printed gold electrode to enhance aptamer loading via amine group conjugation. The chemically synthesized gold nanostars can further improve electron transfer kinetics and provide additional binding sites for single‐stranded DNA probes. Bioprobe and modified electrode were comprehensively characterized by transmission electron microscope, scanning electron microscopy, Zeta potential, energy dispersive spectroscopy, selected area electron diffraction, X‐ray photoelectron spectroscopy, and atomic force microscope. Differential pulse voltammetry (DPV) and square wave voltammetry (SWV) of pulse voltametric techniques were executed separately in AFB1 solutions for testing the performance of this prepared biosensor. Comparative analysis revealed that both methods exhibited a linear detection range of 10 ⁻⁴ to 10 ³ ng/mL for AFB ₁ . Nevertheless, the DPV method achieved a lower limit of 2.25 × 10 ⁻⁵ ng/mL than the SWV method, with a detection limit of 3.18 × 10 ⁻⁵ ng/mL. Meanwhile, the developed biosensor showed excellent stability and reproducibility, establishing its reliability for AFB ₁ quantification in complex matrices.

Due to the price and demand of Ophiocordyceps sinensis having increased dramatically, adulteration with other fungi is a common problem. Thus, a reliable method of authentic O. sinensis identification is essential. In the present work, a rapid DNA extraction and double-tailed recombinase polymerase amplification (RPA) coupled with nucleic acid hybridization lateral flow strip (NAH-LFS) was developed to distinguish authentic O. sinensis ingredients from other fungi substitutes. In the presence of O. sinensis, the RPA amplicons with two ssDNA tails in the opposite ends, which could simultaneously bind with the SH-probes on gold nanoparticles (AuNPs) and capture the probe on the test line, formed visible red bands. RPA combined with NAH-LFS can efficiently detect O. sinensis DNA down to 1.4 ng/μL; meanwhile, the specificity test validated no cross reaction with common adulterants, including Cordyceps gunnii, Cordyceps cicadae, Cordyceps militaris, yungui Cordyceps, and Ophiocordyceps nutans. The whole RPA-NAH-LFS could be completed within 16 min. The RPA-NAH-LFS results in detecting 20 commercial O. sinensis samples are consistent with PCR-AGE and RT-PCR, confirming the feasibility of the RPA-NAH-LFS method. In conclusion, these results are expected to facilitate the application of RPA-NAH-LFS in the authentication detection of O. sinensis materials, providing a convenient and efficient method for O. sinensis quality control.

In this study, a novel electrochemical aptamer sensor for detecting ochratoxin A (OTA) was constructed. First, a gold-copper alloy film was prepared via electrochemical deposition, and copper was selectively dissolved in constant potential mode for obtaining the nano-porous gold modified screen-printed carbon electrodes (NPG/SPCE). Then, 2-mercaptoethylamine was dropped on the NPG/SPCE surface and Au-S covalent bonds were formed for immobilizing the metal. Glutaraldehyde as cross-linking agent was added, which resulted in immobilization and attachment of PAMAM to the 2-mercaptoethylamine through the dehydration condensation reaction. During the preparation process, the nano-porous gold and PAMAM-modified layers were characterized by SEM, XRD, and IR spectroscopy, respectively. The characterization results showed that the nano-porous gold and PAMAM composite films were successfully modified. Finally, the OTA aptamer was cross-linked with PAMAM by glutaraldehyde to complete construction of the Apt/PAMAM/NPG/SPCE sensor. The electrochemical performance of this sensor was tested in ochratoxin A solutions with the DPV method. The results showed that the sensor's reproducibility, stability, and specificity were good. The spiked recoveries in red wine ranged from 99.65%∼101.6%, with a linear range of 0.5 ng/mL∼20 ng/mL and a minimum detection limit of 0.141 ng/mL. Thus, the novel biosensor may provide a promising tool for the trace detection of OTA.

The detection of harmful components in food is of paramount importance in the light of recent food safety incidents caused by foodborne pathogenic bacteria. Aptamer electrochemical biosensors are novel biosensors that use electrode modifications to immobilise aptamers, the biological recognition elements, and then use electrochemical techniques to detect the generated electrical signals. Compared with traditional detection methods, electrochemical aptamer sensors have the advantages of high specificity, high sensitivity, and low cost and have been widely used to detect hazardous components in food. This review summarises these sensors′ current research status and problems in detecting common foodborne pathogenic bacteria and provides an outlook on their development trends.

In this study, a simple label-free biosensor for Brucella was constructed, which based on the screen-printed carbon electrode (SPCE) modified by Recombinant protein G/gold nanoparticles/graphene oxide (RpG/Au/GO). The impedance responses of the proposed biosensor were measured by electrochemical AC impedance method in Brucella antigen gradient concentration solutions. The results showed that the linear range of this biosensor was from 1.6 × 10² CFU/mL to 1.6 × 10⁸ CFU/mL with the minimum detection limit of 3.2 × 10² CFU/mL (S/N = 3). Moreover, the biosensor for Brucella detection possessed acceptable reproducibility with a relative standard deviation of 5.15% and acceptable stability with a relative standard deviation of 4.68%. The spiked recovery rate in actual pasteurized milk samples was more than 92%. Therefore, the developed biosensor exhibits excellent prospects in the selective quantification detection of Brucella abortus.