Salmonella is one of the main causes of foodborne infectious diseases, posing a serious threat to public health. It can enter the food supply chain at various stages of production, processing, distribution, and marketing. High prevalence of Salmonella necessitates efficient and effective approaches for its identification, detection, and monitoring at an early stage. Because conventional methods based on plate counting and real‐time polymerase chain reaction are time‐consuming and laborious, novel rapid detection methods are urgently needed for in‐field and on‐line applications. Biosensors provide many advantages over conventional laboratory assays in terms of sensitivity, specificity, and accuracy, and show superiority in rapid response and potential portability. They are now recognized as promising alternative tools and one of the most on‐site applicable and end user–accessible methods for rapid detection. In recent years, we have witnessed a flourishing of studies in the development of robust and elaborate biosensors for detection of Salmonella in food. This review aims to provide a comprehensive overview on Salmonella biosensors by highlighting different signal‐transducing mechanisms (optical, electrochemical, piezoelectric, etc.) and critically analyzing its recent trends, particularly in combination with nanomaterials, microfluidics, portable instruments, and smartphones. Furthermore, current challenges are emphasized and future perspectives are discussed.

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Exploring new functions of nanomaterials can help facilitate the development of biosensors for the detection of antibiotics. Herein, a new detection modality based on monovalent antigen-induced aggregation (MAA) of immunomagnetic beads (IMBs) was proposed for rapid and label-free detection of enrofloxacin (ENR), which endowed IMBs with the abilities of both sample separation and signal generation. In the presence of ENR, the initially well-dispersed IMBs were aggregated and the degree of aggregation was in a concentration-dependent manner. After exploring the mechanism underlying IMB aggregation and investigating the key parameters affecting it, a label-free biosensing platform was developed for rapid and sensitive detection of ENR. Based on the significant differences in the magnetic separation speed and size between the aggregated and well-dispersed IMBs, two methods were proposed for quantitatively determining ENR, i.e., measuring the turbidity of the IMB supernatant after magnetic separation for a given time and visualizing and calculating the grayscale value of the aggregated IMBs trapped on the surface of a nitrocellulose membrane. A three-dimensional (3D)-printed syringe was designed and fabricated for automatic filtration of IMBs. This immunosensor allowed for sensitive detection of ENR in less than 15 min without any labels. It exhibited a satisfactory limit of detection of 0.79 ng mL–1 and showed the feasibility for ENR detection of spiked chicken meat with recovery rates ranging from 74.8 to 98.3%. The MAA immunosensor can act as a promising tool to detect trace levels of ENR and has the potential to be applied to complex food samples.

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HighlightsA nanobiosensor was developed for rapid detection of enrofloxacin residues in chicken meat.5-Sulfosalicylic acid was adopted in a facile method for pretreatment of chicken meat samples.The detection limit of 14.1 µg kg-1 was below the maximum residue limit for chicken meat.The total detection time from sample pretreatment to result report was less than 1.5 h.Abstract. Antibiotic residues in animal-derived food products have been identified as a potential hazard in human health. Hence, a rapid, simple, and cost-effective method for detection of antibiotics in the food supply chain is highly desirable. The objective of this study was to develop a nanomaterial-based biosensor using immunomagnetic beads (IMBs) and quantum dots (QDs) for rapid and sensitive detection of enrofloxacin (ENR) residues in raw chicken. A 5-sulfosalicylic acid-based pretreatment method was adopted to extract ENR from chicken meat and reduce non-specific adsorption caused by complex food matrices. Two sensing elements were designed and fabricated: antibody functionalized IMBs and ENR-bovine serum albumin (BSA) conjugates modified QDs (QDs-BSA-ENR). Target ENR in samples was first captured and separated by IMBs, and then QDs-BSA-ENR, serving as a competitor and detection probe, was used to react with the residual binding sites on the IMB surfaces. With the presence of captured ENR, the binding of QDs-BSA-ENR to IMBs was competitively inhibited. Finally, the fluorescence intensity of reporting QDs in the QDs-BSA-ENR-IMBs complex at a wavelength of 614 nm was measured for the quantitation of target antibiotics. Under the optimum conditions, the proposed method allowed sensitive detection of ENR in a linear range from 1 to 100 ng mL-1 with a limit of detection (LOD) of 0.94 ng mL-1. The LOD for spiked chicken meat was 14.1 µg kg-1, which was below the maximum residue limits (MRLs) regulated in China and the European Union. The whole analytical procedure from food sampling to result report could be finished in less than 1.5 h. This nanobiosensor showed high potential for rapid and low-cost detection of ENR residues in the poultry supply chain to enhance food safety. Keywords: Enrofloxacin, Immunomagnetic beads, Nanobiosensor, Poultry, Quantum dots, Rapid detection.

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Antibiotic residues in foods pose a serious threat to human health. However, routine analysis techniques require bulky laboratory instruments and skilled personnel or give single-channel analysis results, exhibiting low practicality....

HighlightsA practical magnetic separation device was designed, fabricated, and evaluated for enrofloxacin detection.Coupled with a fluorescent biosensor, the device could automatically process a sample in 50 min.The device performed incubation and magnetic separation using a pipette method.The device has the advantages of low-cost and feasibility for on-site detection.Abstract. Antibiotic residues have been a continuing concern in food safety, raising a great issue in human health. For rapid detection of antibiotics, an automated device was developed that can capture and separate a target analyte based on immunomagnetic beads. This automated separation device is suitable for separating the magnetic beads in a preprocessing step, with liquid transfer and magnetic enrichment functions. The device was combined with a fluorescent biosensor to simplify the cumbersome pretreatment of enrofloxacin. In our experiments, enrofloxacin in water samples was used as the detection object, and the entire process could be completed in less than 50 min with automated operation. The lower limit of detection reached 54 ng mL-1 (S/N = 3). The fluorescent biosensor has been enhanced with this automated separation device for more sensitive rapid detection of antibiotic residues in the food supply chain and environment. Keywords: Antibiotic detection, Automation, Fluorescent biosensor, Immunomagnetic separation, Sample pretreatment.