Paper-Based Biosensor Using Dual-Recognition Molecules for Detection of Staphylococcus aureus in Milk

A Superparamagnetic Platform Enhanced with Metal-Modified Carbon Dots for Rapid Dual-Modal Detection of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a significant pathogen that causes foodborne diseases. Meat, with its abundant nutrients and high water activity, constitutes an ideal niche for S. aureus colonization. Numerous studies have shown that human digestive tract diseases caused by consuming meat products contaminated with S. aureus occur frequently. It is of great significance to strictly monitor S. aureus in meat matrices. A novel biosensor employing dual-signal output was developed through the combination of efficient magnetic separation and dual-modal precise detection. Designed for the rapid enrichment of S. aureus, it significantly boosts detection sensitivity and accuracy, thereby enabling the earlier identification of potential contamination sources. This method uses vancomycin-modified magnetic beads as the capture element, and aptamer-modified nanozymes as the signal element. After magnetic separation, the 3,3′,5,5′-tetramethylbenzidine color reaction can be used to quickly and sensitively detect S. aureus. It achieved a detection limit as low as 10 cfu/mL. Moreover, this dual-signal sensor based on efficient magnetic separation can sensitively detect S. aureus in meat products, thus showing good application prospects in food matrices and further improving the reliability and specificity of detection.

Dual-ligand quantum dot biosensor combining IgY antibodies and DNA aptamers for rapid, on-site detection of staphylococcal enterotoxin A (SEA) in food matrices.

Aptamer-Based Fluorescent Biosensors for Kanamycin Detection in Food Systems: Design Strategies, Sensing Mechanisms, and Practical Applications

Kanamycin (KANA), a widely used aminoglycoside antibiotic in animal husbandry, is associated with residue accumulation in foods due to improper use, threatening food safety. Detecting trace KANA in complex food systems such as dairy, meat, and apicutural products remains challenging because of matrix interferences (e.g., proteins, lipids, and co-existing ions) and limitations of conventional methods, which require labor-intensive pretreatment and sophisticated instrumentation. Aptamer-based fluorescent biosensors have emerged as promising tools for rapid, sensitive KANA detection with high specificity and on-site analysis potential. DNA aptamers act as selective recognition elements that bind KANA and undergo conformational changes for efficient signal transduction. This review summarizes recent advances in fluorescent aptasensors for KANA detection, with an emphasis on food system applications. Aptamer selection strategies are outlined, highlighting split aptamers’ advantages in binding precision and structural stability. Labeled and label-free sensing modes are compared in terms of design principles, analytical performance, and suitability for complex food matrices. Attention is paid to strategies for mitigating matrix interference and improving detection reliability in real samples. Despite progress, challenges remain in sensor stability, reproducibility, and on-site deployment. Overall, aptamer-based fluorescent biosensors provide a powerful platform for rapid antibiotic residue monitoring and advance food safety-oriented sensing technologies.

Recent Progress in Nanoparticle-Based Biosensors for Monitoring Shigella spp. in Food Safety: A Critical Review

Shigella is a foodborne bacterial pathogen with a low infectious dose and significant public health impact. Culture-based and molecular techniques provide reliable identification but are time-consuming. Nanoparticle-based biosensors offer sensitive, selective, and compact alternatives. Recent advances in nanoparticle-based biosensors for Shigella spp. (S. flexneri, S. sonnei, S. dysenteriae, and S. boydii) detection have been reviewed in terms of signal amplification, biorecognition, biological targets, sensor types, and performance in real food matrices. Detection strategies rely on gene-level and whole-cell recognition. Targeting virulence genes, invasion plasmid antigen H (ipaH), provides stable genus-level identification, whereas whole-cell recognition facilitates rapid detection without extensive sample preparation. Optical biosensors, including fluorescence-based methods, surface-enhanced Raman spectroscopy (SERS), and localized surface plasmon resonance (LSPR), achieve low detection limits with strong tolerance to complex food matrices. Electrochemical biosensors offer operational simplicity, portability, and suitability for food screening. Lateral flow and hybrid systems provide rapid detection through simplified assay formats and visual readout, with performance influenced by the balance between speed and sensitivity. Validation in real food matrices shows acceptable recoveries, minimal cross-reactivity, and agreement with reference methods. This overview provides a design-oriented framework for nanoparticle-based biosensor selection in food safety by integrating nanomaterial function, biosensor design, and performance characteristics.

Rapid Broad-Spectrum Colorimetric Detection of Bacteria Using Polylysine-Mediated Gold Nanoparticle Aggregation.

Rapid on-site detection of bacterial contamination remains an urgent need in public health and environmental monitoring. Herein, we report a one-step, label-free colorimetric sensor for broad-spectrum bacterial detection based on a competitive electrostatic mechanism. Cationic poly-l-lysine (PLL) induces the aggregation of anionic, citrate-capped gold nanoparticles (AuNPs), resulting in a distinct red-to-blue color change. In the presence of bacteria, their negatively charged surfaces adsorb PLL, thereby inhibiting AuNP aggregation and maintaining the red color of the dispersion. This strategy enables the visual detection of various Gram-positive and Gram-negative bacteria within 10 min. Using Escherichia coli (E. coli) as a model analyte, the assay reached a detection limit of 720 CFU/mL under the optimized conditions (5 μg/mL PLL, 3 min incubation, 20 mM phosphate buffer at pH 7.5) and exhibited a wide detection range from 102 to 107 CFU/mL (R2 > 0.99). The assay also performed reliably in spiked tap water and drinking water samples, with recoveries of 82-96% and CVs below 10%, demonstrating its potential as a rapid, low-cost screening tool for bacterial contamination in low-matrix water samples.

Multiplex Optical Detection of Bacteria in Water Using a Cell Imprinted Polymer-Based Microfluidic Sensor

Rapid detection of pathogenic bacteria in water is essential for environmental monitoring and public health. Here, we present a duplex microfluidic fluorescence sensor based on bacteria-specific cell-imprinted polymer (CIP) thin films for simultaneous detection of Salmonella enterica and Escherichia coli O157:H7. The sensor is fabricated using a simple, lithography-free approach, where CIP and nonimprinted polymer films are formed directly within laser-cut pressure-sensitive adhesive microchannels on a polymethyl methacrylate substrate. An orthogonal channel design creates six discrete sensing regions, enabling parallel and independent analysis. Detection is achieved through selective bacterial capture within imprinted cavities followed by FITC-based fluorescence readout. The sensor exhibits a concentration-dependent response over 104–107 CFU/mL, with a practical limit of detection of ∼105 CFU/mL. Competitive assays confirm high selectivity, with each CIP region responding preferentially to its target and minimal cross-reactivity in mixed-sample conditions. In addition, the sensor was successfully validated using Salmonella-spiked tap water samples, maintaining a concentration-dependent response, and demonstrating its applicability in realistic water matrices. The platform provides a low-cost, scalable, and portable solution for multiplex bacterial detection, with strong potential for field-deployable water quality monitoring applications.