Sandwich fluorometric method for dual-role recognition of Listeria monocytogenes based on antibiotic-affinity strategy and fluorescence quenching effect

A Dual-Mode Colorimetric and Fluorescence Biosensor Based on a Nucleic Acid Multiplexing Platform for the Detection of Listeria monocytogenes

Listeria monocytogenes (L. monocytogenes) is one of the most prevalent threats, capable of inducing diverse illnesses and presenting a serious threat to public health. Herein, we demonstrate a novel dual-mode colorimetric/fluorescence biosensor based on the exponential amplification reaction and strand displacement reactions (EASDR), which has multiplexing capability that significantly promotes the anchoring and trapping of Pt nanoparticles (Pt NPs) and fluorescent dyes for sensitive detection of Listeria monocytogenes (L. monocytogenes). The method works by targeting specific bacteria with aptamers and promoting repeated EASDR to affect the immobilization of Pt NPs and fluorescent dyes in the orifice plate, which could produce changes in fluorescence and colorimetric signals. The assay achieves a detection limit of 38 CFU/mL in colorimetric and 10 CFU/mL in fluorescence. Furthermore, the developed biosensor can be applied to the analysis of raw food samples (milk), and good recoveries were obtained in spiked food samples. In summary, the dual-mode biosensor improves the accuracy of detection by simultaneously outputting two signals and shows great potential in the specific identification and detection of foodborne pathogens.

Advancing foodborne pathogen detection: a review of traditional and innovative optical and electrochemical biosensing approaches

Foodborne diseases are a significant cause of morbidity (600 million cases) and mortality (420,000 deaths) worldwide every year and are mainly associated with pathogens. Besides the direct effects on human health, they have relevant concerns related to financial, logistics, and infrastructure for the food and medical industries. The standard pathogen identification techniques usually require a sample enrichment step, plating, isolation, and biochemical tests. This process involves specific facilities, a long-time analysis procedures, and skilled personnel. Conversely, biosensors are an emerging innovative approach to detecting pathogens in real time due to their portability, specificity, sensitivity, and low fabrication costs. These advantages can be achieved from the synergistic work between nanotechnology, materials science, and biotechnology for coupling biomolecules in nano-matrices to enhance biosensing performance. This review highlights recent advancements in electrochemical and optical biosensing techniques for detecting bacteria and viruses. Key properties, such as detection limits, are examined, as they depend on factors like the design of the biorecognition molecule, the type of transducer, the target's characteristics, and matrix interferences. Sensitivity levels reported range from 1 to 1 × 10⁸ CFU/mL, with detection times spanning 10 min to 8 h. Additionally, the review explores innovative approaches, including biosensors capable of distinguishing between live and dead bacteria, multimodal sensing, and the simultaneous detection of multiple foodborne pathogens - emerging trends in biosensor development.

Sensitive and specific detection of Listeria monocytogenes in food samples using imprinted upconversion fluorescence probe prepared by emulsion polymerization method

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen with high morbidity and mortality rates, necessitating rapid detection methods. Current techniques, while reliable, are labor-intensive and not amenable to on-site testing. We report the design and synthesis of a novel imprinted upconversion fluorescence probe through Pickering emulsion polymerization for the specific detection of L. monocytogenes. The probe employs trimethylolpropane trimethacrylate and divinylbenzene as cross-linkers, acryloyl-modified chitosan as a functional monomer, and the bacterium itself as the template. The developed probe demonstrated high specificity and sensitivity in detecting L. monocytogenes, with a limit of detection of 72 CFU/mL. It effectively identified the pathogen in contaminated salmon and chicken samples, with minimal background interference. The integration of molecular imprinting and upconversion fluorescence materials presents a potent and reliable approach for the rapid and specific detection of L. monocytogenes, offering considerable potential for on-site food safety testing.

Flower-Shaped PCR Scaffold-Based Lateral Flow Bioassay for Bacillus cereus Endospores Detection

Bacillus cereus, a foodborne pathogen, produces resilient endospores that are challenging to detect with conventional methods. This study presents a novel Flower-Shaped PCR Scaffold-based Lateral Flow Biosensor (FSPCRS-LFB), which employs an aptamer-integrated PCR scaffold as capture probes, replacing the traditional streptavidin-biotin (SA-Bio) approach. The FSPCRS-LFB demonstrates high sensitivity and cost-efficiency in detecting B. cereus endospores, with a limit of detection (LOD) of 4.57 endospores/mL a visual LOD of 102 endospores/mL, and a LOD of 6.78 CFU/mL for endospore-cell mixtures. In chicken and tea samples, the platform achieved LODs of 74.5 and 52.8 endospores/mL, respectively, with recovery rates of 82.19% to 97.88%. Compared to existing methods, the FSPCRS-LFB offers a 3.7-fold increase in sensitivity while reducing costs by 26% over the SA-Bio strategy and 87.5% over rolling circle amplification (RCA). This biosensor provides a rapid, sensitive and cost-effective solution for point-of-care testing (POCT) of B. cereus endospores, expanding detection capabilities and offering novel approaches for pathogen detection.

Aptamers: precision tools for diagnosing and treating infectious diseases

Infectious diseases represent a significant global health challenge, with bacteria, fungi, viruses, and parasitic protozoa being significant causative agents. The shared symptoms among diseases and the emergence of new pathogen variations make diagnosis and treatment complex. Conventional diagnostic methods are laborious and intricate, underscoring the need for rapid, accurate techniques. Aptamer-based technologies offer a promising solution, as they are cost-effective, sensitive, specific, and convenient for molecular disease diagnosis. Aptamers, which are single-stranded RNA or DNA sequences, serve as nucleotide equivalents of monoclonal antibodies, displaying high specificity and affinity for target molecules. They are structurally robust, allowing for long-term storage without substantial activity loss. Aptamers find applications in diverse fields such as drug screening, material science, and environmental monitoring. In biomedicine, they are extensively studied for biomarker detection, diagnostics, imaging, and targeted therapy. This comprehensive review focuses on the utility of aptamers in managing infectious diseases, particularly in the realms of diagnostics and therapeutics.

An upconversion biosensor based on inner filter effect for dual-role recognition of sulfadimethoxine in aquatic samples

Sulfadimethoxine (SDM) as an extensively employed veterinary drug causes potential threats to human health. Herein, a dual recognition mode novel upconversion fluorescence biosensor was designed based on inner filter effect (IFE) to sensitively and rapidly detect SDM in aquatic samples. Aldehyde-functionalized magnetic nanoparticles (MNPs) were applied to recognize and capture SDM, followed by specifically bond with biotin-labeled aptamers. The upconversion nanoparticles and the colored products resulting from the enzyme-catalyzed oxidation of 3,3,5,5-tetramethylbenzidine exhibited an IFE quenching process. Under the optimal condition, the results displayed the fluorescence intensity was correlated with the concentration of SDM within the range of 0.5-1000 ng⋅mL-1 achieving a low limit of detection of 0.13 ng⋅mL-1. The SDM detection system was further employed in the spiked aquatic samples with good recoveries (88.41-96.78 %). Consequently, the constructed fluorescence biosensor provided broad prospects for accuracy and rapid detection of SDM.

Upconversion Fluorescence Nanoprobe-Based FRET for the Sensitive Determination of Shigella

Shigella as a typical foodborne pathogen has strong survivability in the environment or food, leading to infectious diseases, yet its rapid detection technology with high selectivity and sensitivity remains challenging. In this study, complementary strand modified upconversion nanoparticles (UCNPs) can offer stable yellow-green fluorescence at 500–700 nm excited by a 980 nm laser. Importantly, Shigella aptamer modified gold nanoparticles (GNPs) formed by “Au−S” bond act as a fluorescence resonance energy transfer (FRET) donor and recognition element that can bind specifically to Shigella and significantly quench the fluorescence of complementary strand modified UCNPs. As a result, the fluorescence of our developed nanoprobe increased linearly with the increase in Shigella in a wide range from 1.2 × 10² to 1.2 × 10⁸ CFU/mL and the detection limit was as low as 30 CFU/mL. Moreover, the fabricated upconversion fluorescence nanoprobe can achieve Shigella detection in contaminated chicken without enrichment in 1 h.