A review of rapid food safety testing: using lateral flow assay platform to detect foodborne pathogens

Multifunctional Fe3O4@CuS nanoparticle-driven colorimetric and photothermal immunochromatographic test strip for the sensitive detection of Salmonella typhimurium in milk

Magnetic nanoparticles are widely employed as signal labeling reporters in immunochromatographic test strips (ICTS) for detecting foodborne pathogens due to their outstanding anti-interference and magnetic enrichment performance. However, the insufficient colorimetric signal brightness of magnetic nanoparticles results in poor sensitivity, hindering their ability to meet the growing demand for advanced ICTS. Herein, we synthesized Fe3O4@CuS core-shell structure nanoparticles using a facile in-situ growth method. These Fe3O4@CuS nanoparticles exhibit a superior photothermal conversion efficiency of 42.12 % and a magnetization strength of 35 emu/g. We developed a dual-readout format ICTS based on Fe3O4@CuS, incorporating both colorimetric and photothermal formats to enhance sensitivity for Salmonella typhimurium detection. The limit of detection for Fe3O4@CuS-ICTS in the colorimetric and photothermal format was 5 × 10⁴ CFU/mL and 7.7 × 10³ CFU/mL, respectively. Additionally, the average recoveries ranged from 91.25 % to 103.39 %, with variations from 2.2 % to 11.1 %, demonstrating good accuracy and precision. Therefore, this work suggests that Fe3O4@CuS nanoparticles, with their superior magnetic, optical, and photothermal properties, can serve as promising signal labeling reporters to improve the detection performance of ICTS and hold potential for constructing more accurate and sensitive point-of-care testing platforms.

Decentralized food safety and authentication on cellulose paper-based analytical platform: A review

Food safety and authenticity analysis play a pivotal role in guaranteeing food quality, safeguarding public health, and upholding consumer trust. In recent years, significant social progress has presented fresh challenges in the realm of food analysis, underscoring the imperative requirement to devise innovative and expedient approaches for conducting on-site assessments. Consequently, cellulose paper-based devices (PADs) have come into the spotlight due to their characteristics of microchannels and inherent capillary action. This review summarizes the recent advances in cellulose PADs in various food products, comprising various fabrication strategies, detection methods such as mass spectrometry and multi-mode detection, sampling and processing considerations, as well as applications in screening food safety factors and assessing food authenticity developed in the past 3 years. According to the above studies, cellulose PADs face challenges such as limited sample processing, inadequate multiplexing capabilities, and the requirement for workflow integration, while emerging innovations, comprising the use of simplified sample pretreatment techniques, the integration of advanced nanomaterials, and advanced instruments such as portable mass spectrometer and the innovation of multimodal detection methods, offer potential solutions and are highlighted as promising directions. This review underscores the significant potential of cellulose PADs in facilitating decentralized, cost-effective, and simplified testing methodologies to maintain food safety standards. With the progression of interdisciplinary research, cellulose PADs are expected to become essential platforms for on-site food safety and authentication analysis, thereby significantly enhancing global food safety for consumers.

Emerging Nano/Microporous Architectures for Food Hazards: New Strategies for Precise Inspection and New Principles for Controllable Regulation

The big progress of materials science along with chemical engineering and biotechnology has significantly promoted interdisciplinary development, achieving advanced analytical methodologies, improved inspection performance, as well as promising regulation principles for food safety. The very recent progress on nano/microporous architectures for agri-food science, including new strategies for precise inspection and new principles for controllable regulation of food hazards, are summarized and discussed. Major attention is paid to the newly emerged porous architectures with their derivative nano/microstructures contributing to food safety through their instinctive advantages including special material surface, extraordinary porous structure, ease-of-modification, and excellent diversity and variability. This review clearly and logically displays the research road maps and development trends for current food safety issues and give suggestive directions for future outlook as well as the bottleneck problems to be solved, not only smart inspection and analysis but also elimination and control of ever-emerging food hazards.

Sample preparation and detection methods in point-of-care devices towards future at-home testing

Timely and accurate diagnosis is critical for effective healthcare, yet nearly half the global population lacks access to basic diagnostics. Point-of-care (POC) testing offers partial solutions by enabling low-cost, rapid diagnosis at the patient's location. At-home POC devices have the potential to advance preventive care and early disease detection. Nevertheless, effective sample preparation and detection methods are essential for accurate results. This review surveys recent advances in sample preparation and detection methods at POC. The goal is to provide an in-depth understanding of how these technologies can enhance at-home POC devices. Lateral flow assays, nucleic acid tests, and virus detection methods are at the forefront of POC diagnostic technology, offering rapid and sensitive tools for identifying and measuring pathogens, biomarkers, and viral infections. By illuminating cutting-edge research on assay development for POC diagnostics, this review aims to accelerate progress towards widely available, user-friendly, at-home health monitoring tools that empower individuals in personalized healthcare in the future.

Recombinase polymerase amplification combined with lateral flow biosensor for rapid visual detection of Clostridium perfringens in chicken meat and milk

Aims

Clostridium perfringens is one of the major anaerobic pathogen causing food poisoning and animal enteritis. With the rise of antibiotic resistance and the restrictions of the use of antibiotic growth promoting agents (AGPs) in farming, Clostridium enteritis and food contamination have become more common. It is time-consuming and labor-intensive to confirm the detection by standard culture methods, and it is necessary to develop on-site rapid detection tools. In this study, a combination of recombinase polymerase amplification (RPA) and lateral flow biosensor (LFB) was used to visually detect C. perfringens in chicken meat and milk.

Methods and results

Two sets of primers were designed for the plc gene of C. perfringens, and the amplification efficiency and specificity of the primers. Selection of primers produces an amplified fragment on which the probe is designed. The probe was combined with the lateral flow biosensor (LFB). The reaction time and temperature of RPA-LFB assay were optimized, and the sensitivity of the assay was assessed. Several common foodborne pathogens were selected to test the specificity of the established method. Chicken and milk samples were artificially inoculated with different concentrations (1 × 102 CFU/mL to 1 × 106 CFU/mL) of C. perfringens, and the detection efficiency of RPA-LFB method and PCR method was compared. RPA-LFB can be completed in 20 min and the results can be read visually by the LFB test strips. The RPA-LFB has acceptable specificity and the lowest detection limit of 100 pg./μL for nucleic acid samples. It was able to stably detect C. perfringens contamination in chicken and milk at the lowest concentration of 1 × 104 CFU/mL and 1 × 103 CFU/mL, respectively.

Conclusion

In conclusion, RPA-LFB is specific and sensitive. It is a rapid, simple and easy-to-visualize method for the detection of C. perfringens in food and is suitable for use in field testing work.

Method for lysis and paper-based elution-free DNA extraction with colourimetric isothermal amplification

Nucleic acid amplification testing has great potential for point-of-need diagnostic testing with high detection sensitivity and specificity. Current sample preparation is limited by a tedious workflow requiring multiple steps, reagents and instrumentation, hampering nucleic acid testing at point of need. In this study, we present the use of mixed cellulose ester (MCE) paper for DNA binding by ionic interaction under molecular crowding conditions and fluid transport by wicking. The poly(ethylene) glycol-based (PEG) reagent simultaneously provides the high pH for alkaline lysis and crowding effects for ionic binding of the DNA under high salt conditions. In this study, we introduce Paper-based Abridged Solid-Phase Extraction with Alkaline Poly(ethylene) Glycol Lysis (PASAP). The anionic mixed cellulose ester (MCE) paper is used as solid phase and allows for fluid transport by wicking, eliminating the need for pipetting skills and the use of a magnet to retain beads. Following the release of DNA from the cells due to the lytic activity of the PASAP solution, the DNA binds to the anionic surface of the MCE paper, concentrating at the bottom while the sample matrix is transported towards the top by wicking. The paper was washed by dipping it in 40% isopropanol for 10 s. After air-drying for 30 s, the bottom section of the paper (3 mm × 4 mm) was snapped off using the cap of a PCR tube and immersed in the colourimetric loop-mediated isothermal amplification (cLAMP) solution for direct amplification and colourimetric detection. The total sample processing was completed in 15 min and ready for amplification. cLAMP enabled the detection of 102 CFU/mL of Escherichia coli (E. coli) from culture media and the detection of E. coli in milk < 103 CFU/mL (10 CFU) after incubation at 68 °C for 60 min, demonstrating applicability of the method to complex biological samples.

Raman-Activated Cell Ejection for Validating the Reliability of the Raman Fingerprint Database of Foodborne Pathogens

Raman spectroscopy for rapid identification of foodborne pathogens based on phenotype has attracted increasing attention, and the reliability of the Raman fingerprint database through genotypic determination is crucial. In the research, the classification model of four foodborne pathogens was established based on t-distributed stochastic neighbor embedding (t-SNE) and support vector machine (SVM); the recognition accuracy was 97.04%. The target bacteria named by the model were ejected through Raman-activated cell ejection (RACE), and then single-cell genomic DNA was amplified for species analysis. The accuracy of correct matches between the predicted phenotype and the actual genotype of the target cells was at least 83.3%. Furthermore, all anticipant sequencing results brought into correspondence with the species were predicted through the model. In sum, the Raman fingerprint database based on Raman spectroscopy combined with machine learning was reliable and promising in the field of rapid detection of foodborne pathogens.

Recent Advances in Lateral Flow Assays for Viral Protein Detection with Nanomaterial-Based Optical Sensors

Controlling the progression of contagious diseases is crucial for public health management, emphasizing the importance of early viral infection diagnosis. In response, lateral flow assays (LFAs) have been successfully utilized in point-of-care (POC) testing, emerging as a viable alternative to more traditional diagnostic methods. Recent advancements in virus detection have primarily leveraged methods such as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and the enzyme-linked immunosorbent assay (ELISA). Despite their proven effectiveness, these conventional techniques are often expensive, require specialized expertise, and consume a significant amount of time. In contrast, LFAs utilize nanomaterial-based optical sensing technologies, including colorimetric, fluorescence, and surface-enhanced Raman scattering (SERS), offering quick, straightforward analyses with minimal training and infrastructure requirements for detecting viral proteins in biological samples. This review describes the composition and mechanism of and recent advancements in LFAs for viral protein detection, categorizing them into colorimetric, fluorescent, and SERS-based techniques. Despite significant progress, developing a simple, stable, highly sensitive, and selective LFA system remains a formidable challenge. Nevertheless, an advanced LFA system promises not only to enhance clinical diagnostics but also to extend its utility to environmental monitoring and beyond, demonstrating its potential to revolutionize both healthcare and environmental safety.

New insights into the toxicological effects of dietary biogenic amines

Biogenic amines (BA) are molecules with biological functions, which can accumulate at toxic concentrations in foods. Several microorganisms have been identified as responsible for their accumulation at elevated concentrations. Histamine, tyramine and putrescine are the BA most commonly found at highest concentrations. The ingestion of food containing high BA concentrations leads to intoxication with symptoms depending on the BA and the amount consumed. Moreover, there is evidence of synergy between different BA, something of toxicological importance given that some foods accumulate different BA. This work reviews the BA toxic effects and examines recent discoveries regarding their synergy, cytotoxicity and genotoxicity. These advances in the toxicological consequences of ingesting BA contaminated foods support the need to regulate their presence in foods to preserve the consumer's health. However, more research efforts -focused on the establishment of risk assessments- are needed to reach a consensus in their limits in different food matrices.

A novel lateral flow immunochromatographic assay using a recombinant VP2 antigen for total antibody detection of canine parvovirus-2

Canine parvovirus-2 (CPV-2) is a viral disease of dogs causing acute hemorrhagic gastroenteritis and myocarditis with high morbidity and mortality rates. The infection is still widespread all over the world. Vaccines developed against infection have great importance in preventing infection. However, it is difficult to recommend a practical vaccination program without knowing the antibody level of a puppy. Despite widespread vaccination, difficulties in detecting the maternal antibodies in puppies remain the main cause of vaccination failure. The hemagglutination inhibition (HAI) test is the gold standard to determine the immune status of dogs for canine parvovirus 2, but the HAI test has several disadvantages such as the need for fresh porcine blood, well-equipped laboratory, and long incubation periods. In this study, for the first time we developed a colloidal gold-based competitive lateral flow assay (cLFA) system for the rapid detection of total antibodies in canine serum using CPV-2b-VP2 derived from field isolates. The recombinantly expressed capsid protein of CPV-2 in the prokaryotic expression system was used as a labeled molecule in cLFA. We carried out studies on our cLFA system using the standard antibody solution and the clinical samples from vaccinated puppy serum. We compared the results of the LFAs with the HAI test. Competitive lateral flow assay results showed good correlation with the gold standard method, the HAI test. In the developed platform, the limit of detection of the standard antibody was determined to be 375 ng mL-1, while the cut-off level of antibodies was observed to be 1 : 40 HAI titer in clinical samples. Our reported system will be a strong alternative for CPV-2 antibody-based detection applications.

Dual-mode colorimetric and fluorescence biosensors for the detection of foodborne bacteria

Due to the growing demand for detection technologies, there has been significant interest in the development of integrated dual-modal sensing technologies, which involve combining two signal transduction channels into a single technique, particularly in the context of food safety. The integration of two detection signals not only improves diagnostic performance by reducing assumptions, but also enhances diagnostic functions with increased application flexibility, improved accuracy, and a wider detection linear range. The top two output signals for emerging dual-modal probes are fluorescent and colorimetric, due to their exceptional advantages for real-time sensitive sensing and point-of-care applications. With the rapid progress of nanotechnology and material chemistry, the integrated colorimetric/fluorimetric dual-mode systems show immense potential in sensing foodborne pathogenic bacteria. In this comprehensive review, we present a detailed summary of various colorimetric and fluorimetric dual-modal sensing methods, with a focus on their application in detecting foodborne bacteria. We thoroughly examine the sensing methodologies and the underlying principles of the signal transduction systems, and also discuss the challenges and future prospects for advancing research in this field.

A novel photothermal sensing probe based on violet phosphorus for sensitive immunochromatographic sensing detection

Photothermal immunochromatographic sensor is an emerging detection technology, and it is important to develop new sensing probes with excellent photothermal performance to improve its detection performance. In the present study, a novel photothermal sensing probe based on violet phosphorus nanosheets with satisfactory photothermal conversion efficiency (31.1 %) was reported for the first time. A photothermal immunochromatographic sensor using the above probe was applied for visual and photothermal detection of diethylstilbestrol. The diethylstilbestrol concentration was inversely proportional to photothermal sensing signal and showed a good linear correlation in the range of 0.75 ∼ 50 μg·L-1. After optimizing, the visual and photothermal detection limits were 6 μg·L-1 and 0.56 μg·L-1, respectively. The recovery rates in tap water, milk and pork samples ranged from 82.2 % to 115.2 %, with a coefficient of variation (CV) ranging from 2.0 % to 10.8 %. This work not only structured a new type of photothermal probe, but also expanded the application range of violet phosphorus.