Recent advances of food safety detection by nucleic acid isothermal amplification integrated with CRISPR/Cas

CRISPR revolution: Unleashing precision pathogen detection to safeguard public health and food safety

Foodborne pathogens represent a significant challenge to global food safety, causing widespread illnesses and economic losses. The growing complexity of food supply chains and the emergence of antimicrobial resistance necessitate rapid, sensitive, and portable diagnostic tools. CRISPR technology has emerged as a transformative solution, offering unparalleled precision and adaptability in pathogen detection. This review explores CRISPR's role in addressing critical gaps in traditional and modern diagnostic methods, emphasizing its advantages in sensitivity, specificity, and scalability. CRISPR-based diagnostics, such as Cas12 and Cas13 systems, enable rapid detection of bacterial and viral pathogens, as well as toxins and chemical hazards, directly in food matrices. Their integration with isothermal amplification techniques and portable biosensors enhances field applicability, making them ideal for decentralized and real-time testing. Additionally, CRISPR's potential extends beyond food safety, contributing to public health efforts by monitoring antimicrobial resistance and supporting One Health frameworks. Despite these advancements, challenges remain, including issues with performance in complex food matrices, scalability, and regulatory barriers. This review highlights future directions, including AI integration for assay optimization, the development of universal CRISPR platforms, and the adoption of sustainable diagnostic solutions. By tackling these challenges, CRISPR has the potential to redefine global food safety standards and create a more resilient food system. Collaborative research and innovation will be critical to fully unlocking its transformative potential in food safety and public health.

Lift-CM: An integrated lift-heater centrifugal microfluidic platform for point-of-care pathogen nucleic acid detection using isothermal amplification and CRISPR/Cas12a

Pathogen nucleic acid detection technology based on isothermal amplification and CRISPR/Cas12a system offers advantages in terms of high sensitivity, high specificity, and rapidity. However, this method has not been widely applied because of its shortcomings in utilizing conventional instruments, which cannot satisfy the requirements for Point of Care Testing (POCT), such as integration, convenience, and miniaturization. In this study, we developed an integrated lift-heater centrifugal microfluidic platform (Lift-CM) to automate the processes of isothermal amplification and CRISPR/Cas12a detection. A spatially encoded centrifugal microfluidic disc (SEC-disc) was employed to physically separate the amplification and detection processes while expanding the number of targets. The design of the dual-temperature and lift-heating centrifugal mechanism of the Lift-CM platform ensures that there is no manual intervention during amplification and detection processes. A smartphone-based app enables the setting of key parameters and monitoring of the experimental process, presenting results through a generated report that includes real-time fluorescence curves. We analyzed the plasmids of the Crimean-Congo hemorrhagic fever virus, Ebola virus, and five influenza viruses using different amplification methods (RPA/LAMP) to demonstrate the good compatibility of the Lift-CM platform with various amplification schemes. In clinical validation, the detection of H3N2-positive samples was completed within 30 min, and the results were highly consistent with qPCR results. This portable and compact platform offers a novel alternative solution for both clinical and at-home pathogen nucleic acid detection in the future.

Novel Multimode Assay Based on Asymmetrically Competitive CRISPR and Raman Barcode Spectra for Multiple Hepatocellular Carcinoma Biomarkers Detection

Commercial pregnancy test strips (PTS) possess the advantages of lower price, higher stability, and better repeatability and have been popularized to integrate with novel sensing strategies to detect other disease biomarkers, which accelerates the commercialization process of those novel sensing strategies. However, the current integration of novel sensing strategies into commercial PTS still faced the problems of insufficient quantification, low sensitivity, and lack of multiple detection capabilities. Hence, we proposed the concept of "visual classification recognition, spectral signal subdivision" for multiple hepatocellular carcinoma biomarkers (miRNA122 and miRNA233) detection with dual signals based on asymmetric competitive CRISPR (acCRISPR) and surface-enhanced Raman spectroscopy coupling with PTS, named the acCRISPR-PTS-SERS assay. In this assay, acCRISPR was used as a nonamplified cascaded signal amplification method to improve the sensitivity of detection. Two AuNPs-based core-shell Raman tags, each corresponding to different miRNA biomarkers, were used to achieve both visual recognition and spectral segmentation to enhance the quantification of PTS detection and the capability for multiple detection. Under the optimal conditions, the LOD for miRNA122 and miRNA223 were 10.36 and 4.65 fM, respectively. The sensitivity was enhanced by nearly 2 orders of magnitude. In the future, simultaneous hand-held detection for fingerprint barcodes of different cancers can be achieved with the assistance of a microfluidic chip and smartphone.

Machine Learning-Assisted, Dual-Channel CRISPR/Cas12a Biosensor-In-Microdroplet for Amplification-Free Nucleic Acid Detection for Food Authenticity Testing

The development of novel detection technology for meat species authenticity is imperative. Here, we developed a machine learning-supported, dual-channel biosensor-in-microdroplet platform for meat species authenticity detection named CC-drop (CRISPR/Cas12a digital single-molecule microdroplet biosensor). This strategy allowed us to quickly identify and analyze animal-derived components in foods. This biosensor was enabled by CRISPR/Cas12a-based fluorescence lighting-up detection, and the nucleic acid signals can be recognized by a Cas12a-crRNA binary complex to trigger the trans-cleavage of any by-stander reporter single-stranded (ss) DNA, in which nucleic acid signals can be converted and amplified to fluorescent readouts. The ultralocalized microdroplet reactor was constructed by reducing the reaction volume from up to picoliter to accommodate the aforementioned reaction to further enhance the sensitivity to even render an amplification-free nucleic acid detection. Moreover, we established a smartphone App coupled with a random forest machine learning model based on parameters such as area, fluorescent intensity, and counting number to ensure the accuracy of image recording and processing. The sample-to-result time was within 80 min. Importantly, the proposed biosensor was able to accurately detect the ND1 (pork-specific) and IL-2 (duck-specific) genes in deep processed meat-derived foods that usually had truncated DNA, and the results were more robust and practical than conventional real-time polymerase chain reaction after a side-by-side comparison. All in all, the proposed biosensor can be expected to be used for rapid food authenticity and other nucleic acid detections in the future.

Argonaute-Based Nucleic Acid Detection Technology: Advantages, Current Status, Challenges, and Perspectives

Rapid and accurate detection is a prerequisite for precise clinical diagnostics, ensuring food safety, and facilitating biotechnological applications. The Argonaute system, as a cutting-edge technique, has been successfully repurposed in biosensing beyond the CRISPR/Cas system (clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins), which has been extensively researched, but recognition of PAM sequences remains restricted. Argonaute, as a programmable and target-activated nuclease, is repurposed for fabricating novel detection methods due to its unparalleled biological features. In this comprehensive review, we initially elaborate on the current methods for nucleic acid testing and programmable nucleases, followed by delving into the structure and nuclease activity of the Argonaute system. The advantages of Argonaute compared with the CRISPR/Cas system in nucleic acid detection are highlighted and discussed. Furthermore, we summarize the applications of Argonaute-based nucleic acid detection and provide an in-depth analysis of future perspectives and challenges. Recent research has demonstrated that Argonaute-based biosensing is an innovative and rapidly advancing technology that can overcome the limitations of existing methods and potentially replace them. In summary, the implementation of Argonaute and its integration with other technologies hold promise in developing customized and intelligent detection methods for nucleic acid testing across various aspects.

Portable loop-mediated isothermal amplification device with spectrometric detection for rapid pathogen identification

With the rise in extreme weather due to global warming, coupled with globalization facilitating the spread of infectious diseases, there's a pressing need for portable testing platforms offering simplicity, low cost, and remote transmission, particularly beneficial in resource-limited and non-urban areas. We have developed a portable device using loop-mediated isothermal amplification (LAMP) with spectrometric detection to identify Salmonella Typhimurium DNA. The device utilizes the LinkIt 7697 microcontroller and a microspectrometer to capture and transmit spectral signals in real-time, allowing for improved monitoring and analysis of the reaction progress. We built a hand-held box containing a microspectrometer, thermoelectric cooler, ultraviolet LED, disposable reaction tube, and homemade thermal module, all powered by rechargeable batteries. Additionally, we conducted thorough experiments to ensure temperature accuracy within 1 °C under thermal control, developed a heating module with a LinkIt 7697 IoT development board to heat the DNA mixture to the reaction temperature within 3 min, and integrated foam insulation and a 3D-printed frame to enhance the device's thermal stability. We successfully demonstrated the amplification of Salmonella Typhimurium DNA with an impressive sensitivity of 2.83 × 10-4 ng/μL. A remote webpage interface allows for monitoring the temperature and fluorescence during the LAMP process, improving usability. This portable LAMP device with real-time detection offers a cost-effective solution for detecting Salmonella Typhimurium in food products. Its unique design and capabilities make it a promising tool for ensuring food safety.

A programmable sensitive platform for pathogen detection based on CRISPR/Cas12a -hybridization chain reaction-poly T-Cu

Rapid and sensitive detection of pathogenic bacteria is crucial for disease prevention and control. The CRISPR/Cas12a system with the DNA cleavage capability holds promise in pathogenic bacteria diagnosis. However, the sensitivity of CRISPR-based assays remains a challenge. Herein, we report a versatile and sensitive pathogen sensing platform (HTCas12a) based on the CRISPR/Cas12a system, hybridization chain reaction (HCR) and Poly T-copper fluorescence nanoprobe. The sensitivity is improved by HCR and the Poly-T-Cu reporter probe reduces the overall experiment cost to less than one dollar per sample. Our results demonstrate the specific recognition of target nucleic acid fragments from other pathogens. Furthermore, a good linear correlation between fluorescence intensity and target quantities were achieved with detection limits of 23.36 fM for Target DNA and 4.17 CFU/mL for S.aureus, respectively. The HTCas12a system offers a universal platform for pathogen detection in various fields, including environmental monitoring, clinical diagnosis, and food safety.

CRISPR-Cas based diagnostic tools: Bringing diagnosis out of labs

Timely detection is important for the effective management of infectious diseases. Reverse Transcription Polymerase Chain Reaction (RT-PCR) stands as the prime nucleic acid based test that is employed for the detection of infectious diseases. The method ensures sensitivity and specificity. However, RT-PCR is a relatively expensive technique due to the requirement of costly equipment and reagents. Further, it requires skilled personnel and established laboratories that are usually inaccessible in underdeveloped areas. On the other hand, rapid antigen based techniques are cost effective and easily accessible, but are less effective in terms of sensitivity and specificity. CRISPR-Cas systems are advanced diagnostic tools that combine the advantages of both PCR and antigen based detection techniques, and allows the rapid detection with high sensitivity/specificity. The present review aims to discuss the applicability of CRISPR-Cas based diagnostic tools for the infectious disease detection. The review further attempts to highlight the current limitations and future research directions to improve the CRISPR based diagnostic tools for rapid and effective disease detection.

A Thermostable Cas12b-Powered Bioassay Coupled with Loop-Mediated Isothermal Amplification in a Customized "One-Pot" Vessel for Visual, Rapid, Sensitive, and On-Site Detection of Genetically Modified Crops

Genetically modified crops (GMCs) have been discussed due to unknown safety, and thus, it is imperative to develop an effective detection technology. CRISPR/Cas is deemed a burgeoning technology for nucleic acid detection. Herein, we developed a novel detection method for the first time, which combined thermostable Cas12b with loop-mediated isothermal amplification (LAMP), to detect genetically modified (GM) soybeans in a customized one-pot vessel. In our method, LAMP-specific primers were used to amplify the cauliflower mosaic virus 35S promoter (CaMV35S) of the GM soybean samples. The corresponding amplicons activated the trans-cleavage activity of Cas12b, which resulted in the change of fluorescence intensity. The proposed bioassay was capable of detecting synthetic plasmid DNA samples down to 10 copies/μL, and as few as 0.05% transgenic contents could be detected in less than 40 min. This work presented an original detection method for GMCs, which performed rapid, on-site, and deployable detection.

Advances, challenges, and opportunities for food safety analysis in the isothermal nucleic acid amplification/CRISPR-Cas12a era

Global food safety stands out as a prominent public concern, affecting populations worldwide. The recurrent challenge of food safety incidents reveals the need for a robust inspection framework. In recent years, the integration of isothermal nucleic acid amplification with CRISPR-Cas12a techniques has emerged as a promising tool for molecular detection of food hazards, presenting next generation of biosensing for food safety detection. This paper provides a comprehensive review of the current state of research on the synergistic application of isothermal nucleic acid amplification and CRISPR-Cas12a technology in the field of food safety. This innovative combination not only enriches the analytical tools, but also improving assay performance such as sensitivity and specificity, addressing the limitations of traditional methods. The review summarized various detection methodologies by the integration of isothermal nucleic acid amplification and CRISPR-Cas12a technology for diverse food safety concerns, including pathogenic bacterium, viruses, mycotoxins, food adulteration, and genetically modified foods. Each section elucidates the specific strategies employed and highlights the advantages conferred. Furthermore, the paper discussed the challenges faced by this technology in the context of food safety, offering insightful discussions on potential solutions and future prospects.

Recent Advances of DNA-Templated Metal Nanoclusters for Food Safety Detection: From Synthesis, Applications, Challenges, and Beyond

Food safety concerns have become a significant threat to human health and well-being, catching global attention in recent years. As a result, it is imperative to research conceptually novel biosensing and effective techniques for food matrices detection. Currently, DNA-templated metal nanoclusters (DNA-MNCs) are considered as one of the most promising nanomaterials due to their excellent properties in biosensing. While DNA-MNCs have garnered increasing interest, the reviews of design strategies, applications, and futuristic prospects for biosensing have been hardly found especially in food safety. The synthesis of DNA-MNCs and their use as biosensing materials in food contamination detection, including pathogenic bacteria, toxins, heavy metals, residues of pesticides, and others were comprehensively reviewed. In addition, we summarize the properties of DNA-MNCs briefly and discuss the challenges and future trends. The application of DNA-MNCs powered biosensing has been demonstrated and actively studied, which is a promising paradigm for food safety testing that can supplement or even replace current existing methods. Despite the challenges of difficulty regulating accurately, poor stability, low quantum yield, and difficult commercial transformation, the application prospects of DNA-MNCs biosensors are promising. This review aims to provide insights and directions for the future development of DNA-MNCs based food detection technology.

Argonaute-DNAzyme tandem biosensing for highly sensitive and simultaneous dual-gene detection of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA), a common zoonotic multidrug-resistant bacterium, puts a great threat to public health and food safety. Rapid and reliable detection of MRSA is crucial to guide effective patient treatment at early stages of infection and control the spread of MRSA infections. Herein, we developed a Simultaneous dual-gene and ulTra-sensitive detection for methicillin-resistant Staphylococcus aureus using Argonaute-DNAzyme tandem Detection (STAND). Simply, loop-mediated isothermal amplification (LAMP) was used for the amplification of the species-specific mecA and nuc gene, followed by STAND enabled by the site-specific cleavage of programable Argonaute. The Argonaute-DNAzyme tandem reaction rendered a conceptually novel signal amplification and transduction module that was more sensitive (1 or 2 order of magnitude higher) than the original Argonaute-based biosensing. With the strategy, the target nucleic acid signals gene were dexterously converted into fluorescent signals. STAND could detect the nuc gene and mecA gene simultaneously in a single reaction with 1 CFU/mL MRSA and a dynamic range from 1 to 108 CFU/mL. This method was confirmed by clinical samples and challenged by identifying contaminated foods and MRSA-infected animals. This work enriches the arsenal of Argonaute-mediated biosensing and presents a novel biosensing strategy to detect pathogenic bacteria with ultra-sensitivity, specificity and on-site capability.

CRISPR/Cas-Powered Amplification-Free Detection of Nucleic Acids: Current State of the Art, Challenges, and Futuristic Perspectives

CRISPR/Cas system is becoming an increasingly influential technology that has been repositioned in nucleic acid detection. A preamplification step is usually required to improve the sensitivity of CRISPR/Cas-based detection. The striking biological features of CRISPR/Cas, including programmability, high sensitivity and sequence specificity, and single-base resolution. More strikingly, the target-activated trans-cleavage could act as a biocatalytic signal transductor and amplifier, thereby empowering it to potentially perform nucleic acid detection without a preamplification step. The reports of such work are on the rise, which is not only scientifically significant but also promising for futuristic end-user applications. This review started with the introduction of the detection methods of nucleic acids and the CRISPR/Cas-based diagnostics (CRISPR-Dx). Next, we objectively discussed the pros and cons of preamplification steps for CRISPR-Dx. We then illustrated and highlighted the recently developed strategies for CRISPR/Cas-powered amplification-free detection that can be realized through the uses of ultralocalized reactors, cascade reactions, ultrasensitive detection systems, or others. Lastly, the challenges and futuristic perspectives were proposed. It can be expected that this work not only makes the researchers better understand the current strategies for this emerging field, but also provides insight for designing novel CRISPR-Dx without a preamplification step to win practicable use in the near future.