Engineering of an adaptive tandem CRISPR/Cas12a molecular amplifier permits robust analysis of Vibrio parahaemolyticus

Ultrasensitive detection of Vibrio parahaemolyticus based on boric acid-functionalized Eu (III)-based metal-organic framework

This study intends to create a ratiometric fluorescence probe utilizing aptamers for the detection of Vibrio parahaemolyticus (V. parahaemolyticus) in aquatic products. In this design, aptamer-functionalized magnetic nanoparticles specifically capture V. parahaemolyticus, while boric acid on Eu (III)-Based Metal-Organic Framework (Eu-MOF) interacts with glycolipids present on bacterial cells, thereby achieving dual recognition of V. parahaemolyticus. This fluorescent probe quantitatively detects V. parahaemolyticus by measuring the intensity of ratio fluorescence. The sensor demonstrates a detection range from 77 to 7.7 × 107 CFU/mL, possessing a detection threshold down to 1 CFU/mL. Moreover, the developed method based on Eu-MOF had been successfully applied to real samples. To achieve rapid on-site detection of V. parahaemolyticus, the study designed a portable smartphone sensor that confirms its capability for rapidly detecting pathogens and contributes significantly to establishing a system for regulating safety in detecting food and environment.

An integrated and paper-based microfluidic system employing LAMP-CRISPR and equipped with a portable device for simultaneous detection of pathogens

Point-of-care testing methods are essential for the large-scale diagnosis and monitoring of bacterial infections. This study introduces an integrated platform designed for the simultaneous detection of pathogenic bacteria. Users can simply inject samples into the system, which then conducts the entire procedure in a fully automated manner, eliminating the need for external power sources, all within 60 min or less. The innovative paper-based microfluidic system is capable of lysing bacteria and integrating loop-mediated isothermal amplification (LAMP) with the CRISPR/Cas12a system, achieving this with minimal reagent usage on a single piece of paper. The reaction reagents are pre-fabricated as freeze-dried powder on the paper, allowing for long-term storage. A portable and cost-effective detection device has been designed to provide stable temperature control and analyze fluorescent signals, complementing the paper-based microfluidic system. This compact device measures 150 × 150 × 100 mm, weighs less than 1.8 kg, has an average power consumption of under 15 W, and supports external power supply. The device utilizes non-contact QR codes for information transmission, ensuring functionality even in areas without Internet connectivity. This platform is capable of simultaneously detecting five typical pathogenic microorganisms, with a detection limit of 1 copy/μL. It boasts several advantages, including miniaturization, lightweight design, low power consumption, portability, affordability, rapid detection, and ease of operation, making it highly suitable for on-site detection.

"Blue-red-purple" multicolored lateral flow immunoassay for simultaneous detection of GM crops utilizing RPA and CRISPR/Cas12a

Advanced multiplexed testing techniques should be designed and developed to ensure an accurate and reliable evaluation for unknown samples. In this study, an efficient platform coupled with the "Blue-Red-Purple" strategy based on recombinant polymerase amplification (RPA), CRISPR/Cas12a and lateral flow strip was established, which could realize the dual-target detection of CP4-EPSPS and Cry1Ab/Ac in genetically modified crops. The lateral flow immunoassay was developed using different colored microspheres to label the antibodies to realize the visualization of results and avoid cross-reactions. The proposed method exhibits high specificity, sensitivity and stability. The visual detection limits of standard plasmids and real samples reached 10 copies/μL and 0.5 %, respectively, which could be stored at 4 °C for 12 months with high detection ability. Moreover, the entire detection process could be completed within 50 min without any complex instruments or professional operators. These findings indicated that a sensitive, specific, rapid and accurate method was established for on-site detection of GM crops.

Highly sensitive and rapid detection of Vibrio parahaemolyticus using a dual-recognition platform based on functionalized quantum dots and aptamer

As one of the most harmful pathogenic bacteria in shrimp aquaculture, Vibrio parahaemolyticus often causes massive mortality in shrimp. Accurate and rapid detection of V. parahaemolyticus in shrimp farming is essential for avoiding huge economic losses caused by related diseases. In this study, we designed a dual-recognition platform for efficient identification and quantification of V. parahaemolyticus. First, the target bacterium was captured with magnetic beads functionalized by aptamers (Apt-MBs), and then, the broad-spectrum fluorescent probe FcMBL@CdSe-ZnS was used to detect the bacterium based on the interactions between fragment crystallizable mannose-binding lectin (FcMBL) and pathogenic bacteria. The proposed dual-recognition strategy centered around aptamers and FcMBL@CdSe-ZnS was applied to definite quantification of V. parahaemolyticus over a wide range of 10-108 CFU/mL with a limit of detection of 4 CFU/mL within 55 min. The feasibility was demonstrated by using the platform to detect V. parahaemolyticus from shrimp intestine, aquaculture water, and seawater.

CRISPR/Cas12a-Based Indirect Competitive Enzyme-Linked Immunosorbent Assay for Sensitive Detection of Ochratoxin A

The high toxicity and widespread contamination of ochratoxin A (OTA) make it urgent to develop a sensitive method to detect trace OTA in complex food matrices. Herein, an indirect competitive enzyme-linked immunosorbent assay (icELISA)-based on the CRISPR/Cas12a system is described. DNA amplicons with multiple activation sequences of the CRISPR/Cas12a system were pre-prepared to improve detection sensitivity. In the absence of OTA, streptavidin-mediated biotinylated DNA amplicons were captured by the biotinylated secondary antibody on the microplate. The captured DNA amplicons activated the CRISPR/Cas12a system, which thereby effectively cleaved the reporter DNA, producing strong fluorescence. The presence of OTA led to a decrease in DNA amplicons on the microplate, resulting in a decrease in activated Cas12a and ultimately a drop in fluorescence intensity. OTA in food matrices at nanogram per milliliter levels can be detected. Therefore, the new method has great potential in monitoring OTA.

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.

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.