CRISPR/Cas12a-Derived Photoelectrochemical Aptasensor Based on Au Nanoparticle-Attached CdS/UiO-66-NH2 Heterostructures for the Rapid and Sensitive Detection of Ochratoxin A

A CRISPR/Cas12a-based colorimetric AuNPs biosensor for naked-eye detection of pathogenic bacteria in clinical samples

Pathogenic bacteria, such as Pseudomonas aeruginosa, pose significant threats to public health due to their multidrug resistance and association with severe infections. Rapid and reliable detection methods are crucial for timely treatment and effective infection control, especially in resource-limited settings. In this study, we developed a CRISPR/Cas12a-based colorimetric biosensor that leverages Cas12a's trans-cleavage activity to release left single-stranded DNA (lDNA). The released lDNA facilitates hybridization with clDNA-functionalized gold nanoparticles (AuNPs), resulting in a visible color change. The biosensor achieved a detection limit of 100 CFU/reaction for P. aeruginosa within 2 hours, with excellent specificity and robustness, as validated in spiked sputum and blood samples. Clinical testing using 32 blood samples (13 positive, 19 negative) confirmed its high diagnostic accuracy, achieving an AUC of 1 in ROC curve analysis. The platform's simplicity, robustness, and programmability suggest its broad potential for rapid infectious disease diagnostics, particularly in low-resource settings.

Research progress of photoelectrochemical sensors in food detection

Food is the basic of the people, security is the basic of the food. As the quality of life improves, food safety has emerged as a global concern, making the development of simple, rapid, and efficient food safety detection methods critically important. Photoelectrochemical (PEC) sensors are a novel class of sensors developed in recent years that integrate photoelectric technology with biosensing. Owing to their high sensitivity, simple design, low cost, and ease of miniaturization, PEC sensors have found widespread applications in food detection, bioanalysis, clinical diagnostics, and environmental protection. This paper reviews the development of PEC sensors, the basic principles of PEC sensor detection, and the electron transport pathways of semiconductor materials in PEC sensors. It focuses on how photoelectroactive materials and related signal amplification strategies can improve the detection performance of the sensors, as well as the latest research advances of PEC sensors in the detection of food toxins. Finally, the challenges and future trends of PEC sensors in food safety detection are discussed.

Ratiometric fluorescent aptasensor based on DNA-gated Fe3O4@Uio-66-NH2 and Exo I-assisted signal amplification

BACKGROUND

Ochratoxin A (OTA) is toxic secondary metabolites produced by fungi and can pose a serious threat to food safety and human health. Due to the high stability and toxicity, OTA contamination in agricultural products is of great concern. Therefore, the development of a highly sensitive and reliable OTA detection method is crucial to ensure food safety. Although fluorescent sensors have been widely used for OTA detection, they still face challenges such as false positives and insufficient sensitivity, thus further improvement of the detection performance is necessary.

RESULTS

Herein, a ratiometric biosensor based on DNA-gated Fe₃O₄@Uio-66-NH₂ nanocomposites and Nucleic Acid Exonuclease I (Exo I)-assisted signal amplification was constructed for the sensitive detection of OTA. This functional nanocomposite combines magnetic, porous and fluorescent properties. Fe₃O₄ of the core enables efficient magnetic separation, while the porous structure of Uio-66-NH₂ encapsulates the fluorescent dye rhodamine 6G (Rho 6G). In addition, a label-free DNA gating strategy was introduced to control the release of Rho 6G. The sensor performs OTA detection by the fluorescence signal ratio of Fe3O4@Uio-66-NH2 and Rho 6G, which effectively avoids false positives of the sensor. Accelerated release of Rho 6G using Exo I greatly improves the sensitivity of the sensor. The sensor has a low LOD (0.308 ng mL-1) and the recoveries for OTA detection in real samples were 92.4%-116.0 %.

SIGNIFICANCE

The development of this ratiometric fluorescent aptasensor highlights its potential for highly sensitive OTA detection, offering significant advantages in selectivity and accuracy due to its unique DNA-gated mechanism and the dual fluorescence signal ratio strategy. Additionally, the use of Fe₃O₄@Uio-66-NH₂ enables effective magnetic separation, while the Exo I-assisted signal amplification enhances sensitivity, making this sensor a powerful tool for detecting OTA in complex sample matrices with high reliability.

Multi-DNAzymes cascade reaction mediated aptasensors for OTA detection based on the integration of autocatalytic Mg2+-dependent DNAzyme cleavage and entropy-driven circuit

Ochratoxin A (OTA) is a compound of concern due to its potential health effects on humans. Detecting OTA in food is crucial for safeguarding public health. In this study, we fabricated a multi-DNAzyme cascade reaction-mediated colorimetric aptasensors for OTA detection, integrating autocatalytic Mg2+-dependent DNAzyme cleavage (MNAzyme) and an entropy-driven circuit. In brief, the recognition between the aptamer and target OTA led to the release of DNA1. Subsequently, DNA1 hybridized with DNA2, generating an upstream MNAzyme that facilitated the production of a downstream MNAzyme. These MNAzymes possess similar substrate binding arms, enabling them to catalyze the same substrate. The catalytic efficiency of MNAzymes towards the substrates was enhanced due to the increasing concentration of MNAzymes. The cleavage products then triggered an entropy-driven cycle to generate a signal. Under optimal conditions, the sensing system exhibited low detection limits of 48.97 fM for OTA. Additionally, the proposed aptasensor was successfully applied to quantitatively analyze OTA in food samples. Thus, the multi-DNAzyme cascade reaction-mediated colorimetric aptasensors offer an adaptable platform for detecting traces of OTA contaminant in food.

Research Progress of Biosensor Based on Organic Photoelectrochemical Transistor

In order to solve the food safety problem better, it is very important to develop a rapid and sensitive technology for detecting food contamination residues. Organic photoelectrochemical transistor (OPECT) biosensor rely on the photovoltage generated by a semiconductor upon excitation by light to regulate the conductivity of the polymer channels and realize biosensor analysis under zero gate bias. This technology integrates the excellent characteristics of photoelectrochemical (PEC) bioanalysis and the high sensitivity and inherent amplification ability of organic electrochemical transistor (OECT). Based on this, OPECT biosensor detection has been proven to be superior to traditional biosensor detection methods. In this review, we summarize the research status of OPECT biosensor in disease markers and food residue analysis, the basic principle, classification, and biosensing mechanism of OPECT biosensor analysis are briefly introduced, and the recent applications of biosensor analysis are discussed according to the signal strategy. We mainly introduced the OPECT biosensor analysis methods applied in different fields, including the detection of disease markers and food hazard residues such as prostate-specific antigen, heart-type fatty acid binding protein, T-2 toxin detection in milk samples, fat mass and objectivity related protein, ciprofloxacin in milk. The OPECT biosensor provides considerable development potential for the construction of safety analysis and detection platforms in many fields, such as agriculture and food, and hopes to provide some reference for the future development of biosensing analysis methods with higher selectivity, faster analysis speed and higher sensitivity.

Focusing on New Discoveries in Food Technology and Creating a New Future of Nutrition and Health: An Introduction to the 4th International Symposium of Food Science, Nutrition and Health in Dalian, China

The 4th International Symposium on Food Science, Nutrition and Health (ISFSNH) was held at the Shangri-La Hotel in Dalian, China, on May 29-31, 2023. The symposium explored the connotations and needs of "The Great Food Perspective" under the theme "Focusing on new discoveries in food technology and creating a new future of nutrition and health" to better address the global emerging diverse food needs. The ISFSNH covered four areas: (1) food processing theory and technology, (2) food safety and quality control, (3) precision nutrition and health, and (4) creation of nutritious and healthy foods. More than 1000 scholars and entrepreneurs from more than 100 colleges and universities globally attended the conference. This special issue of the Journal of Agricultural and Food Chemistry highlights the important topics of the 4th ISFSNH and includes more than 20 papers.

CRISPR/Cas12a integrated electrochemiluminescence biosensor for pufferfish authenticity detection based on NiCo2O4 NCs@Au as a coreaction accelerator

Meat adulteration has brought economic losses, health risks, and religious concerns, making it a pressing global issue. Herein, combining the high amplification efficiency of polymerase chain reaction (PCR) and the accurate recognition of CRISPR/Cas12, a sensitive and reliable electrochemiluminescence (ECL) biosensor was developed for the detection of pufferfish authenticity using NiCo2O4 NCs@Au-ABEI as nanoemitters. In the presence of target DNA, the trans-cleavage activity of CRISPR/Cas12a is activated upon specific recognition by crRNA, and then it cleaves dopamine-modified single stranded DNA (ssDNA-DA), triggering the ECL signal from the "off" to "on" state. However, without target DNA, the trans-cleavage activity of CRISPR/Cas12a is silenced. By rationally designing corresponding primers and crRNA, the biosensor was applied to specific identification of four species of pufferfish. Furthermore, as low as 0.1 % (w/w) adulterate pufferfish in mixture samples could be detected. Overall, this work provides a simple, low-cost and sensitive approach to trace pufferfish adulteration.