Overview of the American Chemical Society Symposium on Metals and Trace Elements in Food Safety, Health, and Food Quality

DNA nanosphere-enhanced DNAzyme system for sensitive and rapid detection of lead contamination in water and living cells

Lead (Pb2 +) contamination poses significant risks to human health and the environment, necessitating the development of sensitive and rapid detection methods. In this study, we present a DNA nanosphere-enhanced substrate strand-DNAzyme (DS-Sub-Dz) system for the efficient detection of Pb2+ in both environmental and biological samples. The DS was constructed by annealing single-stranded DNA with four palindromic regions and extending sequences at the terminals, simplifying the process and reducing costs compared to traditional long DNA strands. The Sub-Dz, modified with fluorophore (FAM) and quencher (BHQ1), was then grafted onto the DS surface, forming the DS-Sub-Dz system through a hybridization reaction. This system utilizes spatial confinement and a cleavage recycling reaction to amplify the fluorescence signals of FAM, enabling highly sensitive and rapid detection of Pb2+ over a range of 2 nM to 40 μM. With a detection limit (LOD) of 2.0 nM-1000 times lower than the control Sub-Dz system-the DS-Sub-Dz demonstrated exceptional sensitivity. Further tests confirmed its ability to distinguish between various heavy metal ions in tap water. The enhanced cell internalization efficiency, accelerated reaction kinetics, and improved biostability of the DS-Sub-Dz system also enabled successful Pb2+ detection in both water samples and intracellular imaging, showcasing its potential for monitoring lead contamination in environmental and body safety applications.

Safety Considerations of Trace Metals in Locally Produced Nutritive Food-Drinks Consumed in Yenagoa Metropolis, Nigeria

This study assessed the safety of trace metal concentrations in locally produced nutritive food-drinks consumed in Yenagoa metropolis, Bayelsa State, Nigeria. Three different drink types (viz, tiger nut juice, a mixture of tiger nut and soya bean juice and soya bean juice) were purchased from various locations in Yenagoa metropolis, Bayelsa State, Nigeria, between January and February 2024. Thirty samples were analyzed for trace metals using atomic absorption spectrophotometry. Detected metal concentrations ranged from 0.077 to 0.458 mg/L for iron, 0.159 to 1.251 mg/L for copper, 0.000 to 0.070 mg/L for zinc, 0.000 to 0.080 mg/L for cadmium, and 0.000 to 0.068 mg/L for manganese. Three (zinc, manganese, and copper) of the five detected metals had concentrations below the World Health Organization (WHO) and/or Standard Organization of Nigeria (SON) permissible limits using drinking water guidelines. Pearson correlation analysis indicated diverse metal sources, while principal component analysis (PCA) revealed significant variance driven by essential and trace metals. At the same time, crucial metals like zinc and iron dominate, and the presence of cadmium raises health concerns. The results suggest that while iron, zinc, and manganese generally pose minimal health risks, elevated copper and cadmium levels present potential non-carcinogenic risks in some samples. Hazard Index (HI) values (0.673-5.349) highlight the need for regulatory attention due to the cumulative effects of multiple trace metals. Although the calculated cancer risk (CR) values suggest no significant carcinogenic threat, continuous monitoring and mitigation are crucial, particularly for vulnerable populations who may experience prolonged exposure.

Label-free and ultrasensitive detection of environmental lead ions based on spatially localized DNA nanomachines driven by hyperbranched hybridization chain reaction

A label-free fluorescent sensing strategy for the rapid and highly sensitive detection of Pb2+ was developed by integrating Pb2+ DNAzyme-specific cleavage activity and a tetrahedral DNA nanostructure (TDN)-enhanced hyperbranched hybridization chain reaction (hHCR). This strategy provides accelerated reaction rates because of the highly effective collision probability and enriched local concentrations from the spatial confinement of the TDN, thus showing a higher detection sensitivity and a more rapid detection process. Moreover, a hairpin probe based on a G-triplex instead of a G-quadruplex or chemical modification makes hybridization chain reaction more controlled and flexible, greatly improving signal amplification capacities and eliminating labeled DNA probes. The enhanced reaction rates and improved signal amplification efficiency endowed the biosensors with high sensitivity and a rapid response. The label-free detection of Pb2+ based on G-triplex combined with thioflavin T can be achieved with a detection limit as low as 1.8 pM in 25 min. The proposed Pb2+-sensing platform was also demonstrated to be applicable for Pb2+ detection in tap water, river water, shrimp, rice, and soil samples, thus showing great potential for food safety and environmental monitoring.

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.

Integrating Ordered Two-Dimensional Covalent Organic Frameworks to Solid-State Nanofluidic Channels for Ultrafast and Sensitive Detection of Mercury

Grafting specific recognition moieties onto solid-state nanofluidic channels is a promising way for selective and sensitive sensing of analytes. However, the time-consuming interaction between recognition moieties and analytes is the main hindrance to the application of nanofluidic channel-based sensors in rapid detection. Here, we show the integration of ordered two-dimensional covalent organic frameworks (2D COFs) to solid-state nanofluidic channels to achieve rapid, selective, and sensitive detection of contaminants. As a proof of concept, a thiourea-linked 2D COF (JNU-3) as the recognition unit is covalently bonded on the stable artificial anodic aluminum oxide nanochannels (AAO) to fabricate a JNU-3@AAO-based nanofluidic sensor. The rapid and selective interaction of Hg(II) with the highly ordered channels of JNU-3 allows the JNU-3@AAO-based nanofluidic sensor to realize ultrafast and precise determination of Hg(II) (90 s) with a low limit of detection (3.28 fg mL^-1), wide linear range (0.01-100 pg mL^-1), and good precision (relative standard deviation of 3.8% for 11 replicate determination of 10 pg mL^-1). The developed method was successfully applied to the determination of mercury in a certified reference material A072301c (rice powder), real water, and rice samples with recoveries of 90.4-99.8%. This work reveals the great potential of 2D COFs-modified solid-state nanofluidic channels as a sensor for the rapid and precise detection of contaminants in complicated samples.

Recent Progress on Single-Molecule Detection Technologies for Food Safety

Rapid and sensitive detection technologies for food contaminants play vital roles in food safety. Due to the complexity of the food matrix and the trace amount distribution, traditional methods often suffer from unsatisfying accuracy, sensitivity, or specificity. In past decades, single-molecule detection (SMD) has emerged as a way to realize the rapid and ultrasensitive measurement with low sample consumption, showing a great potential in food contaminants detection. For instance, based on the nanopore technique, simple and effective methods for single-molecule analysis of food contaminants have been developed. To our knowledge, there has been a rare review that focuses on SMD techniques for food safety. The present review attempts to cover some typical SMD methods in food safety, including electrochemistry, optical spectrum, and atom force microscopy. Then, recent applications of these techniques for detecting food contaminants such as biotoxins, pesticides, heavy metals, and illegal additives are reviewed. Finally, existing research challenges and future trends of SMD in food safety are also tentatively proposed.