Onsite/on-field analysis of pesticide and veterinary drug residues by a state-of-art technology: A review

Fluorescence Resonance Energy Transfer (FRET)-Based Sensor for Detection of Foodborne Pathogenic Bacteria: A Review

Sensitive and rapid determination of foodborne pathogenic bacteria is of practical importance for the control and prevention of foodborne illnesses. Nowadays, with the prosperous development of fluorescence assays, fluorescence resonance energy transfer (FRET)-derived diagnostic strategies are extensively employed in quantitative analysis of different pathogenic bacteria in food-related matrices, which displays a rapid, simple, stable, reliable, cost-effective, selective, sensitive, and real-time way. Considering the extensive efforts that have been made in this field so far, we here discuss the up-to-date developments of FRET-based diagnostic approaches for the determination of key foodborne pathogens like Staphylococcus aureus, Escherichia coli, Vibrio parahaemolyticus, Salmonella spp., Campylobacter spp., and Bacillus cereus in complex food-related matrices. Moreover, the principle of this technology, the choosing standards of acceptor-donor pairs, and the fluorescence properties are also profiled. Finally, the current prospects and challenges in this field are also put forward.

A sensitive fluorescent assay based on gold-nanoclusters coated on molecularly imprinted covalent organic frameworks and its application in malachite green detection

Malachite green (MG), as a parasiticide, is widely used in aquaculture to increase the production of the fishery industry. It poses a great danger to both the food system and the human body. In this study, a one-pot reverse microemulsion polymerization was employed to combine the gold nanoclusters (AuNCs) with molecularly imprinted polymers (MIPs) and covalent organic frameworks (COFs) to synthesize an efficient fluorescent hybrid probe (AuNCs@COFs@MIPs) for selective detection of MG. The specific recognition of AuNCs@COFs@MIPs towards MG triggers the fluorescence quenching of AuNCs. The fluorescent response was linearly related to the concentration over the range of 10-150 nmol/L with a limit of detection of 2.78 nmol/L. In addition, the proposed probe was further applied to fish and water samples. A favorable recovery ranged from 97.34 to 101.51 % toward trace amounts of MG indicating its promising application for detecting residue of veterinary drugs.

Advances in functional photonic crystal materials for the analysis of chemical hazards in food

Chemical contaminants in food generally include natural toxins (mycotoxins, animal toxins, and phytotoxins), pesticides, veterinary drugs, environmental pollutants, heavy metals, and illegal additives. Developing a low-cost, simple, and rapid detection technology for harmful substances in food is urgently needed. Analytical methods based on different advanced materials have been developed into rapid detection methods for food samples. In particular, photonic crystal (PC) materials have a unique surface periodic structure, structural color, a large surface area, easy integration with photoelectronic and magnetic devices which have great advantages in the development of rapid, low-cost, and highly sensitive analytical methods. This review focuses on the PC materials in the view of their fabrication processes, functionalized recognition components for the specific recognition of hazardous substances, and applications in the separation, enrichment, and detection of chemical hazards in real samples. Suspension array based on three-dimensional PC microspheres by droplet-based microfluidic assembly is a great promising and powerful platform for food safety detection fields. For the PCs selective analysis, biological antibodies, aptamers, and molecularly imprinted polymers (MIPs) could be modified for specific recognition of target substances, particularly MIPs because of their low-cost and easy mass production. Based on these functional PCs, various toxic and hazardous substances can be selectively enriched or recognized in real samples and further quantified in combination of liquid chromatography method or optical detection methods including fluorescence, chemiluminescence, and Raman spectroscopy.

Red-Emitting Polymerizable Guanidinium Dyes as Fluorescent Probes in Molecularly Imprinted Polymers for Glyphosate Detection

The development of methodologies to sense glyphosate has gained momentum due to its toxicological and ecotoxicological effects. In this work, a red-emitting and polymerizable guanidinium benzoxadiazole probe was developed for the fluorescence detection of glyphosate. The interaction of the fluorescent probe and the tetrabutylammonium salt of glyphosate was studied via UV/vis absorption and fluorescence spectroscopy in chloroform and acetonitrile. The selective recognition of glyphosate was achieved by preparing molecularly imprinted polymers, able to discriminate against other common herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (dicamba), as thin layers on submicron silica particles. The limits of detection of 4.8 µM and 0.6 µM were obtained for the sensing of glyphosate in chloroform and acetonitrile, respectively. The reported system shows promise for future application in the sensing of glyphosate through further optimization of the dye and the implementation of a biphasic assay with water/organic solvent mixtures for sensing in aqueous environmental samples.