Pharmacological treatments and risks for the food chain

Recent Advances in the Detection of Food Toxins Using Mass Spectrometry

Edibles are the only source of nutrients and energy for humans. However, ingredients of edibles have undergone many physicochemical changes during preparation and storage. Aging, hydrolysis, oxidation, and rancidity are some of the major changes that not only change the native flavor, texture, and taste of food but also destroy the nutritive value and jeopardize public health. The major reasons for the production of harmful metabolites, chemicals, and toxins are poor processing, inappropriate storage, and microbial spoilage, which are lethal to consumers. In addition, the emergence of new pollutants has intensified the need for advanced and rapid food analysis techniques to detect such toxins. The issue with the detection of toxins in food samples is the nonvolatile nature and absence of detectable chromophores; hence, normal conventional techniques need additional derivatization. Mass spectrometry (MS) offers high sensitivity, selectivity, and capability to handle complex mixtures, making it an ideal analytical technique for the identification and quantification of food toxins. Recent technological advancements, such as high-resolution MS and tandem mass spectrometry (MS/MS), have significantly improved sensitivity, enabling the detection of food toxins at ultralow levels. Moreover, the emergence of ambient ionization techniques has facilitated rapid in situ analysis of samples with lower time and resources. Despite numerous advantages, the widespread adoption of MS in routine food safety monitoring faces certain challenges such as instrument cost, complexity, data analysis, and standardization of methods. Nevertheless, the continuous advancements in MS-technology and its integration with complementary techniques hold promising prospects for revolutionizing food safety monitoring. This review discusses the application of MS in detecting various food toxins including mycotoxins, marine biotoxins, and plant-derived toxins. It also explores the implementation of untargeted approaches, such as metabolomics and proteomics, for the discovery of novel and emerging food toxins, enhancing our understanding of potential hazards in the food supply chain.

Covalently Functionalized Graphene with Molecularly Imprinted Polymers for Selective Adsorption and Electrochemical Detection of Chloramphenicol

In this report, we have presented a novel route to attach molecularly imprinted polymers (MIPs) on the surface of reduced graphene oxide (rGO) through covalent bonding. First, the surface of rGO was modified with maleic anhydride (MA) via a Diels-Alder reaction using a deep eutectic solvent (DES). Next, 3-propyl-1-vinylimidazolium molecular units were anchored and polymerized in the presence of ethylene glycol dimethacrylate (EGDMA) using chloramphenicol (CAP) as the template. Primarily, we investigated the effect of the molar ratio of individual precursors on the adsorption capacity of synthesized materials and accordingly fabricated the electrochemical sensor for CAP detection. Electrochemical results evidenced that the covalent bonding of MIP units enhanced the sensitivity of the respective sensor toward CAP in water as well as in real honey samples with high selectivity, stability, and reproducibility. This synthesis strategy involves the covalent binding of MIP on rGO materials via click chemisty under sonication power excluding harmful solvents and energy-intensive processes and thus could be a motivation for developing future electrochemical sensors through similar "green" routes.

Application of Multiplexed Aptasensors in Food Contaminants Detection

The existence of contaminants in food poses a serious threat to human health. In recent years, aptamer sensors (aptasensors) have been developed rapidly for the detection of food contaminants because of their high specificity, design flexibility, and high efficiency. However, the development of high-throughput, highly sensitive, on-site, and cost-effective methods for simultaneous detection of food contaminants is still restricted due to multiple signal overlap or mutual interference and cross-reaction between different analytes with similar molecular structures. To overcome these problems, this Review summarizes some effective strategies from the articles published in recent years about multiplexed aptasensors for the simultaneous detection of food contaminants. This work focuses on the application of multiplexed aptasensors to simultaneously detect antibiotics, pathogens, and mycotoxins in food. These aptasensors mainly contain fluorescent aptasensors, electrochemical aptasensors, surface-enhanced Raman scattering-based aptasensors, microfluidic chip aptasensors, and paper-based multiplexed aptasensors. In addition, this Review also covers the application of nucleic acid cycle amplification and nanomaterial amplification strategies to improve the detection sensitivity. Finally, the limitations and challenges in the design of multiplexed aptasensor are also taken into account.

A simple and rapid sensing strategy based on structure-switching signaling aptamers for the sensitive detection of chloramphenicol

A simple and rapid sensing strategy was proposed for chloramphenicol (CAP) detection based on structure-switching signaling aptamers. In this protocol, the aptamer can bind to both the fluorophore (FAM)-labeled complementary strand and the quencher (BHQ1)-labeled complementary strand, thus leading to the effective quenching of FAM fluorescence by BHQ1. However, when CAP is present, the structure switch is reversed because the aptamer recognizes CAP, resulting in fluorescence recovery. Such a fluorescence-sensing platform can monitor CAP within a good linear range (1-100 ng/mL), with a detection limit of 0.70 ng/mL. Cross-reactivity with other common antibiotics is negligible, indicating the excellent selectivity of the strategy. Moreover, as the aptamers are not modified, this method is simple and low-cost. The present work reveals a new direction for detecting CAP or other target compounds without prior knowledge of the secondary or tertiary structures of the aptamer.

Novel label-free and high-throughput microchip electrophoresis platform for multiplex antibiotic residues detection based on aptamer probes and target catalyzed hairpin assembly for signal amplification

Novel label-free and multiplex aptasensors have been developed for simultaneous detection of several antibiotics based on a microchip electrophoresis (MCE) platform and target catalyzed hairpin assembly (CHA) for signal amplification. Kanamycin (Kana) and oxytetracycline (OTC) were employed as models for testing the system. These aptasensors contained six DNA strands termed as Kana aptamer-catalysis strand (Kana apt-C), Kana inhibit strand (Kana inh), OTC aptamer-catalysis strand (OTC apt-C), OTC inhibit strand (OTC inh), hairpin structures H1 and H2 which were partially complementary. Upon the addition of Kana or OTC, the binding event of aptamer and target triggered the self-assembly between H1 and H2, resulting in the formation of many H1-H2 complexes. They could show strong signals which represented the concentration of Kana or OTC respectively in the MCE system. With the help of the well-designed and high-quality CHA amplification, the assay could yield 300-fold amplified signal comparing that from non-amplified system. Under optimal conditions, this assay exhibited a linear correlation in the ranges from 0.001ngmL^-1 to 10ngmL^-1, with the detection limits of 0.7pgmL^-1 and 0.9pgmL^-1 (S/N=3) toward Kana and OTC, respectively. The platform has the following advantages: firstly, the aptamer probes can be fabricated easily without labeling signal tags for MCE detection; Secondly, the targets can just react with probes and produce the amplified signal in one-pot. Finally, the targets can be simultaneously detected within 10min in different channels, thus high-throughput measurement can be achieved. Based on this work, it is estimated that this detection platform will be universally served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.

Development of a new fluorescence immunochromatography strip for detection of chloramphenicol residues in chicken muscles

BACKGROUND

Chloramphenicol (CAP), an antimicrobial drug that is widely used in animal feed, would have a negative effect on human health due to its low elimination rate and relatively high residue in animal food. It is important to develop a rapid and economic method to determine CAP in animal food to ensure that human health is not affected.

RESULTS

A new fluorescence immunochromatography strip was developed and established for the detection of CAP residue in chicken muscles for the first time. A CAP-bovine serum albumin conjugate, monoclonal antibody and polyclonal antibody against CAP were applied to constitute a fluorescence immunochromatography strip. The fluorescence intensity was detected by a charge-coupled device scanner and transformed to a digital value. The CAP linearity working range was from 0.1 ng mL(-1) to 20 ng mL(-1) with a limit of detection of 0.1 ng mL(-1) within 10 min. The performance of the strip assay was compared with a commercial ELISA kit and the correlation coefficient was 0.99, which indicated that the new strip assay had a good quantification ability for CAP.

CONCLUSION

The fluorescence immunochromatography strip was successfully applied to the detection of CAP residues in chicken samples. To our knowledge, it is the first report regarding the development of a fluorescence immunochromatography method for screening CAP in animal samples.

In vitro selection and characterization of DNA aptamers recognizing chloramphenicol

Chloramphenicol (Cam), although an effective antibiotic, has lost favour due to some fatal side effects. Thus there is an urgent need for rapid and sensitive methods to detect residues in food, feed and environment. We engineered DNA aptamers that recognize Cam as their target, by conducting in vitro selections. Aptamers are nucleic acid recognition elements that are highly specific and sensitive towards their targets and can be synthetically produced in an animal-friendly manner, making them ethical innovative alternatives to antibodies. None of the isolated aptamers in this study shared sequence homology or structural similarities with each other, indicating that specific Cam recognition could be achieved by various DNA sequences under the selection conditions used. Analyzing the binding affinities of the sequences, demonstrated that dissociation constants (K(d)) in the extremely low micromolar range, which were lower than those previously reported for Cam-specific RNA aptamers, were achieved. The two best aptamers had G rich (>35%) nucleotide regions, an attribute distinguishing them from the rest and apparently responsible for their high selectivity and affinity (K(d)∼0.8 and 1μM respectively). These aptamers open up possibilities to allow easy detection of Cam via aptamer-based biosensors.