Deoxynivalenol (DON) and zearalenone (ZEN) are mycotoxins that contaminate a wide range of grains and crops. In this study, a one-step time-resolved single-channel immunochromatographic test strip ...based on europium ion polystyrene fluorescence microspheres was first developed for sensitive and quantitative detection of DON and ZEN. The concentration of the artificial antigen and the mass ratio of the monoclonal antibody to fluorescent microspheres for conjugation were optimized to simplify the sample addition process during immunochromatographic assay and improve the on-site detection efficiency. The limits of detection (LOD) of the single-channel immunochromatographic test strip for DON and ZEN detection were 0.17 and 0.54 μg/L, respectively. Meanwhile, the dual-channel immunochromatographic test strip was designed to simultaneously detect DON and ZEN, with LODs of 0.24 and 0.69 μg/L achieved for DON and ZEN, respectively. The developed test strips also yielded recovery results consistent with that obtained by LC-MS/MS for DON and ZEN detection in real samples of wheat and corn flour, confirming the practicability and reliability of the test strip. The developed immunochromatographic test strips realize quick and sensitive detection of DON and ZEN, exhibiting potential for broad applications in the point-of-care testing platform of multiple mycotoxins in agricultural products.
Graphic abstract
Antibiotic resistance has become a serious threat to food safety and public health globally. Therefore, the development of a sensitive, quick, and simple method for antibiotic susceptibility testing ...is an urgent and crucial need. A novel concentration gradient microfluidic chip was designed in this work to generate antibiotic concentration gradient, culture bacteria, and produce fluorescence emission. An in-house-assembled fluorescence detection platform was constructed, and experiments were conducted to verify the linearity of the generated concentration gradient, explore the appropriate incubation time and flow rate for the microfluidic chip, and study the effect of long-term acid-based food processing on antibiotic susceptibility testing. Experimental results show that the concentration gradient generated by the microfluidic chip exhibited good linearity, stability, and controllability. The appropriate flow rate and incubation time for the microfluidic chip were 2 μL/min and 5 h, respectively. The use of this microfluidic chip for testing antibiotic resistance of
Salmonella
to ofloxacin and ampicillin generated results that were completely consistent with test results obtained using the gold-standard method. Furthermore,
Salmonella
showed greater sensitivity to antibiotics under strong acid conditions, confirming the potential influence of acid-based food processing on antibiotic susceptibility testing of real samples. The designed microfluidic chip provides a high-throughput, sensitive, and rapid antibiotic susceptibility testing method that combines the microfluidic chip and the fluorescence detection platform. The application of this method would facilitate determination of antibiotic-resistant bacterial strains for clinicians and researchers, and enable monitoring of changes in bacterial resistance during food processing.
There are many kinds of estrogens, and endogenous estrogens produce a variety of estrogen metabolites with similar structure but with different physiological effects after metabolism in vivo. Studies ...have shown that estrone (E1) widely occurs in the environment and animal-derived food. Because of its estrogen effect, E1 can have adverse effects on the human body as an endocrine disruptor. In this study, we found that E1 and 2-hydroxyestrone (2-OH-E1), the hydroxylation metabolite of estrogen, have opposite proliferative effects on breast cancer cells (MCF-7) through cell proliferation experiments and comparison of their effects by molecular docking and detection of ROS, Ca2+, and cell pathway proteins. The effects of 2-methoxyestrone (2-MeO-E1) and 16α-hydroxyestrone (16α-OH-E1) on the biochemical and protein levels of MCF-7 were further studied to compare the effects of metabolic sites and modes on estrogen effects. Hydroxylation of E1 at the C2 site weakened the estrogen effect, down-regulated the expression of the mammalian target of rapamycin (mTOR) and protein kinase B (Akt) pathway proteins, inhibited the proliferation of cancer cells, and enhanced anti-oxidative stress and anti-inflammation. Methoxylation at the C2 position also inhibited the expression of inflammatory and oxidative stress pathway proteins but did not greatly affect the estrogen effects. However, hydroxylation on C16 had no significant effect on the biological effects of estrogen. Therefore, the structural changes of estrogen on C2 are important reasons for the different physiological effects of estrogen and its metabolites. Thus, by regulating the gene Cytochrome P450 1B1(CYP1B1), which affects the hydroxylation metabolism of estrogen, and promoting the hydroxylation of estrone at the C2 position, the estrogen effect of estrone can be effectively reduced, thus reducing the harm its poses in food and the environment.
•Hydroxylation at the C2 position of estrone reduces the estrogen effects of estrone.•Estrone and 2-hydroxyestrone have opposite biological effects on MCF-7.•The effect of estrogen hydroxylation metabolism on estrogen effect is greater than that of methoxylation.•The effect of estrogen C2 site metabolism on estrogen effect was greater than that of C16 site metabolism.•GLU353, an estrogen receptor residue, affects estrogen effects.
A light-addressable potentiometric sensor (LAPS) is a semiconductor electrochemical sensor based on the field-effect which detects the variation of the Nernst potential on the sensor surface, and the ...measurement area is defined by illumination. Thanks to its light-addressability feature, an LAPS-based chemical imaging sensor system can be developed, which can visualize the two-dimensional distribution of chemical species on the sensor surface. This sensor system has been used for the analysis of reactions and diffusions in various biochemical samples. In this review, the LAPS system set-up, including the sensor construction, sensing and substrate materials, modulated light and various measurement modes of the sensor systems are described. The recently developed technologies and the affecting factors, especially regarding the spatial resolution and temporal resolution are discussed and summarized, and the advantages and limitations of these technologies are illustrated. Finally, the further applications of LAPS-based chemical imaging sensors are discussed, where the combination with microfluidic devices is promising.
Salmonella
, one of the most common foodborne pathogens, poses a serious threat to human health. In recent years, the antibiotic resistance of
Salmonella
has become serious as well, which has ...strengthened the harm of
Salmonella
to human health. In this paper, a simple and effective electrochemical approach was developed to obtain profile of the antimicrobial susceptibility. Screen-printed carbon electrodes (SPCEs) were used to detect various concentrations of target bacteria at the same time, which have good stability, low cost, and easy mass production. The electroactive redox, resazurin, was used to monitor levels of metabolically active bacteria. As a demonstration, the antibacterial effect of ofloxacin and penicillin on
Salmonella gallinarum
(
S. gallinarum
) isolates was evaluated, and the minimum inhibitory concentration (MIC) was measured as well. In the real sample measurement, the MIC obtained was similar to that obtained by conventional antimicrobial susceptibility testing (AST). In this assay, bacterial activity was quantified sensitively and accurately, and the detection time was greatly reduced compared with conventional AST (16–20 h), which means that metabolic capacity of live bacteria could be observed after 1 h of incubation. We were able to clearly detect bacteria above 10
2
CFU/m. This method aims to nonspecific and can be widely applied to the detection of a variety of drug-resistant bacteria, providing an experimental basis for the rational use of antibiotics and bacterial resistance mechanisms.
The goal of this study is development and validation of a method to confirm and quantify milk allergens in food products based on liquid chromatography-tandem multiple reactions-monitoring, mass ...spectrometry (LC-MRM/MS). Here, emphasis was placed on two whey proteins, α-lactalbumin (α-La) and β-lactoglobulin (β-Lg), plus a third, αs1-casein (αs1-CN), known to be the main allergenic components of milk. Five marker peptides (one for α-La, two for β-Lg and two for αs1-CN) and three quantitative marker peptides from the digestion of standard milk proteins were identified using matrix-assisted laser desorption/ionization with tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS). Optimization of enzymatic hydrolysis conditions were defined as 37 °C for 16 h. The linearity ranges for the three allergenic proteins (α-La, β-Lg and αs1-CN) were 0.97–31.25 μg/mL, 0.48–31.25 μg/mL and 0.48–31.25 μg/mL, respectively. The assays were validated for absolute quantification of three milk proteins with satisfactory results, which indicates that the established mass method is suitable for the expression of levels in daily food.
•A LC-MRM/MS method for simultaneous determination of multi-allergens is proposed.•Identification and quantification of marker peptides is the core mechanism.•MRM parameter and enzymatic hydrolysis were strictly controlled.
Microcystins (MCs) are a class of toxins that are mainly produced by cyanobacteria. Among them, microcystin-leucine arginine (MC-LR) is one of the most toxic and harmful of the freshwater toxins, and ...it has caused many accidents and threats to human health. In the present study, we report a neoteric lateral flow fluorescent microsphere immunochromatographic assay (FM-ICA) combined with UV light detection to rapidly and quantitatively detect MC-LR in freshwater food, based on direct competitive immunoreactions on chromatographic strips. In the method, MC-LR artificial antigen, MC-LR-bovine serum albumin (MC-LR-BSA), and goat anti-rabbit immunoglobulin G (IgG) were labelled with europium (Eu) nanospheres that functioned as a luminescence tracer. Goat anti-mouse IgG and rabbit IgG were spread on a nitrocellulose (NC) membrane for the test (T) line and control (C) line, respectively. The optimal parameters were 1 mg/mL for the goat anti-mouse IgG and rabbit IgG, 20 μg of MC-LR-BSA conjugated with Eu nanospheres, 1:100 for the dilution of Eu-MC-LR-BSA, and a 1:30000 dilution of anti-MC-LR monoclonal antibody (mAb) with an assay time of 15 min. The working range of the MC-LR standard curve was 0.1–5.0 μg/L with a limit of detection (LOD) of 0.0542 μg/L and a 50% inhibitory concentration (IC50) of 0.5613 μg/L. The average recoveries of the FM-ICA for detecting MC-LR in real samples ranged from 90.1 to 109.3%, with coefficients of variation under 15.8%. The FM-ICA test strips for quantitative determination of MC-LR provide sensitive, simple, and rapid performance, and can be used to monitor freshwater samples.
•An immunochromatographic assay based on FMs to detect MC-LR was proposed.•Goat anti-mouse IgG and rabbit IgG were worked for the test and control line.•The assay can quantitatively detect MC-LR within 15 min with a portable device.•The method is highly sensitive with a detection limit of 0.0542 μg/L.
Saxitoxin (STX) is one of the paralytic shellfish poisons (PSP) that endanger people’s health. It is necessary to develop methods for the on-site rapid detection for STX in order to prevent safety ...accidents. An enzyme-linked immunosorbent assay (ELISA) is timesaving and effective, but it is not suitable for large-scale in-field tests due to the expensiveness of commercial ELISA kits and the bulkiness of a microtiter plate reader (MTPR). In this study, a portable smartphone-based colorimetric analyzer (SBCA) with a cost-effictive enhanced gold nanoparticle-based ELISA (EGNB-ELISA) was proposed for STX detection. In a bicinchoninic acid (BCA) protein assay (R2 = 0.9939) and a glucose assay (R2 = 0.9937), SBCA was shown to be in good agreement with MTPR. EGNB-ELISA had a 12.5-fold lower detection limit (0.4 ng/mL) and a lower detection range (1 – 50 ng/mL, Y = 0.4037X + 0.3564, R2 = 0.9797) than the classical ELISA. The recovery rate ranged over 89.1 – 112.2%. The whole detection system, combining both homemade SBCA and ENGB-ELISA, is expected to satisfy the needs of on-site STX sample tests to guarantee seafood safety.
MicroRNA (miRNA) links closely to the occurrence and development of many diseases, and the relationships between miRNA and mycotoxin and pathogenic bacteria also draw attentions. Therefore, in ...addition to clinical diagnosis, there is significant potential by sensing miRNAs for toxicity evaluation of food hazards. However, ultra-low levels, small inherent size and highly similar segments of miRNAs present a challenge to the profiling of miRNA expression, making effective methods crucially important. In this review, limitations of traditional miRNA detection methods are discussed. Then, a summary on miRNA sensing and imaging based on DNA nanostructure is provided. Next, signal amplification and ratiometric detection using sensitive electrochemical and fluorescence signals is focused. At last, challenges and potential opportunities of miRNA detection for wide application are proposed.
•Relationships between miRNA and disease, bacteria and mycotoxins are explained.•MiRNA detections with DNA nanostructure using electrochemical and fluorescence signal are presented.•Nucleic acid amplification and ratiometric strategies based on DNA nanostructures for miRNA detection are reviewed.•Further research and challenges of miRNA sensing and future directions in this field are also explained.
3-Chloropropane-1,2-diol (3-MCPD) is a heat-produced contaminant formed during the preparation of soy sauce worldwide. The present investigation was conducted to determine the molecular aspects of ...3-MCPD toxicity on human embryonic kidney cells (HEK293). Cell viability and apoptosis were assessed in response to exposure to 3-MCPD using the MTT assay and high-content screening (HCS). DNA damage, intracellular reactive oxygen species (ROS) and apoptosis-related proteins were evaluated. Genes related with apoptosis were detected by qPCR-array for further understanding the 3-MCPD induced cell apoptosis signaling pathway. Our results clearly showed that 3-MCPD treatment inhibits cell proliferation and reactive oxygen species generation. qPCR-array indicated that nine apoptotic genes were up-regulated more than 2-fold and six down-regulated more than 2-fold. Genes associated with the mitochondrial apoptotic pathway, especially BCL2 family genes, changed significantly, indicating that the mitochondrial apoptotic pathway is activated. Death receptor pathway-related genes, TNFRSF11B and TNFRSF1A, changed significantly, indicating that the death receptor pathway is also activated, resulting in the inhibition of cell growth and proliferation as well as induction of apoptosis. To sum up, the experiment results indicated that 3-MCPD induced HEK293 cell toxicity through the death receptor pathway and mitochondrial pathway.
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