Inflammation has been shown to play a critical role in the development of many diseases. In this study, we used metabolomics to evaluate the inflammatory effect of lipopolysaccharide (LPS) and the anti-inflammatory effect of glabridin (GB, a polyphenol from Glycurrhiza glabra L. roots) in RAW 264.7 cells. Multivariate statistical analysis showed that in comparison with the LPS group, the metabolic profile of the GB group was more similar to that of the control group. LPS impacted the amino acid, energy, and lipid metabolisms in RAW 264.7 cells, and metabolic pathway analysis showed that GB reversed some of those LPS impacts. Metabolomics analysis provided us with a new perspective to better understand the inflammatory response and the anti-inflammatory effects of GB. Metabolic pathway analysis can be an effective tool to elucidate the mechanism of inflammation and to potentially find new anti-inflammatory agents.Keywords: anti-inflammatory effect; cell metabolomics; LPS; metabolism pathway analysis; polyphenols;

A novel immunosensor for the detection of microcystin-LR (MC-LR) was constructed with use of immunochromatographic test strips (ICTS). Quantum dots were chosen to be the fluorescent labels for the immune sensor in ICTS because of their excellent optical and electronic properties with a relatively narrow emission spectrum. The detection sensitivity of the ICTS was related to the concentration of the fluorescent probe and the amount of the MC-LR standards. Under optimal conditions, with MC-LR as the target, the ICTS sensor had a linear range from 0.25 to 5 μg/L, with a correlation coefficient of 0.9901 and a detection limit of 0.1 μg/L. Furthermore, the repeatability of the ICTS was good, and the coefficient of variation was 10%. The ICTS immunosensor allows the reliable detection of MC-LR in water, and has potential in simple, sensitive detection applications.

•A immunomagentic probe for reducing of AFB1 contamination in liquid food was proposed.•It has 28 fold higher capability on AFB1 collection than Fe3O4 probe in vegetable oil.•Immunomagentic probe is reusable and can be removed from liquid food with a magnet.•A MTB existing in freshwater was found and acclimated to produce 15 nm magnetosomes.Here, a magnetotactic bacterium (MTB) existing in freshwaters was acclimated and mass propagations for producing natural magnetosomes with diameter about 15 nm at ordinary ambient. It was found that the magnetosomes which are mainly composed of iron oxide and iron sulfide hold pretty well magnetic features. Furthermore, the developed magnetosomes-AFB1 antibody immunomagentic probes through chemical bonding AFB1 polyclonal antibody onto the natural magnetosomes maintain 28 fold capability on collection of AFB1 toxin in vegetable oil compared to conventional Fe3O4 magnetic nanoparticle-AFB1 antibody probes. Recovery ratio up to 93.7% from commercial vegetable oil with artificial AFB1 contamination during 15 min collection were demonstrated. Through circular dichroism (CD) spectral measurements, the mechanism of magnetosomes probe was interpreted for proposing the practical way with high-performance on controlling the aflatoxins contamination in liquid foods basing on immunomagentic separation technique.

•An electrochemical biosensor was developed to evaluate individual and combined mycotoxin toxicity.•Laminin and collagen were used to immobilize cells to potentially mimic cell-ECM interactions in vivo.•The sensor is label-free, easy to use, and has instantaneously detection.•The SPCE and mini workstation made the method disposable, cost-effective, and portable.•This study provides a promising alternative to conventional cytotoxicity evaluation methods.A simple and convenient cell-based electrochemical biosensor was developed to assess the individual and combined toxicity of deoxynivalenol (DON), zearalenone (ZEN), and Aflatoxin B1 (AFB1) on Hep G2 cells. The sensor was modified in succession with AuNPs (gold nanoparticles), cysteamine, and laminin. The cells interacting with laminin formed tight cell-to-electrode contacts, and collagen was used to maintain cell adhesion and viability. Electrochemical impedance spectroscopy (EIS) was developed to evaluate mycotoxin toxicity. Experimental results show that DON, ZEN, and AFB1 caused a significant decrease in cell viability in a dose dependent manner. The EIS value decreased with concentrations of DON, ZEN, and AFB1 in the range of 0.01–20, 0.1–50, and 0.1–3.5 μg/mL, and IC50 obtained using the developed method was 48.5, 59.0, and 3.10 μg/mL, respectively. A synergistic effect was observed between DON and ZEN, an additive effect was observed between DON and AFB1, and an antagonism effect was found in the binary mixtures of ZEN and AFB1 and ternary mixtures. These results were confirmed via CCK-8 assay. Utilizing SEM, we found that cells treated with mycotoxins caused significant changes in cell morphology, thus lessening cell adsorption and impedance reduction. Biological assay indicated that EIS patterns correlated with [Ca2+]i concentrations and apoptosis and necrotic cells ratios, thus effecting electrochemical signals. This method is simpler, more convenient, sensitive, and has a quicker response rate than most conventional cytotoxicity evaluation methods.Download high-res image (245KB)Download full-size image

•The fast and robust sensor with excellent specificity and sensitivity for patulin detection.•Using carbon dots, chitosan，combined with Au nanoparticles to modify the MIP sensor.•Molecularly imprinted polymer technology is applied in the electrochemical detection of patulin.In this paper, molecular imprinting technique was applied to the electrochemical sensor. We used 2-oxindole as dummy template, ρ-Aminothiophenol (ρ-ATP) as functional monomers, combined with the high sensitivity of electrochemical detection, to achieve a specific and efficient detection of patulin in fruit juice. In addition, carbon dots and chitosan were used as the modifying material to improve electron-transfer rate, expand the electroactive surface of glassy carbon electrode and enhance strength of the signal. The Au–S bond and hydrogen bond were employed to complete the assembly of the ρ-ATP and 2-oxindole on the surface of the electrode. Then, polymer membranes were formed by electropolymerization in a polymer solution containing ρ-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP) and the template molecule 2- oxindole. After elution, the specific cavity can adsorb the target patulin. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed to monitor the electropolymerization process and its optimization. Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) analyses were used for characterization. This was the first time that the molecularly imprinted polymer (MIP) technology combined with carbon dots, chitosan and Au nanoparticles modification and was applied in the electrochemical detection of patulin. The linear response range of the MIP sensor was from 1 × 10–12 to 1 × 10−9 mol L−1 and the limit of detection (LOD) was 7.57 × 10–13 mol L−1. The sensor had a high-speed real-time detection capability, low sample consumption, high sensitivity, low interference, good stability and could become a new promising method for the detection of patulin.

•Aqueous ClO2 was used to investigate the reaction behavior of F. graminearum.•The first-order kinetic model determined the inactivation kinetics of F. graminearum spore.•A disinfection method of aqueous ClO2 application on Fusarium graminearum contaminated wheat.Fusarium graminearum is the main worldwide causal agent of Fusarium head blight grain disease. The production of mycotoxin caused by Fusarium head blight epidemics of wheat affects the flour and malt products, which results in heavy economic losses to farmers. In this paper, an inactivation procedure for F. graminearum F7875 spores was tested and found to follow a first-order kinetic model. We characterized the inactivation of F7875 by aqueous chlorine dioxide (ClO2) under different concentrations (5–15 mg L−1). The results suggest that aqueous ClO2 significantly enhanced inactivation of F7875 at high concentration (15 mg L−1) compared to lower concentration of 5 and 10 mg L−1. The time required for a five-log reduction of F7875 spores was calculated based on the established models. Observed by scanning electron microscope, the ClO2 destroys the structure of the outer coats of F7875, the surface of F7875's hyphal appeared smooth prior to treatment, but after treatment with 30 mg L−1 aqueous ClO2, it appeared rugged and wrinkled. In conclusion, our study shows that treatment with aqueous ClO2 is an effective, fast, and safe method to control F. graminearum in grain production.

The cause of toxicity induced by 3-chloro-1,2-propanediol (3-MCPD) remains under investigation, and progress towards understanding this toxicity has been limited by the lack of sensitive and reliable biomarkers. Global metabolomics were analyzed to characterize the phenotypical biochemical perturbations and potential mechanisms of the 3-MCPD-induced toxicity. 3-MCPD was administered to Wistar rats (60 mg per kg bw, oral) for 7, 21, and 35 days and urine samples were collected at each time point. The urinary metabolomics was performed by 1H NMR, and the NMR spectrum signals of the detected metabolites were normalized and analyzed by orthogonal pattern recognition methods (PCA and OPLS-DA). This analysis revealed a time- and dose-dependency of the biochemical perturbations induced by 3-MCPD toxicity. Several metabolites responsible for glycine, serine and threonine metabolism, taurine and hypotaurine metabolism and nicotinate and nicotinamide metabolism revealed that 3-MCPD produced serious kidney toxicity, consistent with clinical biochemistry and histopathology. Significant changes in seven identified metabolites were validated as phenotypic biomarkers of 3-MCPD toxicity. Overall, our work demonstrates the powerful use of metabolomics for improved detection of toxicity and biomarker discovery and highlights the powerful predictive potential of such analyses for understanding food toxicity.

•A novel cell co-culture microfluidic chip with electrochemical sensor was developed.•An intelligent capillary was designed to control the cell-to-cell communication.•Dynamic analysis of allergen-induced cell reaction was performed by impedance test.•Label-free, on-site, and real-time monitoring of RBL-2H3 and ANA-1 was achieved.In this study a novel cell-to-cell electrochemical microfluidic chip was developed for qualitative and quantitative analysis of food allergen. Microfluidic cell culture, food allergen-induced cell morphological changes, and cell metabolism measurements were performed simultaneously using the aforementioned device. RBL-2H3 mast cells and ANA-1 macrophages have been used within a cell co-culture model to observe their allergic response when they are introduced to the antigen stimulus. Two cell cultivation microfluidic channels are located in the microfluidic chip, which is fabricated with four groups of gold electrodes, with an additional “capillary”. In order to detect the allergic response, the cells were stimulated with dinitrophenylated bovine serum albumin (DNP-BSA) without anti-DNP IgE incubation. When exocytosis occurs, the cell-secreted inflammatory cytokines were measured by enzyme-linked immuno sorbent assay (ELISA) and cell impedance changes were detected using cell-based electrochemical assay. Results indicate that the real-time cell allergic response are accurately monitored by this electrochemical microfluidic chip, which provides a general example of rapidly prototyped low-cost biosensor technology for applications in both food allergen detection and investigation.

•A sensitive murine macrophage cell sensor has been developed for early detection of LPS.•The sensor utilized magnetism to immobilize cells and showed excellent regeneration.•Electrochemical signals were correlated with the microvilli and the calcium concentration.In this study, a sensitive and simple electrochemical murine macrophage (Ana-1) cell sensor has been developed for early detection of lipopolysaccharides (LPS) to evaluate the toxicity of pathogenic bacteria. Magnetic glassy carbon electrode (MGCE), which possesses excellent reproducibility and regeneration qualities, was modified with a nanocomposite to improve electrochemical signals and enhance the sensitivity. The synthesized magnetic nanoparticles (MNPs) were internalized into murine macrophages, which completed the immobilization of macrophages onto the modified electrode for evaluating the cytotoxicity of LPS by electrochemical impedance spectroscopy (EIS). The MNPs facilitated reusability of the proposed sensor by allowing removal of the magnetic core from the electrode. Our results indicated that LPS caused a marked decrease in electrochemical impedance in a dose-dependent manner in range of 1–5 μg/mL. By SEM, we found that microvilli on the plasma membrane became scarce and the membrane became smooth on cells incubated with LPS, which lessens the absorption of cells to reduce the impedance. And biological assay indicated that EIS patterns were correlated with the calcium concentration in cells, and suggested that [Ca2+]i production increased in cells incubated with LPS and its mobilization altered electrochemical signals. Compared with conventional methods, this electrochemical test is inexpensive, highly sensitive, and has a quick response, and thus provides a new avenue for evaluating the cytotoxicity of pathogens.

•Magnetic molecularly imprinted electrochemical sensor was firstly developed to detect AHL.•Magnetic pre-concentration and molecularly imprinted electrochemical determination steps showed high selectivity.•Electrochemical signal presented an excellent linear relationship with DMHF, providing potential applications in AHL detection.•Magnetic glassy carbon electrode exhibited good regeneration and appropriate recovery.We have developed a novel and economical electrochemical sensor to measure Gram-negative bacterial quorum signaling molecules (AHLs) using magnetic nanoparticles and molecularly imprinted polymer (MIP) technology. Magnetic molecularly imprinted polymers (MMIPs) capable of selectively absorbing AHLs were successfully synthesized by surface polymerization. The particles were deposited onto a magnetic carbon paste electrode (MGCE) surface, and characterized by electrochemical measurements. Differential Pulse Voltammetry (DPV) was utilized to record the oxidative current signal that is characteristic of AHL. The detection limit of this assay was determined to be 8×10−10 mol L−1 with a linear detection range of 2.5×10−9 mol L−1 to 1.0×10−7 mol L−1. This Fe3O4@SiO2-MIP-based electrochemical sensor is a valuable new tool that allows quantitative measurement of Gram-negative bacterial quorum signaling molecules. It has potential applications in the fields of clinical diagnosis or food analysis with real-time detection capability, high specificity, excellent reproducibility, and good stability.

•The stem-loop DNA biosensor owns superior mismatched discrimination ability.•Gold nanoparticles can effectively avoid the aggregation of the graphene sheets.•Multilayer graphene–gold nanocomposite gets the better electron conductivity.•The biosensor provided high sensitivity towards peanut allergen-Ara h1.•The biosensor was applied to determinate allergen-Ara h1 in peanut milk beverage.In this study, we developed an electrochemically-amplified, stem-loop DNA biosensor to detect the peanut allergen Ara h1. Specifically, we electrodeposited a multilayer graphene–gold nanocomposite onto a glassy carbon electrode and then immobilised a thiolated hairpin DNA–biotin probe onto the modified electrode surface. The multilayer graphene–gold composite has good dispersion ability, and can amplify the electrochemical signal due to its high electron-transfer efficiency. The probe was switched to an “off” state in the presence of target DNA. The prepared biosensor demonstrated a linear response ranging from 10−16 to 10−13 M, with an ultrasensitive detection limit of 0.041 fM. Moreover, the biosensor showed excellent selectivity, as well as the ability to discriminate between a complementary target and a one-base mismatch or non-complementary sequence. Results show that this prepared DNA biosensor can be successfully used to detect the peanut allergen Ara h1 in a peanut milk beverage. Findings can be applied to the prevention of allergic reactions, thus improving human health and safety.

The electrochemical genosensor is one of the most promising methods for the rapid and reliable detection of pathogenic bacteria. In a previous work, we performed an efficient electrochemical genosensor detection of Staphylococcus aureus by using lead sulfide nanoparticles (PbSNPs). As a continuation of this study, in the present work, the electrochemical genosensor was used to detect Escherichia coli O157:H7. The primer and probes were designed using NCBI database and Sigma-Aldrich primer and probe software. The capture and signalizing probes were modified by thiol (SH) and amine (NH2), respectively. Then, the signalizing probe was connected using cadmium sulfide nanoparticles (CdSNPs), which showed well-defined peaks after electrochemical detection. The genosensor was prepared by immobilization of complementary DNA on the gold electrode surface, which hybridizes with a specific fragment gene from pathogenic to make a sandwich structure. The conductivity and sensitivity of the sensor were increased by using multiwalled carbon nanotubes (MWCNT) that had been modified using chitosan deposited as a thin layer on the glass carbon electrode (GCE) surface, followed by a deposit of bismuth. The peak currents of E. coli O157:H7 correlated in a linear fashion with the concentration of tDNA. The detection limit was 1.97 × 10–14 M, and the correlation coefficient was 0.989. A poorly defined current response was observed as the negative control and baseline. Our results showed high sensitivity and selectivity of the electrochemical DNA biosensor to the pathogenic bacteria E. coli O157:H7. The biosensor was also used to evaluate the detection of pathogen in real beef samples contaminated artificially. Compared with other electrochemical DNA biosensors, we conclude that this genosensor provides for very efficient detection of pathogenic bacteria. Therefore, this method may have potential application in food safety and related fields.

The electrochemical behavior of electroactive species in a pheochromocytoma cell (PC-12) suspension was studied to establish a simple and rapid measurement method to obtain strong and direct electrochemical responses that objectively reflect cell viability. Two electrochemical signals of the PC-12 suspension, caused by the oxidation of guanine, xanthine, adenine and hypoxanthine, were simultaneously detected by using a glass carbon electrode modified with a multi-walled carbon nanotube–graphene nanosheet hybrid film. The presence of the four purines in the PC-12 cell cytoplasm was verified by HPLC assay using a DAD system and LC-MS analysis. Additionally, a linear relationship between the peak currents of purines in the cell suspension and culture time was found, which is in accord with the cell counts. The cytotoxic effect of acrylamide (0.1 mM to 10 mM) on cells was evaluated by differential pulse voltammetry (DPV) analysis, which detected a decrease in the voltammetric response of purines in the cytoplasm, in agreement with that obtained by the MTT test and with morphological analysis. Therefore, the voltammetric response of the ultrasonicated PC-12 cell suspension could be used to monitor cell growth and to evaluate the effects of potential toxic hazards on cells, and in drug screening.

We investigate here the selective cytotoxicity of 3-chloro-1,2-propanediol (3-MCPD) on HEK293 cells by analyzing the cell growth inhibition, morphological changes, intracellular reactive oxygen species (ROS) production, and DNA damage. We further demonstrate that 3-MCPD inhibits the growth of cells and induces 8-hydroxy-2′-deoxyguanosine (8-OH-dG) generation via ROS-mediated oxidative DNA damage in HEK293 cells. To provide a detection system, we fabricated a modified electrode with poly(3-acetylthiophene) (P3AT), for electrochemical detection of 8-OH-dG in oxidation-damaged cells. By.electropolymerization using cyclic voltammetry (CV), we deposited 3-acetylthiophene (3-AT) on a glassy carbon electrode (GCE). The conducting polymer, P3AT, greatly enhances the peak current via the dramatic electrocatalytic effect on the oxidation of 8-OH-dG. We further examined the effects of pre-concentration potential, time, scan rate, and pH value on voltammetric behavior and detection of 8-OH-dG. Under optimal conditions, the anodic peak currents of differential pulse voltammetry (DPV) maintain a linear relationship with the 8-OH-dG concentration between 0.5 and 35 μM, with a correlation coefficient of 0.9963. We estimated the detection limit of 8-OH-dG to be 31.3 nM (S/N = 3). The proposed modified electrode demonstrates excellent reproducibility and stability, making it an ideal candidate for amperometric detection of 8-OH-dG. We performed the detection on real cell samples with satisfactory results.

•Methylene blue (MB) is utilized as the electrochemical hybridization indicator.•The proposed strategy could detect the target DNA down to the level of 3.3×10−16 M.•We applied this sensor for the analysis of real samples (water) with 10 CFU mL−1.This paper presents a new electrochemical DNA biosensor constructed using a substrate electrode composed of a novel nanocomposite material prepared using gold nanoparticles (Au-NPs) and multiwalled carbon nanotubes (MWCNTs) and further modified with an Au electrode (AuE), which was used as the substrate electrode. A single-stranded DNA (ssDNA) probe was immobilized on the Au-NPs/CS–MWCNTs/AuE electrode by means of facile gold–thiol affinity, which resulted in hybridization with the target ssDNA sequence. Hybridization reactions were assessed by using the reduction peak current of methylene blue (MB) as an electrochemical indicator. The advantages of the nanomaterials were found to include high surface area, favorable electronic properties, and strong electrocatalytic activity. The amount of ssDNA adsorbed on the electrode surface was increased and the electrochemical response of MB accelerated. The differential pulse voltammetric responses of MB were in line with the specific target ssDNA sequence within the concentration range 1.0×10−15–1.0×10−8 M with the detection limit 3.3×10−16 M (3σ). In the colony forming unit (CFU) we were able to detect 10 CFU mL−1of Staphylococcus aureus in the tap water, achieving good discrimination ability between one- and three-base mismatched ssDNA sequences. The polymerase chain reaction (PCR) amplification products of S. aureus nuc gene sequence were also detected with satisfactory results.

•Spongy gold film/mutiwalled carbon nanotube modified DNA sensor has been fabricated.•Streptavidin–horseradish peroxidase is utilized as signal amplification.•The proposed strategy could detect the target DNA down to the level of 0.013 fmol.•We applied the developed sensor for the analysis of real samples (peanut) with good results.In this paper, a highly sensitive biosensor was constructed for peanut allergen Ara h1 detection. The biosensor was constructed by coating a glassy carbon electrode with a chitosan-mutiwalled carbon nanotube nanocomposite and then adding a spongy gold film via electro-deposition to increase the effective area. The probe switched from an “on” to an “off” state in the presence of target DNA, which detached biotin from the electrode surface. This also detached streptavidin–horseradish peroxidase (HRP-SA), which was bound to the electrode via specific interaction with biotin. The HRP-SA catalyzed chemical oxidation of hydroquinone by H2O2 to form benzoquinone, and when it was detached, electrochemical reduction of the signal of benzoquinone could be used to monitor DNA hybridization via chronoamperometry. Under optimum conditions, a wide dynamic detection range (3.91×10−17–1.25×10−15 mol L−1) and a low detection limit (1.3×10−17 mol L−1) were achieved for the complementary sequence. Furthermore, the DNA biosensor exhibited an excellent ability to discriminate between a complementary target and a one-base mismatch or non-complementary sequence. The sensor was successfully applied to Ara h 1 analysis in peanuts.

•This work provide a high and rapid methodology for detection of potential pathogenic Aeromonas.•High sensitive MWCNT–Chi–Bi was used to increase the sensibility of sensor.•The biosensor could discriminate between target and non-target gene.•The biosensor was used for practical detection in spiked tap water.In this paper, we reported the construction of new high sensitive electrochemical genosensor based on multiwalled carbon nanotubes–chitosan–bismuth complex (MWCNT–Chi–Bi) and lead sulfide nanoparticles for the detection of pathogenic Aeromonas. Lead sulfide nanoparticles capped with 5′-(NH2) oligonucleotides thought amide bond was used as signalizing probe DNA (sz-DNA) and thiol-modified oligonucleotides sequence was used as fixing probe DNA (fDNA). The two probes hybridize with target Aeromonas DNA (tDNA) sequence (fDNA–tDNA–szDNA). The signal of hybridization is detected by differential pulse voltammetry (DPV) after electrodeposition of released lead nanoparticles (PbS) from sz-DNA on the surface of glass carbon electrode decorated with MWCNT–Chi–Bi, which improves the deposition and traducing electrical signal. The optimization of incubation time, hybridization temperature, deposition potential, deposition time and the specificity of the probes were investigated. Our results showed the highest sensibility to detect the target gene when compared with related biosensors and polymerase chain reaction (PCR). The detection limit for this biosensor was 1.0×10−14 M. We could detect lower than 102 CFU mL−1 of Aeromonas in spiked tap water. This method is rapid and sensitive for the detection of pathogenic bacteria and would become a potential application in biomedical diagnosis, food safety and environmental monitoring.

•The MIP sensor is promising for clinical diagnostics of cholesterol•The MIP sensor equipped with MWNTs.•The LOD and LOQ of MIP sensor is fairly low.•The sensor has a high sensitivity, low interference and good stability.A novel electrochemical sensor for cholesterol (CHO) detection based on molecularly imprinted polymer (MIP) membranes on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWNTs) and Au nanoparticles (AuNPs) was constructed. p-Aminothiophenol (P-ATP) and CHO were assembled on the surface of the modified GCE by the formation of Au–S bonds and hydrogen-bonding interactions, and polymer membranes were formed by electropolymerization in a polymer solution containing p-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP) and the template molecule CHO. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were used to monitor the electropolymerization process and its optimization, which was further characterized by scanning electron microscopy (SEM). The linear response range of the MIP sensor was between 1×10−13 and 1×10−9 mol L−1, and the limit of detection (LOD) were 3.3×10−14 mol L−1. The proposed system has the potential for application in clinical diagnostics of cholesterol with high-speed real-time detection capability, low sample consumption, high sensitivity, low interference and good stability.

Rapid early detection of food contamination is the main key in food safety and quality control. Biosensors are emerging as a vibrant area of research, and the use of DNA biosensor recognition detectors is relatively new. In this study a genomic DNA biosensor system with a fixing and capture probe was modified by a sulfhydryl and amino group, respectively, as complementary with target DNA. After immobilization and hybridization, the following sandwich structure fixing DNA–target DNA–capture DNA–PbS NPs was formed to detect pathogenic bacteria (Staphylococuus aureus EF529607.1) by using GCE modified with (multiwalled carbon nanotubes–chitosan–bismuth) to increase the sensitivity of the electrode. The modification procedure was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The sandwich structure was dissolved in 1 M nitric acid to become accessible to the electrode, and the PbS NPs was measured in solution by differential pulse voltammetry (DPV). The results showed that the detection limit of the DNA sensor was 3.17 × 10–14 M S. aureus using PbS NPs, whereas the result for beef samples was 1.23 ng/mL. Thus, according to the experimental results presented, the DNA biosensor exhibited high sensitivity and rapid response, and it will be useful for the food matrix.

In this study, we developed a rat basophilic leukemia cell (RBL-2H3) fluorescence sensor to detect and identify the major fish allergen parvalbumin (PV). We constructed and transfected a CD63-enhanced green fluorescent protein (EGFP) plasmid into RBL cells through a highly efficient, lipid-mediated, DNA-transfection procedure. Stable transfectant RBL cells were then obtained for a cell fluorescence assay with confocal laser scanning microscopy. Results show that the cell surface expression of CD63 reflects degranulation, indicating that a fluorescence assay with these cells could efficiently measure the activation of antigen-stimulated transfectant cells and detect antigens with a nanogram level. Therefore, this cell-based fluorescence biosensor technique for detecting fish PV exhibits promise for quantifying fish PV after anti-PV immunoglobulin E (IgE) stimulation. Results show that fluorescence intensities increased with purified PV concentrations from 1 to 100 ng/mL, with a detection limit of 0.35 ng/mL [relative standard deviation (RSD) of 4.5%], confirmed by β-hexosaminidase assays. These rat basophilic leukemia (RBL) mast cells transfected with the CD63–EGFP gene and responded to PV only when they were sensitized with the specific IgE antibody. This demonstrates the utility of this highly sensitive biosensor for food allergen detection and prediction.

In this work, a novel electrochemical sensor for 3-chloro-1,2-propandiol (3-MCPD) detection based on a gold nanoparticle-modified glassy carbon electrode (AuNP/GCE) coated with a molecular imprinted polymer (MIP) film was constructed. p-Aminothiophenol (p-ATP) and 3-MCPD were self-assembled on a AuNP/GCE surface, and then a MIP film was formed by electropolymerization. The 3-MCPD template combined with p-ATP during self-assembly and electropolymerization, and the cavities matching 3-MCPD remained after the removal of the template. The MIP sensor was characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and scanning electron microscopy (SEM). Many factors that affected the performance of the MIP membrane were discussed and optimized. Under optimal conditions, the DPV current was linear with the log of the 3-MCPD concentration in the range from 1.0 × 10–17 to 1.0 × 10–13 mol L–1 (R2 = 0.9939), and the detection limit was 3.8 × 10–18 mol L–1 (S/N = 3). The average recovery rate of 3-MCPD from spiked soy sauce samples ranged from 95.0% to 106.4% (RSD < 3.49%). Practically, the sensor showed high sensitivity, good selectivity, excellent reproducibility, and stability during the quantitative determination of 3-MCPD.

A novel electrochemical sensor for acrylamide (AM) detection based on molecularly imprinted polymer (MIP) membranes was constructed. p-Aminothiophenol (P-ATP) and AM were assembled on the surface of a gold nanoparticle (AuNP) modified glass carbon electrode (GCE) by the formation of Au–S bonds and hydrogen-bonding interactions, and polymer membranes were formed by electropolymerization in a polymer solution containing P-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP) and a dummy template molecule propanamide (PMA). A novel molecularly imprinted sensor (MIS) was obtained after the removal of PMA. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were used to monitor the electropolymerization process and its optimization, which was further characterized by scanning electron microscopy (SEM). The linear response range of the MIS was between 1 × 10−12 and 1 × 10−7 mol L−1, with a detection limit of 0.5 × 10−12 mol L−1. This research provides a fast, sensitive and real-time method for the detection of AM in a real sample without complex pretreatment and with average recoveries higher than 95% and a relative standard deviation (RSD) lower than 3.73%. All the obtained results indicate that the MIS is an effective electrochemical technique to determine AM in real-time and in a complicated matrix.

•A sensitive surface enhanced fluorescence (SEF) immunosensor for microcystin-LR was developed.•Gold nano-crosses as fluorescence enhancement nanoparticles label molecule were developed.•SEF effect was influenced by the size, shape and distribution of the gold nanoparticles with enhancement factor 2.3 to 35 folds.A surface-enhanced fluorescence (SEF) immunosensor for the detection of microcystin-LR was developed using Au nano-crosses as fluorescence enhancement nanoparticles and cy5 as a fluorescence label molecule. The SEF effects of cy5 in the proximity of Au nanorods and gold nano-crosses was investigated by using Au nanorods or nano-crosses coated negative-charged glass surfaces. Fluorescence measurements indicated that SEF was influenced by the size, shape and distribution of the Au nanoparticles, with an appropriate spacer layer between the Au nanoparticles and the cy5. The enhancement factor was from 2.3- to 35-fold. Under optimal conditions, the SEF immunosensor exhibited a good linear response at microcystin-LR concentrations of 0.02–16 ng mL−1 (R2=0.9981). The limit of detection was 0.007 ng mL−1 with little adsorption of microcystin-RR, microcystin-LW, and microcystin-LF. High microcystin-LR recoveries were obtained from naturally contaminated fish samples. The SEF immunosensor allows the reliable detection of microcystin-LR in seafood, and has potential in simple, sensitive detection applications.

We report on a sensitive, simple, label-free impedance-based immunoelectrode for the determination of microcystin-LR (MCLR). The surface of the electrode was modified with a composite made from multiwalled carbon nanotubes and an ionic liquid, and with immobilized polyclonal antibody against MCLR. Cyclic voltammetry and impedance spectroscopy were applied to characterize the modified electrode. It is found that the multi-walled carbon nanotubes act as excellent mediators for the electron transfer between the electrode and dissolved hexacyanoferrate redox pair, while the ionic liquid renders it biocompatible. The method exhibits a wide linear range (0.005 μg•L-1 to 1.0 μg•L-1), a low detection limit (1.7 ng•L-1) and a long-term stability of around 60 days. The ionic liquid 1-amyl-2,3-dimethylimidazolium hexafluorophosphate gave the best impedimetric response. The new immunoelectrode is sensitive, stable, and easily prepared. It has been successfully applied to the determination of MCLR in water samples.

•A simple UV assay for the simultaneous detection of Pefloxacin and Microcystin-LR was developed.•Modified gold nanorods exhibiting two different peaks were applied to simultaneous UV detection.•Artificial antigen (antigen-OVA) modified biological magnetosome as signal amplification probes.A simple longitudinal surface plasmon resonance (LSPR) assay for the simultaneous detection of Pefloxacin and Microcystin-LR in seafoods has been developed for the first time using antibody-functionalized gold nanorods as signal probes and antigen-ovalbumin modified biological magnetosomes as signal amplification probes. The gold nanorods exhibit two different LSPR peaks, at around 695 nm and 863 nm, the positions of which were sensitive to changes in the local environment but can be subjected to simultaneous UV–vis detection. The biological magnetosomes produced by the magnetotactic bacteria not only act as a substrate for the immobilization of artificial antigen, but also enable signal enhancement and rapid separation, because of good dispersivity, biocompatibility and superparamagnetic properties. Under optimal conditions, magnetosome-enhanced LSPR assays showed a good linear response over the range 1–20 ng mL−1 (R2=0.9978 and R2=0.9992) with little adsorption to Enrofloxacin, Sarafloxacin, Ciprofloxacin, Norfloxacin, Microcystin-RR, Microcystin-LW, and Microcystin-LF, and compared with magnetosome-free LSPR assays, the response signal was amplified 2.5–5.0 fold. Furthermore, LSPR assays were successful in the analysis of Pefloxacin and Microcystin-LR in naturally contaminated seafood samples and high recoveries were achieved. Indications are that this LSPR assay promises reliable simultaneous detection of Pefloxacin and Microcystin-LR in seafoods, and holds the potential of novel applications in exploiting this multiple simultaneous UV–vis detection.

This study describes the synthesis of a molecularly imprinted polymer (MIP) as a novel solid-phase extraction adsorbent. The MIP consisted of pefloxacin (PEF) as a template, methacrylic acid (MAA) as a functional monomer, and silica gel particles as a support. The MIP was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and static adsorption. The MIP allowed the selective extraction of the fluoroquinolones PEF and enrofloxacin (ENR) and the simultaneous elimination of interfering components from milk matrices. Good linearity was obtained in a range of 2.5–500 ng mL−1, with correlation coefficients (R2) >0.999. The average recovery rates of PEF and ENR ranged from 92.04 to 98.31 %, and the detection limits were 0.8–1.5 ng mL−1. This work provides a sensitive and selective tool for the detection of PEF and ENR residues in milk and potentially in other foods.

A novel electrochemical DNA sensor was developed by using a stem–loop probe for peanut allergen Ara h 1 detection. The probe was modified with a thiol at its 5′ end and a biotin at its 3′ end. The biotin-tagged “molecular beacon”-like probe was attached to the surface of a gold electrode to form a stem–loop structure by self-assembly through facile gold–thiol affinity. 6-Mercaptohexanol (MCH) was used to cover the remnant bare region. The stem–-loop probe was “closed” when the target was absent, and then the hybridization of the target induced the conformational change to “open”, along with the biotin at its 3′ end moved away from the electrode surface. The probe conformational change process was verified by circular dichroism (CD); meanwhile, electron-transfer efficiency changes between probe and electrode were proved by electrochemical impedance spectroscopy (EIS). The detection limit of this method was 0.35 fM with the linear response ranging from 10–15 to 10–10 M. Moreover, a complementary target could be discriminated from one-base mismatch and noncomplementarity. The proposed strategy has been successfully applied to detect Ara h 1 in the peanut DNA extracts of peanut milk beverage, and the concentration of it was 3.2 × 10–13 mol/L.

•Demonstrated the individual and combinatorial effect of commonly occurring mycotoxins- AFB1, DON and ZEN.•Showed that, ranking based on cytotoxicity is DON > AFB1 > ZEN when tested individually.•Showed that, binary (except for AFB1+ZEN) and tertiary combinations of mycotoxins leads to additive or synergistic effects.•Demonstrated the utility of high content screening and mathematical modelling of data for elucidating combinatorial cytotoxicity of mycotoxins.To understand the combinatorial toxicity of mycotoxins, we measured the effects of individual, binary and tertiary combinations of Aflatoxin B1 (AFB1), Deoxynivalenol (DON) and Zearalenone (ZEN) on the cell viability and cellular perturbations of HepG2 and RAW 264.7 cells. The nature of mycotoxins interactions was assessed using mathematical modeling (Chou-Talalay). Mechanisms of cytotoxicity were studied using high content screening (HCS) that probed cytotoxicity responses, such as changes in intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), intracellular calcium ([Ca2+]i) flux, and cell membrane damage. Our results showed that individual cytotoxicity of mycotoxins in a decreasing order was DON>AFB1>ZEN. Varying combinations of mycotoxins at differing concentrations showed different types of interactions. Most of the mixtures showed increasing toxic effects-synergism and/or addition while antagonistic effects were observed with combination of AFB1+ZEN. Generally, combination of mycotoxins showed significantly increased intracellular ROS production and [Ca2+]i flux, and decreased MMP in both cell lines, showing that the synergistic and additive effects of mycotoxin combination originate from perturbations of multiple cellular functions. Additionally, this study demonstrated the applicability of HCS for gaining mechanistic understanding on the toxicity of individual as well as combinatorial mycotoxins, and also provided scientific bases for formulating regulatory policies.

•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.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.

We investigate here the selective cytotoxicity of 3-chloro-1,2-propanediol (3-MCPD) on HEK293 cells by analyzing the cell growth inhibition, morphological changes, intracellular reactive oxygen species (ROS) production, and DNA damage. We further demonstrate that 3-MCPD inhibits the growth of cells and induces 8-hydroxy-2′-deoxyguanosine (8-OH-dG) generation via ROS-mediated oxidative DNA damage in HEK293 cells. To provide a detection system, we fabricated a modified electrode with poly(3-acetylthiophene) (P3AT), for electrochemical detection of 8-OH-dG in oxidation-damaged cells. By.electropolymerization using cyclic voltammetry (CV), we deposited 3-acetylthiophene (3-AT) on a glassy carbon electrode (GCE). The conducting polymer, P3AT, greatly enhances the peak current via the dramatic electrocatalytic effect on the oxidation of 8-OH-dG. We further examined the effects of pre-concentration potential, time, scan rate, and pH value on voltammetric behavior and detection of 8-OH-dG. Under optimal conditions, the anodic peak currents of differential pulse voltammetry (DPV) maintain a linear relationship with the 8-OH-dG concentration between 0.5 and 35 μM, with a correlation coefficient of 0.9963. We estimated the detection limit of 8-OH-dG to be 31.3 nM (S/N = 3). The proposed modified electrode demonstrates excellent reproducibility and stability, making it an ideal candidate for amperometric detection of 8-OH-dG. We performed the detection on real cell samples with satisfactory results.

A novel electrochemical sensor for acrylamide (AM) detection based on molecularly imprinted polymer (MIP) membranes was constructed. p-Aminothiophenol (P-ATP) and AM were assembled on the surface of a gold nanoparticle (AuNP) modified glass carbon electrode (GCE) by the formation of Au–S bonds and hydrogen-bonding interactions, and polymer membranes were formed by electropolymerization in a polymer solution containing P-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP) and a dummy template molecule propanamide (PMA). A novel molecularly imprinted sensor (MIS) was obtained after the removal of PMA. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were used to monitor the electropolymerization process and its optimization, which was further characterized by scanning electron microscopy (SEM). The linear response range of the MIS was between 1 × 10−12 and 1 × 10−7 mol L−1, with a detection limit of 0.5 × 10−12 mol L−1. This research provides a fast, sensitive and real-time method for the detection of AM in a real sample without complex pretreatment and with average recoveries higher than 95% and a relative standard deviation (RSD) lower than 3.73%. All the obtained results indicate that the MIS is an effective electrochemical technique to determine AM in real-time and in a complicated matrix.