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When rats were treated with different dosages of nicotine, nicotinic acetylcholine receptors (nAChRs) were observed in activated, sub-acute desensitized, acute desensitized, and chronic desensitized states. The activities of cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) were assayed in the respective rat brains. The results showed that the activities of PKA and PKC could not be modified when brain nAChRs were in an activated state. However, the activities of PKA and PKC decreased when brain nAChRs were in a sub-acute state, an acute state or a chronic desensitized state induced by repeated administration of nicotine. These results suggest that desensitized nAChRs in the rat brain can inhibit the activities of PKA and PKC, which may be responsible for nicotine dependence.

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 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 10(2) 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.

A novel molecularly imprinted material based on silica microparticles was synthesized by surface polymerization with 3-chloro-1,2-propandiol (3-MCPD) as a template molecule. The molecularly imprinted polymer (MIP) was characterized by infrared spectroscopy and scanning electron microscopy. The adsorption of 3-MCPD by MIP was measured by gas chromatography with electron capture detection (GC-ECD) and an equilibrium binding experiment. Scatchard analysis revealed that the maximum apparent binding capacities of the MIP and non-imprinted polymer (NIP) were 67.64 and 23.31 μmol/g, respectively. The new adsorbent was successfully used in solid-phase extraction (SPE) to selectively enrich and determine 3-MCPD in soy sauce samples. The MIP-SPE column achieves recoveries higher than 92.7% with a relative standard deviation of less than 1.83%. The MIP-SPE-GC protocol improved the selectivity and eliminated the effects of template leakage on quantitative analysis and could be used for the determination of 3-MCPD in other complex food samples.

Zearalenone (ZEN) contamination of corn and cereal products is a serious health hazard throughout the world and its elimination by microbial methods is now being widely examined. In this study, an Aspergillus niger strain, FS10, isolated from Chinese fermented soybean, was shown to reduce levels of ZEN in corn steep liquor (CSL). Spores, mycelium and culture filtrate of the strain FS10 were tested for their ability to remove ZEN. The results indicated that strain FS10 could remove 89.56% of ZEN from potato dextrose broth (PDB) medium. Mycelium and culture filtrate decreased the ZEN content by 43.10% and 68.16%, respectively. The contaminated corn steep liquor initially contained ZEN 29 μg/ml, 60.01% of which could be removed by strain FS10. To demonstrate the loss of toxicity in vivo, the culture filtrate incubated with the contaminated corn steep liquor for 48 h was administered to rats. The results indicated that the contaminated corn steep liquor severely damaged liver and kidney tissue. Rats administered with contaminated corn steep liquor treated with the strain FS10 culture filtrate showed significantly less severe liver and kidney damage, and organ index values were comparable to the non-ZEN-exposed control (p

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.

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 695nm and 863nm, 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 1-20ngmL(-1) (R(2)=0.9978 and R(2)=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.

The authors wish to add the first affiliation address “Synergetic Innovation Center of Food Safety and Nutrition, School of Food Science, Jiangnan University” to the correspondence author, Lili Tang’s affiliations on the first page of their paper published in Toxins [1].[...]

Detection of pathogenic bacteria in food is most important for food safety and quality control, and the critical step it chooses the rapid, sensitive and more economical method to extract DNA to produce high quality and decrease the time-consuming of measuring. Extraction of nucleic acids is the first step in most molecular biology studies and in all recombinant DNA techniques, but the difficult access steps and critical of analysis. Here we report, describe and compare the simple and fast methods of extraction (physical, boiling, phenol/ethanol and commercial kit) methods, from pure culture and then from beef samples. The quantity and quality of extraction methods were confirmed by polymerase chain reaction, agarose gel electrophoresis, and spectrophotometer nanodrop. Results revealed that the efficiently for all three methods were significant compared with the commercial kit, however, in pure culture the boiling method sex tract its more efficient, convenient and cheaper method for template preparation and significant when it compare with other methods while in beef samples experimental results showed that the phenol/ethanol method extract its more significantly.

The α subunit of β-conglycinin is a major allergen in soybean. The objective of this study was to predict and identify the linear immunoglobulin (Ig)E epitopes of the soybean α subunit of β-conglycinin. Three immunoinformatics tools were used to predict the potential epitopes and were confirmed by dot-blot inhibition using sera from soybean allergic subjects. As a result, 15 peptides were predicted and assembled by solid-phase synthesis. Eleven epitopes were identified by the dot-blot inhibition test. Moreover, peptide 3 had IgE binding capability with all sera(5/5) tested, while peptide 1, 4, 6, 8 and12 could bind to 4/5 of the sera samples. Secondary structure prediction of peptide 3 and circular dichroism test validated that the structure of peptide 3 was a random coil.

In this paper, a novel electrochemical immunosensor to detect staphylococcal enterotoxin B based on bio-magnetosomes, polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid, was developed, and found to exhibit high sensitivity and stability. The specific antibody to staphylococcal enterotoxin B conjugated with the magnetosomes showed rapid immunoreactions and good dispersion, which contributed to the formation of a nanostructurally smooth and dense film on the surface of a gold electrode. Polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid were used to modify the electrode as mediators to improve the electron transfer and offer an excellent biocompatible microenvironment for the antibody to retain its activity to enhance the response of the electrochemical sensor. Under optimal conditions, the developed immunosensor showed a good linear response in the range from 0.05 to 5 ng/mL (R(2)=0.9957) with a detection limit as low as 0.017 ng/mL, compared with the one without magnetosomes (0.05-5 ng/mL, 0.033 ng/mL), this developed immunosensor showed a wider response range and a reduced detection limit. And a good specificity with little adsorption to staphylococcal enterotoxin A, C and Na(+), K(+), Ca(2+) was obtained. Moreover, the immunosensor exhibited a good long-time stability at 4 °C reaching up to 60 days, which showed a relatively long working life. Meanwhile the immunosensor could be regenerated four times using NaOH elution. The sensor also displayed a good repeatability with a relative standard deviation of 5.02% for staphylococcal enterotoxin B detection (1 ng/mL, n=9). Furthermore, high recoveries in milk samples from 81% to 118% were achieved and successfully applied to milk sample detection. The obtained results demonstrate that the developed electrochemical immunosensor is a promising tool for the detection of staphylococcal enterotoxin B in food.

Desensitization is an intriguing characteristic of ligand-gated channels, whereby a decrease or loss of biological response occurs following prolonged or repetitive stimulation. Nicotinic acetylcholine receptors (nAChRs), as a member of transmitter gated ion channels family, also can be desensitized by continuous or repeated exposure to agonist. Desensitization of nicotinic receptors can occur as a result of extended nicotine exposure during smoking or prolonged acetylcholine when treatment of Alzheimer's disease (AD) with cholinesterase inhibitors, or anticholinesterase agent poisoning. Studies from our lab have shown that nAChRs desensitization is not a nonfunctional state and we proposed that desensitized nAChRs could increase sensitivity of brain muscarinic receptor to its agonists. Here, we will review the regulation of nicotinic receptor desensitization and discuss the important biological function of desensitized nicotinic receptors in light of our previous studies. These studies provide the critical information for understanding the importance of nicotinic receptors desensitization in both normal physiological processing and in various disease states.

This study aimed to assess whether nicotine prevented glutamate neurotoxicity in PC12 cells, and to identify the molecular mechanisms of any effects. The results showed that glutamate neurotoxicity in PC12 cells could be prevented by treatment with nicotine at concentrations of 10 nmol x l(-1) - 1 mmol x l(-1). This effect was in turn found to be inhibited by the application of the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine. Nicotine significantly decreased the basal level of intracellular free Ca(+2) and enhanced the buffering action on Ca(+2) overload induced by high concentrations of glutamate (5 mmol x l(-1)). In addition, nicotine treatment up-regulated the mRNA and protein expression of apoptosis-related factors including bcl-2 mRNA and protein, but down-regulated the expression of bax mRNA and protein. It is concluded that the protective effects of nicotine against the neurotoxicity induced by glutamate are mediated by nAChRs, due to the increased buffering action on Ca(+2)and the modulation of apoptotic processes.

A novel acrylamide (AA) molecularly imprinted material based on silica microparticles was synthesized successfully by a surface polymerization method using propionamide (PAM) as a template molecule, methacrylic acid (MAA) as a functional monomer, and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The molecularly imprinted polymers (MIP) on the surfaces of silica microparticles were characterized using infrared spectroscopy and scanning electron microscopy, and the results suggested that the MIP was successfully grafted onto the silica surface. The amount of AA adsorbed on the MIP was measured using high-performance liquid chromatography (HPLC) and equilibrium binding experiments. The results of static adsorption equilibrium experiments and Scatchard analysis showed that compared with non-imprinted polymers, the imprinted polymer had a significantly higher adsorption capacity for AA. Scatchard analysis revealed that two classes of binding sites were formed in the MIP with dissociation constants of 0.182 and 0.099 μmol mL−1, and the maximum apparent binding capacities were 16.18 and 54.18 μmol g−1. The new adsorbent was successfully used in solid-phase extraction (SPE) to selectively enrich and determine AA in fried food samples. The experimental results indicated that the MIP-SPE column gave recoveries higher than 93% with a relative standard deviation (RSD) of less than 2.24%, much better than those obtained using a commercial C18-SPE column, which gave a recovery of less than 24% with RSD < 2.07%. The developed MIP-SPE/HPLC protocol improved the selectivity and eliminated the effects of template leakage on quantitative analysis, and could be used for the determination of AA in complex food samples.