METTL3 promotes oxaliplatin resistance of gastric cancer CD133+ stem cells by promoting PARP1 mRNA stability.

Oxaliplatin is the first-line regime for advanced gastric cancer treatment, while its resistance is a major problem that leads to the failure of clinical treatments. Tumor cell heterogeneity has been considered as one of the main causes for drug resistance in cancer. In this study, the mechanism of oxaliplatin resistance was investigated through in vitro human gastric cancer organoids and gastric cancer oxaliplatin-resistant cell lines and in vivo subcutaneous tumorigenicity experiments. The in vitro and in vivo results indicated that CD133+ stem cell-like cells are the main subpopulation and PARP1 is the central gene mediating oxaliplatin resistance in gastric cancer. It was found that PARP1 can effectively repair DNA damage caused by oxaliplatin by means of mediating the opening of base excision repair pathway, leading to the occurrence of drug resistance. The CD133+ stem cells also exhibited upregulated expression of N6-methyladenosine (m6A) mRNA and its writer METTL3 as showed by immunoprecipitation followed by sequencing and transcriptome analysis. METTTL3 enhances the stability of PARP1 by recruiting YTHDF1 to target the 3'-untranslated Region (3'-UTR) of PARP1 mRNA. The CD133+ tumor stem cells can regulate the stability and expression of m6A to PARP1 through METTL3, and thus exerting the PARP1-mediated DNA damage repair ability. Therefore, our study demonstrated that m6A Methyltransferase METTL3 facilitates oxaliplatin resistance in CD133+ gastric cancer stem cells by Promoting PARP1 mRNA stability which increases base excision repair pathway activity.

Determination of trace aflatoxin M1 (AFM1) residue in milk by an immunochromatographic assay based on (PEI/PSS)4 red silica nanoparticles.

Aflatoxin M1 (AFM1) residues in milk pose a major threat to human health, so there is an urgent need for a simple, rapid, and sensitive method for the determination of trace AFM1 in milk. In this study, a competitive immunochromatographic assay (ICA), using visual (PEI/PSS)4 red silica nanoparticles (SiNPs) as signal amplification probes, was used for the highly sensitive detection of AFM1. The (PEI/PSS)4 red SiNPs were used to label AFM1 monoclonal antibody (mAb) to prepare ICA for the detection of AFM1. After exploring the optimal conditions of mAb and immunoprobe dosage conditions, the lowest visual detection limit (VDL) of AFM1 in phosphate-buffered saline with Tween 20 (PBST, 10 mM, pH 7.4, containing 1% BSA, 3% sucrose, 1% trehalose, and 0.5% Tween 20) can reach 0.1 pg/mL. The intuitive visually visible value of AFM1 in both PBST and milk was 10 pg/mL. The results showed that the immunochromatographic system based on high chroma color (PEI/PSS)4 red SiNPs has high sensitivity and broad application prospects for the detection of trace AFM1 residues in milk. The high chroma (PEI/PSS)4 red SiNPs are expected to be a convenient biomarker for improving the sensitivity of immune chromatography bands. Graphical abstract The schematic diagram shows the detection principle. In this work, in the competitive experiment, (PEI/PSS)4 red SiNPs were selected as visual labeling materials, and the specific antibody combined with the labeled material was selected as an immune probe. The AFM1-BSA antigen coupled with the macromolecular BSA was fixed on the T line of the nitrocellulose (NC) membrane. The AFM1 in sample solution competes with AFM1-BSA for the specific binding site of immune probe. The detection sensitivity of this method for AFM1 is obtained by judging the change of the red signal intensity produced by the positive sample, compared with the color at the T line of the negative sample.

Ultramarine blue nanoparticles as a label for immunochromatographic on-site determination of ractopamine.

A competitive immunochromatographic assay (ICA) is presented and used for on-site determination of ractopamine (RAC). Ultramarine blue nanoparticles were directly separated from ultramarine blue industrial products by centrifugation (< 10,000 rpm and > 4000 rpm) and used as visible labels in ICAs. The ultramarine blue nanoparticles were coated by polyacrylic acid (PAA), which provides carboxyl groups on the surface of ultramarine blue nanoparticles. An anti-RAC monoclonal antibody (mAb) was covalently immobilized on the carboxyl-modified ultramarine blue nanoparticle surface via diimide-activated conjugation between the carboxyl groups on the ultramarine blue nanoparticle surface and the amino groups of the antibodies. RAC and BSA-modified RAC competitively bind to the anti-RAC mAb on the ultramarine blue nanoparticles. The blue band in the test line is generated by the accumulation of ultramarine blue nanoparticles and is negatively associated with the RAC content. Under optimal conditions, the visual limit of detection (vLOD) of this ICA for RAC is 2.0 ng mL-1, 2.0 ng mL-1, and 1.0 ng mL-1 in phosphate-buffered saline (PBS), feed samples, and pork samples, respectively. The ultramarine blue nanoparticle-based ICA also shows no cross activity with salbutamol, clorprenaline, clenbuterol, or terbutaline. Graphical abstract Schematic representation of the ultramarine blue nanoparticles immunochromatographic assay for detection of ractopamine (RAC) based on competitive method. The ultramarine blue nanoparticles were screened from commercial ultramarine pigments for the first time and used to detect ractopamine.

A silica nanoparticle based 2-color immunochromatographic assay for simultaneous determination of clenbuterol and ractopamine.

An immunochromatographic assay (ICA) is presented that can be applied to simultaneous detection of clenbuterol (CLE) and ractopamine (RAC). It is making use of two red and blue silica nanoparticles (SiNPs) that act as labels for encoding the antibodies. This design permits multiplexed analysis in a single test line and does not require an external source for photoexcitation. Anti-CLE was labeled with red SiNPs, and anti-RAC with blue SiNPs. The capture antigens CLE-BSA and RAC-BSA were placed onto the conjugate pad and the test line of the test strip, respectively. Under bare eye examination, no cross-colored lines or nonspecific bioconjugate adsorption were observed, and the visible limit of detections for CLE (red) and RAC (blue) are 3 and 2 ng‧mL-1, respectively. This design allows for multiplexed detection with reduced device dimensions and costs, and with easy integration and manufacturing. Conceivably, the method may be extended to simultaneous determination of numerous other analytes. Graphic abstract The principle of qualitative detection strategy of multiplex immunochromatographic assay for clenbuterol (CLE) and ractopamine (RAC) is schematically illustrated. Depending on the type and ratio of organic dyes, the color of colored silica nanoparticle can be tuned from red to purple and even to black (lower right corner).

A non-enzymatic electrochemical immunoassay for quantitative detection of Escherichia coli O157:H7 using Au@Pt and graphene.

Herein, a non-enzymatic sandwich-type electrochemical immunoassay was fabricated for quantitative monitoring of Escherichia coli O157:H7 (E. coli O157:H7). Silica coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) were modified with mouse anti-E. coli O157:H7 monoclonal antibody (Ab1) to act as capture probes to reduce detection time and increase the sensitivity of the immunoassay. The Au@Pt nanoparticles were loaded on neutral red (NR) functionalized graphene to form composite complex rGO-NR-Au@Pt. rGO-NR-Au@Pt has high specific surface area and good biocompatibility. rGO-NR-Au@Pt was used as the carriers of detection antibodies (Ab2). Au@Pt catalyzed the reduction of hydrogen peroxide (H2O2) to detection of E. coli O157:H7 with the thionine (TH) as electron mediator to effectually amply the current signal. Under the optimized conditions, a linear relationship between the reduction peak current change (ΔIpc) and the logarithm of the E. coli O157:H7 concentration is obtained in the range from 4.0 × 103 to 4.0 × 108 CFU mL-1 and the limit of detection (LOD) is 4.5 × 102 CFU mL-1 at a signal-to-noise ratio of 3. The immunoassay exhibits acceptable specificity, reproducibility and stability on the detection of E. coli O157:H7. Furthermore, the immunoassay showed good performance in pork and milk samples. The results suggest that this immunoassay will be promising in the food safety area.

Electrochemical sandwich immunoassay for Escherichia coli O157:H7 based on the use of magnetic nanoparticles and graphene functionalized with electrocatalytically active Au@Pt core/shell nanoparticles.

A highly sensitive electrochemical sandwich immunoassay is described for determination of Escherichia coli O157:H7 (E. coli O157:H7). Silica coated magnetite nanoparticles (Fe3O4) were modified with primary antibody to capture E. coli O157:H7. Gold-platinum core/shell nanoparticles (Au@Pt NPs) with different Pt shell thicknesses were prepared via changing the molar ratio of H2PtCl6 to HAuCl4 in the precursor solution. The optimized Au@Pt NPs exhibit enhanced activity in the electrocatalytic reduction of hydrogen peroxide (H2O2). The Au@Pt NPs were modified with graphene that was functionalized with Neutral Red, and then used as an electrochemical label for secondary antibodies and horseradish peroxidase (HRP). The sandwich immunocomplexes were magnetically absorbed on a 4-channel screen printed carbon electrode. Due to the catalysis of the Au@Pt NPs and HRP, the signal is strongly amplified in the presence of H2O2 when using thionine as the electron mediator. Under optimal conditions, the immunoassay has a linear response in the 4.0 × 102 to 4.0 × 108 CFU·mL-1 concentration range, with a limit of detection of 91 CFU·mL-1 (at an S/N ratio of 3). Graphical abstract Preparation of Au@Pt core/shell nanoparticles with different Pt shell thickness (A), rGO-NR (B), rGO-NR-Au@Pt-Ab2-HRP (C) and the preparation and the detection process of the immunoassay (D). rGO: reduced graphene oxide, GO: graphene oxide, NR: Neutral Red, HRP: horseradish peroxidase, AuNPs: gold nanoparticles, Fe3O4@SiO2: Silica coated magnetite nanoparticles, 4-SPCE: 4-channel screen printed carbon electrode.

Rapid electrochemical quantification of Salmonella Pullorum and Salmonella Gallinarum based on glucose oxidase and antibody-modified silica nanoparticles.

In this article, a facile and sensitive electrochemical method for quantification of Salmonella Pullorum and Salmonella Gallinarum (S. Pullorum and S. Gallinarum) was established by monitoring glucose consumption with a personal glucose meter (PGM). Antibody-functionalized magnetic nanoparticles (IgG-MNPs) were used to capture and enrich S. Pullorum and S. Gallinarum, and IgG-MNPs-S. Pullorum and IgG-MNPs-S. Gallinarum complexes were magnetically separated from a sample using a permanent magnet. The trace tag was prepared by loading polyclonal antibodies and high-content glucose oxidase on amino-functionalized silica nanoparticles (IgG-SiNPs-GOx). With a sandwich-type immunoassay format, IgG-SiNPs-GOx were added into the above mixture solution and conjugated to the complexes, forming sandwich composites IgG-MNPs/S. Pullorum and S. Gallinarum/IgG-SiNPs-GOx. The above sandwich composites were dispersed in glucose solution. Before and after the hydrolysis of glucose, the concentration of glucose was measured using PGM. Under optimal conditions, a linear relationship between the decrease of glucose concentration and the logarithm of S. Pullorum and S. Gallinarum concentration was obtained in the concentration range from 1.27 × 102 to 1.27 × 105 CFU mL-1, with a detection limit of 7.2 × 101 CFU mL-1 (S/N = 3). This study provides a portable, low-cost, and quantitative analytical method for bacteria detection; thus, it has a great potential in the prevention of disease caused by S. Pullorum and S. Gallinarum in poultry. Graphical abstract A schematic illustration of the fabrication process of IgG-SiNPs-GOD nanomaterials (A) and IgG-MNPs (B) and experimental procedure of detection of S. Pullorum and S. Gallinarum using GOD-functionalized silica nanospheres as trace tags based on PGM (C).

Voltammetric sandwich immunoassay for Cronobacter sakazakii using a screen-printed carbon electrode modified with horseradish peroxidase, reduced graphene oxide, thionine and gold nanoparticles.

The authors describe a sandwich-type of electrochemical immunoassay for rapid determination of the foodborne pathogen Cronobacter sakazakii (C. sakazakii). Polyclonal antibody against C. sakazakii (anti-C. sakazakii) and horseradish peroxidase were immobilized on a nanocomposite consisting of reduced graphene oxide, thionine and gold nanoparticles (AuNPs) that was placed on a screen-printed carbon electrode (SPCE). Thionine acts as an electron mediator which also shortens the electron transfer pathway from the conjugated HRP to the electrode surface and amplifies the electrochemical signal. The AuNPs, in turn, improve the electron transfer rate and increase the surface area for capturing antibody. The morphologies of the electrodes were characterized by means of field emission scanning electron microscopy. The electrochemical performance of the immunoassay was evaluated by cyclic voltammetry and differential pulse voltammetry. Under optimal experimental conditions, the electrochemical immunoassay, best operated at a woking potential of -0.18 V (vs. Ag/AgCl) and scan rate of 20 mV/s has a linear response that covers the 8.8 × 104 to 8.8 × 108 CFU·mL-1 C. sakazakii concentration range, with a 1.0 × 104 CFU·mL-1 detection limit (at an S/N ratio of 3). The assay was applied to the detemination of C. sakazakii in spiked infant milk powder and gave recoveries ranging from 92.0 to 105.7%. Graphical abstract A sandwich-type electrochemical immunosensor was designed for C. sakazakii based on the use of rGO. TH, HRP, antibody and AuNPs were anchored on rGO. The nanocomposites were used as traces tag and H2O2 as enzyme substrates. AuNPs were modified on SPCE by electrodeposition.

Performance of the subsurface flow constructed wetlands for pretreatment of slightly polluted source water.

The slightly polluted source water of Yellow River was pretreated in a horizontal subsurface flow constructed wetland (HSFCW) and a lateral subsurface flow constructed wetland (LSFCW) in the Ji'nan city Reservoir, Shandong, China. During almost one years run, the results showed that at the hydraulic loading rate of 1 m/day, the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), ammonium nitrogen (NH4 (+)-N) and total phosphorus (TP) in the HSFCW were 48.9, 51.4, 48.7 and 48.9 %, respectively, and the corresponding removal efficiencies in the LSFCW were 50.51, 53.12, 50.44 and 50.83 %, respectively. The HSFCW and LSFCW had a similar high potential for nutrients removal and LSFCW was slightly better. According to the China standard for surface water resources (GB3838-2002), mean effluent COD can reach the Class I (≤ 15 mg/L), and NH4 (+)-N and TP and TN can reach nearly the Class I (≤ 0.015 mg/L), the Class III (≤ 0.05 mg/L) and the Class IV (≤ 1.5 mg/L), respectively. It can be concluded that the slightly polluted source water from Reservoir was pretreated well by the constructed wetland.

A disposable immunosensor for Enterobacter sakazakii based on an electrochemically reduced graphene oxide-modified electrode.

A disposable immunosensor based on electrochemically reduced graphene oxide (ERGO) was developed for the detection of Enterobacter sakazakii. First, the graphene was deposited on a screen-printed carbon electrode (SPCE) by an electrochemical method. Second, the horseradish peroxidase-labeled bacteria-specific antibody was assembled onto the modified electrode to enhance the sensitivity of the immunosensor. The immunosensor constructed in this study can sensitively and rapidly detect E. sakazakii, and this method may contribute to further foodborne pathogen detection. In addition, this ERGO-modified SPCE could also provide new insights into the development of immunosensors for other bacteria to facilitate rapid detection.

Graphene-coated fiber for solid-phase microextraction of triazine herbicides in water samples.

Graphene is a novel and interesting carbon material that could be used for the separation and purification of some chemical compounds. In this investigation, graphene was used as a novel fiber-coating material for the solid-phase microextraction (SPME) of four triazine herbicides (atrazine, prometon, ametryn and prometryn) in water samples. The main parameters that affect the extraction and desorption efficiencies, such as the extraction time, stirring rate, salt addition, desorption solvent and desorption time, were investigated and optimized. The optimized SPME by graphene-coated fiber coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) was successfully applied for the determination of the four triazine herbicides in water samples. The linearity of the method was in the range from 0.5 to 200 ng/mL, with the correlation coefficients (r) ranging from 0.9989 to 0.9998. The limits of detection of the method were 0.05-0.2 ng/mL. The relative standard deviations varied from 3.5 to 4.9% (n=5). The recoveries of the triazine herbicides from water samples at spiking levels of 20.0 and 50.0 ng/mL were in the range between 86.0 and 94.6%. Compared with two commercial fibers (CW/TPR, 50 µm; PDMS/DVB, 60 µm), the graphene-coated fiber showed higher extraction efficiency.

A disposable immunosensor for Shigella flexneri based on multiwalled carbon nanotube/sodium alginate composite electrode.

A novel Shigella flexneri immunosensor based on horseradish peroxidase-labeled antibodies to S. flexneri (HRP-anti-S. flexneri) immobilized by physical adsorption on the multiwalled carbon nanotube (MWCNT)/sodium alginate (SA) composite modified screen-printed electrode surface was successfully fabricated. In this strategy, MWCNT/SA biocomposite acted as the matrix to adsorb and immobilize HRP-anti-S. flexneri. The modified electrodes were characterized with an atomic force microscope and cyclic voltammetry (CV). The analytical performance of the proposed immunosensor toward S. flexneri was investigated by CV. Under optimal conditions, the linear range of S. flexneri was from 104 to 10¹¹ cfu/ml with a detection limit of 3.1×10³ cfu/ml (signal/noise=3). The specificity, reproducibility, stability, and accuracy of the proposed immunosensor were also evaluated. The proposed immunosensor showed simply fabricative, economical, efficient, and potential application for early assessment of S. flexneri.

[Development of the soft independent modelling of class analogies model to discrimination Vibrio parahemolyticus by Smartongue].

OBJECTIVE: To explore a new rapid detection method for detecting of Food pathogens. METHOD: We used the Smartongue, to determine the composition informations of the liquid culture samples and combined with soft independent modelling of class analogies (SIMCA) to analyze their respective species, then set up a Smartongue -SIMCA model to discriminate the V. parahaemolyticus. RESULTS: The Smartongue has 6 working electrodes and three frequency segments, we can built 18 discrimination models in one detection. After comparing all the 18 discrimination models, the optimal working electrodes and frequency segments were selected out, they were: palladium electrode in 1 Hz frequency segment, tungsten electrode in 100 Hz and silver electrode in 100 Hz. Then 10 species of pathogenic Vibrio were discriminated by the 3 models. The V. damsela, V. metschnikovii, V. alginalyticus, V. cincinnatiensis, V. metschnikovii and V. cholerae O serogroup samples could be discriminated by the SIMCA model of V. parahaemolyticus with palladium electrode 1 Hz frequency segment; V. mimicus and V. vulnincus samples could be discriminated by the SIMCA model of V. parahaemolyticus with tungsten electrode 100 Hz frequency segment; V. carcariae and V. cholerae non-O serogroup samples could be discriminated with the SIMCA model of V. parahaemolyticus in silver electrode 100 Hz frequency segment. The accurate discrimination of ten species of Vibrio samples is 100%. CONCLUSION: The Smartongue combined with SIMCA can discriminate V. parahaemolyticus with other pathogenic Vibrio effectively. It has a promising future as a new rapid detection method for V. parahaemolyticus.

High-sensitivity detection of two H7 subtypes of avian influenza viruses (AIVs) by immunochromatographic assay with highly chromatic red silica nanoparticles.

In this work, a sensitive and quantitative immunochromatographic assay (ICA) detection method for avian influenza viruses (AIVs) of the H7 hemagglutinin (HA) antigen was established based on highly chromatic red silica nanoparticles (SiNPs). It can detect two H7 subtypes of influenza viruses, H7N2 and H7N9. The highly chromatic red SiNPs were prepared by adsorbing C.I. Direct Red 224 on the surface of the SiNPs for multiple times using the layer by layer (LbL) self-assembly method under the electrostatic action of ethylene imine polymer (PEI) and poly(sodium-p-styrenesulfonate) (PSS). The highly chromatic red silica nanoparticles modified with anti-H7 HA mAb1 were used as immunodetection probes. The accumulated highly chromatic red SiNPs on the T-line can be observed by the naked eye to qualitatively detect the H7 HA antigen. The quantitative analysis is carried out by using a camera and Image J software. Within the range of 0.1-10 ng mL-1, the linear equation between the H7 HA antigen concentration and the peak area of the T-line gray value was y = 868.9722 + 435.4836X (R2 = 0.9716), and the limit of detection (LOD) of this method was 0.08 pg mL-1 (S/N = 3). The highly chromatic red SiNP based ICA for the detection of H7 HA has no cross activity with other subtypes of influenza viruses. This method of combining highly chromatic colored markers with ICA has great potential in practical applications for the rapid and quantitative detection of other types of AIVs.

High expression of vinculin predicts poor prognosis and distant metastasis and associates with influencing tumor-associated NK cell infiltration and epithelial-mesenchymal transition in gastric cancer.

In the process of epithelial-mesenchymal transition (EMT), epithelial cancer cells transdifferentiate into mesenchymal-like cells with high motility and aggressiveness, resulting in the spread of tumor cells. Immune cells and inflammation in the tumor microenvironment are the driving factors of EMT, but few studies have explored the core targets of the interaction between EMT and tumor immune cells. We analyzed thousands of cases of gastric cancer and gastric tissue specimens of TCGA, CPTAC, GTEx and analyzing QPCR and IHC data of 56 gastric cancer patients in SYSU Gastric Cancer Research Center. It was known that EMT has an important connection with the infiltration of NK cells, and that the expression of vinculin may be the target of the phenomenon. The increased expression of vinculin is closely related to the aggressiveness and distant metastasis of cancer, which affects the survival prognosis of the patient. Moreover, through in vitro experiments under 3D conditions, we found that vinculin, cell invasion and metastasis are clearly linked. VCL can affect EMT and tumor immunity by regulating EPCAM gene expression. The role and mechanism of action of vinculin have been controversial, but this molecule may downregulate EpCAM (epithelial cellular adhesion molecule) and its own role in gastric cancer through DNA methylation, causing NK cells to enrich into tumor cells and kill tumor cells. At the same time, it promotes the occurrence of EMT, which in turn causes tumor metastasis and thus poorer prognosis.

[Fabrication and evaluation of the enzyme immunosensor for rapid detection of Vibrio parahaemolyticus based on chitosan-SiO2 hybrid membrane].

OBJECTIVE: To improve the key technology of immunesensors in immobilizing bio-sensitive element and keeping its bioactivity, an enzyme immunosensor based on chitosan-SiO(2) (CS-Sio(2)) hybrid membrane was fabricated. To estimate the new immunosensor Vibrio parahaemolyticus which was the main pathogens of aquatic products. METHODS: A CS-SiO(2) hybrid membrane was prepared using sol-gel method. The enzyme immunosensor was fabricated by coating the membrane and horseradish peroxidase labeled Vibrio parahaemolyticus antibody (HRP-anti-VP) on the surface of four-channel screen-printed carbon electrode. The immunosensor was characterized by cyclic voltammetry. Vibrio parahaemolyticus could be detected according to the decrease percentage (DP) of peak current before and after immune response, while cyclic voltammetry was used as an electrochemical mean to detect the products of the enzymatic reaction. Seven kinds of bacteria, like Vibrio alginolyticus, were selected for specific experiments. RESULTS: By studying the infrared spectrum of three kinds of films, the CS-SiO(2) hybrid membrane was prepared and HRP-anti-VP was fixed in the hybrid membrane. Under the optimum conditions of immunoreaction and electrochemical detection, the DP of peak current before and after immune response showed a linear relation with lgC in the range of 10(4) - 10(9) cfu/ml, while the linear regression equation was: DP = 6.5 lgC-3.319, the correlation coefficient was 0.9958 and the detection limit was 6.9 x 10(3) cfu/ml (S/N = 3). The immunosensor possessed acceptable specificity, reproducibility (RSD < 6%), stability (the amperometric response was 95% of the initial response after a week) and accuracy (96.7% of the results obtained by the immunosensor were in agreement with those obtained by GB/T 4789.7-2003). CONCLUSION: The enzyme immunosensor based on CS-SiO(2) hybrid membrane gave a good performance in rapid detection of Vibrio parahaemolyticus.

[Detection of pathogenic Vibrio by smartongue].

OBJECTIVE: Electronic tongue is a modern analysis instrument and can detect very well the comprehensive information of liquid samples. Based on this, we employed the electronic tongue to detect the bacteria liquid culture, with the purpose of developing a new rapid method for the detection and identification of food-borne pathogens. METHODS: A novel voltammetric electronic tongue, smart tongue, was used to detect and differentiate 11 species of pathogenic Vibrio. Principal component analysis (PCA) was used to extract the relevant information obtained by the smart tongue. From the data evaluation, the score plots of PCA were obtained. RESULTS: According to the plots, we chose the most feasible working electrodes at the most favorable frequency segments were determined for our purpose. The results showed that the best electrode arrays and frequency segments to differentiate pathogenic Vibrio were titanium electrode in 100 Hz, silver electrode in 100 Hz and tungsten electrode in 1 Hz and 10 Hz, respectively. We differentiated 11 species of pathogenic Vibrio independently in the score plot of tungsten electrode in 1 Hz. We also distinguished all the Vibrio with the combination of two of other three electrodes and frequencies. CONCLUSION: Smartongue could differentiate well 11 species of pathogenic Vibrio from the results analysed by PCA. It has a promising future as a novel modern rapid analytical technology for detecting and distinguishing the pathogenic Vibrio. The method and results could be a good stencil-plate to the research of detecting the other food-borne pathogens with smartongue, and good reference information for the further study.

A novel immunochromatographic assay using ultramarine blue particles as visible label for quantitative detection of hepatitis B virus surface antigen.

Ultramarine blue particles as a novel visible label has been used to develop immunochromatographic assay (ICA). The ultramarine blue particles, as a sodalite mineral with formula: (Na,Ca)8[(S,Cl,SO4,OH)2(Al6Si6O24)], can generate a blue visible signal were used as a label for ICA. Ultramarine blue particles were applied to a sandwich immunoassay to detect hepatitis B virus surface antigen (HBsAg). Ultramarine blue particles were separated from ultramarine blue industrial product by centrifugation. The polyacrylic acid (PAA) was used to modify the carboxyl group on the surface of ultramarine blue particles. The goat anti-HBsAg monoclonal antibody was modified on ultramarine blue particles by EDC/NHS activation of the carboxyl groups. In the presence of HBsAg, the immune ultramarine blue particles were bound on test line zone and forming a blue line on ICA strip which was directly readout by naked eye and quantitatively measured by Image J software. Under optimal conditions, the color depth of test line was linearly correlated with the concentration of HBsAg in concentration range from 1 to 50 ng mL-1. The calibration equation was y = 385.796 + 97.2298x (R2 = 0.9872), with limit of detection (LOD) of 0.37 ng mL -1(S/N = 3). The sensitivity of this novel ICA was better than that of ICA based on traditional gold nanoparticles as reporter probe. The ultramarine blue particles offer an alternative type of visible label nanomaterial for the development of ICA.

Effects of elevated CO2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China.

An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m2) and CO2 levels (350 and 700 micromol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m2). Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon (6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.

[A multi-frequency large amplitude pulse sensor system to monitor the growth of food-borne pathogens].

OBJECTIVE: We explored whether a smart electronic tongue as a rapid technique, combining with specifically statistics analyze system, could monitor the growth of the three food-borne pathogens. METHODS: The smart electronic tongue, multi-frequency large amplitude pulse was based on voltammetry. We used it to detect the comprehensive information about a sample and the change process of the medium in 16 periods of time. We analyzed the complex data information in statistics with principal component analysis. According to principal component scores plot, we analyzed the sample. RESULTS: The growth of Staphylococcus aureus in liquid medium could be monitored by tungsten electrode in 100 Hz frequency segment of multi-frequency large amplitude pulse voltammetry, platinum electrode in 1 Hz, and both silver electrode and titanium electrode in 10 Hz. The growth of Escherichia coli O157:H7 could be measured by gold electrode in 100 Hz frequency segment, while platinum electrode in 1Hz, titanium electrode in 1Hz and tungsten electrode in 100 Hz. Then, palladium electrode was efficient to Bacillus subtilis in 1 Hz, 10 Hz, 100 Hz. CONCLUSION: We used the multi-frequency large amplitude pulse sensor system combining with principal component analysis for the first time. It has a promising future as a modern rapid analytical technology for detecting the growth of microbe.