Plant and Food Inspection Center

Nanjing, China

Plant and Food Inspection Center

Nanjing, China
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Chen X.,Jiangnan University | Huang Y.,Jiangnan University | Duan N.,Jiangnan University | Wu S.,Jiangnan University | And 6 more authors.
Microchimica Acta | Year: 2014

We present an improved method for the selection of single-stranded DNA aptamers that can recognize fumonisin B1 (FB1). FB1 is a carcinogenic mycotoxin mainly found in corn and corn-based food products worldwide, posing a global threat to feed and food safety. Selection was based on the mag-SELEX (magnetic bead systematic evolution of ligands by exponential enrichment) technology modified by adopting free analogs of targets rather than immobilized targets for counter selections. Firstly, aptamer candidates for FB1 were selected from an 80 nt random DNA library after 13 rounds of selection. Next, binding assays were performed for affinity evaluation, and circular dichroism spectroscopy was used to investigate their conformation. A high-affinity aptamer designated as F10 (with a dissociation constant of 62 ± 5 nM) was identified and tested for its specificity by competitive binding assays. The results demonstrate that this improved mag-SELEX technology facilitates aptamer screening because it avoids the tedious immobilization of counter-selection molecules on magnetic beads. The aptamers obtained by this technique open new possibilities for the detection of FB1 via aptasensors. [Figure not available: see fulltext.] © 2014 Springer-Verlag Wien.

Wu L.-L.,Jiangnan University | Wang L.-Y.,Jiangnan University | Xie Z.-J.,Jiangnan University | Xue F.,Plant and Food Inspection Center | Peng C.-F.,Jiangnan University
RSC Advances | Year: 2016

This paper reported that the peroxidase-like activity of DNA-Ag/Pt nanoclusters (NCs) can be inhibited selectively by Hg2+. The interaction between Hg2+ and the DNA-Ag/Pt NCs was discussed through characterization by TEM, DLS and XPS, etc. It was found that the integration of both Hg0 and Hg2+ to the DNA-Ag/Pt NCs resulted in the DNA-Ag/Pt NCs aggregation and the decrease of Pt2+ content on the DNA-Ag/Pt NCs surface, which finally impaired their catalytic activity. Based on the above mechanism, a colorimetric detection for Hg2+ was developed with a detection limit (LOD) of 5.0 nM and a linear range from 10 nM to 200 nM. The method was highly selective toward Hg2+ over other common metal ions, low-cost and simple, which facilitated the application of detecting Hg2+ in tap water. © 2016 The Royal Society of Chemistry.

Wu S.,Jiangnan University | Duan N.,Jiangnan University | Zhu C.,Plant and Food Inspection Center | Ma X.,Jiangnan University | And 2 more authors.
Biosensors and Bioelectronics | Year: 2011

A novel and sensitive immunoassay for the simultaneous detection of aflatoxin B 1 (AFB 1) and ochratoxin A (OTA) in food samples was developed by using artificial antigen-modified magnetic nanoparticles (MNPs) as immunosensing probes and antibody functionalized upconversion nanoparticles (UCNPs) as signal probes. NaY 0.78F 4:Yb 0.2, Tm 0.02 and NaY 0.28F 4:Yb 0.7,Er 0.02 UCNPs were prepared and functionalized, respectively, with immobilized monoclonal anti-AFB 1 antibodies and anti-OTA antibodies as signal probes. Based on a competitive immunoassay format, the detection limit for both AFB 1 and OTA under optimal conditions was as low as 0.01ngmL -1, and the effective detection range was from 0.01 to 10ngmL -1. The proposed method was successfully applied to measure AFB 1 and OTA in naturally contaminated maize samples and compared to a commercially available ELISA method. The high sensitivity and selectivity of this method is due to the magnetic separation and concentration effect of the MNPs, the high sensitivity of the UCNPs, and the different emission lines of Yb/Tm and Yb/Er doped NaYF 4 UCNPs excited by 980nm laser. Multicolor UCNPs have the potential to be used in other applications for detecting toxins in the field of food safety and other fields. © 2011 Elsevier B.V.

Chen X.,Jiangnan University | Huang Y.,Jiangnan University | Duan N.,Jiangnan University | Wu S.,Jiangnan University | And 5 more authors.
Journal of Agricultural and Food Chemistry | Year: 2014

A high-affinity ssDNA aptamer that specifically binds to T-2 toxin was generated by the systemic evolution of ligands by exponential enrichment (SELEX) procedure assisted by graphene oxide (GO). After 10 rounds of selection against T-2 toxin, a highly enriched ssDNA pool was sequenced and the representative aptamers were subjected to binding assays to evaluate their affinity and specificity. Circular dichroism spectroscopy was also used to study the inherent interaction of T-2 toxin and the preferred aptamer Seq.16, which demonstrated a low dissociation constant (Kd) of 20.8 ± 3.1 nM and excellent selectivity for T-2 toxin. Using the selected aptamer Seq.16 as the recognition element, an aptamer-based fluorescent bioassay was developed for the measurement of T-2 in beer samples with a linear range from 0.5 to 37.5M (R2 = 0.988) and a limit of detection (LOD) of 0.4M. The results indicate that GO-SELEX technology is appropriate for the screening of aptamers against small-molecule toxins, offering a promising application for aptamer-based biosensors. © 2014 American Chemical Society.

Xue F.,Hefei University of Technology | Xue F.,Plant and Food Inspection Center | Wu J.,Hefei University of Technology | Chu H.,Hefei University of Technology | And 7 more authors.
Microchimica Acta | Year: 2013

We present an electrochemical aptasensor for rapid and ultrasensitive determination of the additive bisphenol A (BPA) and for screening drinking water for the presence of BPA. A specific aptamer against BPA and its complementary DNA probe were immobilized on the surface of a gold electrode via self-assembly and hybridization, respectively. The detection of BPA is mainly based on the competitive recognition of BPA by the immobilized aptamer on the surface of the electrode. The electrochemical aptasensor enables BPA to be detected in drinking water with a limit of detection as low as 0. 284 pg mL-1 in less than 30 min. This extraordinary sensitivity makes the method a most powerful tool for on-site monitoring of water quality and food safety.[Figure not available: see fulltext.] © 2012 Springer-Verlag Wien.

Peng C.,Jiangnan University | Duan X.,Jiangnan University | Song S.,Jiangnan University | Xue F.,Plant and Food Inspection Center
International Journal of Molecular Sciences | Year: 2013

It is challenging to detect 7-aminonitrazepam (7-ANZP) residue in animal tissues simply and sensitively by the enzyme-linked sorbent immunoassay (ELISA) method. This paper demonstrates that utilizing a bioconjugate of gold nanoparticles and enzyme-labeled antibody as a signal probe increases the sensitivity of a traditional ELISA for 7-ANZP by nearly 20 times. The sensitivity of this ELISA for 7-ANZP was 5.6 pg/mL in buffer, and the limit of detection (LOD) of 0.18 μg/kg for 7-ANZP in urine could be achieved after the urine samples were simply hydrolyzed and diluted by buffer. This simple and sensitive method has potential application for improving the sensitivity of ELISA methods against various small molecules. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Sun X.,Nankai University | He J.,Plant and Food Inspection Center | Cai G.,Plant and Food Inspection Center | Lin A.,Plant and Food Inspection Center | And 6 more authors.
Journal of Separation Science | Year: 2010

A novel molecularly imprinted polymer monolith was prepared by the room temperature ionic liquid-mediated in situ molecular imprinting technique, using norfloxacin (NOR) as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker. The optimal synthesis conditions and recognition properties of NOR-imprinted monolithic column were investigated. The results indicated that the imprinted monoliths exhibited good ability of selective recognition against the template and its structural analog. Using the fabricated material as solid-phase extraction sorbent, a sample pre-treatment procedure of molecularly imprinted solid-phase extraction coupling with HPLC was developed for determination of trace quinolone residues in animal tissues samples. The recoveries ranging from 78.16 to 93.50% for eight quinolones antibiotics such as marbofloxacin, NOR, ciprofloxacin, danofloxacin, difloxacin, oxolinic acid, flumequine and enrofloxacin were obtained. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Xue F.,Plant and Food Inspection Center
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2010

OBJECTIVE: To characterize the genes of Campylobacter jejuni isolates and to genotype the strains from chicken, cow, duck, pig and red-crowned Crane during 2006 to 2008 by multilocus sequence typing (MLST). METHODS: To choose 7 pairs Campylobacter jejuni home-keeping gene, gltA, aspA, glnA, glyA, pgm, tkt and uncA as target gene, PCR was applied to detect 42 samples in East China between 2006-2008. Sequencing, analysis and comparation of the genes were done. RESULT: Typing the 42 isolates by MLST and finding 24 new sequence typing types. CONCLUSION: MLST is a useful method to evuluate Campylobacter jejuni genes and gene evolution.

Zhang Z.,Nanjing Medical University | Lu H.,Nanjing Medical University | Lu H.,Plant and Food Inspection Center | Huan F.,Nanjing Medical University | And 5 more authors.
International Journal of Cancer | Year: 2014

Cytochrome P450 2A13 (CYP2A13), mainly expressed in human respiratory tract, is highly efficient in the metabolic activation of aflatoxin (AF) B1 (AFB1) and is assumed to play a role in human lung tumorigenesis in airborne AFB1 exposure. To validate the assumption, we exposed human bronchial epithelial (BEAS-2B) cells stably expressing CYP2A13 (B-2A13), CYP1A2 (B-1A2) and CYP2A6 (B-2A6) to 0.1-10 nM AFB1 for 30-50 passages. B-2A13 cells showed increased sensitivity to 0.1 nM AFB1-induced neoplastic transformation and the formation of tumors in nude mice were observed at passage 30 (P30) while it occurred at P50 B-1A2 cells. B-2A6, similar to vector control, showed no neoplastic transformation in this condition. Additionally, AFB1-DNA adducts and 8-OHdG significantly increased in transformed P40 B-2A13, in parallel with the upregulation of p-ATR, p-BRCA1, Mre11, Rad50 and Rad51. However, the apoptosis of P40 cells was near normal, while the expression of Bax, C-Caspase 3 and C-PARP increased passage-dependently. Inhibition of ATR (ATR siRNA or NU6027) reversely increased the apoptosis of P40 B-2A13 cells in parallel with the upregulation of Bax, C-Caspase 3 and C-PARP, suggesting that ATR plays an important role in maintaining cell survival via antiapoptosis. Additionally, activation of ATR was necessary to neoplastic transformation since blockage of ATR in P40 cells inhibited DNA damage repair response and anchorage-independent growth. Our data demonstrated that CYP2A13 played a critical role in AFB1-induced neoplastic transformation. ATR-mediated the dysfunction of apoptosis and DNA damage repair might be involved. These results help establish a linkage between airborne AFB1 and human respiratory carcinoma. What's new? Produced by certain foodborne fungi, aflatoxin B1 (AFB1) floats through the air in dust and enters the lungs, particularly in people who work in food processing. Cytochrome P450 2A13 (CYP2A13) helps metabolize AFB1 and is thought to play a role in causing lung tumors in the presence of AFB1. To test whether this is true, the authors took cells expressing CYP2A13 and exposed them to AFB1. Compared with cells expressing other enzymes, those expressing CYP2A13 were more likely to become cancerous and form tumors in mice. In those cells, the authors found signs of DNA damage, as well as dysregulation of damage repair and apoptosis, suggesting a possible mechanism for how the tumors are getting started. © 2013 UICC.

Lu X.,Tianjin University of Science and Technology | Lu X.,Washington State University | Huang Q.,Nankai University | Miller W.G.,U.S. Department of Agriculture | And 7 more authors.
Journal of Clinical Microbiology | Year: 2012

A novel strategy for the rapid detection and identification of traditional and emerging Campylobacter strains based upon Raman spectroscopy (532 nm) is presented here. A total of 200 reference strains and clinical isolates of 11 different Campylobacter species recovered from infected animals and humans from China and North America were used to establish a global Raman spectroscopy-based dendrogram model for Campylobacter identification to the species level and cross validated for its feasibility to predict Campylobacter-associated food-borne outbreaks. Bayesian probability coupled with Monte Carlo estimation was employed to validate the established Raman classification model on the basis of the selected principal components, mainly protein secondary structures, on the Campylobacter cell membrane. This Raman spectroscopy-based typing technique correlates well with multilocus sequence typing and has an average recognition rate of 97.21%. Discriminatory power for the Raman classification model had a Simpson index of diversity of 0.968. Intra- and interlaboratory reproducibility with different instrumentation yielded differentiation index values of 4.79 to 6.03 for wave numbers between 1,800 and 650 cm-1 and demonstrated the feasibility of using this spectroscopic method at different laboratories. Our Raman spectroscopy-based partial least-squares regression model could precisely discriminate and quantify the actual concentration of a specific Campylobacter strain in a bacterial mixture (regression coefficient,>0.98; residual prediction deviation, >7.88). A standard protocol for sample preparation, spectral collection, model validation, and data analyses was established for the Raman spectroscopic technique. Raman spectroscopy may have advantages over traditional genotyping methods for bacterial epidemiology, such as detection speed and accuracy of identification to the species level. Copyright © 2012, American Society for Microbiology. All Rights Reserved.

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