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Luo L.,South China Agricultural University | Yang J.-Y.,South China Agricultural University | Xiao Z.-L.,South China Agricultural University | Zeng D.-P.,Guangzhou Wanlian Biotechnologies Co. | And 7 more authors.
RSC Advances | Year: 2015

Histamine (HA) is an essential test item for fishery samples. However, the fast and effective determination of HA is difficult due to its simple structure and small molecular size. In this study, a sensitive and specific monoclonal antibody against p-nitrobenzoylated histamine (NPHA), which can be easily obtained from the reaction of HA and p-nitrobenzoic acid N-hydroxysuccinimide ester (PNBA-OSu) under mild conditions, was generated for the first time. Based on this mAb, an immunochromato-graphic assay strip (ICA strip) using a colloidal gold nano particles-antibody (GNPs) probe for rapid detection of HA in saury samples was established. After screening the coating antigens and optimization of analytical parameters, a heterologous coating based ICA strip exhibited the most excellent detection ability with a visual detection limit (VDL) of 6.0 mg kg-1 in qualitative experiments and a detection limit (by a strip reader) of 1.0 mg kg-1 in semi-quantitative experiments for saury samples, with no cross-reactivity with HA analogs. Good correlation between the ICA strip with liquid chromatography-tandem mass spectrometry was achieved for spiked and naturally contaminated saury samples. Overall, this method is suitable for screening of HA residue for large scale fish samples in a quick, simple and low-cost manner. This journal is © The Royal Society of Chemistry. Source


Luo L.,South China Agricultural University | Xu Z.-L.,South China Agricultural University | Yang J.-Y.,South China Agricultural University | Xiao Z.-L.,South China Agricultural University | And 6 more authors.
Journal of Agricultural and Food Chemistry | Year: 2014

Novel haptens were designed and synthesized to prepare antibodies against free histamine, but none resulted in producing suitable antibodies for developing an enzyme-linked immunosorbent assay (ELISA). However, an antiserum was obtained having high specificity and affinity to p-nitrobenzoylated histamine (NPHA), which can be easily formed from reaction between histamine and p-nitrobenzoic acid N-hydroxysuccinimide ester (PNBA-OSu) under mild conditions. Based on rabbit polyclonal antibodies, a competitive indirect ELISA (ciELISA) for histamine determination in foods was developed. After ciELISA and derivatization optimization, the assay showed good sensitivity, with limits of detection of 1.8 mg/kg, 93.6 μg/L, and 93.6 μg/kg in fish, red wine, and yoghurt, respectively, with negligible cross-reactivity with related biogenic amines and amino acids. Average recovery of histamine in fortified food samples ranged from 80.9% to 110.1% with coefficients of variation below 16.3%. Good correlation between the ciELISA and liquid chromatography-tandem mass spectrometry was obtained for spiked food samples. © 2014 American Chemical Society. Source


Wang D.-Y.,Guangxi University for Nationalities | Zou H.-H.,Guangxi Normal University | Hu F.-L.,Yulin Normal University | Li Y.-J.,Zhongshan Quality Supervision and Inspection Institute of Agricultural Products
Inorganic Chemistry Communications | Year: 2012

Three new complexes, [Co 2(oba)(dbca)(H 2O) 2]·5(H 2O) (1) [Co 2(oba)(dbca)(H 2O) 2]·DMF(H 2O) (2) and [Co 6(oba) 6(pyr) 8]·2.5H 2O (3) (H 2oba = 4,4′-oxydibenzoic acid, H 2dbca = diphenic acid, py = pyridine, DMF = N,N-dimethyl formamide) have been synthesized and characterized by infrared spectrum, thermal gravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. 3D network of 1 contains interesting water clusters between the layers. Complex 2 displays similar configuration of 1 except that the free DMF molecules occupy the channel which is formed by the host. Complex 3 shows the (2,5)-connection network by using the py as the solvent. The magnetic property of complex 1 is also presented. © 2012 Elsevier B.V. Source


Rao M.F.,South China Agricultural University | Li Y.J.,Zhongshan Quality Supervision and Inspection Institute of Agricultural Products | Dong J.X.,University of California at Davis | Wu W.J.,South China Agricultural University | And 3 more authors.
Analytical Methods | Year: 2016

A broad-specificity, single-chain antigen-binding fragment (scFab) for the detection of O,O-diethyl organophosphorus pesticides (DPPs) was produced and characterized. A recombinant plasmid encoding an Fab with broad specificity towards a specific class of DPPs was used as a template for amplification of the antibody heavy (Fd) and light (κ) chain genes, which were then cloned in two different orientations with the (Gly4Ser)3 linker. SDS-PAGE and western blotting were used to identify expression of the scFabs. Indirect competitive ELISA (icELISA) was used to test the immunology activity of two different κ/Fd orientations. The optimal scFab orientation was determined by characterizing the expression, specificity, and stability in comparison with their homologous scFv and Fab. The 50% inhibition of binding (IC50) values of the κ-linker-Fd scFab for coumaphos and parathion determined by icELISA were ∼1.5 ng mL-1 and 3.1 ng mL-1, respectively, surpassing that of the reverse scFab orientation, Fd-linker-κ (3.7 μg mL-1 and 8.5 μg mL-1, respectively). The IC50 of the κ-linker-Fd scFab was also similar to that of Fab and was relatively low in comparison with that of scFv. The concentration of scFab in the expression extract against the antigen was consistent with that of scFv, while Fab displayed a lower concentration in comparison with both scFv and scFab. After incubation for 9 days, scFab and Fab still exhibited high antigen-binding activity while scFv showed almost no remaining affinity. Analysis of DPP-spiked vegetable samples demonstrated that scFab-based detection using icELISA and gas chromatography by the QuEChERS approach yielded good sensitivity and reproducibility for monitoring food safety. © The Royal Society of Chemistry 2016. Source


Hu F.-L.,Yulin Normal University | Yang X.,Huaihua College | Li Y.-J.,Zhongshan Quality Supervision and Inspection Institute of Agricultural Products
Journal of Coordination Chemistry | Year: 2012

In this article, two copper(II) complexes, [Cu(2,2′-bpy) 2(ppac)](H2O)7 (1) and [Cu2(2, 2′-bpy)4(ppac)](HCO2̄)2(H 2O)16 (2), have been synthesized (H2ppac=p- phenylenediacetic acid, 2,2′-bpy=2,2′-bipyridine). We report structural evidence of discrete water clusters in the solid state. An unusual 1-D water tape notated T4(2)6(2) is present in complex 1. Complex 2 displays a hydrogen-bonded pillar-layered structure that is constituted by lattice waters. An unprecedented water cluster notated as T4(1)6(1)6(2) is present in complex 2. The units act as supramolecular glue in the aggregation of copper(II) complexes to give a 3-D cage-like network through hydrogen bonds. Preliminary investigation on electrochemical properties of the complexes is presented. © 2012 Taylor & Francis. Source

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