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ABSTRACT: A novel Ca(2+)-sensitive fluorescent probe was synthesized and characterized with a coupled method that coupled di[2-(N,N-dicarboxylmethyl)amino]ethyl ether (EGTA) to the surface of mercaptoethylamine-modified CdTe quantum dots (CdTe/MA-EGTA QDs). The application of this probe to detect intercellular Ca(2+) change in the leaf cells of Arabidopsis thaliana was studied. Results from transmission electron micrographs showed that the particle size of CdTe/MA-EGTA was about 3-4nm; the fluorescent spectrum indicated that the excitation spectral ranged from 350 to 490nm with a narrow and symmetric emission spectral peak at 565nm when excited by 400nm, and capillary electrophoresis demonstrated that CdTe/MA-EGTA was obtained by a coupling reaction. When the detected conditions were set as an excitation wavelength of 514nm and detection wavelength of 561-604nm, the increase of Ca(2+) in A. thaliana leaf cells and the rapidly quenching effect of fluorescence signal induced by exogenous treatment of jasmonate acid (JA) could be measured using laser scanning confocal microscopy. The quenching rate of traditional Ca(2+)-sensitive fluorescent probe Fluo-3 reached about 80% within a minute when exciting at 488nm, which was much faster than the novel fluorescent probe CdTe/MA-EGTA. CdTe/MA-EGTA, however, was better at resisting photo bleaching and was more suitable for long-term tracking and monitoring than Fluo-3.
Journal of inorganic biochemistry 09/2012; 118C:39-47. · 3.25 Impact Factor
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ABSTRACT: Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0-6.5) to Sudan I-IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18 min was needed for MIP-coated SPME operation. The detection limits of 21-55 ng L(-1) were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME-LC-MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes.
Analytica chimica acta 06/2012; 731:40-8. · 4.31 Impact Factor
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ABSTRACT: In this research, a novel strategy was developed to prepare molecularly imprinted polymer (MIP) coated solid-phase microextraction fibers on a large scale with Sudan I as template and stainless steel fibers as substrate. More than 20 fibers could be obtained in one glass tube, and the efficiency and coating repeatability were enhanced remarkably in contrast with the yield of only one fiber in our previous works. The obtained MIP-coated stainless steel fibers were characterized by homogeneous and highly cross-linked coating, good chemical and thermal stabilities, high extraction capacities, and specific selectivities to Sudan I-IV dyes. Based on the systemic optimization of extraction conditions, a simple and cost-effective method based on the coupling of MIP-coated SPME with high-performance liquid chromatography was developed for the fast and selective determination of trace Sudan I-IV dyes in hot chili powder and poultry feed samples. The limits of detection of Sudan I-IV dyes were within 2.5-4.6 ng g(-1), and the spiked recoveries were in the range of 86.3-96.3% for hot chili powder sample and 84.6-97.4% for poultry feed sample.
Journal of chromatography. A 11/2011; 1219:39-46. · 4.19 Impact Factor
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ABSTRACT: A novel liquid-liquid-solid microextraction (LLSME) method was developed to overcome the well-known water-compatibility problem of molecularly imprinted polymers (MIPs). The enrichment factors with MIP-LLSME method were within 70-210 for trace chloroacetanilide herbicides under optimized extraction conditions. The method was characterized by simplicity, low solvent-consumption and high selectivity, and it was suitable for the one-step pretreatment of various aqueous samples such as river water and farm water.
Journal of chromatography. A 06/2011; 1218(25):3935-9. · 4.19 Impact Factor
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ABSTRACT: A molecularly imprinted polymer (MIP) with metolachlor as the template molecule was first coated on the surface of stainless steel fibers through chemical bonding. Despite 12 times repeated coating procedures, a homogenous, porous, and highly cross-linked MIP coating was obtained with thickness of 17.4 µm (RSD of 6.1%). The specific selectivity of MIP coating to metolachlor and three metabolites could be concluded with 4.4, 4.1, 3.9, and 2.9 times higher extraction amounts of metolachlor, hydroxymetolachlor, deschlorometolachlor, and desmethylmetolachlor than that of the NIP coating, respectively, and good extraction capabilities for chloroacetanilide herbicides were found with the MIP-coated SPME stainless steel fiber. For validation, the fiber was applied for the extraction of metolachlor, propisochlor, and butachlor in spiked corn and soybean samples, and the recoveries of 90.7–92.6%, 86.4–87.9, and 85.4–87.5% were obtained, respectively.
Analytical Letters 05/2011; 44(7):1358-1370. · 1.02 Impact Factor
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ABSTRACT: Degradation of phoxim in river water was fully explored in this paper. Effects of pH, temperature, and photoirradiation on the degradation were investigated in detail. The results indicated that the degradation was characterized by a first-order process; UV irradiation and the increase of pH and temperature substantially accelerated the degradation. To fully characterize the degradation mechanism, HPLC-MS/MS was utilized to identify the degradation intermediates. Five intermediates were identified as phoxom, phoxom dimer, O,O,O',O'-tetraethyldithiopyrophosphate, O,O,O'-triethyl-O'-2-hydroxyethyldisulfinylpyrophosphate, and O,O,O'-triethyl-O'-2-hydroxyethyldithiopyrophosphate. On the basis of the results of the intermediate analysis, the degradation pathways of phoxim under the present experimental conditions were proposed. Through conversion of a thiophosphoryl into a phosphoryl group, some phoxim was converted to phoxom, most of which further formed dimer. Another portion of phoxim transformed to O,O,O',O'-tetraethyldithiopyrophosphate via nucleophilic substitution and photolysis. Thereafter, O,O,O',O'-tetraethyldithiopyrophosphate underwent hydroxylation to form O,O,O'-triethyl-O'-2-hydroxyethyldithiopyrophosphate or sulfur oxidation first and then hydroxylation to produce O,O,O'-triethyl-O'-2-hydroxyethyldisulfinylpyrophosphate. The understanding of phoxim's degradation mechanism in this study will be critical to its safety assessment and increase the understanding of the fate of phoxim in environment water.
Journal of Agricultural and Food Chemistry 01/2011; 59(1):312-21. · 2.82 Impact Factor
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ABSTRACT: The multiple bulk copolymerization method, which was developed in our previous works, was further investigated with prometryn, tetracycline, and propranolol as templates for the preparation of molecularly imprinted polymer (MIP) coatings on silicon fibers for solid-phase microextraction. The preparation conditions (e.g., the solvent, monomer, crosslinker, component proportions, polymerization time, and number of coating procedures) were investigated systemically in an effort to enhance the coating thickness, surface morphology, and reproducibility. The methodology was examined, and some common specialties were explored in the preparation of three MIP-coated fibers. Even after the coating procedure was repeated 10 times, the prometryn, tetracycline, and propranolol MIP-coated fibers were prepared reproducibly with coating-thickness relative standard deviations of 2.6, 3.0, and 5.1%, respectively; they were highly homogeneous, and a compact morphological structure was obtained. The extraction capacities of prometryn, tetracycline, and propranolol with corresponding MIP-coated fibers were approximately 10.4, 3.9, and 3.3 times as much as those with the nonimprinted polymer (NIP)-coated fibers, respectively, and the selectivity factors of prometryn, tetracycline, and propranolol MIP coatings for the template molecules and structural analogues were 2.2–10.4, 2.2–3.9, and 1.3–3.3, respectively, in comparison with the corresponding NIP coatings. In comparison with commercial polydimethylsiloxane/divinylbenzene coatings that were approximately 3 times thicker, the extracted amounts of prometryn, tetracycline, and propranolol were 4.2, 12.3, and 7.7 times higher with prometryn, tetracycline, and propranolol MIP coatings, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Applied Polymer Science 11/2010; 120(3):1266 - 1277. · 1.29 Impact Factor
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ABSTRACT: A molecularly imprinted polymer (MIP) with metolachlor as template was firstly coated on stainless steel fiber through chemical bonding strategy to solve the fragility problem of silica fiber substrate for solid-phase microextraction. The surface pretreatment of stainless steel fiber and the polymerization conditions were investigated systematically to enhance the preparation feasibility and MIP coating performance, and then a porous and highly cross-linked MIP coating with 14.8-microm thickness was obtained with over 200 times re-usability which was supported by non-fragile stainless steel fiber adoption. The MIP coating possessed specific selectivities to metolachlor, its metabolites and other chloroacetanilide herbicides with the factors of 1.1-4.6. Good extraction capacities of metolachlor, propisochlor and butachlor were found with MIP coating under quick adsorption and desorption kinetics, and the detection limits of 3.0, 9.6 and 38 microg L(-1) were achieved, respectively. Moreover, the MIP-coated stainless steel fiber was evaluated for trace metolachlor, propisochlor and butachlor extraction in the spiked soybean and corn samples, and the enrichment factors of 54-60, 27-31 and 15-20 were obtained, respectively.
Journal of chromatography. A 09/2010; 1217(38):5875-82. · 4.19 Impact Factor
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ABSTRACT: The CdSe quantum dots (QDs) modified by mercapto-beta-cyclodextrin (CD) were synthesized and characterized by transmission electron microscopy, powder X-ray diffraction, excitation and emission spectra, and fluorescence lifetime. When lambda(ex)=370nm, the fluorescence peak of CdSe/CD QDs is at 525nm. Phenanthroline (Phen) is able to quench their fluorescence, which can be recovered by the addition of DNA. The quenching and restoration of fluorescence intensity were found to be linearly proportional to the amount of Phen and DNA, respectively. The variation of the fluorescence intensity of the CdSe/CD QDs-Phen system was studied, and it was demonstrated to result from a static mechanism due to the formation of a Phen inclusion complex with the CdSe QDs modified by mercapto-beta-cyclodextrin. The fluorescence recovery was due to the binding of DNA with Phen in the inclusion complex, leading to the freeing of the CdSe/CD QDs. The binding constants and sizes of the binding sites of the Phen-DNA interaction were calculated to be 1.33x10(7)mol(-1)L and 10.79bp.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2010; 75(5):1617-23. · 2.10 Impact Factor
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ABSTRACT: An improved multiple co-polymerization technique was developed to prepare a novel molecularly imprinted polymer (MIP)-coated solid-phase microextraction (SPME) fiber with propranolol as template. Investigation was performed for the characteristics and application of the fibers. The MIP coating was highly crosslinked and porous with the average thickness of only 25.0 microm. Consequently, the adsorption and desorption of beta-blockers within the MIP coating could be achieved quickly. The specific selectivity was discovered with the MIP-coated fibers to propranolol and its structural analogues such as atenolol, pindolol, and alprenolol. In contrast, only non-specific adsorption could be shown with the non-imprinted polymer (NIP)-coated fibers, and the extraction efficiencies of propranolol and pindolol with the MIP-coated fibers were higher markedly than that with the commercial SPME fibers. A MIP-coated SPME coupled with high-performance liquid chromatography (HPLC) method for propranolol and pindolol determination was developed under the optimized extraction conditions. Linear ranges for propranolol and pindolol were 20-1000 microg L(-1) and detection limits were 3.8 and 6.9 microg L(-1), respectively. Propranolol and pindolol in the spiked human urine and plasma samples, extracted with organic solvent firstly, could be simultaneous monitored with satisfactory recoveries through this method.
Journal of Chromatography 12/2008; 1216(2):190-7. · 4.53 Impact Factor
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ABSTRACT: Molecularly imprinted polymer (MIP) is widely used in many fields because of its characteristics of high selectivity, chemical stability and easy preparation. To enhance the selectivity and applicability of solid-phase microextraction (SPME), a novel MIP-coated SPME fiber was firstly prepared by multiple co-polymerization method with tetracycline as template. It could be coupled directly to high-performance liquid chromatography (HPLC) and used for trace analysis of tetracyclines (TCs) in complicated samples. The characteristics and application of the fibers were investigated. The electron microscope provided a crosslinked and porous surface, and the average thickness of the MIP coating was 19.5 microm. Compared with the non-imprinted polymer (NIP) coated fibers, the special selectivity to tetracycline and structure-similar oxytetracycline, doxycycline, chlortetracycline were discovered with the MIP-coated fibers. The adsorption and desorption of TCs with the MIP-coated fiber could be achieved quickly. A method for the fluorimetric determination of four TCs by the MIP-coated SPME coupled with HPLC was developed. The optimized extraction conditions such as extraction solvent, desorption solvent, and stirring speed were studied. Linear ranges for the four TCs were 5.00-200 microg/L and detection limits were within the range of 1.0-2.3 microg/L. The method was applied to simultaneous multi-residue analysis of four TCs in the spiked chicken feed, chicken muscle, and milk samples with the satisfactory recoveries.
Journal of Chromatography 05/2008; 1188(2):97-107. · 4.53 Impact Factor
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ABSTRACT: A novel molecularly imprinted polymer (MIP) coated solid-phase microextraction (SPME) fiber that could be coupled directly to high-performance liquid chromatography (HPLC) was prepared with prometryn as the template molecule. The characteristics and application of this fiber were investigated. Electron microscope photographs indicated that the MIP coating with average thickness of 25.0 microm was homogeneous and porous. The extraction yield of prometryn with the MIP-coated fibers was 10 times as much as that with the non-imprinted polymer (NIP) coated fibers. And special selectivity to other triazines which have similar structure to prometryn was discovered with the MIP-coated fibers. A method for the determination of triazines by the MIP-coated SPME coupled with HPLC was developed. The optimized extraction conditions were studied. Detection limits for the triazines studied were within the range of 0.012-0.090 microg/L. The method was applied to five triazines determination in the spiked soybean, corn, lettuce, and soil samples with the recoveries of 78.0-103.5%, 82.4-113.4%, 75.5-83.4%, and 81.0-106.1%, respectively. The MIP-coated fibers are suitable for the selective extraction of trace triazines in complicated samples.
Journal of Chromatography 05/2007; 1147(1):1-9. · 4.53 Impact Factor
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ABSTRACT: To study of the quality standard about Jinshui Liujun decoction.
The chronic broncitis model of rat was induced by injecting LPS into rat's trachea. Then, the number of WBC, SV, PS were detected.
Both Jinshui Liujun decoction and hesperidin can improve the content of PS and reduce the number of WBC. There were statistical difference between the therapeutic groups and the model group, and the changes of bronchi between the therapeutic group were similar. But the SV of hesperidin group was bigger than Jinshui Liujun decoction group, and the PS of hesperidin group was less than Jinshui Liujun decoction group.
It was feasible that the content of hesperidin in Jinshui Liujun decoction was as primary quality control index.
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials 08/2002; 25(7):484-6.
