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91.
Degradation of liposome cluster caused by the interaction with endocrine disrupting chemicals (EDCs)
The interaction between endocrine disrupting chemicals (EDCs) and liposome clusters was investigated using UV-vis spectroscopy and observed by microscope. Since liposome clusters are composed of small unilamellar liposomes and membrane proteins, they are regarded as a model of plasma membranes. The size of each cluster was 10microm in diameter. UV-vis spectroscopy of liposome clusters showed an apparent absorption at 300nm which was affected by the interaction with EDCs. Four EDCs caused an alteration in absorption in a concentration-dependence manner between 0.1 and 10ppm (i.e. 0.1-10mg/l). Microscopic observation showed that the effect was caused by the degradation of liposome clusters while degradation was induced by the interaction; liposome was broken down by EDCs. This report suggests that the liposome cluster can be applied for universal detection of EDCs based on the interaction between a plasma membrane model and EDCs. 相似文献
92.
Microalgal cell disruption induced by acoustic cavitation was simulated through solving the bubble dynamics in an acoustical field and their radial kinetics (chemical kinetics of radical species) occurring in the bubble during its oscillation, as well as calculating the bubble wall pressure at the collapse point. Modeling results indicated that increasing ultrasonic intensity led to a substantial increase in the number of bubbles formed during acoustic cavitation, however, the pressure generated when the bubbles collapsed decreased. Therefore, cumulative collapse pressure (CCP) of bubbles was used to quantify acoustic disruption of a freshwater alga, Scenedesmus dimorphus, and a marine alga, Nannochloropsis oculata and compare with experimental results. The strong correlations between CCP and the intracellular lipid fluorescence density, chlorophyll-a fluorescence density, and cell particle/debris concentration were found, which suggests that the developed models could accurately predict acoustic cell disruption, and can be utilized in the scale up and optimization of the process. 相似文献
93.
A novel in-drop derivatisation liquid-phase microextraction procedure with an ion-pairing agent is developed and optimised for the extraction of endocrine-disrupting chemicals. The ethyl esters of the analytes were rapidly formed in the organic drop and analysed by gas chromatography. The effects of various parameters such as rate and time of agitation, ion-pairing agent and reactant concentration, pH and temperature were studied systematically to optimise the process and bring out the locale of reaction in the organic drop. A study of the mechanistic pathways of the overall procedure is attempted leading to interesting findings and delineating important points of the kinetics and mechanism. A mechanistic model is proposed on the basis of the theory of mass transfer with chemical reaction in two liquid phases. The O-ethoxycarbonyl derivatisation appears to take place in the bulk organic phase. The system provides insight into the first reported analytical case of single-drop extraction-preconcentration-derivatisation assisted by an ion-pairing transfer and has all of the interesting facets of chemical reaction in which the role of mass transfer comes into picture.The analytical features of the method are acceptable and the overall relative standard deviations of the intra-day repeatability (n = 5) and inter-day reproducibility were <3.9% and <5.4%, respectively, for gas chromatography-mass spectrometry analyses and <4.3% and <7.1% for gas chromatography-flame ionisation detection analyses. The method was applicable to urine and surface water samples. The LODs ranged between 0.2-1.3 ng mL−1 and 8.5-26.5 ng mL−1 for GC/MS and GC/FID analyses, respectively. 相似文献
94.
Ferraz N Carnevia D Nande G Rossotti M Miguez MN Last JA Gonzalez-Sapienza G 《Analytical and bioanalytical chemistry》2007,389(7-8):2195-2202
Vitellogenin (VTG) and choriogenin (CHO) are valuable biomarkers of endocrine-disrupting compound (EDC) exposure in fish.
Existing immunoassays are limited to a few species, which restricts their use for the analysis of local wildlife sentinels.
Using C. facetum as a relevant South American model fish, this work presents a new strategy for the preparation of antibodies to VTG and CHO,
with zero cross-reactivity with fish serum components. Recombinant fragments of Cichlasoma facetum VTG (280-mer) and CHO (223-mer) were prepared by degenerate primer RT-PCR and expression in E. coli. Polyclonal and monoclonal antibodies prepared with these antigens were used to develop rapid dotblot assays for VTG and
CHO. Both the polyclonal and monoclonal antibodies prepared with the recombinant antigens reacted against the native proteins
adsorbed on to nitrocellulose allowing the set up of sensitive dotblot assays. The VTG assay was further validated with spiked
samples and purified native VTG. Exposure experiments with several estrogenic compounds revealed the potential of C. facetum as a sensitive biomonitor that produced measurable responses at concentrations of 100 ng L−1 of 17-beta-estradiol, 100 ng L−1 of ethynylestradiol, and 6.6 μg L−1 of nonylphenol. The approach described here may be applied to other native species to produce highly specific and sensitive
rapid tests. It may be particularly advantageous for species that cannot be kept in captivity or when homogeneous purification
of the immunizing proteins is particularly challenging. In conclusion, we present a novel approach to develop a strategy for
the generation of immunoassay reagents for vitellogenin (VTG) and choriogenin (CHO), which will facilitate regional studies
on the impact of endocrine-disrupting chemicals on local wildlife. 相似文献
95.
Miao He Cui Yang Renjie Geng Xiangai Zhao Lian Hong Xiangfan Piao Tie Chen Maurizio Quinto Donghao Li 《Analytica chimica acta》2015
Phthalate esters (PAEs) are commonly used as nonreactive plasticisers in vinyl plastics to increase the flexibility of plastic polymers. Numerous studies have indicated that the PAEs as a class of endocrine-disrupting chemicals. In addition, the studies have also shown that a major source of human exposure to phthalates is the diet. To date, the largest problem in PAEs analysis is the high blank value because PAEs are widely used in various applications and products. To overcome this shortcoming, gas purge microsyringe extraction (GP-MSE) was applied, which established a new and low-blank-value analytical method for PAE analysis to analyse PAEs in foodstuffs. In this study, GP-MSE was used as a clean-up method, and the overall recoveries ranged from 85.7 to 102.6%, and the RSD was less than 10%. More importantly, this method can overcome the problem of the high blank value in PAE analysis. This method was applied for measuring PAEs in 78 foodstuffs. The results showed that a wide variety of PAE concentrations were found in the different groups, and the content of PAEs (varies from 658 to 1610 ng g−1 fresh weight) is greatest in seafood. The concentrations were in the following order: DEHP > DBP > DEP ≈ DMP > BBP ≈ DNOP. Finally, the daily intake of PAEs was estimated for adults based on the levels of PAEs in foodstuffs. The total EDIdiet values of 3.2 and 12.9 μg kg−1 bw d−1 were calculated for DEHP based on the mean and highest concentrations in foodstuffs, respectively. 相似文献
96.
研究市场需求和生产成本同时扰动时非线性需求供应链的最优应对策略.首先在稳定条件下提出供应链的收益共享协调合约;生产成本和需求扰动会导致原有的收益共享合约不再协调,提出了供应链在一体化决策时应对双因素同时发生扰动的最优策略;进一步提出了改进的收益共享合约协调分散化决策的供应链系统.最后运用数值实验对模型进行了验证. 相似文献
97.
Production of runaway electrons during disruptions has been observed in the HT‐7 Tokamak. The runaway current plateaus, which can carry part of the pre‐disruptive current, are observed in lower‐hybrid current drive (LHCD) limiter discharges. It is found that the runaway current can mitigate the disruptions effectively. We can use gas puffing to increase the line‐averaged density to restrain the runaway electrons and rebuild the plasmas after the disruptions. Detailed observations are presented on the runaway electrons generated following disruptions in the HT‐7 tokamak discharges. The results indicate that the magnetic oscillations play a significant role in the loss of runaway electrons in disruptions. There are two important preconditions to rebuild plasmas by runaway electrons after the disruptions. One of them are weak magnetic oscillations; another one are LHWs (lower‐hybrid waves) (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
98.
99.
《Analytical letters》2012,45(11):1412-1425
Background: Lipid removal from biological samples can be achieved by addition of concentrated sulfuric acid. However, certain persistent organic pollutants (POPs) such as chlorophenols are decomposed by sulfuric acid treatment and, thus, a more gentle lipid reduction method is needed for extraction of many environmental contaminants from biological samples. Membrane dialysis extraction (MDE) is a non-disruptive method to extract POPs from biological matrices. Methods: Human breast milk samples were spiked with radiolabelled p,p′-dichlorodiphenyl trichloroethane ([C-14]-DDT) as a POP proxy and extracted using solid phase extraction (SPE). The extracts obtained were dialyzed by MDE in low-density polyethylene tubings containing a mixture of n-hexane and dichloromethane for 24 h, 48 h, or 72 h. Results: The lipid content was reduced by 86.2% after one dialysis cycle of 24 h using MDE, and 87.1% recovery of the [C-14]-DDT standard was obtained. The DDT recovery could be further increased up to 96.3% and 98.1% by repeating the dialyses for one or two more cycles, respectively. However, the increased [C-14]-DDT recovery includes a concomitant increase in lipid carryover from 13.8% with one dialysis cycle to 22.1% with three cycles. Conclusion: An SPE procedure for extracting POPs from breast milk and dialytic conditions for isolation of the extracted POP with minimal lipid carryover was established. The method is nondestructive and acceptable recoveries can be obtained within a single solvent shift as demonstrated by spiking standards. The lipid carryover was minimized, and the method may be considered for lipid removal before HPLC or GC analysis of environmental contaminants. 相似文献
100.
《Analytical letters》2012,45(5):787-799
A C18 stationary phase was synthesized for a custom-made HPLC column. When compared to a commercial C18 column, better chromatographic performances were obtained. This column was successfully applied for simultaneous determination of p,p′-DDT, o,p′-DDT, benzo(a)anthracene, benzo(b)fluoranthene, and benzo(a)pyrene in waters by high performance liquid chromatography coupled with dual detectors (diode array and fluorescence detectors) combined with solid phase extraction. Low method detection limits were obtained, i.e., p,p′-DDT: 0.5 µg L?1, o,p′-DDT: 1 µg L?1, benzo(a)anthracene: 2.5 ng L?1, benzo(b)fluoranthene: 5 ng L?1, and benzo(a)pyrene: 2.5 ng L?1. High recoveries that ranged from 82 to 94% were obtained for all compounds. 相似文献