Arabian Journal of Chemistry
·
2018
·
IF 2.969
Dashuang Fan,Zhiguo Hao,Peizhu Zheng,Jihua Zhao,Weiguo Shen
The influence of water-soluble polyethylene glycols PEG200 on the properties of sodium bis(2-ethylhexyl)-sulfosuccinate (AOT) water-in-isooctane microemulsions has been investigated by conductivity measurement and isothermal titration microcalorimetry (ITC). The percolation temperatures ( T p ), the thermodynamic properties of droplet aggregation and the interaction enthalpy (−Δ H φ ) between droplets for AOT/water/PEG200/isooctane with different PEG concentrations and a fixed molar ratio of water to surfactant ω = 22.2 were determined. Based on a two-stage thermodynamic approach of the percolation, we obtained the fusion enthalpy (Δ H f 0 ) of the close contact droplets by a combination of the droplet aggregation enthalpy (Δ H ag 0 ) and −Δ H φ . It was found that both (−Δ H φ ) and (Δ H f 0 ) varied with the concentration of PEG200 ( c PEG ) and had the extreme value at c PEG = 25 g L −1 . This phenomenon was interpreted by the variation of interface rigidity due to the varied distributions of added PEG200 between the water pool and the surfactant interface.
研究领域:
胶体化学
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物理化学
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DOI
高影响因子
Analytical Methods
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2014
·Vol. 6
·期 21
·8627-8632
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IF 1.938
Jinjiao Shi,Ligang Chen
In this study, we investigated the possibility of reverse micelles which were used for the determination of rhodamine B in lipsticks followed by high performance liquid chromatography (HPLC). The reverse micelle of surfactant sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate (AOT) was formed in n-hexane. First, the samples were preprocessed by reverse micelle extraction, and then rhodamine B was extracted from the mixture with methanol by back-extraction. The effects of different parameters including the concentration of surfactant, pH, amount of potassium chloride, ultrasonic time and type of organic solvents were evaluated and optimized during reverse micelle formation. The limit of detection of rhodamine B was 0.01 μg g−1. The intra-day and inter-day precisions expressed as relative standard deviations were 3.6% and 4.5%, respectively. The recovery of rhodamine B obtained was 95.0%. The reverse micelle method proposed for the determination of rhodamine B in real samples of lipsticks has the advantages of simplicity, speed, high precision, low detection limit and the use of inexpensive equipment.
研究领域:
分析化学
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食品与化妆品安全
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药物分析
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分子检测
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环境与健康
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2020
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IF 5.065
Wei Jin,Rongrong Wang,Xirong Huang
The horseradish peroxidase (HRP) mediated synthesis of conducting polyaniline (PANI) was investigated in detail in the bicontinuous microemulsion stabilized by both sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and dodecyl sulfobetaine (SB-12). The addition of zwitterionic surfactant SB-12 not only reduces the phase inversion temperature of the anionic surfactant AOT stabilized microemulsion, but also enhances the catalytic performance of the solubilized HRP. Compared with the previously reported AOT/SDS stabilized bicontinuous microemulsion, the present AOT/SB-12 stabilized bicontinuous microemulsion is much more suitable for the expression of the catalytic activity of HRP; moreover, the conductivity of the resulting PANI improves greatly (a 15-fold increase in conductivity). The present results indicate further that the catalytic activity of HRP and its stability are crucial for the biosynthesis of PANI in bicontinuous microemulsions. To understand the underlying mechanism of the medium effects, electron spin resonance (ESR), UV–vis-NIR and small-angle X-ray scattering (SAXS) spectroscopies were used to investigate the effects of the oil-to-water ratio ( α ) and the surfactant concentration ( γ ) of the present bicontinuous microemulsion on the conductivity of resulting PANI. Results show that the bicontinuous microemulsion stabilized by both AOT and SB-12 still has a template role in the biosynthesis of PANI and the PANI conductivity is mainly determined by the microstructure of the template and by the microstructure-dependent activity and stability of the solubilized HRP. Lower α and γ values are beneficial to the enzymatic synthesis of high-quality PANI. The present study is of great help not only to deepen the understanding of the template role of anionic surfactant aggregates in the biosynthesis of conducting PANI, but also to develop new strategies for the biosynthesis of high quality PANI.
研究领域:
生物化学
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材料科学
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2024
·
IF 5.3
Yu Chen,Xirong Huang
CHAPS (3-[(3-cholamidopropyl) dimethylammonio]-1-propane sulfonate), a biocompatible zwitterionic surfactant derived from bile salt, has attracted great attention due to its distinct molecular structure and aggregation behavior. Addition of a low level of CHAPS to AOT (sodium bis(2-ethylhexyl) sulfosuccinate) reverse micelles has been found to be able to enhance the catalytic activity of the solubilized lipase. In this study, the effect of CHAPS on the lipase-catalyzed selective synthesis of (S)-n-octyl ibuprofen ester was investigated in AOT reverse micelles at 37 °C. The results demonstrate that the presence of CHAPS in AOT reverse micelle enhances both the yield and the enantiomeric excess (ee) value of (S)-n-octyl ibuprofen ester, especially at low water content. With 8 mM CHAPS in AOT reverse micelle ([AOT] = 100 mM, [H 2 O]/[AOT] = 12, pH = 7.0), a 48-hour yield of 34.2 % could be obtained, which is approximately twice that without CHAPS. In addition, the ee value of the product is increased from 89.1 % to 98.2 %. To understand the mechanism of the CHAPS effect, dynamic light scattering, fluorescence emission spectroscopy and Fourier transform infrared spectroscopy techniques were used to characterize the size of the reverse micelle, the conformation of the solubilized lipase and the activity of the bulk water in the reverse micelle. It reveals that at low water content, the addition of CHAPS enlarges the size of AOT reverse micelle, stabilizes the lipase conformation and reduces the nucleophilicity of bulk water in AOT reverse micelle. The synergistic effect of the aforementioned factors results in the improvement of the enzymatic synthesis of the ester. The above research provides scientific support for the lipase-based preparation of chiral acids/alcohols in the reverse micellar system.
研究领域:
生物化学
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酶工程
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有机合成
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DOI
高影响因子
RSC Advances
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2021
·Vol. 11
·期 39
·23968-23974
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IF 3.361
Tianxiang Yin,Xingnan Zhou,Jing Shi
Carbon dots (CDs) have drawn considerable attention in recent decades due to their outstanding biocompatibility and environmental friendliness. In this study, we synthesized ionic liquid (1-aminopropyl-3-methyl-imidazolium bromide)-modified carbon dots (IL-CDs) showing good peroxidase-like activity. Furthermore, we investigated their enzymic behavior in the presence of two different amphiphilic molecules, namely tert-butanol (TBA, a typical hydrotrope) and sodium bis (2-ethylhexyl) sulfosuccinate (AOT, a typical anionic surfactant). In an aqueous solution of TBA, a microscopic heterogeneous structure was formed in a certain concentration range of TBA, which resulted in an anomaly in the reaction process. However, in the AOT aqueous solution, the situation became more complicated. IL-CDs formed vesicles or precipitation at different concentrations of AOT, which led to different enzymic activities of IL-CDs due to the variance in the structure and the surface electronic density.
研究领域:
纳米材料
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生物化学
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环境科学
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DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2020
·
IF 5.065
Wei Jin,Rongrong Wang,Xirong Huang
A bicontinuous microemulsion system consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), sodium dodecylsulfate (SDS), an aqueous solution (a 0.1 M disodium hydrogenphosphate/citric acid buffer solution of pH = 4.3), and decane was investigated in detail for applications as reaction medium for the horseradish peroxidase (HRP)/hydrogen peroxide-mediated synthesis of the conductive form of polyaniline (PANI). To formulate the optimal single-phase microemulsion with the phase inversion temperature being close to room temperature , the T - γ fishlike phase diagram of the AOT/SDS-buffer-decane pseudoternary system was determined. The effects of the surfactant concentration ( γ ), the oil-to-water ratio ( α ) and the temperature ( T ) on the conductivity of the resulting PANI and the underlying mechanism were investigated using UV–vis-NIR, ESR and small-angle X-ray scattering (SAXS) techniques. Results show that the bicontinuous microemulsion plays a template role in the PANI biosynthesis, and the PANI conductivity also depends on the activity and stability of the solubilized HRP, which are determined by the microdomain size of the microemulsions and the reaction temperature. As far as γ is concerned, it is found that as γ increases, the microdomain size of the bicontinuous microemulsion as well as the activity of the solubilized HRP decreases significantly, leading to a great decrease of the PANI conductivity. Compared with γ , the change of α has small effect on the PANI conductivity. As the α -dependent microdomain size changes little with increasing α , the small change of the PANI conductivity should be ascribed mainly to the HRP activity. For T , over the range of 20 °C–35 °C, it has a slight effect on the microdomain size of the bicontinuous microemulsion, but it has a marked effect on the enzymatic properties of HRP. As the temperature increases, the activity of HRP increases, but its thermal stability decreases greatly. Therefore, the thermal stability of HRP is the major factor causing that the PANI conductivity decreases significantly with increasing T . The present work deepens the understanding of the template effect of anionic surfactant aggregates in the biosynthesis of conducting PANI. To the best of our knowledge, this work is the first study of the use of bicontinuous microemulsions as reaction media for the enzymatic synthesis of a conducting polymer .
研究领域:
材料科学
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生物化学
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DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2014
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IF 3.552
Jia-Pei Wang,Jun-Sheng Chen,Guang-Jiu Zhao
In this work, we have reported our study on the controversial issue whether methanol molecules can be effectively encapsulated by surfactant AOT to form true reverse micelles. We compared the different photophysical properties of coumarin 153 (C153) in methanol/AOT/n-heptane reverse micelles and methanol/n-heptane binary mixture by means of steady-state absorption, fluorescence and time-resolved fluorescence spectroscopies. In the reverse micelles, the fluorescence emission spectra of C153 were dependent on the excitation wavelength, while in binary mixtures, the excitation wavelength dependence was not observed. The biexponential decay curves of C153 in reverse micelles give a further confirmation for the two different environments where C153 molecules reside in. In other words, C153 molecules can exist both inside the core of the reverse micelles and outside of it. These results proved that the methanol can be effectively encapsulated by AOT in n-heptane solvents to form stable methanol/AOT/n-heptane reverse micelles.
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DOI
高影响因子
APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2020
·Vol. 192
·期 2
·392-414
·
IF 2.277
Chen Sunni,Li Jing,Fu Zejian,Wei Guohua,Li Hongyan,Zhang Bin,Zheng Liufeng,Deng Zeyuan
Phytosterols are regarded as compounds able to reduce total and low-density lipoprotein cholesterol in the blood, and their esterified derivatives could help to improve the effectiveness of this function. In the present study, the water/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/isooctane reverse micelle (RM) system was set up as a reaction medium for Candida rugosa lipase AY30 (CRL AY30) to synthesize β-sitosterol laurate (β-SLE). The product was identified by TLC, FT-IR, and HPLC–APCI–QqQ–MS/MS and quantified by HPLC. Through stepwise optimization, it was found that CRL AY30 had the highest activity in the water/AOT/isooctane RM system where 50 mM PBS with a pH of 7.5 was adopted as water core to carry CRL AY30, and the proportion of [CRL AY30] (mg/mL), [water] (mM), and [AOT] (mM) was set in 3:375:25, respectively, in isooctane. After screened with single-factor experiments, the esterification reaction conditions in the CRL AY30–water/AOT/isooctane RM system were further optimized by the response surface method as follows: the mole ratio of β-sitosterol to lauric acid of 1:3.5 (25 mM β-sitosterol), the enzyme load of 18% (w/w total reactants), the reaction temperature of 47 °C, and the reaction time of 48 h. As a result, the maximum esterification rate was up to 88.12 ± 0.79%.
研究领域:
生物化学
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食品科学
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制药工程
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产品关联
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Xiaonan Li,Xirong Huang
Here, a functionalized organic salt composed of [N k,k,k,k ] + ( k = 1–4) and [MES] - (2-(N-morpholino)ethanesulfonate), i.e., Good’s buffer ionic liquid with self-buffering and biocompatible properties, was chosen as electrolyte as well as buffer to construct a H 2 O/AOT/isooctane bicontinuous microemulsion for enzymatic synthesis of polyaniline (PANI). Studies on the effects of the functionalized organic salt on the phase behavior indicate that [N k,k,k,k ][MES] can tune the phase inversion temperature of AOT-stabilized oil-water microemulsion system through changing the cationic alkyl chain length, exhibiting the properties of both inorganic salt and co-alcohol. More interestingly, the stability of horseradish peroxidase (HRP) solubilized in the H 2 O(0.1 M [N 1,1,1,1 ][MES], pH = 4.5)/AOT/isooctane bicontinuous microemulsion is much better than that formulated with mixed surfactants AOT/SB-12 and inorganic salt. Studies on the HRP-catalyzed oxidative polymerization of aniline in the present bicontinuous microemulsion indicates that at low surfactant content and high oil-water ratio, the present microemulsion resulted in a PANI with better conductivity than the counterpart reported elsewhere. This work is of guiding significance for constructing a less-component and enzyme-compatible bicontinuous microemulsion for template-assisted biopolymerization.
研究领域:
材料科学
·
生物化学
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DOI
高影响因子
危险品化学品经营许可证（带存储）