The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Xiaoyong Wang - One of the best experts on this subject based on the ideXlab platform.
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shift of acid base Equilibrium of curcumin in its complexes with gemini surfactant hexamethylene 1 6 bis dodecyldimethyl ammonium bromide
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014Co-Authors: Xiaoyong WangAbstract:Abstract Surfactant micelles are suitable carriers for solubilizing and stabilizing curcumin that is a natural polyphenolic compound with many biological and pharmacological activities but suffers poor bioavailability. In this paper, the acid–base Equilibrium of curcumin (Cur 0 = Cur − + H + ) has been studied in surfactant concentration dependent complexes of curcumin with gemini surfactant hexamethylene-1,6-bis-(dodecyldimethyl ammonium bromide) (12-6-12). The absorption and fluorescence spectra of curcumin show that Cur − electrostatically binds with cationic 12-6-12 monomer to form curcumin/monomer complexes, whereas Cur 0 and Cur − are located in the palisade layer of 12-6-12 aggregates with different positions in curcumin/premicelle and curcumin/micelle complexes. The increase of surfactant concentration often leads to the right-shift of acid–base Equilibrium of curcumin and higher amount of anionic Cur − , as shown in the fluorescence spectra, p K a1 and [Cur − ]/[Cur 0 ] of curcumin. By contrast, the added salt is found to be beneficial for curcumin to shift the acid–base Equilibrium to the left side and keep in neutral Cur 0 .
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Shift of acid–base Equilibrium of curcumin in its complexes with gemini surfactant hexamethylene-1,6-bis-(dodecyldimethyl ammonium bromide)
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014Co-Authors: Xiaoyong WangAbstract:Abstract Surfactant micelles are suitable carriers for solubilizing and stabilizing curcumin that is a natural polyphenolic compound with many biological and pharmacological activities but suffers poor bioavailability. In this paper, the acid–base Equilibrium of curcumin (Cur 0 = Cur − + H + ) has been studied in surfactant concentration dependent complexes of curcumin with gemini surfactant hexamethylene-1,6-bis-(dodecyldimethyl ammonium bromide) (12-6-12). The absorption and fluorescence spectra of curcumin show that Cur − electrostatically binds with cationic 12-6-12 monomer to form curcumin/monomer complexes, whereas Cur 0 and Cur − are located in the palisade layer of 12-6-12 aggregates with different positions in curcumin/premicelle and curcumin/micelle complexes. The increase of surfactant concentration often leads to the right-shift of acid–base Equilibrium of curcumin and higher amount of anionic Cur − , as shown in the fluorescence spectra, p K a1 and [Cur − ]/[Cur 0 ] of curcumin. By contrast, the added salt is found to be beneficial for curcumin to shift the acid–base Equilibrium to the left side and keep in neutral Cur 0 .
Mikiharu Kamachi - One of the best experts on this subject based on the ideXlab platform.
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effect of counterion condensation on the acid base Equilibrium of a ph sensitive merocyanine dye covalently attached to polyelectrolytes
Journal of Polymer Science Part A, 1993Co-Authors: Yotaro Morishima, Yuji Higuchi, Mikiharu KamachiAbstract:Effects of monovalent and divalent counterions on the Acid-Base Equilibrium of a pH-sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28<ξ<2.8) were investigated. Added chloride salts of Li + , Na + , K + , and NH 4 + (<0.2 MM) had essentially no effect on pK observed (pK obs ) for the Equilibrium. By contrast, the salts of Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ caused a significant decrease in pK obs for the copolymers with larger ξ. With smaller ξ, most likely when ξ<0.5, no decrease in pK obs was observed upon addition of the salts of divalent cations
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Effect of counterion condensation on the acid‐base Equilibrium of a pH‐sensitive merocyanine dye covalently attached to polyelectrolytes
Journal of Polymer Science Part A: Polymer Chemistry, 1993Co-Authors: Yotaro Morishima, Yuji Higuchi, Mikiharu KamachiAbstract:Effects of monovalent and divalent counterions on the Acid-Base Equilibrium of a pH-sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28
Yotaro Morishima - One of the best experts on this subject based on the ideXlab platform.
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effect of counterion condensation on the acid base Equilibrium of a ph sensitive merocyanine dye covalently attached to polyelectrolytes
Journal of Polymer Science Part A, 1993Co-Authors: Yotaro Morishima, Yuji Higuchi, Mikiharu KamachiAbstract:Effects of monovalent and divalent counterions on the Acid-Base Equilibrium of a pH-sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28<ξ<2.8) were investigated. Added chloride salts of Li + , Na + , K + , and NH 4 + (<0.2 MM) had essentially no effect on pK observed (pK obs ) for the Equilibrium. By contrast, the salts of Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ caused a significant decrease in pK obs for the copolymers with larger ξ. With smaller ξ, most likely when ξ<0.5, no decrease in pK obs was observed upon addition of the salts of divalent cations
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Effect of counterion condensation on the acid‐base Equilibrium of a pH‐sensitive merocyanine dye covalently attached to polyelectrolytes
Journal of Polymer Science Part A: Polymer Chemistry, 1993Co-Authors: Yotaro Morishima, Yuji Higuchi, Mikiharu KamachiAbstract:Effects of monovalent and divalent counterions on the Acid-Base Equilibrium of a pH-sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28
Tahei Tahara - One of the best experts on this subject based on the ideXlab platform.
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Acid−Base Equilibrium at an Aqueous Interface: pH Spectrometry by Heterodyne-Detected Electronic Sum Frequency Generation
The Journal of Physical Chemistry C, 2011Co-Authors: Shoichi Yamaguchi, Kankan Bhattacharyya, Tahei TaharaAbstract:We applied interface-selective heterodyne-detected electronic sum frequency generation (HD-ESFG) to the pH spectrometry of an air/cationic surfactant/water interface in order to obtain insight into an acid−base Equilibrium at the interface. We used an indicator molecule adsorbed at the interface to probe local pH and local effective polarity. We obtained unprecedentedly high quality spectral data of the interfacial pH spectrometry, which clearly indicates that this interface has higher pH than the bulk owing to the positive charge of the head group of the surfactant. In addition, we found that the air/surfactant/water interface and the micelle interface of the same surfactant are essentially equivalent in local pH and local effective polarity.
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acid base Equilibrium at an aqueous interface ph spectrometry by heterodyne detected electronic sum frequency generation
Journal of Physical Chemistry C, 2011Co-Authors: Shoichi Yamaguchi, Kankan Bhattacharyya, Tahei TaharaAbstract:We applied interface-selective heterodyne-detected electronic sum frequency generation (HD-ESFG) to the pH spectrometry of an air/cationic surfactant/water interface in order to obtain insight into an acid−base Equilibrium at the interface. We used an indicator molecule adsorbed at the interface to probe local pH and local effective polarity. We obtained unprecedentedly high quality spectral data of the interfacial pH spectrometry, which clearly indicates that this interface has higher pH than the bulk owing to the positive charge of the head group of the surfactant. In addition, we found that the air/surfactant/water interface and the micelle interface of the same surfactant are essentially equivalent in local pH and local effective polarity.
Rong Guo - One of the best experts on this subject based on the ideXlab platform.
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acid base Equilibrium of puerarin in ctab micelles
Journal of Pharmaceutical and Biomedical Analysis, 2007Co-Authors: Rong GuoAbstract:Electronic absorption spectra, fluorescence emission spectra, 1HNMR and ab initio quantum calculation are used to study the Acid-Base Equilibrium of puerarin in cetytrimethylammonium bromide (CTAB) micelles with different microstructures and microenvironments. Experiments suggest the microenvironment provided by CTAB micelle cause the Acid-Base Equilibrium of puerarin to move to the deprotonation reaction. The changes in the chemical shifts of the individual groups of protons in CTAB indicate that the location of puerarin changes from the inner to the outer of the CTAB micelles with an increase in puerarin concentration, which enhances the interaction between puerarin and CTAB. The binding of puerarin with CTAB micelle is a spontaneous (deltaG<0) and endothermic process (deltaH<0), and the hydrophobic and electrostatic force is the main driving force for its solubilization.
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Acid-Base Equilibrium of puerarin in CTAB micelles.
Journal of pharmaceutical and biomedical analysis, 2006Co-Authors: Rong GuoAbstract:Electronic absorption spectra, fluorescence emission spectra, 1HNMR and ab initio quantum calculation are used to study the Acid-Base Equilibrium of puerarin in cetytrimethylammonium bromide (CTAB) micelles with different microstructures and microenvironments. Experiments suggest the microenvironment provided by CTAB micelle cause the Acid-Base Equilibrium of puerarin to move to the deprotonation reaction. The changes in the chemical shifts of the individual groups of protons in CTAB indicate that the location of puerarin changes from the inner to the outer of the CTAB micelles with an increase in puerarin concentration, which enhances the interaction between puerarin and CTAB. The binding of puerarin with CTAB micelle is a spontaneous (deltaG
