Ammonium 8-anilino-1-naphthalenesulfonate Research Articles

Modulation of anionic reverse micellar interface with non-ionic surfactants can regulate enzyme activity within the micellar waterpool

In this contribution, we have studied the effect of replacing anionic surfactant 1,4-bis(2-ethylhexyl)sulphosuccinate (AOT) by nonionic surfactant(s) of varying hydrophilic-lipophilic balance (HLB) on the structure, dynamics and activity of water encapsulated in reverse micelles (RMs) formed in a biocompatible oil isopropyl myristate (IPM). The sizes of the RM droplets are measured using dynamic light scattering (DLS) technique, while the structure of water in the RM waterpool is determined using FTIR spectroscopy. The solvation dynamics in these systems is obtained by time-resolved fluorescence spectroscopy using ammonium 8-anilino-1-naphthalenesulfonate (ANS) as the fluorophore. We spectroscopically measure the enzymatic activity of α-chymotrypsin on the substrate Ala-Ala-Phe-7-amido-4-methyl-coumarin (AMC) in these mixed RM systems. It has been found that the rate could either be enhanced or reduced depending on the HLB of the added Brij(s). Such result could be found useful in modulating the reaction for specific applications.

Cooperative molecular recognition of dyes by two bis(β-cyclodextrin)s with aromatic, sulfur-containing, diamine tethers

The molecular binding behavior of two bis(β-cyclodextrin (CD))s, that is, 4,4′-diaminodiphenylsulfone-bridged bis(β-CD) 2 and 4,4′-diaminodiphenyldisulfide-bridged bis(β-CD) 3 with some representative organic dyes, i.e., acridine red (AR), neutral red (NR), ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 2-(p-toluidinyl)naphthalenesulfonate (TNS), rhodamine B (RhB), and brilliant green (BG), has been investigated at 25 °C in phosphate buffer (pH 7.20) by ultraviolet, fluorescence and 2D NMR spectroscopy. The fluorescence of ANS, TNS, AR, and NR are enhanced, whereas that of RhB is quenched, by inclusion complexation with both host compounds. The results obtained show bridged bis(β-CD)s 2 and 3 with dye guests give higher complex stability constants (KS) than those of the native β-CD 1, through cooperative binding of two hydrophobic CD cavities with one guest. In addition, the KS values of all guests with host 3 are much larger than those with 2 except for NR as guest. The 2D 1H NOESY spectrum of host 3 and RhB was acquired to confirm the cooperative binding mode. The molecular binding ability of dyes by hosts 1–3 are discussed from the viewpoint of the size and shape-fitting relationship between host and guest.

Investigation of the Complexation Behavior of a New Polymer with Cyclodextrin and Crown Ether Side Groups by Fluorescence Spectroscopy

AbstractA thermoresponsive terpolymer of N‐isopropylacrylamide (NIPA), 6‐N‐allylamino‐6‐deoxy‐β‐cyclodextrin (AA‐β‐CD) and 4‐acryloylamido‐benzo‐15‐crown‐5 (AAB‐15‐crown‐5) was synthesized by free radical polymerization to a combined supramolecular host system. The complexation of a fluorescent dye, namely ammonium 8‐anilino‐1‐naphthalenesulfonate (ANS), as guest molecule was investigated via fluorescence spectroscopy. In presence of the terpolymer, the fluorescence of ANS was highly increased compared to native β‐CD and the copolymers of NIPA and AA‐β‐CD or AAB‐15‐crown‐5.

Synthesis of novel bis(β‐cyclodextrin)s linked with aromatic diamine and their molecular recognition with model substrates

AbstractNovel β‐cyclodextrin (β‐CD) dimers with aromatic diamine linkers, 1,3‐(aminomethyl)‐benzylamine‐bridged bis(6‐amino‐6‐deoxy‐β‐CD) (2), 4,4′‐diaminodiphenylmethano‐bridged bis(6‐amino‐6‐deoxy‐β‐CD) (3), and 4,4′‐ ethylenedianiline‐bridged bis(6‐amino‐6‐deoxy‐β‐CD) (4), were synthesized. The inclusion complexation behaviors of these compounds, together with 4,4′‐aminophenyl ethyl‐bridged bis(6‐amino‐6‐deoxy‐β‐CD) (5), with substrates such as acridine red (AR), neutral red (NR), ammonium 8‐anilino‐1‐naphthalenesulfonate (ANS), sodium 2‐(p‐toluidinyl) naphthalenesulfonate (TNS), rhodamine B (RhB), and brilliant green (BG), were investigated by ultraviolet, fluorescence, circular dichroism, and 2D NMR spectroscopy. The results indicated that the two linked CD units cooperatively bound to a guest, and the molecular binding affinity toward substrates, especially curved guest ANS and linear guests such as NR and AR, was increased. The linker length between two CD units played a crucial role in the molecular recognition of the hosts with guest dyes. The binding constants of the hosts for AR, TNS, ANS, and RhB decreased with increasing linker length in hosts 2‐4. Moreover, structurally similar hosts 3 and 5 exhibited very different binding behavior for the guests. Host 5 showed much higher Ks values toward positively charged guests and lower Ks toward negatively charged guests than host 3. The 2D NMR spectra of hosts 3 and 5 with RhB were acquired to understand the binding difference between 3 and 5. The molecular binding ability and selectivity of model substrates by these hosts were sufficiently investigated to reveal not only the cooperative contributions of the linker group and CD cavities upon inclusion complexation with dye guest molecules, but also the controlling factors for the molecular selective binding. Copyright © 2008 John Wiley & Sons, Ltd.

Synthesis of a Novel Anthraquinone Diamino-Bridged Bis(β-cyclodextrin) and Its Cooperative Binding toward Guest Molecules

A novel anthraquinone diamino-bridged bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 was synthesized. The inclusion complexation behaviors of the native <TEX>$\beta$</TEX> -cyclodextrin 1 and the novel bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 with guests, such as acridine red (AR), neutral red (NR), ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 2-(p-toluidinyl) naphthalenesulfonate (TNS) and rhodamine B (RhB) were investigation by fluorescence, circular dichroism and 2D NMR spectroscopy. The spectral titrations were performed in phosphate buffer (pH 7.20) at 25 <TEX>${^{\circ}C}$</TEX> to give the complex stability constants (Ks) and Gibbs free energy changes (−<TEX>${\Delta}G^0$</TEX>) for the stoichiometric 1:1 inclusion complexation of host 1 and 2 with guests. The results indicated that the novel bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 greatly enhanced the original binding affinity of the native <TEX>$\beta$</TEX> -cyclodextrin 1. Typically, bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 showed the highest binding constant towards ANS up to 34.8 times higher than that of 1. The 2D NMR spectra of bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 with RhB and TNS were performed to confirm the binding mode. The increased binding affinity and molecular selectivity of guests by bis(<TEX>$\beta$</TEX> -cyclodextrin) 2 were discussed from the viewpoint of the size/shape-fit concept and multipoint recognition mechanism.

Molecular Recognition of a Novel Bridged Bis(&lt;EM&gt;β&lt;/EM&gt;-cyclodextrin) Tethered with Aromatic Diamine for Dyes

A novel bridged bis(β-cyclodextrin)with rigid aromatic diamino tethers,3,3'-methylenedianilino-briged-bis(6-aimino-6-deoxy-β-cyclodextrin)(2),was synthesized by the reaction of mono-[6-o-(p-tolysulfonyl)]-β-cyclodextrin with 3,3'-methylenedianiline.The inclusion complexation behaviors of native β-cyclodextrin(1)and the novel briged(β-cyclodextrin)(2)with some organic dyes,i.e.,acridine red(AR),neutral red(NR),sodium 6-toluidino-2-naphthalenes-ulfonate(TNS),ammonium 8-anilino-1-naphthalenesulfonate(ANS),rhodamine B(RhB)and brilliant green(BG)were investigated at 25 ℃ in aqueous phosphate buffer solution(pH=7.20)by means of fluorescence and ultraviolet spectroscopy.The spectral titrations gave the complex stability constants(KS)and Gibbs free energy changes(ΔG0)for the stoichiometry 1∶1 inclusion complexation of hosts examined with dye molecules.The obtained results demonstrated that bis(β-cyclodextrin)2 showed much higher binding ability and molecular selectivity toward these guest dyes than native β-cyclodextrin 1.Typically,dimmer 2 displayed the highest binding ability upon inclusion complexation with BG,affording 22.2 times higher KS value than native β-cyclodextrin.The cooperative binding ability of the bis(β-cyclodextrin)was discussed from the viewpoints of size/shape-fit interaction and multiple recognition mechanism.

Spectrophotometric Study on the Controlling Factor of Molecular Selective Binding of Dyes by Bridged Bis(β-cyclodextrin)s with Diselenobis(benzoyl) Linkers

A series of beta-cyclodextrin (beta-CD) dimers with 4,4'-diselenobis(benzoyl) linkers, that is, 6,6'-[4,4'-diselenobis(benzoyloxyl)]-bridged bis(beta-CD) (1a), 6,6'-[4,4'-diselenobis[2-(benzoylamino)ethyleneamino]]-bridged bis(beta-CD) (2a), and 6,6'-[4,4'-diselenobis[2-(benzoylamino)-3,6-diazaoctylamino]]-bridged bis(beta-CD) (3a), were synthesized in moderate yields by the reaction of 4,4'-diselenobis(benzoic acid) with beta-CD or oligo(ethylenediamino)-6-deoxy-beta-CD. Their binding behaviors with some structure-related substrates, such as acridine red (AR), neutral red (NR), rhodamine B (RhB), ammonium 8-anilino-1-naphthalenesulfonate (ANS), and 6-p-toluidino-2-naphthalenesulfonic acid (TNS), were investigated in aqueous phosphate buffer solution (pH 7.20) at 298.15 K by means of fluorescence, NMR, as well as circular dichroism spectroscopy and compared with those of their 2,2'-diselenobis(benzoyl)-linked analogues, that is, 6,6'-[2,2'-diselenobis(benzoyloxyl)]-bridged bis(beta-CD) (1b), 6,6'-[2,3'-diselenobis[2-(benzoylamino)ethyleneamino]]-bridged bis(beta-CD) (2b), and 6,6'-[2,2'-diselenobis[2-(benzoylamino)-3,6-diazaoctylamino]]-bridged bis(beta-CD) (3b). The results showed that bis(beta-CD)s 1a-3a, whose Se-Se bonds were located at the para position of the carboxyl group, gave stronger binding abilities toward nonlinear guests (RhB and ANS) than their analogues 1b-3b, whose Se-Se bonds were located at the ortho position relative to the carboxyl group. The molecular binding ability and selectivity of model substrates by these ditopic hosts were sufficiently discussed to reveal not only the cooperative contributions of the linker group and CD cavities upon inclusion complexation with dye guest molecules but also the controlling factors for the molecular selective binding.

Spectrophotometric Study of Selective Binding Behaviors of Dye Molecules by Pyridine- and Bipyridine-Modified β-Cyclodextrin Derivatives with a Functional Tether in Aqueous Solution

Four β-cyclodextrin (β-CD) derivatives bearing pyridine or bipyridine linkers, i.e., mono[6-(3-pyridinecarboxamide)ethyleneamino-6-deoxy]-β-CD (2), mono[6-(4-pyridinecarboxamide)ethyleneamino-6-deoxy]-β-CD (3), N,N‘-bis(2-aminoethyl)-2,2‘-bipyridine-4,4‘-dicarboxamide-bridged bis(6-amino-6-deoxy-β-CD) (4), N,N‘-bis(2-aminoethyl)-2,2‘-bipyridine-3,3‘-dicarboxamide-bridged bis(6-amino-6-deoxy-β-CD) (5), and their copper(II) complexes (6 and 7) were selected as molecular receptors to explore the conformation−function relationship of oligo(β-CD)s. The original conformations of hosts 4−7 and their inclusion complexation behaviors with some guest molecules, i.e., ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 6-(p-toludino)-2-naphthalenesulfonate (TNS), and rhodamine B (RhB), were comprehensively investigated by means of UV−vis, 2D NMR, and fluorescence spectroscopy. The results indicated that these oligo(β-CD)s, especially bis(β-CD) 5 and its copper(II) complex 7, exhibited the significantly enhanced ...

Cooperative molecular recognition of dyes by dyad and triad cyclodextrin-crown ether conjugates.

Three beta-cyclodextrin (beta-CyD) derivatives with crown ether units, that is N-(4'-benzo-15-crown-5)-6-imino-6-deoxy-beta-CyD (2), 6,6'-[N-(4,4'-dibenzo-18-crown-6)-imino]-bridged bis(beta-CyD)(3), and 2,2'-[O-(4',5'-benzo-15-crown-5)-ethyl]-bridged bis (beta-CyD)(5), were synthesized as cooperative recognition receptor models. Their molecular binding behavior with four representative fluorescent dyes, i.e., ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium-6-toluidino-2-naphthalene-sulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB), was investigated in buffer solutions (pH = 7.20) at 25 degreesC by means of circular dichroism, NMR and fluorescence spectroscopy. 2D-ROESY experiments showed that dyad host 2 and triad host 3 adopted a CyD-guest-crown ether binding mode, while triad host 5 adopted a CyD-guest-CyD binding mode, upon inclusion complexation with guest molecules. Therefore, hosts 2 and 3 showed high molecular recognition ability towards charged guests, giving an enhanced binding ability up to 115 times for ANS by 3 and fairly high molecular selectivity up to 1450 times for the ANS/AR pair by 2 as compared with native beta-CyD in an aqueous phosphate buffer solution. On the other hand, host 5 was found to be able to effectively recognize the shape of a guest molecule, showing significantly higher binding ability towards linear guests. The binding affinities and molecular recognition abilities of these CyD-crown ether conjugates towards guest molecules are discussed from the viewpoint of electrostatic and/or hydrophobic interactions, size/shape-fit concept, and multiple recognition mechanism between host and guest.

Cooperative self-assembly and molecular binding behavior of cyclodextrin-crown ether conjugates mediated by alkali metal ions.

In order to quantitatively investigate their molecular binding ability, a series of cyclodextrin-crown ether conjugates containing beta-cyclodextrin (beta-CyD) and crown ether units, i.e.N-(benzoaza-15-crown-5)acylaminomethylene tethered 6-diethylenetriamino-6-deoxy-beta-CyD, N-(benzoaza-15-crown-5)acylaminomethylene tethered 6-triethylenetetraamino-6-deoxy-beta-CyD and 4',5'-dimethylene-benzo-15-crown-5 tethered 6-diethylenetriamino-6-deoxy-beta-CyD, have been prepared as ditopic molecular receptors. Their inclusion complexation behavior with four representative fluorescent dyes, i.e. ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 6-toluidino-2-naphthalenesulfonate (TNS), acridine red (AR) and rhodamine B (RhB), has been comprehensively investigated in aqueous NaH2PO4/Na2HPO4 or KH2PO4/K2HPO4 buffer solution (pH 7.20) by means of circular dichroism, fluorescence, and 2D NMR spectra. The results indicate that the self-assembly of crown ether modified beta-CyD mediated by potassium ion exhibits a dimeric structure, which significantly enhances the original binding ability and molecular selectivity of parent beta-CyD and its derivatives towards guest molecules through the cooperative binding of two hydrophobic CyD cavities with one guest. This cooperative binding mode of K+/CyD-crown ether systems are further confirmed by Job's experiments and 2D NMR investigations. Attributed to the positive contributions from the metal-ligated crown ether cap and K+-mediated dimerization of CyDs, the binding constant (Ks) values of CyD-crown ether conjugates toward ANS are 10-83 times higher than that of beta-CyD. The increased binding ability and molecular selectivity of CyD-crown ether conjugates are discussed from the viewpoints of size/shape-fit and multiple recognition mechanism.

Molecular Recognition and Cooperative Binding Ability of Fluorescent Dyes by Bridged Bisβ-cyclodextrin)s Tethered with Aromatic Diamine

A novel bridged bis(β-cyclodextrin),m-phenylenediimino-bridged bis(6-imino-6-deoxy-β-cyclodextrin) (2), was synthesized by the reaction of m-phenylenediamine and 6-deoxy-6-formyl-β-cyclodextrin. The inclusion complexation behavior of the novel bridged bis(β-cyclodextrin) 2,as well as native β-cyclodextrin (1),p-phenylenediamino-bridged bis(6-amino-6-deoxy-β-cyclodextrin) (3) and 4,4'-bianilino-bridged bis(6-amino-6-deoxy-β-cyclodextrin) (4) with representative fluorescent dye molecules, i.e., acridine red (AR), neutral red (NR), Rhodamine B (RhB), ammonium 8-anilino-1-naphthalenesulfonate (ANS) and sodium 6-toluidino-2-naphthalenesulfonate (TNS), was investigated at 25 °C in aqueous phosphate buffer solution (pH 7.20) by means of fluorescence, and circular dichroism, as well as 2D NMR spectrometry. The spectrofluorometric titrations have been performed to calculate the complex stability constants (KS) and Gibbs free energy changes (Δ G°) for the stoichiometric 1 : 1 inclusion complexation of 1–4 with fluorescent dye molecules. The results obtained demonstrated that bis(β-cyclodextrin)s 2–4 showed much higher affinities toward these guest dyesthan native β-cyclodextrin 1. Typically, dimer 2 displayed the highest binding ability upon inclusion complexation with ANS, affording 35 times higher KS value than native β-cyclodextrin. The significantlyenhanced binding abilities of these bis(β-cyclodextrin)s are discussed from thebinding mode and viewpoints of size/shape-fit concept and multiple recognition mechanism.

Molecular Recognition of Bridged Bis(β‐cyclodextrin) s Linked by Phenylenediseleno Tether on the Primary or Secondary Side with Fluorescent Dyes

AbstractA novel β‐cyclodextrin dimer, 2, 2′‐o‐phenylenediseleno‐bridged bis (β‐cyclodextrin) (2), has been synthesized by reaction of mono‐[2‐O‐(p‐tolylsulfonyl)]‐β‐cyclodextrin and poly(o‐phenylenediselenide). The complexation stability constants (K2) and Gibbs free energy changes (‐ΔG°) of dimer 2 with four fluorescence dyes, that is, ammonium 8‐anilino‐1‐naphthalenesulfonate (ANS), sodium 6‐(p‐toluidino)‐2‐naphthalenesulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB) have been determined in aqueous phosphate buffer solution (pH = 7.2, 0.1 mol‐L−1) at 25 °C by means of fluorescence spectroscopy. Using the present results and the previously reported corresponding data of β‐cyclodextrin (1) and 6, 6′‐o‐phenylenediseleno‐bridged bis (β‐cyclodextrin) (3), binding ability and molecular selectivity are compared, indicating that the bis (β‐cyclodextrin)s 2 and 3 possess much higher binding ability toward these dye molecules than parent β‐cyclodextrin 1, but the complex stability constant for 2 linked from the primary side is larger than that of 3 linked from the secondary side, which is attributed to the more effective cooperative binding of two hydrophobic cavities of host 3 and the size/shape‐fit relationship between host and guest. The binding constant (K2,) upon inclusion complexation of host 3 and AR is enhanced by factor of 27.3 as compared with that of 1. The 2D 1H NOESY spectrum of host 2 and RhB is performed to confirm the binding mode and explain the relative weak binding ability of 2.

Synthesis of Novel β-cyclodextrin Derivatives Bearing a 1-naphthyloxamino-oligo(ethyleneamino) Moiety and their Inclusion Complexation with some Fluorescent Dyes

Two novel g -cyclodextrin derivatives bearing a (1-naphthyloxamino)-ethyleneamino ( 4 ) or (1-naphthyloxamino)-diethylenediamino ( 5 ) moiety have been synthesized by a convenient method in 34% and 30% yields, respectively. Examinations of the circular dichroism (CD) spectra and fluorescence lifetime revealed that the naphthyloxamino-oligo (ethyleneamino) moiety tethered to g -cyclodextrin is not deeply embedded in the hydrophobic cavity of g -cyclodextrin itself even in the absence of a guest. The inclusion complexation behavior of 4 and 5 with some fluorescent dyes, i.e. ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 2-( p -toluidinyl)naphthalenesulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB), was assessed in aqueous phosphate buffer solution (pH 7.2) at 25C by fluorometric titration to give the complex stability constants ( K S ) and Gibbs free energy changes ( j G 0 ) for the stoichiometric 1:1 inclusion complexation with the fluorescent dyes. The results obtained indicate that the naphthyloxamino-oligo(ethyleneamino) moiety attached to the g -cyclodextrin ( 1 ) can alter not only the original molecular binding-ability of the parent g -cyclodextrin, but also the molecular selectivity through the micro-environment changes of cyclodextrin cavity, which are discussed from the viewpoints of the size/shape-fit concept and the stereochemical complementary relationship between host cyclodextrin and model substrate.

Molecular Recognition Studies on Supramolecular Systems 34. Synthesis of Aromatic Diamino-bridged Bis(β-cyclodextrin)s and their Inclusion Complexation with Dye Molecules

A series of 6,6'-bis( g -cyclodextrin)s with rigid aromatic diamino tethers, i.e. p -phenylenediamino-bridged-bis(6-amino-6-deoxy- g -cyclodextrin) ( 3 ), 4,4'-bianilino-bridged-bis(6-amino-6-deoxy- g -cyclodextrin) ( 4 ) and 3,3'-bianilino-bridged-bis(6-amino-6-deoxy- g -cyclodextrin) ( 5 ), have been synthesized by the reaction of mono[6- O -( p -toluenesulfonyl)]-( g -cyclodextrin) with corresponding materials. The inclusion complexation behavior of native g -cyclodextrin ( 1 ), mono-(6-anilino-6-deoxy)- g -cyclodextrin ( 2 ), and novel bis( g -cyclodextrin) 3 - 5 with some representative dyes, i.e. ammonium 8-anilino-1-naphthalenesulfonate (ANS), Brilliant Green, Methyl Orange, Acridine Red and Rhodamine B, was investigated at 25C in aqueous phosphate buffer solution (pH 7.20) by means of fluorescence, ultraviolet, circular dichroism spectrometry as well as fluorescence lifetime measurement. The spectrophotometric titrations gave the complex stability constants ( K S ) and Gibbs free energy changes ( j G 0 ) for the stoichiometric 1:1 inclusion complexation of hosts examined with dye molecules. As compared with 1 or 2 , bridged bis( g -cyclodextrin)s displayed significantly enhanced binding abilities towards these dyes. Typically, dimer 3 showed the highest binding ability upon inclusion complexation with acridine red affording 17 times higher K S for 3 than for 1 . The molecular binding abilities and selectivities of dyes by bridged bis( g -cyclodextrin)s have been discussed from the viewpoint of induced-fit interaction and multipoint recognition mechanism.

Inclusion complexation of ?-cyclodextrin and 6-O-?-�maltosyl- and 2-O-(2-hydroxypropyl)-?-cyclodextrins �with some fluorescent dyes

Spectrofluorimetric titrations were performed in aqueous phosphate buffer (pH 7.20, 0.1 mol dm ˇ3 )t o determine the binding constants of b-cyclodextrin (1), mono(6-O-a-maltosyl)-b-cyclodextrin (2) and mono(2-O-(2- hydroxypropyl))-b-cyclodextrin (3) with four fluorescent dyes, ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 2-(p-toluidino)naphthalene-6-sulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB). The fluorescence of ANS, TNS and AR were enhanced, whereas that of RhB was quenched, by the inclusion complexation with b-cyclodextrin hosts 1-3. It was found that the binding ability of the three cyclodextrin hosts generally decreases in the order 1> 3> 2, which indicates that the hydrophobicity of the substituent affects the original binding ability of parent b-cyclodextrin to some extent. On the other hand, the size, shape and charge of the guest are the crucial factors which dominate the stability of the supramolecular complex formed. Copyright © 2000 John Wiley & Sons, Ltd.

Surface Potential of Mixed Micelles Composed of Dibucaine Hydrochloride and Heptaethylene Glycol Dodecyl Ether.

The surface potential (Δψ) of the mixed micelles composed of dibucaine hydrochloride (DC) and nonionic heptaethylene glycol dodecyl ether (HED) has been estimated by measuring the fluorescence intensity of ammonium 8-anilino-1-naphthalenesulfonate (ANS) as a fluorescent probe. The value of +Δψ increases with an increasing mole fraction of DC (XDC) and decreases with increasing ionic strength (I). These changes are due to the effects of the ositive charge of DC and of the ionic atmosphere of Cl-, respectively. Surface charge density (σ) was, therefore, determined from Δψ according to the Gouy-Chapman theory, with a results that σ is nearly independent of I and proportional to XDC. These results have led to a conclusion that the state of the diffuse layer surrounding the Stern layer at the micelle surface is represented well by the Gouy-Chapman theory.

Surface Potential of Mixed Micelles Composed of Prostaglandin B2 and Heptaethylene Glycol Dodecyl Ether by the Fluorescence Method

Abstract The surface state of negatively charged mixed micelles prepared by addition of prostaglandin B2 (PGB2) to nonionic heptaethylene glycol dodecyl ether (HED) has been investigated and the surface potential (Δψ) of the micelles has been estimated by measuring the fluorescence intensity of ammonium 8-anilino-1-naphthalenesulfonate (ANS) as a fluorescent probe. Since the binding constant of ANS, k, is dependent on the surface potential of the micelle, the value of Δψ was determined according to the equation Δψ=−59.16log(k0⁄k) at 25°C, where k0 is the k of HED micelle. The value of |−Δψ| increases with increasing mole fraction of PGB2 (XPGB2) and decreases with increasing ionic strength (J). These changes are due to the effects of the negative charge of PGB2 and of ionic atmosphere of Na+, respectively. Surface charge density (σ) was, therefore, determined from Δψ according to the Gouy-Chapman theory, with a result that σ is nearly independent of J and proportional to XPGB2. These results have led to a conclusion that the state of the diffuse layer surrounding the Stern layer on the micelle surface is represented well by the Gouy-Chapman theory as well as a previous result for the system of sodium dodecyl sulfate (SDS) and HED. The value of |−σ| for PGB2 micelle is less than that for SDS micelle, which suggests that PGB2 forms a loosely packed micelle.