表面活性剂单体引起的细胞膜失稳

表面活性剂常用于细胞裂解、脂质体外排与膜组分搜集等.但在临界成胶束浓度以下,它如何以单体状态与生物膜作用的机制与调控仍存在很多疑问.本文研究了表面活性剂带电性对膜失稳的影响.石英电子微天平检测发现非离子型Triton X-100产生了最显著的磷脂膜结构三维再组装.荧光显微观测表明膜表面生成了非稳的出芽微泡,在机械扰动下可发生解离.该表面活性剂溶液环境中的体外细胞也出现了活力丧失.但是,离子型CTAB与SDS却无法触发相似的膜失稳与细胞失活效应.分析认为,由于不存在后两者体系中的单体间静电排斥, Triton X-100更易高效地插入生物膜,从而诱导膜结构再组装.研究深化了表面活性剂与生物膜作用机制的理解,对表面活性剂在生物医药、膜组分萃取等领域的深化应用提供了指导与帮助.     

NOE Effect of Sodium Dodecyl Sulfate in Monomeric and Micellar Systems by NMR Spectroscopy

This paper describes the particular nuclear Overhauser effect (NOE) of sodium dodecyl sulfate (SDS) in monomeric and micellar systems. Two-dimensional NOE spectroscopy nuclear magnetic resonance (NMR) spectra of SDS in solution with concentration lower and higher than critical micellar concentration were recorded. In the first case diagonal and cross-peaks have different signs, and the opposite one was in the second case. This paper discusses theoretical background of this effect and we supposed that particular NOE can be used for inspection of SDS micelle formation during NMR researches. As a rough estimate of micelles formation an approach based on the difference between the chemical shifts in the monomer and micellar form of SDS was used.     

FT-EPR study of photoionization in micellar solutions

Fourier Transform EPR (FT-EPR) was used to study the formation and decay of free radicals produced by photoionization of phenothiazine (PTH) solubilized in aqueous SDS and Triton X-100 micellar solutions in the absence and presence of electron acceptors. CIDEP spectra produced by PTH photoionization in micellar solution differ from those found in homogeneous solution. The effect is attributed to changes in relative importance of single-photon, singlet excited state, and biphotonic, triplet excited state, photoionization. With quinone acceptors present in the bulk aqueous phase, photoionization of PTH in SDS, results in instantaneous formation of quinone anion radicals that carry the spin polarization of the precursor hydrated electrons. If the acceptor is anchored in the micelle, electron capture cannot compete with electron escape into the aqueous phase. Instead, anion radicals are formed primarily by reductive quenching of³PTH*. This process gives rise to a spectrum that is attributed to long-lived spin-correlated radical pairs, [PTH⁺…Q^?].     

正十二烷基硫酸钠在聚丙烯酰胺溶液中聚集的1H NMR研究

利用核磁共振自旋-晶格弛豫时间（T₁）、自旋-自旋弛豫时间（T₂）、自扩散系数（D）以及二维核Overhause增强谱（2D NOESY）技术研究了表面活性剂正十二烷基硫酸钠（SDS）在聚丙烯酰胺（PAM）浓度固定为10 g/L水溶液中的聚集. 结合与SDS水溶液体系核磁共振实验数据比较,得到了如下信息：（1） 当溶液中有PAM存在时,SDS分子的运动性下降,临界聚集浓度提前;（2） 随着SDS浓度的增加,PAM分子的自扩散性能下降,同时分子链的柔软性也下降了;（3） 2D NOESY谱结果表明,PAM与SDS分子间未发生直接的缔合作用.     

在相反电荷表面活性剂存在下阳离子瓜尔胶水溶液流变行为

合成了阳离子瓜尔胶(CG),研究了其水溶液在十二烷基硫酸钠(SDS)存在下的流变行为．测定结果表明,随SDS浓度的增加,溶液零切黏度增加了3个数量级以上．小幅振荡剪切实验结果表明模量几乎和SDS浓度无关,但是驰豫时间则随着SDS浓度增加而迅速增加．因此,SDS的加入将会使交联点的强度增加,但是不会改变交联点密度．SDS对CG流变行为的影响可以用两阶段模型加以描述．在SDS存在下CG水溶液流变行为主要受到由SDS胶束形成的交联点的控制．根据Arrhenius公式得到的瓜儿胶水溶液的流动活化能在将SDS分子疏水尾端从胶束移到水相之中所需能量是一致的.     

Dielectric relaxation studies of alkanols solubilized by sodium dodecyl sulphate aqueous solutions

Considerable attention has been paid in recent years to the influence of alcohols on ionic micellar structures, alcohol co-surfactants most commonly employed in the preparation of microemulsions. Dielectric relaxation spectroscopy (DRS) is a versatile tool to monitor the dynamic process of such micellar systems. We report here the changes in the dielectric constant of the medium and the relaxation time of micellar solutions of sodium dodecyl sulphate (SDS) in water in the presence and absence of alkanols—hexan-1-ol, octan-l-ol, decan-l-ol and 1,2-ethanediol. The time domain dielectric data were obtained in the reflection mode in the frequency range of 10 MHz to 20 GHz using a HP54750A sampling oscilloscope and HP 54754A TDR plug-in-module. The sample is held at 303 K in a SMA cell with an effective pin length of 1.35 mm. We have determined the relaxation time (τ) using the Cole–Cole method. The relative viscosity ηr on the micellar solutions were also determined. The result shows that the dielectric constant increases linearly with SDS concentration in pure aqueous solutions up to 400 mM and decreases thereafter. The relaxation times are of the order of 15 ps to 25 ps and are far greater than that of Debye rotational relaxation of the monomer species. It is assigned to the dispersion step to water molecules surrounding to hydrophobic particles or the “bound water”. The addition of alcohols results in a linear increase in relaxation time in all the systems. As the concentration of SDS increases τ/ηr attains a near constant value showing that solubilization becomes more difficult at these concentrations. Our results show that the alcohol molecules are solubilized at the surface of the SDS micelle (i.e.) the micelle–water interface.     

十二烷基硫酸钠自组装过程中分子间相互作用力的垂直偏振拉曼光谱研究

Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.     

Magnetic field effect on electron transfer reactions of flavin derivatives associated with micelles

The magnetic field effects (MFEs) on the electron transfer reactions from indole derivatives to flavin derivatives in micellar solutions are studied. The MFEs on the free radical yields observed by transient absorption (TA) reflect effectively the association of the donor and acceptor molecules with the micelles. In the system of riboflavin and indole, the MFE increases rapidly with increasing concentration of sodium dodecyl sulfate (SDS) higher than the critical micellar concentration. In contrast, in the system of flavin mononucleotide and indole, the increase of MFE is very slow even at higher concentrations of SDS. This result shows that riboflavin is well associated with the SDS micelle and the diffusion process of the radical pair is restricted by the micellar cages. The MFE in the system of riboflavin and indole is twice as large as that of riboflavin and tryptophan. This result shows the difference of the dynamics of radicals in micelles. The escape rate of the cation radical generated from tryptophan is much faster than that generated from indole. The dependence of the MFEs on the type of surfactant is studied. The effect of the Coulomb force between the ionic reactant molecules and the charged head group of the surfactant and the effect of the molecular size are discussed by comparison of the MFE intensities.     

Characterization of mixed micelles of sodium cumene sulfonate with sodium dodecyl sulfate and cetyl trimethylammonium bromide by SANS,FTIR spectroscopy and NMR spectroscopy

The aqueous solutions of sodium cumene sulfonate (NaCS) and its mixtures with cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) are studied by Small Angle Neutron Scattering (SANS), Fourier Transform Infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy. The compositions of mixed micelles are determined using Rubingh's Regular Solution Theory. NaCS when added to CTAB solution leads to the formation of long rod shaped micelles with dramatic increase in the CTAB aggregation number. Its addition to SDS on the other hand results in the formation of smaller mixed micelles where parts of SDS molecules in the micelle are replaced by NaCS molecules. NaCS–SDS mixed micelles prefer elongated ellipsoidal geometry in order to accommodate short NaCS molecules. The FTIR spectroscopy results indicate enhanced ordering of CTAB tails inside the NaCS–CTAB mixed micelles with reduction in the gauche/trans conformer ratio. Addition of NaCS to SDS on the other hand results in decreased ordering of SDS tails, as compared to SDS micelles alone. The chemical shifts observed in ¹H NMR spectra of NaCS–SDS and NaCS–CTAB mixture indicate that NaCS resides near the surface of the SDS micelle.     

NMR法研究短链芳烃及其衍生物在胶束中的增溶作用

本文应用高分辨¹H-NMR谱和相图,研究了十种短链芳烃及其衍生物,在十二烷基硫酸钠胶束中的增溶作用,获得这些增溶物在胶束中的增溶位置和增溶量的详细结果。这对了解这一类增溶物的增溶机理有实际意义。     

Effect of surfactants on the spectrofluorimetric properties of zearalenone

The chemiluminescent properties of the estrogenic mycotoxin zearalenone in the presence of aqueous micellar media were investigated using steady state fluorescence techniques. Micelles of surfactants sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and non-ionic Triton X-100 enhanced the fluorescence intensity of zearalenone in aqueous solutions. The binding constants have been determined and indicate zearalenone has the highest affinity for Triton X-100, followed by CTAB, and then by SDS. The encapsulation of zearalenone by the micelles studied is spontaneous and exothermic. The selective microenvironments provided by organized micellar systems offer an attractive medium to modulate fluorescence detection of zearalenone.     

SDS胶束溶液在石油类污染物荧光光谱测量中的应用

提出了一种以十二烷基硫酸钠(SDS)胶束溶液为溶剂增溶、增敏、增稳石油类物质的新方法。研究了石油类物质的荧光强度随SDS胶束溶液浓度的变化规律,确定了其溶剂SDS胶束溶液的最佳浓度为0.1 mol·L-1。使用FLS920荧光光谱仪测量得到不同稀释浓度的汽油、柴油、煤油SDS胶束溶液的三维荧光光谱矩阵(EEMs),分析了瑞利(Rayleigh)散射、拉曼(Raman)散射以及仪器光谱特性对测量光谱的影响,经过光谱校正,建立了三种油的SDS胶束溶液在激发波长为250～400 nm、发射波长为260～500 nm范围内的三维荧光光谱图,并确定了在一定浓度范围内荧光强度与浓度具有良好的线性关系。在相同条件下,用同样的方法配制各种浓度汽油、柴油、煤油水溶液作对比,验证了SDS胶束溶液作为石油类物质的溶剂可以使水中石油类物质的溶解度增加、荧光强度增大、稳定性更好,实现了石油类物质可以不依赖于某些有毒溶剂萃取,又解决了其水中溶解度低不宜定量的问题。     

Structural Transition in the Micellar Assembly: A Fluorescence Study

Structural transition can be induced in charged micelles by increasing the ionic strength of the medium. Thus, spherical micelles of sodium dodecyl sulfate (SDS) that exist in water at concentrations higher than the critical micelle concentration assume an elongated rod-like structure in the presence of an increased electrolyte concentration. This is known as sphere-to-rod transition. In this paper, we characterize the change in organization and dynamics that is accompanied by the salt-induced sphere-to-rod transition in SDS micelles using wavelength-selective fluorescence and other steady-state and time-resolved fluorescence parameters. Since the change in micelle organization during such structural transition may not be limited to one region of the micelle, we have selectively introduced fluorophores in two distinct regions of the micelle. We used two probes, N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (NBD-PE) and 25-[N-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-methyl]amino]-27-norcholesterol (NBD-cholesterol), for monitoring the two regions of the micelle. NBD-PE monitors the interfacial region of the micellar assembly, while NBD-cholesterol acts as a reporter for the deeper regions of the micellar interior. Our results show that wavelength-selective fluorescence, in combination with other fluorescence parameters, offers a powerful way to monitor structural transitions induced in charged micelles. These results could be significant to changes in membrane morphology observed under certain physiological conditions.     

A thermodynamic and photophysical study of the effects of thiourea on the micellar properties of aqueous sodium dodecyl sulphate solution

The micellar properties of sodium dodecyl sulphate (SDS) in aqueous thiourea solutions were investigated with the aim of studying the effect of thiourea on these properties. The critical micelle concentrations (cmc) and the degree of dissociation of the micelle were determined by the conductometric method over the temperature range 298–323 K for different concentrations of thiourea. The cmc values of the surfactant in the presence of thiourea were obtained by following the change in the relative intensities of vibrational fine structure of the pyrene fluorescence spectra. The aggregation numbers were determined by employing the static quenching fluorescence method. The cmc values in the presence of varying electrolyte concentrations (NaCl) were obtained with 8-anilinonaphthalene 1-sulphonate (ANS) as a fluorescence probe, and from these values the degree of dissociation was calculated. The mass action model was applied in the present study to obtain various thermodynamic parameters of micellization. All these properties were compared with the micellar properties of an aqueous urea/SDS system, and it was found that thiourea is a better demicellization agent.     

A laser flash photolysis study of the dynamic behaviour of radical pairs in micellar solutions under ultrahigh magnetic fields of up to 30 T

The photo-induced hydrogen abstraction reactions of benzophenone in aqueous micellar SDS and Brij 35 solutions, decafluorobenzophenone in an aqueous micellar Brij 35 solution and naphthoquinone in an aqueous micellar SDS solution were investigated at room temperature under pulsed magnetic fields of 0–29.6T. In each of these reactions, the radical pair decay rate is found to decrease with increasing field from 0 to about 3 T and to increase with increasing field above 3 T. The escape radical yield is found to increase with increasing field from 0 to about 3 T and to decrease with increasing field above 3 T. These magnetic field effects are explained in terms of the relaxation mechanism. In each of the Brij 35 micellar solution systems, the anisotropy in the g tensor of the ketyl radical and its correlation time are evaluated from the observed effects.     

光谱法研究吡罗红G与十二烷基硫酸钠的相互作用

为了探讨染料在纺织染色等领域的应用性,采用应用最为广泛的光谱法研究了阴离子表面活性剂十二烷基硫酸钠与吡罗红G的相互作用.发现当阴离子表面活性剂单体与吡罗红G形成缔合物时,荧光发生猝灭;随着表面活性剂浓度的进一步增加,表面活性剂形成的胶束与吡罗红G作用,导致出现一个新的、更强的荧光峰.同时考察了硫酸钠和尿素对二者相互作用...     

Effect of surfactants on the aggregation of pyronin B and pyronin Y in aqueous solution

Molecular dynamics of pyronin B (PyB) and pyronin Y (PyY) in aqueous solution containing different surfactants were investigated by using absorption and fluorescence spectroscopy techniques. First, the interactions of PyB and PyY with the negatively charged surfactant sodium dodecyl sulphate (SDS) were investigated in the below and above critical micelle concentration (cmc). The H-aggregate formation of the dye compounds was observed for below the cmc of SDS surfactant. The absorbance of H-aggregate absorption band of PyB and PyY decreased according to the aggregate-monomer equilibrium by increasing SDS surfactant concentration towards the cmc. Therefore, equilibrium constants of the aggregate formation and oscillator strengths of monomer and aggregate of the dye compounds were calculated from spectral studies. Moreover, aggregate formation dynamics was discussed in terms of thermodynamic functions by using temperature studies. The interactions of PyB and PyY with the positively charged hexadecyltrimethylammonium bromide (CTAB) and neutral Triton X-100 (TX-100) were also studied and it was observed that there was no aggregate formation on the absorption and fluorescence spectra for below and above the cmc.     

HP-β-CD消除SDS对SDBS同步荧光光谱的影响

十二烷基苯磺酸钠(SDBS)与十二烷基苯磺酸钠(SDS)之间的相互作用,能对SDBS的检测产生明显干扰。实验结果表明,在水溶液中SDS不仅可以增大SDBS的同步荧光强度,还能显著降低SDBS的表观临界胶束浓度。按SDBS的摩尔计量比加入1∶1的羟丙基-β-环糊精(HP-β-CD),可以消除SDS对SDBS的同步荧光强度的干扰。相比于形成胶束,在SDS/SDBS水溶液中,SDBS单体优先选择与HP-β-CD形成量比1∶1的包结物。当水溶液中HP-β-CD的浓度由0增加至0.900 mmol·L~(-1)时,复配体系中SDBS形成胶束的标准摩尔吉布斯函变ΔγGθm由-39.681 k J·mol-1增加至-37.580 k J·mol~(-1)。加入适量HP-β-CD后,能够准确检测SDS/SDBS水溶液中SDBS的含量(临盘采油厂T5站地层水样),方法的回收率为101.0%~101.6%。FT-IR及1H-NMR分析表明,SDBS分子进入HP-β-CD分子内腔的大口径端并形成量比1∶1的包结物,是消除SDS对SDBS检测干扰的根本原因。     

Synthesis,physicochemical, and biological activities of novel N‐acyl tyrosine monomeric and Gemini surfactants in single and SDS/CTAB–mixed micellar system

A series of single‐chained N‐acyl tyrosine surfactants with varying chain lengths (C₁₀‐C₁₈) and degree of unsaturation, as well as an N‐acyl Gemini tyrosine surfactant with chain length C₁₂, were synthesized, and the structures were confirmed using spectral analysis. The effect of chain length and level of unsaturation on the physicochemical and antibacterial properties of the N‐acyl tyrosine surfactants was evaluated. The C₁₂ derivative displayed the optimum antibacterial activity among the single chain surfactants, and the presence of double bond in the oleoyl derivative enhanced the antibacterial activity over its saturated analogue. The N‐acyl Gemini surfactant displayed the highest antibacterial activity among the series and also showed greater micelle forming ability than its single chain analogue. Mixed micellar behavior of the N‐acyl Gemini surfactant with conventional cationic (CTAB) and anionic (SDS) surfactants in aqueous solution was studied. The negative value of the interaction parameter β₁₂ observed for the N‐acyl Gemini in binary mixture with CTAB surfactant indicated a synergistic interaction within the mixed micellar system. However, the binary mixture with SDS displayed antagonistic behavior. The binary mixture of N‐acyl Gemini surfactant with CTAB displayed better antibacterial activity and foaming properties than with SDS mixtures. Optimum antibacterial activity was observed for N‐acyl Gemini surfactant with mole ratio 0.4 to 0.6 in the CTAB binary mixture, at which the lowest ocular irritation index was observed. Overall, the study showed that the Gemini surfactant in combination with the conventional surfactant CTAB can be used as potential ingredients in detergent and pharmaceutical formulations.     

Micelle induced generation of photovoltage using Fluorescein dye

Photovoltage generation using Fluorescein dye in aqueous and aqueous-micellar medium at different pH has been studied in photogalvanic cell. The photopotential and photocurrent generated were maximum in non-ionic micellar medium. The observed solar energy efficiency in non-ionic micellar medium, diethylene glycol hexadecyl ether (Brij-52) was 0.06% and maximum power of the cell was 15.5 μw. The output of the cell was sensitive to surfactant nature. The rate constants of the reactions during photovoltage growth and decay were calculated. The thermodynamic properties of the cell were also discussed. A comparison of the micelle induced photovoltage generation of anionic dye Fluorescein with cationic dye Safranine T in different micellar media and at different pH has been presented.