Neutral Surfactant Triton X-100 Research Articles

Surfactant mediated modulation of photophysics and self-assembly process of a small, substituted phenol

5-(tert-Butyl)-2-hydroxy-1,3- isophthalaldehyde (5-tBHI) exhibits a large Stokes shifted emission spectrum, irrespective of excitation wavelength in aqueous solution and thus can be useful in bio-imaging. It is imperative to understand the binding of 5-tBHI in micelles as micelle represent the simplest mimic of biological membrane. Hence, the interaction of 5-tBHI with cationic surfactant cetyltrimethylammonium bromide (CTAB), anionic surfactant sodium dodecyl sulfate (SDS), and neutral surfactant Triton X-100 (TX-100) was investigated. This help us elucidate the interplay of hydrophobicity and pH to modulate the ground and excited state intra/inter-molecular proton transfer processes of the probe. The absorption and fluorescence spectra of 5-tBHI have been found to be highly sensitive towards hydrophobicity and electrostatic interactions. However, no particular trend was observed, suggesting an incomplete encapsulation of the probe in the micelles. The observation from the steady state spectra could not be rationalized completely based on the time resolved fluorescence decays in the nanosecond-picosecond regime, suggesting that the processes are ultrafast in nature. Subsequently, analyses of fluorescent transients in femtosecond-picosecond regime provided a better explanation to match well with the steady state phenomena. It was found that pH has a dominant role to guide the direction of the two-state keto-enol tautomerisation. However, the effect of hydrophobicity can not be neglected as it pushes the equilibrium to the enol form. Furthermore, Fluorescence Lifetime Imaging Microscopy (FLIM), supported by SEM images, provide a pictorial idea of how the aggregation of the probe in neat water is affected by the nature of the surfactants. It further shows that SDS, with an acidic local pH favours the aggregation process, over CTAB and TX-100.

Selective detection of Triton X-100 based organized media by a 1-D coordination polymer of Cu(II) in water: Fluorescence spectroscopic and microstructural investigations

The luminescent feature of a one dimensional coordination polymer (CP) of Cu(II) in water has been employed as the fluorescent probe for investigating the interactions of the neutral CP with different neutral, cationic, and anionic type surfactants in water medium. The CP detects the neutral surfactant Triton X-100 based organized media in water. In the detection technique the monomeric unit of Cu(II)-CP is assembled at the palisade layer of Triton X-100 in water which has also been experimentally explored by fluorescence spectroscopic and field emission scanning electron microscopic (FESEM) investigations. Even the possible mechanistic pathway regarding the selective fluorometric interaction of Triton X-100 based organized media in water medium with the water solution of CP has been scrutinized through the fluorescent spectroscopic experiments using a standard chaotropic agent like urea.

Micelle-induced versatile sensing behavior of bispyrene-based fluorescent molecular sensor for picric acid and PYX explosives.

The effect of surfactant micelles on the photophysical properties of a cationic bispyrene fluorophore, Py-diIM-Py, was systemically examined. The results from series of measurements including UV-vis absorption, steady-state fluorescence emission, quantum yield, fluorescence lifetime, and time-resolved emission spectra reveal that the cationic fluorophore is only encapsulated by the anionic sodium dodecyl sulfate (SDS) surfactant micelles and not incorporated in the cationic dodecyltrimethylammonium bromide (DTAB) and neutral Triton X-100 (TX100) surfactant micelles. This different fluorophore location in the micellar solutions significantly influences its sensing behavior to various explosives. Fluorescence quenching studies reveal that the simple variation of micellar systems leads to significant changes in the sensitivity and selectivity of the fluorescent sensor to explosives. The sensor exhibits an on-off response to multiple explosives with the highest sensitivity to picric acid (PA) in the anionic SDS micelles. In the cationic DTAB micelles, it displays the highest on-off responses to PYX. Both the sensitivity and selectivity to PYX in the cationic micelles are enhanced compared with that to PA in the anionic micelles. However, the poor encapsulation in the neutral surfactant TX100 micelles leads to fluorescence instability of the fluorophore and fails to function as a sensor system. Time-resolved fluorescence decays in the presence of explosives reveal that the quenching mechanism of two micellar sensor systems to explosives is static in nature. The present work demonstrates that the electrostatic interaction between the cationic fluorophore and differently charged micelles plays a determinative role in adjusting its distribution in micellar solutions, which further influences the sensing behavior of the obtained micellar sensor systems.

Determination of the parameters of the rotational diffusion of complexes of serum albumins with Triton X-100 from analysis of tryptophan fluorescence

The rotational diffusion of complexes of human serum albumin (HSA) and bovine serum albumin (BSA) with neutral surfactant Triton X-100 is study by analyzing the polarized tryptophan fluorescence and its parameters are determined (rotational relaxation time, diffusion coefficient, effective radius). Similarities in the solubilization of both proteins are revealed: an effective solubilization BSA and HSA in solutions containing neutral surfactant Triton X-100 is achieved at concentration of the latter of 0.3 mM, slightly greater than its critical micelle concentration (0.25 mM), with the most significant effect taking place at pH 5.0, a value close to the isoelectric points of the proteins.

Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on propanol to propionaldehyde conversion in aqueous media

Oxidation of propanol by chromic acid produces propionaldehyde under kinetic condition [propanol]T≫[Cr(VI)]T. This oxidation reaction is performed also in presence of micellar catalysts (anionic, cationic and neutral) and hetero-aromatic nitrogen bases promoters (picolinic acid, 2,2′-bipyridine, 1,10-phenanthroline) in aqueous media. The product is confirmed by 2,4-DNP test and 1H NMR spectroscopy. Anionic surfactant sodium dodecyl sulphate (SDS), neutral surfactant triton X-100 (TX-100) accelerated the reaction both in presence and absence of promoters whereas cationic surfactant N-cetyl pyridinium chloride (CPC) inhibited the reaction. Combination of SDS and bipy is found to be the most efficient for this oxidation.

Salt Effect on the Ultrafast Proton Transfer in Niosome

Excited state proton transfer (ESPT) of pyranine (8-hydroxypyranine-1,3,6-trisulfonate, HPTS) in a niosome is studied by fluorescence correlation spectroscopy (FCS) and femtosecond up-conversion. The niosome consists of a neutral surfactant triton X-100 (TX-100) and cholesterol. FCS studies suggest that in the presence of niosome almost all of the HPTS is transferred to the niosome and the amount of free HPTS present in bulk water is negligible. The time constant of initial proton transfer (τ(PT)) in niosome (40 ps) is ∼8 times slower than that (5 ps) in bulk water, while the time constants of recombination (τ(rec)) and dissociation (τ(diss)) are ∼4 times and ∼1.5 times slower in niosome, respectively. On addition of NaCl, the rate of ESPT is markedly retarded both in free water and in niosome. In the niosome, τ(PT) slows down to 80 ps in 1 M NaCl and 225 ps in 4 M NaCl.

Photophysics of DNA staining dye Propidium Iodide encapsulated in bio-mimetic micelle and genomic fish sperm DNA

Photophysical processes in Propidium Iodide (PI), the well known DNA staining dye, have been exploited in homogeneous as well as heterogeneous medium by steady state and time resolved spectroscopy. The DNA staining dye PI exhibits intermolecular proton transfer reaction in aqueous and hydrogen-bonding acceptor solvents due to the formation of quinonoid structure which is acidic in nature. Time resolved emission spectroscopy also predicts the hydrogen bond donor ability of PI. The target dye interacts only with anionic surfactant sodium dodecylsulphate but not with cationic surfactant cetyltrimethylammonium bromide and neutral surfactant Triton X-100 and this interaction is found to be electrostatic in nature. We have further scrutinized the mode of binding of PI with fish sperm DNA. The effect of addition of urea, fluorescence quenching phenomenon, CD measurements reveal that the probe binds to DNA through intercalative style.

Spectroscopic determination of Critical Micelle Concentration in aqueous and non-aqueous media using a non-invasive method

In this present study, we report on new methodology for determining the Critical Micelle Concentration (CMC) of a neutral surfactant Triton X-100 (TX-100) both in aqueous and non-aqueous media based on a non-invasive approach. The presence of the phenyl moiety of TX-100 was made use of as an intrinsic fluorophore and steady-state and time-resolved spectroscopy has been used to characterize the micellar systems. There are reports that external fluorophores may bring about some structural changes in the systems and the perturbations caused by these fluorophores in micellar systems may affect the shape and size of the micelles. We have also used three probes namely ANS, Rh6G and C-480 to determine the CMC of TX-100 both in aqueous and non-aqueous media and the values obtained agree very well with those estimated by the non-invasive techniques. Interestingly, for our system, we have conclusively proved that the external probes have almost no effect on the process of micellization. Although, both the invasive and non-invasive technologies report almost the same values of CMC, yet the latter methodology is free from any external perturbations and this makes the micellar/reverse micellar system, which may interact with other biological systems less prone to any physical distortions.

Purification, characterization and thermodynamics of antifungal protease from Streptomyces sp. A6

A 20 kDa antifungal serine protease from Streptomyces sp. A6 was purified to 34.56 folds by gel permeation chromatography. The enzyme exhibited highest activity at neutral to near alka- line pH 7-9 and 55 °C. Neutral surfactant triton X-100 enhanced the activity by 4.12 fold. The protease activity also increased (109.9-119%) with increasing concentration of urea (2-8 mole/l). The enzyme was identified as serine protease with 67% similarity to SFase 2 of Streptomyces fradiae by MALDI-LC-MS/MS analysis. Determination of kinetic constants k(m) , V(max) , k(cat) and k(cat) /k(m) suggested higher affinity of enzyme for N-Suc-Ala-Ala-Val-Ala-p NA (synthetic substrate for chymotrypsin activity). The enzyme was highly stable at temperature prevailing under field conditions (40 °C) as apparent from K(d) and t(1/2) values, 0.0065 and 106.75 min, respectively and high ΔG* and negative ΔS * values, 87.17 KJ/mole and -126.95 J/mole, respectively. Thermal stability and increased activity of protease in presence of commonly used chemical fertilizer, urea, suggested its feasibility for agricultural applications. The present study is the first report on thermodynamic and kinetic properties of an antifungal protease from Streptomyces sp. A6. The study reflects potential of this enzyme for biocontrol of fungal plant pathogens.

Rapid analysis of free fatty acid composition in Brassica rapa L. and Brassica napus L. extracts by surface-assisted laser desorption/ionization time-of-flight mass spectrometry

A rapid and simple technique was developed to identify free fatty acids in mixtures by the surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) using powdered carbon aerogels as a “matrix”. A 3% solution of a neutral surfactant Triton X-100 was used as a fixing agent of carbon particles as well as a suppressor of background peaks. The extraction of free fatty acids from Brassica napus (rape) and Brassica rapa (turnip) seeds was performed by using both methanol-chloroform mixture and supercritical fluid extraction techniques. The quantitative analysis of the seed composition was carried out to demonstrate the effectiveness of the developed method. The detection limits were determined using a mixture of ten standard fatty acids and were found to be 3 ng of each acid per spot.

Lysine acetylation can generate highly charged enzymes with increased resistance toward irreversible inactivation

This paper reports that the acetylation of lysine epsilon-NH3(+) groups of alpha-amylase--one of the most important hydrolytic enzymes used in industry--produces highly negatively charged variants that are enzymatically active, thermostable, and more resistant than the wild-type enzyme to irreversible inactivation on exposure to denaturing conditions (e.g., 1 h at 90 degrees C in solutions containing 100-mM sodium dodecyl sulfate). Acetylation also protected the enzyme against irreversible inactivation by the neutral surfactant TRITON X-100 (polyethylene glycol p-(1,1,3,3-tetramethylbutyl)phenyl ether), but not by the cationic surfactant, dodecyltrimethylammonium bromide (DTAB). The increased resistance of acetylated alpha-amylase toward inactivation is attributed to the increased net negative charge of alpha-amylase that resulted from the acetylation of lysine ammonium groups (lysine epsilon-NH3(+) --> epsilon-NHCOCH3). Increases in the net negative charge of proteins can decrease the rate of unfolding by anionic surfactants, and can also decrease the rate of protein aggregation. The acetylation of lysine represents a simple, inexpensive method for stabilizing bacterial alpha-amylase against irreversible inactivation in the presence of the anionic and neutral surfactants that are commonly used in industrial applications.

Simultaneous determination of zinc and copper(II) with 1-(2-pyridylazo)2-naphthol in micellar media by spectrophotometric H-point standard addition method

The H-point standard addition method (HPSAM) was applied to handling spectrophotometric data for simultaneous determination of Zn2+ and Cu2+ or selective determination of Zn2+ in the presence of Cu2+. The ligand 1-(2-pyridylazo)2-naphthol (PAN) and its metal complexes (Zn-PAN and Cu(II)-PAN) were made water-soluble by the neutral surfactant Triton X-100, and therefore, no extraction with organic solvents was required. The method is based on the difference in absorbance of formed complexes between Zn2+ and PAN, at two different wavelengths at pH = 9.2. The formation of both the complexes was complete within five minutes. Zn2+ can be determined in the range of 0.2–25 µg/mL with satisfactory accuracy and precision in the presence of excess of Cu2+ and most other metal ions. Interference effects of common anions and cations were studied. Under working conditions, the proposed method was successfully applied to the simultaneous determination of Zn2+ and Cu2+ in several real and synthetic mixtures with different concentration ratio of Zn2+ and Cu2+.

Comparison of Partial Least Squares Regression and H-Point Standard Addition Method for Simultaneous Spectrophotometric Determination of Zinc, Cobalt and Nickel by 1-(2-Pyridylazo)2-Naphthol in Micellar Media

Simultaneous spectrophotometric methods are described for the determination of Zn2+, Co2+ and Ni2+ by 1-(2-pyridylazo)2-naphthol (PAN) in micellar media, using absorbance correction-H-point standard addition method (HPSAM) and partial least squares (PLS) regression. The ligand and its metal complexes, i.e. Zn2+-PAN, Co2+-PAN and Ni2+-PAN, were made water-soluble by the neutral surfactant Triton X-100, and therefore extraction with organic solvents was no longer required. Formation of all of these complexes was complete within 10 min at pH 9.2. The linear range was 0.1–1.5 mg L−1 for Zn2+, 0.1–2.0 mg L−1 for Co2+ and 0.1–2.0 mg L−1 for Ni2+. The relative standard deviation (RSD) for the simultaneous determination of 0.50 mg L−1 each of Zn2+, Ni2+ and Co2+ by applying the H-point standard addition method was 2.55%, 2.04% and 3.70%, respectively. The total relative standard error for applying the PLS method to 9 synthetic samples in the linear ranges of these metals was 1.8%. Interference effects of common anions and cations were studied, and both methods were applied to the simultaneous determination of Zn2+, Co2+ and Ni2+ in alloy samples.

H-point standard addition method for simultaneous spectrophotometric determination of Co(II) and Ni(II) by 1-(2-pyridylazo)2-naphthol in micellar media

A very simple and selective spectrophotometric method for simultaneous determination of Co(II) and Ni(II) by 1-(2-pyridylazo) 2-naphthol (PAN), in micellar media, using H-point standard addition method (HPSAM) is described. The ligand and its metal complexes (Co(II)–PAN and Ni(II)–PAN) were made water-soluble by the neutral surfactant Triton X-100, and therefore, no extraction with organic solvents was required. Formation of both the complexes was complete within 10 min at pH 9 (adjusted by ammonia buffer). The linear range was 0.10–2.00 μg ml −1 for Co(II) and 0.05–1.50 μg ml −1 for Ni(II). The relative standard deviation (R.S.D.) for the simultaneous determination of 0.50 μg ml −1 each of Co(II) and Ni(II) was 2.32 and 3.13%, respectively. Interference effects of common anions and cations were studied and the method was applied to simultaneous determination of Co(II) and Ni(II) in alloy samples. The method was compared with derivative spectrophotometric method.

Pressure Effect on Solvation Dynamics in Micellar Environment

Solvation dynamics of an excited solvatochromic probe molecule in micellar environment has been studied as a function of pressure. In addition to steady-state spectrum, time-dependent fluorescence Stokes shift of coumarin 153 in aqueous solution of typical neutral surfactant Triton X-100 was measured at high pressures using time-correlated single-photon counting techniques with a time-resolution of 20 ps. It was found that polarity of the microenvironment decreases with increasing pressure. The solvation dynamics exhibits bimodal relaxation behavior with two characteristic time constants of 198 ps and 1.63 ns at atmospheric pressure. The solvation time becomes shorter with increasing pressure. The bimodal relaxation and its pressure dependence is considered as closely connected with the pressure effect on the hydrogen bonding of water molecules. And also the model assuming an equilibrium between “bound water” and “free water” within the Stern layer of micelles is discussed.

Optode Membrane for Determination of Nicotine via Generation of Its Bromoethane Derivative

A plasticized poly(vinyl chloride) optode membrane incorporated with a valinomycin ionophore, a H(+)-selective chromoionophore (ETH 5294), and a lipophilic potassium tetrakis(4-chlorophenyl)borate was used as a reversible sensing device for the indirect optical determination of nicotine. Nicotine was extracted from a tobacco product (1-5 g) and converted to its bromoethane derivative (NBD(+)Br(-)) by reacting with a solution of bromoethane in ethanol. NBD(+)Br(-) in a solution of 0.05 M boric acid-Borax buffer and 0.2 mM Triton X-100 was extracted into the bulk of the membrane and subsequently caused changes in optical absorption of the sensing layer. The response slope, dynamic working range, detection limit, sensitivity, selectivity, effects of buffer solution and neutral surfactant Triton X-100, and lifetime were discussed in detail. The response was pH dependent. At pH 8.5, the detection range was extended from 0.4 μM to 1 mM. Typical response times (t(95)) of the samples were 2-4 min. The optode method was successfully used to detect nicotine in a tobacco sample from the market (average content 0.720%; RSD 0.044%; n = 11). The interference of K(+) on the optode method can be prevented by the pre-extraction procedure. Malic acid and citrate showed no interferences. The recovery of nicotine as NBD(+) was 84-119% in the range 0.035-5% nicotine. The result was satisfactory compared with an AOAC UV standard method.

Observation of the Dynamic and Collective Behavior of Surfactant Molecules at a Water/Nitrobenzene Interface by a Time-Resolved Quasi-Elastic Laser-Scattering Method

A spectroscopic technique of time-resolved quasi-elastic laser-scattering measurement was applied to monitor the dynamic and collective behavior of anionic surfactant sodium dodecyl sulfate (SDS) and neutral surfactant Triton X-100 molecules around their critical micelle concentrations (cmc's) at a water/nitrobenzene liquid/liquid interface. The time courses of the capillary-wave frequencies after the injection of the surfactant solutions into the water phase were investigated. We found that the dynamic and collective behavior of these two kinds of surfactant molecules at the interface differ from that of the cationic surfactant cetyltrimethylammonium bromide we reported previously. Our results suggested that for SDS the monomolecules at the interface coexist with some molecular aggregates such as micelles at the interface; for Triton X-100, the monolayer at the interface was disrupted and some molecular aggregates, such as micelles, were formed at the interface.

Spectroscopic characterization of meso-tetrakis(1-methylpyridinium-4-yl)porphyrins, [(TMpyP)H2]4+ and [(TMpyP)M]4+, in aqueous micellar media, where M = VO2+, Cu(II), and Zn(II)

Spectroscopic characterization of ((TMpyP)H{sub 2}){sup 4+} and ((TMpyP)M){sup 4+}, where M = Cu(II), Zn(II), or VO{sup 2+} and TMpyP = meso-tetrakis(1-methylpyridinium-4-yl)porphyrin, was carried out in water and in aqueous solutions containing the anionic surfactant sodium dodecyl sulfate (SDS), the cationic surfactant cetyltrimethylammonium bromide (CTAB), or the neutral surfactant Triton X-100 (TX-100). UV-visible, {sup 1}H NMR, and ESR spectra data indicate that these tetracationic porphyrins interact with and exist as monomeric entities in the anionic SDS micelle. In contrast, neither the cationic nor the neutral micelle shows an interaction with the investigated porphyrins. Comparisons are made between the data for tetracationic and tetraanionic porphyrins in different micellar media and it is suggested that intercalation of the positively charged porphyrins in SDS is due to Coulombic rather than hydrophobic interactions.

Micellar effects on the aggregation of tetraanionic porphyrins. Spectroscopic characterization of free-base meso-tetrakis(4-sulfonatophenyl)porphyrin, (TPPS)H2, and (TPPS)M (M = zinc(II), copper(II), and vanadyl) in aqueous micellar media

UV-visible, 1 H NMR, and ESR characterization of free-base tetraanionic meso-tetrakis(4-sulfonatophenyl)porphyrin, (TPPS)H 2 , and (TPPS)M (M=Zn(II), Cu(II), VO 2+ ) were carried out in water and in aqueous solutions containing either the cationic surfactant cetyltrimethylammonium bromide (CTAB), the anionic surfactant sodium dodecyl sulfate (SDS), or the neutral surfactant Triton X-100(TX-100)