Micelle-forming Agent Research Articles

Decoding the Promiscuous Activity of Bile Salt Hydrolase

The recently identified bile salt hydrolase (BSH) from gastrointestinal bacteria catalyzes the formation of bacterial bile acid amidates (BBAAs), significantly impacting host metabolism. While this activity was characterized as promiscuous, the underlying mechanism was not explored. This commentary proposes that BSH exhibits condition promiscuity, where typical hydrolytic enzymes catalyze synthetic reactions under specific conditions. Drawing parallels with micellar enzymology, we suggest that bile salts, acting as both substrates and micelle-forming agents, create an environment conducive for BSH to catalyze amidation. This represents a potential first in vivo demonstration of such a mechanism. Future investigations should explore BSH-catalyzed reactions with bile salts below critical micelle concentrations and alternative surfactants to validate this hypothesis.

Xanthan gum toughen ionically conductive hydrogels for flexible and artificial epidermis sensors with multifunctionality and self-healability

Conductive hydrogels that possess hydrophobic interaction have gained much attention in fields like strain sensors, soft robotics, tissue engineering, human-machine interaction, and biomedical sensors due to their excellent stretchability and effective energy dissipation mechanism. However, their use is limited due to poor mechanical performance, low sensing ability, lack of response time, and deficiency of self-healing capability. To overcome these limitations, acrylamide-co-butylacrylate/xanthan gum-based hydrophobically associated conductive hydrogels were designed. Amphiphilic sodium dodecyl sulfate was employed both as a cross-linker and a micelle-forming agent, while LiCl make the hydrogel as an ionic conductive material. The obtained hydrogels show fracture stress and fracture strain of 661kPa and 1100% respectively. The measured conductivity was 0.21Sm−1 and the strain sensing of the designed hydrogel reached up to 800%. Similarly, the designed hydrogels show remarkable sensitivity (Gauge factor = 28.8 at an applied strain of 800%) which is useful in the detection of a wide range of human motions. Finger, wrist, elbow, and knee joint movement can be easily detected with these hydrogels. Furthermore, the hydrogel can detect speaking, facial expressions, and pressure sensing. The designed hydrogels showed an excellent response and recovery time of 0.15 s and 0.13 s respectively. During multiple stretching and un-stretching cycles for 140 s, the designed hydrogels show continuous linear response without any current drop or fracture. Therefore the as-fabricated hydrogel presents a novel opportunity for its application in various fields such as flexible conductive material, strain sensors, human motion detection devices, and tissue engineering.

Guar gum reinforced conductive hydrogel for strain sensing and electronic devices

Hydrophobically associated conductive hydrogels got great attention due to their excellent properties like stretchability, energy dissipation mechanism, and strain sensor. But hydrophobically associated hydrogels have poor mechanical properties and time response to external stimuli. To enhance the mechanical properties and response to stimuli, Acrylamide- co-Butyl acrylate/Gum based conductive hydrogels were prepared. SDS works as a cross-linker and micelle-forming agent while NaCl makes hydrogel as conductive. The results show that our % strain sensing reached up to 400 %, and fracture stress and fracture strain reached to 0.5 MPa and 401 % respectively. Besides this, it's having an excellent response to continuous stretching and unstretching multiple cycles without any fracture up to 180 s and an excellent time response of 190 s. The conductivity of the hydrogel was 0.20 Sm−1. The hydrophobic hydrogels showed a clear and quick response to human motions like finger, wresting, writing, speaking, etc. Interestingly, our prepared hydrogels can detect the mood of the human face. Similarly, the hydrogels were found efficient in bridging the surface of electronic devices with human skin. This indicates that our prepared hydrogels can monitor human body motion and will replace the existing materials used in strain sensors in the near future.

Hexafluorobutanol primary alcohol ethoxylate-based supramolecular solvent formation and their application in direct microextraction of malachite green and crystal violet from lake sediments.

A new type of hexafluorobutanol (HFB) primary alcohol ethoxylate (AEO)-based supramolecular solvent (SUPRAS) with density higher than water was prepared for the first time. HFB acted as AEO micelle-forming agent and density-regulating agent for SUPRAS formation. The prepared SUPARS was applied as extraction solvent for vortex-assisted direct microextraction of malachite green (MG) and crystal violet (CV) from lake sediment followed by high-performance liquid chromatographic determination. In the present work, SUPRASs prepared from AEO with different carbon chains as the amphiphiles and various coacervation agents were investigated. SUPARS formed from MOA-3 and HFB provided better extraction efficiency in comparison with other SUPRASs. Parameters influencing the extraction recovery of target analytes including the type and volume of AEO, volume of HFB, and vortex time were investigated and optimized. Under optimized conditions, linearity in the range of 2.0-400μgg-1 for MG and 2.0-500μgg-1 for CV with acorrelation coefficient higher than 0.9947 was obtained. Limits of detection of 0.5μgg-1 and relative standard deviations in the range of 0.9-5.8% were obtained. Compared to conventional extraction techniques for analysis of analytes in solid samples, the proposed method reduced sample usage and eliminated a primary extraction process by using a toxic organic solvent. The proposed method is simple, fast, and green and can be used for the analysis of target analytes in solid samples.

Fabrication of wormhole-like YSZ and Ni-YSZ by the novel soft-hard template CTAB/NaCl-assisted route. Suppressing Ni coalescence in SOFC

A novel one-pot synthesis route leading to the formation of a wormhole-like structure was developed for the successful fabrication of porous YSZ and Ni-YSZ systems. This method involved co-precipitation in the presence of the micelle-forming agents CTAB/Pluronic P123 and crystallising NaCl. The obtained skeletons were mechanically stable and presented almost 50% uniform, open porosity without using any additional pore-formers. The fabricated 0.3 M CTAB/NaCl Ni-YSZ showed better long-term electrical stability in hydrogen than a traditional Ni-YSZ cermet. It resulted from the suppression of Ni structural changes throughout the anode scaffold. Moreover, higher electrochemical activity of this novel anode is expected due to the smaller particle sizes of Ni/YSZ, high homogeneity, highly developed TPB, and better interfacial interaction between the Ni and YSZ. Therefore, the novel soft-hard templating method is recognised as a promising route for the fabrication of the YSZ or Ni-YSZ with a highly developed microstructure and improved stability.

Curcumin micelles entrapped in eudragit S-100 matrix: a synergistic strategy for enhanced oral delivery.

Background:Therapeutic activities of curcumin (CUR) via oral administration are hampered by the lack of bioavailability due to its poor water solubility and rapid degradation in GI tract.Materials & methods:This preliminary study developed CUR micelle-eudragit S100 (EUD) dry powder (CM-EDP) spray-dried formulations. Poloxamer 407 was used as a micelle-forming agent and EUD as an entrapping matrix for protection over hydrolysis and enzymes in the GI tract.Results:The morphology of CM-EDP showed agglomeration with cratering on the surface of particles. Differential thermal analysis and x-ray diffractometry data exhibited evidence that CUR was converted into amorphous solid. An increased concentration of micelle-forming and dispersion matrix polymers resulted in a high fraction of drug being converted into the amorphous state. A significant increase in dissolution by 7–10 times was achieved compared with that of raw CUR.Conclusion:The present study disclosed the CM-EDP potency for future development of CUR oral formulation.

Extraction of Histidine, Proline, and Methionine and Their Mixtures Using Systems Based on N-VinylFormamide

Methods are proposed for the extraction of amino acids histidine, methionine, and proline from aqueous media with water-soluble polymers for their subsequent determination by capillary electrophoresis. Regularities of the interphase distribution of analytes in water–salt extraction systems based on poly-N-vinyl formamide and its copolymer with N-vinylimidazole are revealed and their efficiency is proved. The rate of formation of a two-phase system water-soluble polymer–aqueous salt solution of amino acid is substantially affected by the molecular weight and intrinsic viscosity of the extractant. The effect of the volume ratio of water and organic phases on the efficiency of extraction of histidine, methionine, and proline is studied, also on their simultaneous presence; quantitative characteristics of the process are calculated. Homo- and copolymers of N-vinylformamide are used for the efficient extraction and extraction separation of a histidine−methionine mixture. Partition coefficients and the recoveries of amino acids are specified in the systems containing poly-N-vinylformamide and its copolymer with N-vinylimidazole in the presence of an ammonium sulfate salting-out agent. The conditions for the electrophoretic determination of amino acids are optimized, i.e., the composition of the buffer solution and the type and concentration of the micelle-forming agent. The developed method for the electrophoretic separate determination of amino acids with the preliminary extraction of the target components with water-soluble polymers can be recommended for routine analyses in determining the safety of foodstuffs, energy drinks, and pharmaceuticals.

Hexafluoroisopropanol-alkanol based high-density supramolecular solvents: Fabrication, characterization and application potential as restricted access extractants

Hexafluoroisopropanol-alkanol (C6–C12) supramolecular solvents were proposed and their application potential as restricted access extraction solvents was assessed. Hexafluoroisopropanol acts as alkanol reverse micelle-forming agent and density-regulating agent for the supramolecular solvent synthesis. The formation of supramolecular solvent only needs a small percentage of hexafluoroisopropanol (<10% v/v for alkanol <5% v/v) and is almost not affected by the pH (2-11) and low ionic strength (NaCl <3%, w/v) of aqueous medium. The supramolecular solvents have higher density than water and consist of reversed micellar aggregates with irregular mesh structures and hydrophilic inner cavities, and the hydrophilic cavity size is obviously dependent on the hexafluoroisopropanol amount in the bulk system but almost not relevant to the alkanol amount. The hydrogen-bond and hydrophobic interactions of hexafluoroisopropanol with alkanol and the hydrogen-bond force between hexafluoroisopropanol and water play crucial roles in the formation of supramolecular solvent. The supramolecular solvents not only do not or slightly dissolve macromolecules (proteins, polysaccharides, and humic acid sodium), but also can effectively exclude them in extraction procedure; meanwhile, they can extract small molecules from complex samples with high extraction rate (even near 100% through optimization). The extraction mechanism involves the hydrophilic inner cavity size of supramolecular aggregates and the interactions (hydrogen-bond, hydrophobic) between supramolecular solvent and analytes. The suitability of supramolecular solvents as extractants was evaluated by extracting and determining chlorophenols in real water samples, coupled with high performance liquid chromatography-ultraviolet detector. The enrichment factors of 72–147 were obtained. Limits of detection were from 0.38 to 0.57 ng mL−1. The recoveries ranged from 96.0 to 107.9%, and intra-day and inter-day precisions were less than 4.0%. The novel hexafluoroisopropanol-alkanol supramolecular solvents have promising potential as restricted access extractants.

Remediation of TENORM scale waste generated from petroleum industry using single and mixed micelles solutions

Treatment of TENORM scale wastes generated from oil and gas production that contaminated by different radionuclides is an important societal, environmental, economical and technological challenge, due to the rise number of sites contaminated by these radionuclides. Bench-scale laboratory experiments were conducted to determine the removal characteristics of radium isotopes from TENORM-scale. This scale waste contained high level radioactivity (44,610 Bq/kg) due to the presence of radium isotopes (35,100 Bq/kg for 226Ra and 9510 Bq/kg for 228Ra). In this study, three different types of surfactants polyoxyethylene sorbitanmonooleate (Tween-80), cetyltrimethylammonium bromide (CTAB) and sodium-dodecylsulfate (SDS) as micelle-forming agents were used for treating scale wastes by separating the most contaminated fraction of the TENORM-scale for disposal. It is found that the highest efficiency of radium isotopes was about 52% and 55% for 226Ra and 228Ra, respectively using single micelles systems. Combined effect of mixed micelles produces synergistic effect in the remediation process, where the removals reached to about 80% for 226Ra and 228Ra were obtained using mixed micelles solutions. The scale-washing process water used in TENORM scale extractive washing is treated with conventional wastewater treatment technology or reused in successive washing for new scale waste. The results also point out that the treated water from the washing step was more effective compared to distilled water, probably due to surfactants contained in treated water. The data obtained in these studies may be considered as promising and efficient to treatment of TENORM scales economically.

Analysis of new charge-neutral DNA/RNA analogues phosphoryl guanidine oligonucleotides (PGO) by gel electrophoresis

Analysis and isolation of new charge-neutral phosphoryl guanidine oligonucleotides (PGO) by vertical slab electrophoresis were tested at different pH values (3–11) or in the presence of SDS as a micelle-forming agent. The most convenient way to analyze and purify phosphoryl guanidine oligonucleotides was by denaturing PAGE (8 M urea) at pH 3. The mobility of PGO is dependent on their A + C content. To analyze PGO containing only G, T or U, denaturing PAGE at pH 11 can be used, although the conditions need to be optimized. Bands were visualized by UV shadowing or Coomassie Brilliant Blue staining.

A study of the adsorption of silver nanoparticles by high-performance liquid chromatography

The method of high-performance liquid chromatography has been used to study the adsorption of stable silver nanoparticles, which were obtained by radiation-chemical synthesis in reverse micellar solutions of H2O + Ag+/Aerosol OT/isooctane composition. Adsorption was conducted on polar and nonpolar sorbents. It has been determined that almost all nanoparticles are retained on nonpolar sorbent C18; however, their binding is not strong. After accumulation of a particular amount of nanoparticles, they leave a column with effluent. It has been shown that the adsorption and optical properties of silver nanoparticles almost do not change after the adsorption-desorption cycle on C18. It has been determined that, on polar silica gel, the adsorption of silver nanoparticles proceeds less intensely (fewer than half of the particles move to the near-surface layer of the sorbent; however, their interaction with surface is very strong and they were not desorbed. For nanoparticles and the molecules of the micelle-forming agent Aerosol OT, adsorption isotherms have been plotted. Based on the obtained results, possible mechanisms of adsorption of nanoparticles on the surface of polar and nonpolar sorbents have been considered.

Chiral separation using capillary electromigration techniques based on ligand exchange principle

Over the last couple of decades, researchers have developed diverse chiral separation methods emerged from a few chiral separation principles. This review article is primarily focused on the application of chiral ligand-exchange (CLE) principle in capillary electromigration techniques, such as capillary electrophoresis (CE) and capillary electrochromatography (CEC). First, the most commonly used CLE-CZE separation mode by using different kinds of central ions, such as Cu(II), Zn(II), borate ion, and other metal ions, has been introduced. Meanwhile, several kinds of surfactants have been applied as the micelle-forming agents in the CLE micellar electrokinetic chromatography mode. The highlight of recent research of CLE-CEC is the exploitation of novel columns for chiral separation. Then, two kinds of capillary columns, packed capillary and monolithic capillary column, have been briefly described. Finally, the effective application of these chiral separation methods has been presented, including the application in life science and food analysis area.

Application of the Ferguson principle to the antibacterial activity of mono- and multi-component solutions of quaternary ammonium surface-active agents.

Abstract Critical micelle concentrations (cmc) have been measured by the surface tension method for binary mixtures of dodecyltrimethyl-ammonium bromide with tetradecyltrimethylammonium bromide, binary mixtures of C14/C16 homologues, a ternary mixture of the C12/C14/C16 compounds and additionally for each component individually. The antibacterial activities of the systems against Escherichia coli were determined by a British Standard Method (B.S. 3286: 1960). Thermodynamic activities of the solutions at two survivor levels, calculated from the physical and biological measurements, were sufficiently constant to sustain the Ferguson principle for these micelle-forming antibacterial agents. A theoretical treatment of micelle formation for multi-component solutions of surfactants gave cmc’s by calculation in close agreement with the experimentally determined values. The purity and composition of the surfactants was determined by gas liquid chromatography.

The Role of Bromide Ions in Seeding Growth of Au Nanorods

We report our findings on the important role of bromide ions in the seeding growth process of Au nanorods. The seed-mediated process constitutes a well-developed method for synthesizing gold nanorods in high yield, which is facilitated by a micelle-forming surfactant, cetyltrimethylammonium bromide (CTA-Br). Despite the tremendous work in recent years, the growth mechanism of Au nanorods has not been fully understood. Contrary to the widely accepted mechanism of CTA(+) micelle-templated growth of Au nanorods, we have identified the critical role of bromide ions in the seeding growth of Au nanorods. We found that even when the micelle-forming agent (CTA(+)) concentration is below its critical micelle concentration (cmc), bromide ions added in the form of NaBr can successfully effect the growth of Au nanorods in good yield. By controlling the concentration of externally added bromide ions, the rod shape and dimensions of the resulting Au nanoparticles can be readily controlled in the presence of only a minimum amount of CTABr (as a steric stabilizer for nanorods). High-resolution TEM studies show that the as-formed nanorods are perfectly single crystalline, instead of penta-twinned ones, and are bound by {111} and {100} facets with a [110] direction as the elongation direction. A mechanism is proposed to account for the seeding growth of single crystalline Au nanorods. Overall, this work explicitly demonstrates that Br(-) indeed serves as an important shape-directing agent for gold nanorod formation in the seed-mediated process.

Micellar liquid chromatography for lipophilicity determination of new biologically active 1,3-purinodiones

A series of newly synthesized 1,3-purinodiones with potential anticonvulsant activity, exhibiting affinity to adenosine A(1) and/or A(2A) receptors, were subjected to micellar LC (MLC) with SDS as micelle-forming agent and n-propanol as organic modifier. Two C18 silica-based columns were employed in MLC: a particle one and a monolithic. In parallel, those derivatives were also analyzed in RP-LC on four silica-based columns and on an immobilized artificial membrane column. The correlations between the relevant logarithms of the retention factors of analytes obtained in MLC, immobilized artificial membrane and RP-LC systems on the one hand, and the calculated log P (clog P) and log D values (clog D) on the other, were examined. The level of the correlations of retention data from MLC and RP-LC systems with clog P and clog D obtained is similar but it could be stressed that MLC allows increasing the speed of analysis and using only one mobile phase. Moreover, there is no need of applying an extrapolation procedure in lipophilicity determination. Therefore, the MLC systems, providing chromatographic data in a fast and efficient manner, were demonstrated as promising alternatives to the classical RP-LC systems to estimate the lipophilicity of drugs and drug candidates.

Multidimensional Separation of Chiral Amino Acid Mixtures in a Multilayered Three-Dimensional Hybrid Microfluidic/Nanofluidic Device

Microscale total analysis systems (microTAS) allow high-throughput analyses by integrating multiple processes, parallelization, and automation. Here we combine unit operations of microTAS to create a device that can perform multidimensional separations using a three-dimensional hybrid microfluidic/nanofluidic device composed of alternating layers of patterned poly(methyl methacrylate) and nanocapillary array membranes constructed from nuclear track-etched polycarbonate. Two consecutive electrophoretic separations are performed, the first being an achiral separation followed by a chiral separation of a selected analyte band. Separation conditions are optimized for a racemic mixture of fluorescein-isothiocyanate-labeled amino acids, serine and aspartic acid, chosen because there are endogenous D-forms of these amino acids in animals. The chiral separation is implemented using micellar electrokinetic chromatography using beta-cyclodextrin as the chiral selector and sodium taurocholate as the micelle-forming agent. Analyte separation is monitored by dual-beam laser-induced fluorescence detection. After separation in the first electrophoretic channel, the preselected analyte is sampled by the second-stage separation using an automated collection sequence with a zero-crossing algorithm. The controlled fluidic environment inherent to the three-dimensional architecture enables a series of separations in varying fluidic environments and allows sample stacking via different background electrolyte pH conditions. The ability to interface sequential separations, selected analyte capture, and other fluidic manipulations in the third dimension significantly improves the functionality of multilayer microfluidic devices.

A novel, environmentally friendly sodium lauryl ether sulfate‐, cocamidopropyl betaine‐, cocamide monoethanolamine‐containing buffer for MEKC on microfluidic devices

A new buffer has been developed for fast, high-efficiency separations of amino acids by MEKC. This buffer was more environmentally friendly than the most commonly used surfactant-containing buffers for MEKC separations. It used a commercially available dishwashing soap by Seventh Generation (Burlington, VT, USA), which contained three micelle-forming agents. The mixed micelles were composed of sodium lauryl ether sulfate (anionic), cocamidopropyl betaine (zwitterionic), and cocamide monoethanolamine (non-ionic). The optimized buffer contained 5.0% w/w Seventh Generation Free & Clear dishwashing soap, 10 mM sodium borate, and was completely void of organics. The lack of organics and the biodegradability of the surfactant molecules made this buffer more environmentally friendly than typical SDS-containing buffers. This new buffer also had a different selectivity and provided faster separations with higher separation efficiencies than SDS-based buffers. Fast separations of BODIPY FL labeled amino acids yielded peaks with separation efficiencies greater than 100,000 in less than 20 s.

Capillary electrokinetic chromatography of insulin and related synthetic analogues

With the implementation of recombinant DNA technology in the pharmaceutical industry, some synthetic insulins have been developed in order to improve the therapy of diabetes. These analogues differ only slightly in the amino acid sequence, therefore displaying a great challenge for analytical chemistry. Within the work presented in this paper, capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC) with sodium dodecylsulphate (SDS) as micelle-forming agent, and microemulsion electrokinetic chromatography (MEEKC) with microemulsions consisting of SDS, n-octane and 1-butanol were investigated for the separation of human insulin and five synthetic analogues. Best results were achieved with a solvent-modified MEKC system consisting of 100 mM sodium dodecyl sulphate and 15% acetonitrile in 10 mM borate buffer (pH 9.2). A similar system based on perfluorooctanoic acid as micelle-forming agent in ammonium acetate (pH 9.2) was successfully employed for the hyphenation with a quadrupole/time-of-flight mass spectrometer via a sheath-flow interface. In this case, detection limits at 10 mg/L could be achieved.

Electrophoretic separation of tea flavanoids in the modes of capillary (zone) electrophoresis and micellar electrokinetic chromatography

Conditions for electrophoretic separation of tea phenolic enantiomers, (+)-catechin and (−)-epicatechin, by capillary (zone) electrophoresis using β-cyclodextrin as a component of the working electrolyte are developed. Optimization is made of the conditions for separating a multicomponent mixture of ionic and neutral polyphenols from various tea samples in the mode of micellar electrophoretic chromatography using sodium dodecyl sulfate as a micelle-forming agent and urea as an additive to the phosphate buffer.

Determination of s-Triazine Herbicides by Micellar Electrokinetic Chromatography Using Sodium Dodecyl Sulfate

It was shown that Simazine, Atrazine, Propazine, and Prometryne can be separated by micellar electrokinetic chromatography using sodium dodecyl sulfate as a micelle-forming agent. The detection limits were found to be 0.1 mg/L for Simazine and 0.05 mg/L for Atrazine, Propazine, and Prometryne at a signal-to-noise ratio of 2 in a buffer electrolyte containing 10 mM sodium tetraborate and 30 mM sodium dodecyl sulfate. The time of separation was 12 min.