Reverse Micelle System Research Articles

Unveiling Eco-Friendly Reverse Micelle Systems: Dimethyl Carbonate as a Novel Biocompatible Solvent.

In this study, we systematically explored the characteristics of dimethyl carbonate (DMC)/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) in the presence of water using dynamic light scattering (DLS), proton nuclear magnetic resonance (1H NMR), and molecular probes. DMC, a biocompatible solvent, enables the formulation of AOT RMs without the need for a co-surfactant. DLS revealed that as the water content increased, the droplet sizes grew larger. 1H NMR studies indicated that at low water content, water molecules interacted with DMC via hydrogen bonding. This interaction promoted the penetration of DMC toward the interface, affecting the solvation of AOT's sulfonate group. At higher water content, a competition for hydrogen bonding emerged between water-water and water-surfactant molecules, leading to distinct interfacial properties, as evidenced by molecular probes. The critical micellar concentration for DMC/AOT/water RMs was 7x10-3 M, similar to RMs formed with other biocompatible solvents. The presence of water facilitated the solvation of the surfactant's polar regions, promoting the RMs formation. The polarity of this system was measured using the ET(30) value. This novel micellar system holds significant potential in various fields, including catalysis, nanomaterials, and green chemistry.

Interface-based kinetic model considering the integral stereoselectivity of lipases on tricapryloylglycerol in a reverse micelle system

Lipases are essential enzymes with unique selectivity, making them valuable in industrial applications. Understanding the integral stereoselectivity of lipases during triacylglycerol (TAG) hydrolysis is crucial for producing high-value products, such as structured lipids. This study developed an analytical method and an interface-based kinetic model to determine integral stereoselectivities on tricapryloylglycerol (TCG), a medium-chain TAG. The analytical method used an HPLC system that simultaneously separated TCG and its hydrolysates with resolution factors of >2.4 and relative standard deviation of retention times <0.3 % within 15 min. The interface-based kinetic model was established to determine the integral stereoselectivities according to the characteristics of the reaction system. The model provided better fitting results for TCG and trioleoylglycerol hydrolysis than a previous model, indicating the successful application in both medium- and long-chain TAGs. This study expanded our understanding of integral stereoselectivity and could facilitate the development of various structured lipid syntheses.

Influence of the presence of ions on the dielectric properties of reverse micelle systems

AOT/isooctane/water reverse micelle solution was doped with ionic salts solutions: sodium chloride, potassium chloride, tetramethylammonium chloride, tetramethylammonium bromide, sodium butyrate and sodium benzoate. Each system was investigated for the influence of ionic additives on dielectric properties: electric permittivity, conductivity and nonlinear dielectric effect (NDE). Studies showed that addition of salts noticeably changes the dielectric parameters. Based on the salts used in this research, the most common effect is a decrease of electric permittivity, conductivity and NDE effect. However, addition of some ions can lead to their increase, which was proved in the case of sodium benzoate. The registered changes were explained based on the percolation effect and changes in rigidity of the micellar surfactant shell due to the incorporation of the dissolved ions into the micellar structure.

Characterization of 10MAG/LDAO reverse micelles: Understanding versatility for protein encapsulation

Reverse micelles (RMs) are spontaneously organizing nanobubbles composed of an organic solvent, surfactants, and an aqueous phase that can encapsulate biological macromolecules for various biophysical studies. Unlike other RM systems, the 1-decanoyl-rac-glycerol (10MAG) and lauryldimethylamine-N-oxide (LDAO) surfactant system has proven to house proteins with higher stability than other RM mixtures with little sensitivity to the water loading (W0, defined by the ratio of water to surfactant). We investigated this unique property by encapsulating three model proteins – cytochrome c, myoglobin, and flavodoxin – in 10MAG/LDAO RMs and applying a variety of experimental methods to characterize this system's behavior. We found that this surfactant system differs greatly from the traditional, spherical, monodisperse RM population model. 10MAG/LDAO RMs were discovered to be oblate ellipsoids at all conditions, and as W0 was increased, surfactants redistributed to form a greater number of increasingly spherical ellipsoidal particles with pools of more bulk-like water. Proteins distinctively influence the thermodynamics of the mixture, encapsulating at their optimal RM size and driving protein-free RM sizes to scale accordingly. These findings inform the future development of similarly malleable encapsulation systems and build a foundation for application of 10MAG/LDAO RMs to analyze biological and chemical processes under nanoscale confinement.

Characterizing the composition dependence of exchange rates in reverse micelle systems by stopped-flow fluorescence

Characterizing the composition dependence of exchange rates in reverse micelle systems by stopped-flow fluorescence

Impact of lipid matrix composition on the activity of membranotropic enzymes galactonolactone oxidase from Trypanosoma cruzi and L-galactono-1,4-lactone dehydrogenase from &lt;i&gt;Arabidopsis thaliana&lt;/i&gt; in the system of reverse micelles

The study of many membrane enzymes in an aqueous medium is difficult due to the loss of their catalytic activity, which makes it necessary to use membrane-like systems, such as reverse micelles of surfactants in nonpolar organic solvents. However, it should be taken into account that micelles are a simplified model of natural membranes, since membranes contain many different components, a significant part of which are phospholipids. In this work, we studied the impact of the main phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), on the activity of membrane enzymes using galactonolactone oxidase from Trypanosoma cruzi (TcGAL) and L-galactono-1,4-lactone dehydrogenase from Arabidopsis thaliana (AtGALDH) as an examples. Effect of the structure (and charge) of the micelle-forming surfactant itself on the activity of both enzymes has been studied using an anionic surfactant (AOT), a neutral surfactant (Bridge-96), and a mixture of cationic and anionic surfactants (CTAB and AOT) as an examples. The pronounced effect of addition of PC and PE lipids on the activity of AtGALDH and TcGAL has been detected, which manifests as increase in catalytic activity and significant change in the activity profile. This can be explained by formation of the tetrameric form of enzymes and/or protein-lipid complexes. By varying composition and structure of the micelle-forming surfactants (AOT, CTAB, and Brijdge-96 and their combinations) it has been possible to change catalytic properties of the enzyme due to effect of the surfactant on the micelle size, lipid mobility, charge, and rigidity of the matrix itself.

Impact of Lipid Matrix Composition on Activity of Membranotropic Enzymes Galactonolactone Oxidase from Trypanosoma cruzi and L-Galactono-1,4-Lactone Dehydrogenase from Arabidopsis thaliana in the System of Reverse Micelles.

The study of many membrane enzymes in an aqueous medium is difficult due to the loss of their catalytic activity, which makes it necessary to use membrane-like systems, such as reverse micelles of surfactants in nonpolar organic solvents. However, it should be taken into account that the micelles are a simplified model of natural membranes, since membranes contain many different components, a significant part of which are phospholipids. In this work, we studied impact of the main phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), on activity of the membrane enzymes using galactonolactone oxidase from Trypanosoma cruzi (TcGAL) and L-galactono-1,4-lactone dehydrogenase from Arabidopsis thaliana (AtGALDH) as examples. Effect of the structure (and charge) of the micelle-forming surfactant itself on the activity of both enzymes has been studied using an anionic surfactant (AOT), a neutral surfactant (Brij-96), and a mixture of cationic and anionic surfactants (CTAB and AOT) as examples. The pronounced effect of addition of PC and PE lipids on the activity of AtGALDH and TcGAL has been detected, which manifests as increase in catalytic activity and significant change in the activity profile. This can be explained by formation of the tetrameric form of enzymes and/or protein-lipid complexes. By varying composition and structure of the micelle-forming surfactants (AOT, CTAB, and Brij-96) it has been possible to change catalytic properties of the enzyme due to effect of the surfactant on the micelle size, lipid mobility, charge, and rigidity of the matrix itself.

Lecithin Reverse Micelle System is Promising in Constructing Carrier Particles for Protein Drugs Encapsulated Pressurized Metered‐Dose Inhalers

AbstractProtein drugs contained within pressurized metered dose inhalers (pMDIs) show immense potential for fundamental research and industrial applications, owing to their high bioavailability, convenient administration, and cost‐effectiveness. To deliver protein drugs efficiently, researchers have reached a consensus on the use of carrier particles. However, the main obstacle impeding the commercial availability of pMDI carrier particles is their low stability. This instability is primarily attributed to particle aggregation caused by the Ostwald ripening phenomenon and chemical degradation by water sensitivity of protein drugs. This study proposes the utilization of lecithin, a carrier material possessing an amphiphilic structure, to overcome this bottleneck. By constructing lecithin‐based reverse micelle systems with protein drugs encapsulated within the high‐polarity microdomain, this work anticipates an improvement in the stability of carrier particles within pMDIs. Specifically, the formation of crystalline phases in the reverse micelle systems can control carrier particle size through crystalline self‐limiting effect, preventing particle aggregation. Additionally, the low‐polarity microdomain of the carrier serves as a hydrophobic barrier, shielding protein drugs from water and preventing chemical degradation. Consequently, this work believes that the lecithin‐based reverse micelle system holds significant potential in providing new theoretical insights and experimental support for the advancement of pMDIs containing protein drugs.

Dyeing of Linen Fabrics in Supercritical CO2 Using a Reverse Micellar System with Ionic Liquid Domains

ABSTRACT In order to realize the anhydrous dyeing of linen fabric with reactive dyes in supercritical CO2, a supercritical CO2 ionic liquid reverse micelle system was constructed, and the dyeing process of linen fabric in this system was studied. In this system, linen fabric can be dyed with reactive dyes without special pretreatment. The results show that the dyeing depth of linen fabric can be significantly improved by increasing the amount of surfactant. With the increase in temperature, the dyeing depth first increases and then decreases. The dyeing pressure displays little effect on the dyeing depth. After dyeing, there are a lot of floating colors on the surface of the fabric. Increasing the temperature and prolonging the dyeing time are conducive to dye fixation on the fabric. Adding a certain amount of dimethyl sulfoxide (DMSO) to the system can improve the dyeing performance significantly. In this paper, the best dyeing conditions of linen fabric are as follows: w, 1.2; surfactant conc. 3.5 × 10−2 g/mL; T, 90°C; t, 180 min; p, 21MPa; DMSO concentration, 76.8 mmol/L.

Lipase B from Candida antarctica in Highly Saline AOT-Water-Isooctane Reverse Micelle Systems for Enhanced Esterification Reaction

Butyl oleate synthesis by the lipase B from Candida antarctica (CalB) under extreme halophilic conditions was investigated in the present research through the AOT/Water/Isooctane reverse micellar system. The impact of aqueous content (Wo=H2OSurfactant) and NaCl variation on the enzymatic activity of CalB in the butyl oleate reaction in reverse micelles was explored. The results indicated that, based on the increase of NaCl, it is remarkable to achieve higher enzymatic activity up to 444.85 μmolmin at 5 M NaCl and Wo = 10, as the best esterification conditions at pH 7.2 and 30 °C. However, it was clear that butyl oleate synthesis by lipase CalB increased based on the reduction in the average reverse micelle size, where reverse micelle sizes were determined by dynamic light scattering (DLS). This increase in butyl oleate synthesis demonstrated the potential of reverse micelles as systems that enhance mass transport phenomena in heterogeneous biocatalysis. Furthermore, reverse micelles are promising systems for extreme halophilic lipases research.

Dual fluorescent hollow silica nanofibers for in situ pH monitoring using an optical fiber.

This study reports a sensitive and robust pH sensor based on dual fluorescent doped hollow silica nanofibers (hSNFs) for in situ and real-time pH monitoring. Fluorescein isothiocyanate (FITC) and tris(2,2'-bipyridyl)dichlororuthenium(ii) hexahydrate (Ru(BPY)3) were chosen as a pH sensitive dye and reference dye, respectively. hSNFs were synthesized using a two-step method in a reverse micelle system and were shown to have an average length of 6.20 μm and average diameter of 410 nm. The peak intensity ratio of FITC/Ru(BPY)3 was used to calibrate to solution pH changes. An optical-fiber-based fluorescence detection system was developed that enabled feasible and highly efficient near-field fluorescence detection. The developed system enables fully automated fluorescence detection, where components including the light source, detector, and data acquisition unit are all controlled by a computer. The results show that the developed pH sensor works in a linear range of pH 4.0-9.0 with a fast response time of less than 10 s and minimal sample volume of 50 μL, and can be stored under dark conditions for one month without failure. In addition, the as-prepared hSNF-based pH sensors also have excellent long-term durability. Experimental results from ratiometric sensing confirm the high feasibility, accuracy, stability and simplicity of the dual fluorescent hSNF sensors for the detection of pH in real samples.

Magnetosome-inspired synthesis of soft ferrimagnetic nanoparticles for magnetic tumor targeting

Magnetic targeting is one of the most promising approaches for improving the targeting efficiency by which magnetic drug carriers are directed using external magnetic fields to reach their targets. As a natural magnetic nanoparticle (MNP) of biological origin, the magnetosome is a special "organelle" formed by biomineralization in magnetotactic bacteria (MTB) and is essential for MTB magnetic navigation to respond to geomagnetic fields. The magnetic targeting of magnetosomes, however, can be hindered by the aggregation and precipitation of magnetosomes in water and biological fluid environments due to the strong magnetic attraction between particles. In this study, we constructed a magnetosome-like nanoreactor by introducing MTB Mms6 protein into a reverse micelle system. MNPs synthesized by thermal decomposition exhibit the same crystal morphology and magnetism (high saturation magnetization and low coercivity) as natural magnetosomes but have a smaller particle size. The DSPE-mPEG-coated magnetosome-like MNPs exhibit good monodispersion, penetrating the lesion area of a tumor mouse model to achieve magnetic enrichment by an order of magnitude more than in the control groups, demonstrating great prospects for biomedical magnetic targeting applications.

A preliminary study on preparation, characterization, and prebiotic activity of a polysaccharide from the edible mushroom Ramaria flava.

Polysaccharides derived from edible mushrooms were sources of new prebiotic compounds. Limited studies of their prebiotic effects, as well as the presence of residual dark colors, impede their use as prebiotics in the food industry. To boost the prebiotic value of polysaccharides from the edible mushroom Ramaria flava, a decolorization method, and the physicochemical characterization and prebiotic potential of the decolorized polysaccharide (DRFP) were investigated in this study. The reversed micelle system consisting of n-hexanol/isooctane (3:7, v/v) and 200 mM surfactant (CTAB) was an appropriate decolorized method for R. flava crude polysaccharide. That decolorized polysaccharide was 101.68 kDa and contained glucose, galactose, mannose, fucose, xylose, rhamnose, arabinose, and glucuronic acid in a ratio of 40.61:26.97:17.72:7.78:6.31:0.11:0.06:0.44. Furthermore, DRFP exhibited typical shear-thinning behavior and possessed good thermal stability. And 98.76% of DRFP was allowed to transit through the oral cavity and gastrointestinal tract nearly indigestibly in vitro fermentation. It also revealed a prebiotic availability through stimulating Lactobacillus rhamnosus proliferation and inducing enterocoel acidification. When utilized as a carbon source, DRFP significantly improves the production of short-chain fatty acids by L. rhamnosus, particularly acetic, propionic, isobutyric, and hexanoic acids. Therefore, this work suggests the further application of R. flava polysaccharides as emerging prebiotics, which may be used as an ingredient in functional food and nutraceutical products. PRACTICAL APPLICATIONS: Prebiotics could regulate gut microbial community and are closely associated with host health. This work reported that a decolorized polysaccharide (DRFP) prepared from the edible mushroom Ramaria flava was indigestible and could improve Lactobacillus rhamnosus proliferation and short-chain fatty acid production, which could provide useful information for the application of DRFP as a prebiotic additive in the food industry.

Surface Mapping and Functional Interactions of GPx4, a Cytoprotective Peripheral Membrane Protein

The study of peripheral membrane proteins (PMPs) has long been fraught with difficulty due to the need for reliable and robust membrane models. Many PMPs are soluble in an inactive state and recruited to the membrane to perform their respective function. This is the source of difficulty: the small size of the proteins and their inherent dynamic interactions with membranes and specific lipids make them incredibly challenging to characterize using X‐ray crystallography or cryo‐EM. Using protein NMR and better optimized membrane mimics, a robust study of PMPs may proceed.Glutathione peroxidase 4 (GPx4) is a PMP with the unique function of protection of membranes from lipid hydroperoxidation. This enzyme prevents cell death from ferroptosis by engaging the membrane and reducing lipid hydroperoxides. GPx4 has emerged as a high‐profile therapeutic target due to the ability of inhibitors to leverage ferroptosis against certain types of cancer cells.We utilize a wide variety of membrane models and native substrates to map the binding interaction of the GPx4 with the membrane and substrate lipids. Electrostatic interactions of the cationic patch are also found to be important in the moonlighting function of GPx4 as a cross‐linker of DNA‐bound protamines. Finally, our experimentally determined membrane interface using DPC micelles to formulate and confirm a novel DLPC:DPC reverse micelle system that can act as a membrane model for future PMP studies. The novel DLPC:DPC formulation is the first step in developing reverse micelles as more biologically accurate membrane models that can be tuned depending on membrane chemistry.

Photophysical properties and rotational dynamics of coumarin 30 dye in reverse micelle systems

In this study, photophysical properties and photodynamics of Coumarin 30 (C30) dye were studied in detail in reverse micelles by using spectroscopy techniques. The reverse micelle systems (RM) were created using three different surfactants: anionic, cationic, and neutral. Photophysical and rotational dynamics of C30 were maped and interpreted as function of W0 by using the fluorescence quantum yields, fluorescence lifetime values, radiation and non-radiation rate constants, anisotropy values and rotational relaxation times. We have found that C30 is an applicable probe for the assignment of microviscosity of different reverse micelle media.

Roles of Surfactants in Oriented Immobilization of Cellulase on Nanocarriers and Multiphase Hydrolysis System.

Surfactants, especially non-ionic surfactants, play an important role in the preparation of nanocarriers and can also promote the enzymatic hydrolysis of lignocellulose. A broad overview of the current status of surfactants on the immobilization of cellulase is provided in this review. In addition, the restricting factors in cellulase immobilization in the complex multiphase hydrolysis system are discussed, including the carrier structure characteristics, solid-solid contact obstacles, external diffusion resistance, limited recycling frequency, and nonproductive combination of enzyme active centers. Furthermore, promising prospects of cellulase-oriented immobilization are proposed, including the hydrophilic-hydrophobic interaction of surfactants and cellulase in the oil-water reaction system, the reversed micelle system of surfactants, and the possible oriented immobilization mechanism.

Membrane-Mimicking Reverse Micelles for High-Resolution Interfacial Study of Proteins and Membranes.

Despite substantial advances, the study of proteins interacting with membranes remains a significant challenge. While integral membrane proteins have been a major focus of recent efforts, peripheral membrane proteins (PMPs) and their interactions with membranes and lipids have far less high-resolution information available. Their small size and the dynamic nature of their interactions have stalled detailed interfacial study using structural methods like cryo-EM and X-ray crystallography. A major roadblock for the structural analysis of PMP interactions is limitations in membrane models to study the membrane recruited state. Commonly used membrane mimics such as liposomes, bicelles, nanodiscs, and micelles are either very large or composed of non-biological detergents, limiting their utility for the NMR study of PMPs. While there have been previous successes with integral and peripheral membrane proteins, currently employed reverse micelle (RM) compositions are optimized for their inertness with proteins rather than their ability to mimic membranes. Applying more native, membrane-like lipids and surfactants promises to be a valuable advancement for the study of interfacial interactions between proteins and membranes. Here, we describe the development of phosphocholine-based RM systems that mimic biological membranes and are compatible with high-resolution protein NMR. We demonstrate new formulations that are able to encapsulate the model soluble protein, ubiquitin, with minimal perturbations of the protein structure. Furthermore, one formula, DLPC:DPC, allowed the encapsulation of the PMPs glutathione peroxidase 4 (GPx4) and phosphatidylethanolamine-binding protein 1 (PEBP1) and enabled the embedment of these proteins, matching the expected interactions with biological membranes. Dynamic light scattering and small-angle X-ray scattering characterization of the RMs reveals small, approximately spherical, and non-aggregated particles, a prerequisite for protein NMR and other avenues of study. The formulations presented here represent a new tool for the study of elusive PMP interactions and other membrane interfacial investigations.

Kinetic modeling of lipase-catalysed hydrolysis of triacylglycerol in a reverse micelle system for the determination of integral stereoselectivity

A kinetic model for lipase-catalysed stepwise hydrolysis of triacylglycerol was developed for quantification of integral stereoselectivity.

Micellar formation by soft template electropolymerization in organic solvents

HypothesisThe formation of porous nanostructures on surfaces and the control of their size and shape is fundamental for various applications. The creation of nanotubes is particularly difficult to implement without the aid of hard and rigid templates. Recently, methods that form nanotubular structures in a straightforward manner and without direct templating, e.g. soft templating, have been highly sought after. Here we propose the use of “soft templating” via self-assembly of conducting monomers during electropolymerization in organic solvents as a mean to form porous, nanotubular features. ExperimentsNaphtho[2,3-b]thieno[3,4-e][1,4]dioxine (NaphDOT) is employed as monomer for electropolymerizations conducted in dichloromethane and chloroform containing varying amounts of water. SEM analyses of the resulting surfaces confirms the strong capacity of NaphDOT to form vertically aligned nanotubes. Polymerization solutions analyzed by DLS and TEM reveal the presence of micelles prior to electropolymerization, and the size of the micelles correlates with the inner diameter of the nanotubes formed. FindingsWe show that micelles in polymerization solutions are stabilized by both monomers and electrolytes. We propose a mechanism where reverse micelles are forming a soft-template responsible for the formation of porous nanostructures during electropolymerization in organic, non-polar solvents. In this mechanism, the monomer and electrolyte assume the role of surfactant in the reverse micelle system.

Extraction of peroxidase from apple peel waste mediated by tween 80 reverse micelle system

Plants peroxidase is an important class of oxidoreductases. It exists widely in plants, animals and microorganisms, capable of catalyzing the oxidation of H2O2 phenols, vitamin C, nitrite, colorless dyes, indole and inorganic ion reaction. The reverse micelles extraction operation process is simple, continuous-operation, recyclable solvent, maintaining the native conformation of the protein. And it will not produce secondary pollution to the environment so that it has been gradually applied in the extraction and purification of the enzyme. Experimental operation of this paper was divided into the following two aspects: on the one hand, the selection of extraction technique and methods of detecting enzyme content and activity. We selected coomassie blue staining to determine enzyme content, while using ultraviolet spectrophotometry to resveratrol as a substrate for peroxidase activity assessment. On the other hand, the main aspect was how single factor affected reverse micelles extraction efficiency, including the aqueous phase pH, surfactant concentration and extraction time. By comparing difference of the recovery and purification of peroxidase between multiple different variables under same factors, we could get the optimum conditions: Tween 80 at a concentration of 0.30 mol/L, pH = 4.5, oscillation time of 20 min.