Diameter Of Micelles Research Articles

Laser diagnostics of micellar nanoreactors in ZnSO4/water/AOT/heptane reverse microemulsion system

In the article, for the first time, a method has been developed for remote monitoring of the composition of the reaction medium of micellar nanoreactors and for determining the parameters of nanoparticles during their synthesis using Raman spectroscopy. The sensitivity of spectral characteristics to changes in the size of nanoreactors and the concentration of the nanoparticle precursor in reverse ZnSO4/water/AOT/heptane microemulsions has been experimentally established. It has been shown that the intensity of the band of symmetrical S-O stretching vibrations in the Raman spectrum of the ZnSO4/water/AOT/heptane microemulsion can be used to determine the concentration of ZnSO4 in the micelle cores with the accuracy of 2.4 %. The calibration dependence of the center of mass position of the symmetrical O–H stretching vibrations band of the specified microemulsion on the micelles diameter ensures the determination of the sizes of micellar nanoreactors with an accuracy of 11 %.

Synthesis of Aldehyde‐Functionalized Fluorescent Micelles by Self‐Assembly of a Hybrid Polymer Constructed by Hyperbranched Conjugated Polymer Core with Aldehyde End groups and Polyethylene Glycol Shell

AbstractWater‐dispersible fluorescent nano‐/microspheres have been widely used as fluorescent probes in many fields. In this paper, aldehyde‐functionalized fluorescent micelles are synthesized by self‐assembly of end‐modified hyperbranched poly(m‐phenyleneethynylene‐alter‐p‐phenyleneethynylene)(hb‐PMPE). First, hb‐PMPE with ‐Br end‐groups(hb‐PMPE‐Br) is obtained by the polymerization of AB2 monomer PhBr2–C≡C–Ph–C≡CH, then the reaction of hb‐PMPE‐Br with 4‐ethynylbenzaldehyde (EBA) gives end aldehyde‐functionalized hyperbranched polymer hb‐PMPE‐CHO. Hence, hb‐PMPE‐CHO is reacted with aminooxy methoxypolyethylene glycol‐2000 (NH2O‐MPEG2000) to link poly(ethylene glycol) (PEG) chains to the ends of hb‐PMPE‐CHO with partial residual aldehyde end‐groups, resulting in aldehyde‐functionalized amphiphilic polymer hb‐PMPE‐PEG. Fluorescent micelles with aldehyde‐containing fluorescent hb‐PMPE core and PEG shell are obtained by self‐assembling hb‐PMPE‐PEG in water. The micelle diameter is determined by the PEG content in hb‐PMPE‐PEG, which can be controlled by the reaction weight ratio of NH2O‐MPEG2000/hb‐PMPE‐CHO. When the ratio of NH2O‐MPEG2000/hb‐PMPE‐CHO > 0.75/1, micelles with a diameter < 50 nm are obtained. The water dispersion of hb‐PMPE‐PEG‐1/2 micelles (28.9 nm) emits bright green fluorescence with λmax ≈ 490 nm under UV irradiation, and the emission intensity increases with increasing concentration.

Novel amphiphilic (AB)3‐type star block polymer: Synthesis and micellization study

AbstractAn amphiphilic three‐armed star polymer was synthesized through the polar cycloaddition reaction of a polyethylene glycol‐based macro‐triazide with an Yne‐terminated polycaprolactone in a molar ratio of 1:3 (click chemistry). Thus, each arm is itself a di‐block copolymer branched from the core, which is a 1,3,5‐triazine ring. The attachment of the pre‐synthesized hydrophobic segments to the hydrophilic segments in each arm leads to the creation of a 1,2,3‐triazole ring in the structure. Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (H‐NMR) spectroscopies were used to verify the structures. The micellization process of the prepared amphiphilic polymer was investigated in aqueous medium. For this purpose, the critical micelle concentration (CMC) was specified by the fluorometric method. Using the transmission electron microscopy (TEM) technique, it was observed that spherical self‐assemblies with a mean diameter of <100 nm are formed from the aggregation of the amphiphilic macromolecules. In addition, the hydrodynamic diameter (H) of the polymeric micelles and their size distribution were examined by dynamic light scattering (DLS) technique.

Self-assembling and foaming properties of nonionic, cardanol-based surfactants in aqueous solutions

Surfactants from renewable sources have gained attention due to their potential as substituents for petroleum-based chemicals. In this sense, surfactants based on cardanol, a compound abundant in the cashew nutshell liquid, have been proposed as suitable candidates for this purpose. However, their application is hindered by the lack of quantitative and reliable information about their bulk and surface properties in aqueous solutions. In this work, for the first time, three nonionic, cardanol-derived surfactants (7EO, 9EO, and 12EO), with different number of ethylene oxide (EO) units in the polar headgroup, had their foaming performances analyzed and correlated with their respective surface (equilibrium and dynamic surface tension and surface viscoelasticity) and bulk (cloud points, critical micelle concentration, micelle diameter, and viscosity) properties. Depending on the EO number, different scenarios were seen. Solutions containing the 7EO surfactant were below the cloud point at room temperature and presented antifoaming properties. Aqueous solutions of 9EO and 12EO displayed foamability comparable to solutions prepared with a traditionally employed anionic surfactant (sodium dodecyl sulfate, SDS) at the same concentrations. The surfactant 12EO presented a rapid surface adsorption, thus favoring the formation of large amounts of foam during aeration. Furthermore, solutions of 9EO resulted in foams that were considerably more stable than the ones formed by SDS. Such an enhanced stability was attributed to the presence of elongated micelles, formed at the vicinity of the cloud point, that increased solution viscosity and delayed the liquid drainage in the foams. This surfactant also promoted the formation of highly viscoelastic surface films that contributed to foam stabilization. The obtained results suggest that these surfactants can be used in the formulation of new products with a more sustainable character and with improved properties. Moreover, they indicate the important interchange among bulk aggregates, surface properties and foam stability in aqueous surfactant systems.

Unimer suppression enables supersaturated homopolymer swollen micelles with long-term stability after glassy entrapment.

Micelle sizes are critical for a range of applications where the simple ability to adjust and lock in specific stable sizes has remained largely elusive. While micelle swelling agents are well-known, their dynamic re-equilibration in solution implies limited stability. Here, a non-equilibrium processing sequence is studied where supersaturated homopolymer swelling is combined with glassy-core ("persistent") micelles. This path-dependent process was found to sensitively depend on unimer concentration as revealed by DLS, SAXS, and TEM analysis. Here, lower-selectivity solvent combinations led to the formation of unimer-homopolymer aggregates and eventual precipitation, reminiscent of anomalous micellization. In contrast, higher-selectivity solvents enabled supersaturated homopolymer loadings favored by rapid homopolymer insertion. The demonstrated ∼40-130 nm core-size tuning exceeded prior equilibrium demonstrations and subsequent core-vitrification enabled size persistence beyond 6 months. Lastly, the linear change in micelle diameter with homopolymer addition was found to correlate with a plateau in the interfacial area per copolymer chain.

Effect of cationic surfactant on the physicochemical and antibacterial properties of colloidal systems (emulsions and microemulsions).

Colloidal systems have been used to encapsulate, protect and release essential oils in mouthwashes. In this study, we investigated the effect of cetylpyridinium chloride (CPC) on the physicochemical properties and antimicrobial activity of oil-in-water colloidal systems containing tea tree oil (TTO) and the nonionic surfactant polysorbate 80. Our main aim was to evaluate whether CPC could improve the antimicrobial activity of TTO, since this activity is impaired when this essential oil is encapsulated with polysorbate 80. These systems were prepared with different amounts of TTO (0-0.5% w/w) and CPC (0-0.5% w/w), at a final concentration of 2% (w/w) polysorbate 80. Dynamic light scattering (DLS) results revealed the formation of oil-swollen micelles and oil droplets as a function of TTO concentration. Increases in CPC concentrations led to a reduction of around 88% in the mean diameter of oil-swollen micelles. Although this variation was of only 20% for the oil droplets, the samples appearance changed from turbid to transparent. The surface charge of colloidal structures was also markedly affected by the CPC as demonstrated by the transition in zeta potential from slightly negative to highly positive values. Electron paramagnetic resonance (EPR) studies showed that this transition is followed by significant increases in the fluidity of surfactant monolayer of both colloidal structures. The antimicrobial activity of colloidal systems was tested against a Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureaus) bacteria. Our results revealed that the inhibition of bacterial growth is observed for the same CPC concentration (0.05% w/w for E. coli and 0.3% w/w for S. aureus) regardless of TTO content. These findings suggest that TTO may not act as an active ingredient in polysorbate 80 containing mouthwashes.

Main chain selective polymer degradation: controlled by the wavelength and assembly.

The advent of reversible deactivation radical polymerization (RDRP) revolutionized polymer chemistry and paved the way for accessing synthetic polymers with controlled sequences based on vinylic monomers. An inherent limitation of vinylic polymers stems from their all-carbon backbone, which limits both function and degradability. Herein, we report a synthetic strategy utilizing radical ring-opening polymerization (rROP) of complementary photoreactive cyclic monomers in combination with RDRP to embed photoresponsive functionality into desired blocks of polyvinyl polymers. Exploiting different absorbances of photoreactive cyclic monomers, it becomes possible to degrade blocks selectively by irradiation with either UVB or UVA light. Translating such primary structures of polymer sequences into higher order assemblies, the hydrophobicity of the photodegradable monomers allowed for the formation of micelles in water. Upon exposure to light, the nondegradable blocks detached yielding a significant reduction in the micelle hydrodynamic diameter. As a result of the self-assembled micellar environment, telechelic oligomers with photoreactive termini (e.g., coumarin or styrylpyrene) resulting from the photodegradation of polymers in water underwent intermolecular photocycloaddition to photopolymerize, which usually only occurs efficiently at longer wavelengths and a much higher concentration of photoresponsive groups. The reported main chain polymer degradation is thus controlled by the irradiation wavelength and the assembly of the polymers.

Solubilization mechanism and mass-transfer model of anionic-nonionic gemini surfactants for chlorinated hydrocarbons

Accurate prediction and modeling of the quantitative recovery of chlorinated hydrocarbons in an aquifer by anionic-nonionic gemini surfactants requires estimates of their mass-transfer models and capture mechanisms. In this work, a series of synthesized anionic-nonionic gemini surfactants (GEOnS-m) with different molecular structures were used to solubilize different chlorinated hydrocarbons that contaminate the aquifer. GEOnS-m aggregate showed vesicle, rodlike micelle, and spherical micelle as the ethylene oxide content (EO) number increases. Non-polar chlorinated hydrocarbons (PCE, CT) mainly solubilized in the hydrophobic interior of micelles, and polar chlorinated hydrocarbons (TCE, MCB) mainly solubilized in the “palisade layer” of micelles. Solubilization processes were followed employing first-order and second-order kinetics. The solubilization rate increases with the decrease of EO number of GEOnS-m molecules. In essence, lower interfacial tension reduces the mass-transfer resistance of chlorinated hydrocarbons at the two-phase interface. The diameter of vesicles and spherical micelles increases, and rodlike micelles evenly changed to vesicles as chlorinated hydrocarbons transfer into micelles. The solubilization process of GEOnS-m for chlorinated hydrocarbons conforms to a novel “oil diffusion & micelle reformation model” that represents the coupling to two pre-existing models. And the solubilization mass-transfer mathematical model demonstrated the solubilization mass-transfer coefficient is affected by the combination of surfactant and solubilized organic properties. This study advances the application of solubilization for chlorinated hydrocarbons using anionic-nonionic gemini surfactants in surfactant-enhanced aquifer remediation (SEAR) design.

CTAB induced growth and shrinkage of Pluronics® P103 micelles: Experimental and theoretical rationale

This study offers an insight into the concentration influence of a cationic surfactant- cetyltrimethylammonium bromide (CTAB) having a 16-carbon long alkyl side chain that influences the self-assembly and micellization behaviour of a linear triblock copolymer based on ethylene oxide (EO) and propylene oxide (PO) Pluronic® P103 in aqueous solution. The work makes an exclusive use of a variety of methodologies, such as high sensitivity differential scanning calorimetry (HSDSC), phase behaviour study, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The investigation on the clouding behaviour demonstrates that the cloud point value of 5 %w/v P103, which is typically in the vicinity of 90 °C, rises up to more than 100 °C with the addition on of very low concentration of CTAB. The DLS technique predicted the change in hydrodynamic diameter (Dh) of micelles with temperature and in varying CTAB concentration. The SANS results inferred the morphological changes in the micelles. A comprehensive approach revealing the relationship between the molecular orbital energies of the tested P103 and CTAB were assessed by utilising the computational simulation method with the Gaussian 09 calculation window and Gauss View 5.0.9 software. The perception of CTAB-stabilized Pluronics® micelles is predicted to be much improved from the evaluated optimised descriptors. Additionally, our examined micellar system revealed the solubilization enhancement of a model hydrophobic dye orange-OT utilizing UV–vis spectroscopy.

“Water-in-salt” super concentrated electrolyte clusters are “micelles”

Water-in-salt electrolytes are super concentrated mixtures of salt and water with molal concentration exceeding 20 m. Previous microscopic measurements revealed the presence of clusters. We hypothesize that these clusters are “micelles” because salts contain large “amphiphilic” anions. For verifying this hypothesis, we study bis(trifluoromethanesulfonyl)imide (LiTFSI) within a wide concentration range from 0.1 molal up to 21 molal. We measure conductivity and sound speed. Both methods yield the same value of CMC: 5 m (≈2.9 Molar). Sound speed measurement indicates a decline of the solvating number from 14.2 to below 2 at highest concentration. Assuming micelle diameter as 2 nm, we calculated number of TFSI- anions in a single micelle as 17. Some of them could be neutralized by ion-pairing with Li ions. Nevertheless, the high electric charge causes internal stress that competes with “hydrophobic effect” and shifts the CMC value. Strong DLVO electrostatic repulsion between separate micelles prevents formation of super-micelles and gels at high concentrations, keeping the solution in liquid state.

Preparation, optimization, and characterization of chrysin-loaded TPGS-b-PCL micelles and assessment of their cytotoxic potential in human liver cancer (Hep G2) cell lines

In total, nine TPGS-b-PCL copolymers were synthesized employing distinct TPGS analogues (TPGS 2000, 3500, and 5000). In these copolymers, the length of the PCL chain varied according to the TPGS to PCL molecular weight ratio (1:1, 1:2, and 1:3). The formulation optimization was done by optimizing the drug to polymer ratio, encapsulation efficiency, drug loading, micelle diameter, and polydispersity index (PDI). TPGS3500-b-PCL7000 copolymer (TPGS to PCL ratio 1:2) with drug to polymer ratio 1:30 showed the best percentage encapsulation (63.50 ± 0.45 %) and drug loading (2.05 ± 0.07). The optimal micelle (CHR-M) diameter and PDI were determined to be 94.57 ± 13.40 nm and 0.16 ± 0.02, respectively. CHR-M showed slow release when compared with alcoholic solution of chrysin. Approximately 70.70 ± 6.4 % drug was released in 72 h. The CHR-M demonstrated considerably greater absorption in Hep G2 cells, which confirmed the reliability of the micellar carrier. The MTT assay results showed that the IC50 values for CHR-M were much lower after 24 and 48 h when compared to free chrysin. Therefore, CHR-M may be a viable carrier for active chrysin targeting with improved anticancer potential. Also, it could be a better alternative for the currently available treatment of hepatocellular carcinoma.

Antagonistic Toxic Effects of Surfactants Mixtures to Bacteria Pseudomonas putida and Marine Microalgae Phaeodactylum tricornutum.

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.

Feed restriction as a tool for further studies describing the mechanisms underlying lipolysis in milk in dairy cows

Milk lipolysis is defined as the hydrolysis of triglycerides, which are the main component of milk fat. Short-chain fatty acids (FAs) released in milk are responsible for rancid flavour. In addition, the presence of partial glycerides impairs the functional properties of milk, such as foaming and creaming abilities. Milk lipolysis, a key criterion used to assess milk quality, depends on animal parameters and breeding factors. Low-energy diets are associated with higher levels of spontaneous lipolysis, particularly in late lactation. In this study, dairy cows were fed a restricted diet (i.e. 65% of their ad libitum DM intake (DMI)) to induce spontaneous lipolysis in milk and to study milk composition associated with lipolysis. Two groups of 22 cows each received a control diet (100% of ad libitum DMI) or the restricted diet according to a 2 × 2 crossover design. The restricted diet was fed for five days. As expected, feed restriction increased milk spontaneous lipolysis which was associated with an increase in lipoprotein lipase activity. At the same time, milk yield and protein content decreased and no effect was observed on milk fat content. The increase in spontaneous lipolysis was associated with an increase in milk fat globules diameter, without influencing casein micelles diameter. Feed restriction altered the parameters of dairy cow metabolism, with increases in plasma non-esterified FAs, triglycerides and urea, indicating body fat mobilisation and protein catabolism associated with feed restriction. Feed restriction also altered hormonal parameters, with decreases in plasma insulin, insulin-like growth factor 1 and prolactin. As expected, lipolysis was higher in evening milk and was associated with a larger diameter of milk fat globules. This zootechnical approach will be completed with proteomic, lipidomic and transcriptomic studies of milk and/or mammary gland of animals selected for their extreme lipolysis.

Foaming and emulsifying properties of saponin glycosides: a natural non-ionic surfactant

Most synthetic surfactants are harmful to humans and can cause health problems after prolonged exposure or consumption. This study explores in extensive detail the use of a natural surfactant saponin, extracted from fruit of S. mukorossi, to synthesise oil in water nanoemulsions and gas–liquid foams. The effects of saponin concentration (0.1–2 wt%), pH conditions (2–10) and salt concentration (100–500 mM) on stability and average droplet diameter of sunflower oil-in-water emulsion were investigated. Emulsions were stable at pH 4–10 and salt concentration 100–400 mM for up to 30 days. Critical micellar concentration of 0.5 wt% and the average hydrodynamic diameter of saponin micelle of 4.25 nm are observed. A gas inducing impeller-based device was used to generate foam from saponin solution having different gas hold up values (εG: 0.31, 0.45 and 0.62). Average bubble size of foam and its stability (drainage rate and half-life) are measured. 100% of saponin solution gets incorporated into foam in every trial. Foam drainage rate increased and half-life decreased with increase in gas holdup. It is shown that saponin can be an effective natural and non-toxic alternative to synthetic surfactants for various industrial applications.

Micellization thermodynamics, interfacial behavior, salt-resistance and wettability alteration of gemini hybrid fluorinated surfactant

A new Gemini hybrid surfactant DFCS was prepared to improve salt resistance and interface activity of fluorinated surfactants. This surfactant was expected to be used as a cleanup additive in fracturing and an active agent in water flooding for shale and superlow-permeability sandstone reservoirs. At high salinities, it displayed lower interface tensions than current fluorinated surfactants as well as the obvious non-wettability of water on glass, and the modified natural sandstone surface using DFCS was close to intermediately wetting for the water and oil phases. Also, DFCS exhibited good temperature resistance, and the surface and interface tensions reduced markedly with the temperature below 70 ℃ in water and brine. For DFCS, the molecular area was large, e.g. ACMC= 129.61 Å2 at 30 °C; the micelle formation was entropy-driven, and the spontaneity was stronger than that of reported hybrid surfactants with single −SO3− ion. The TEM observation showed that the diameters of mono-molecules and micelles were respectively 3–5 and 20–30 nm for 1.9 g/L (CMC) DFCS in water. It was found by the UV data that the non-polarity in micellar micro-domains was visibly weaker for Gemini hybrid surfactants in comparison to hydrocarbon surfactants and that salt hardly influenced the sizes of their micelles, resulting in good salt resistance.

Micellar solutions of Pluronic F127 for ocular drug delivery

AbstractThe goal of this research was to prepare drug‐encapsulated polymeric micelles for delivery to the posterior segment of the eye. Solutions of surface active PF127 at the critical micellar concentration (CMC) were prepared in deionized water (DI water) and phosphate buffer (PBS). The CMC of PF127 solution in DI water and PBS solution were found to 0.21 ± 0.04 and 0.16 ± 0.05% (w/v), respectively. In addition, the micellization of the PF127 was observed around 25 and 21°C in DI water and PBS solution, respectively by DSC analysis. The hydrodynamic diameter of the PF127 micelles were found to range between 3 and 4 nm with polydispersity indices ranging between 0.35 ± 0.22 and 0.96 ± 1.52.Curcumin (CUR), a natural dietary compound having an anti‐VEGF properties, was successfully loaded into PF127 copolymers by the thin‐film hydration method. The CUR‐loaded PF127 micelles were confirmed by several characterization techniques including DLS and HPLC. A detailed study of the effect of experimental conditions on both the particle size and drug encapsulation efficiency (%EE) of the CUR micelles was also carried out. CUR‐loaded PF127 micelles with small particle sizes (around 15 nm, PDI = 0.19 ± 0.13) and %EE around 10% were observed at high centrifugation speed. Also, increasing the copolymer‐to‐drug ratio resulted in higher %EE (>90%). Additionally, the CUR‐loaded PF127 micelles were easy to reconstitute in water by manual shaking after lyophilization. These results suggest that PF127 micelles are a promising carrier for delivery of CUR to the eye. Future work will study in more detail about the physicochemical properties and the ability of these micelles to transport CUR across ocular barriers in ex vivo and in vivo trials.

Development and characterization of self-assembling sirolimus-loaded micelles as a sublingual delivery system

The aim of this study was to develop self-assembling micelles of poorly water soluble potent immunosuppressant agent sirolimus (SRL) to enhance the solubility and mucosal permeability as stable aqueous formulations for sublingual administration. D-α-tocopheryl 1000 succinate (TPGS), soy phosphatidylcholine (SPC), and sodium cholate (NaC) were used to prepare the SRL-loaded micelles using the one-step self-assembly method. The mean hydrodynamic diameter of optimal micelles ranged from approximately 13 to 42 nm with low polydispersity index (PDI). The formulations possessed drug loading (DL) and drug encapsulation efficiency (EE) of around 18% and 99%, respectively. SPC caused an increase in mean hydrodynamic diameter and PDI of micelles, but no negative impact on DL and EE values was observed when used at concentrations of ≤25% (w/w) of amphiphiles. However, NaC caused a detrimental effect on the characteristics of micelles in every respect. Ex vivo permeation studies revealed that TPGS-based micelles without SPC were not able to enhance the permeation of SRL compared to the SRL solution through bovine sublingual mucosa. However, the incorporation of SPC into the micelles significantly increased the mucosal permeation of SRL compared to the SRL solution. The optimal formulations maintained their characteristics at 4 °C for at least 90 days. These results support the feasibility of SRL-loaded micelles as a sublingual delivery system.

Effect of 2-ethylbutyric acid on thermodynamics stability of various nonionic surfactants tanshione-loaded micelles

At present, the stability of drug-loaded micelles is scarcely researched. The effects of different amounts of 2-ethylbutyric acid (EBA) on the interface and micelle behavior of Polyoxyl 15 Hydroxystearate (HS15), Kolliphor RH40, Kolliphor ELP and Tween80 (Polysorbate 80) micelles have been studied in this work. Tanshinone (TAN), a fat-soluble extract of Salvia miltiorrhiza was used as a model drug. The surface properties of drug-loaded micelles have been studied, including critical micelle concentration, minimum adsorption area, pC20 and thermodynamic parameters. The results indicated that the addition of the appropriate amount of EBA contributed to the formation of drug-loaded micelles and improved their physical stability. In addition, the same conclusion can be drawn from determining the absorbance of drug-loaded micelles stored by UV–visible spectrophotometry at different times. The hydrodynamic diameter (dη) of drug-loaded micelles was measured by dynamic light scattering (DLS). The dη values of TAN -loaded micelles with and without EBA were different, indicating that the internal structure of the micellar hydrophobic core had varied. In a word, appropriate amount of EBA added can improve the stability of TAN -loaded micelles, which provides a reference for studying the stability of drug-loaded micelles with nonionic surfactants.

Labrasol mediated enhanced solubilization of natural hydrophobic drugs in Pluronic micelles: Physicochemical and in vitro release studies

In present work, the solubilization of two natural hydrophobic drugs Quercetin (QCT) and Curcumin (CUR) has been systematically investigated in Pluronics (P84, F127, F68) and Pluronics-Labrasol mixed micelles. UV–Visible studies confirmed that the solubility, drug loading efficiency, partition coefficient (P), standard free energy of solubilization (ΔG°) of QCT and CUR were significantly higher in Pluronic P84 and P84-Labrasol mixed micelles than other investigated systems. Solubilization locus of both drugs in pluronic and Pluronic-Labrasol mixed micelles was scrutinized by employing DPV measurments. Enhanced solubilization of both drugs in Pluronic P84 and P84-Labrasol mixed micellar solution is also well supported by increased fluorescence intensity in respective fluorescence titrations. Inferences from Dynamic light scattering (DLS) studies revealed that the hydrodynamic diameter (Dh) of Pluronic-Labrasol mixed micelles is smaller than pure Pluronic micelles. Upon the inclusion of QCT and CUR, Dh of both Pluronic and Pluronic-Labrasol mixed micelles was found to be increased. Pluronic and Pluronic-Labrasol mixed micellar formulations exhibited the sustained release behaviour for both QCT and CUR. The improved solubilization of QCT and CUR may serve as an efficient system for sustained drug delivery enabling enhanced oral absorption and bioavailability.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans / Cis Isomers

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing <i>Trans</i> / <i>Cis</i> Isomers