AOT reverse micelles as versatile reaction media for chitosan nanoparticles synthesis

Silibinin solubilization: combined effect of co-solvency and inclusion complex formation

OBJECTIVE

Belonging to the class II drugs according to the biopharmaceutics classification system, silibinin (SLB) benefits from high permeability but suffers poor solubility that negatively affects the development of any delivery system. This research aimed to improve SLB solubility by combined use of co-solvency and complexation phenomena.

METHODS

Solubility studies were performed using the phase solubility analysis according to the shake-flask method in the presence of ethanol and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as a co-solvent and inclusion complexing agent, respectively. SLB release studies from chitosan nanoparticles were carried out in double-wall, diffusion cells using the optimized drug release medium.

RESULTS

SLB solubility was mathematically optimized constraining to using the lowest concentrations of ethanol and HP-β-CD. SLB solubility increased linearly with the increase of HP-β-CD concentration. The solubility in PBS-ethanol mixtures followed a log-linear model. SLB solubility in the presence of the ethanol co-solvent and HP-β-CD complexing agent was optimized by adopting a genetic algorithm suggesting the phosphate buffer saline solution supplemented by 6%v/v ethanol and 8 mM HP-β-CD as an optimized medium. The optimized solution was examined to study SLB release from chitosan nanoparticles (4.5 ± 0.2% drug loading) at 37 °C under static conditions. The sigmoidal release profile of SLB from the particles indicated a combination of erosion and diffusion mechanisms governing drug release from the nanoparticles.

CONCLUSION

SLB solubility in a buffered solution supplemented by ethanol co-solvent and HP-β-CD complexing agent is a function of free drug present in the semi-aqueous media, the drug-ligand binary complex, and the drug/ligand/co-solvent ternary complex.

Impacts of chitosan and its nanoformulations on the metabolic syndromes: a review

A significant public health issue worldwide is metabolic syndrome, a cluster of metabolic illnesses that comprises insulin resistance, obesity, dyslipidemia, hyperglycemia, and hypertension. The creation of natural treatments and preventions for metabolic syndrome is crucial. Chitosan, along with its nanoformulations, is an oligomer of chitin, the second-most prevalent polymer in nature, which is created via deacetylation. Due to its plentiful biological actions in recent years, chitosan and its nanoformulations have drawn much interest. Recently, the chitosan nanoparticle-based delivery of CRISPR-Cas9 has been applied in treating metabolic syndromes. The benefits of chitosan and its nanoformulations on insulin resistance, obesity, diabetes mellitus, dyslipidemia, hyperglycemia, and hypertension will be outlined in the present review, highlighting potential mechanisms for the avoidance and medication of the metabolic syndromes by chitosan and its nanoformulations.

Antimicrobial films fabricated with myricetin nanoparticles and chitosan derivation microgels for killing pathogenic bacteria in drinking water

Pathogenic bacteria in drinking water threaten human health and life. In the work, antimicrobial films composed of myricetin@tannic acid (My@TA) nanoparticles (NPs) and chitosan derivation microgels were developed to kill pathogenic bacteria in drinking water. Hydrophobic My was first made into water soluble My@TA NPs using a solvent exchange method with TA as stabilizer. Polymeric microgels of carboxymethyl chitosan (CMCS)/hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were then fabricated with a blending method. CMCS&HACC/My@TA multilayer films were further deposited on the internal surface of PET bottles by using a layer-by-layer (LbL) assembly technique. The PET bottles coated with the films could effectively kill pathogenic bacteria in water such as S. aureus, E. coli, Staphylococcus epidermidis, Pseudomonas fluorescens, Listeria monocytogenes and methicillin resistant Staphylococcus aureus (MRSA). In addition, CMCS&HACC/My@TA films displayed good antioxidant activity, water resistance, and in vivo biocompatibility with heart, liver, spleen, lung and kidney organs. We believe that the container coated with CMCS&HACC/My@TA films can be applied to prevent microbial contamination of drinking water.

Dioctyl sodium sulfosuccinate surfactant self-assembly dependency of solvent hydrophilicity: a modelling study

The self-assembly of dioctyl sodium sulfosuccinate (AOT) model surfactant in solvent environments of differing polarity is examined by means of dissipative particle dynamics (DPD) bead model parametrized against Hildebrand solubility parameters from atomistic molecular dynamics (MD) simulations. The model predicts that in hydrophobic solvents (e.g. dodecane) the surfactant forms small (Nagg ∼ 8) reverse micellar aggregates, while in a solvent corresponding to water lamellar assembly takes place, in good agreement with literature structural parameters. Interestingly, solvents of intermediate polarity lead to formation of large, internally structured aggregates. In these, the surfactant headgroups cluster within the aggregate, surrounded by a continuous phase formed by the hydrocarbon tails. We show that the partitioning of the headgroups between the aggregate surface layer and the inner clustered phase depends primarily on solvent polarity, and can be controlled by the solvent, but also system composition. Finally, we compare the DPD assembly response to simplified effective interaction potentials derived at dilute concentration limit for the interactions. The comparison reveals that the simplified effective potential descriptions provide good level of insight on the assembly morphologies, despite drastic, isotropic interactions simplification involved.

Pectin-based nanoencapsulation strategy to improve the bioavailability of bioactive compounds

Pectin is one of the polysaccharides to be used as a coating nanomaterial. The characteristics of pectin are suitable to form nanostructures for protection, increased absorption, and bioavailability of different active compounds. This review aims to point out the structural features of pectins and their use as nanocarriers. It also indicates the principal methodologies for the elaboration and application of foods. The research carried out shows that pectin is easily extracted from natural sources, biodegradable, biocompatible, and non-toxic. The mechanical resistance and stability in different pH ranges and the action of digestive enzymes allow the nanostructures to pass intact through the gastrointestinal system and be effectively absorbed. Pectin can bind to macromolecules, especially proteins, to form stable nanostructures, which can be formed by different methods; polyelectrolyte complexes are the most frequent ones. The pectin-derived nanoparticles could be added to foods and dietary supplements, demonstrating a promising nanocarrier with a broad technological application.

Chitosan-Based Nanomaterial as Immune Adjuvant and Delivery Carrier for Vaccines

With the support of modern biotechnology, vaccine technology continues to iterate. The safety and efficacy of vaccines are some of the most important areas of development in the field. As a natural substance, chitosan is widely used in numerous fields-such as immune stimulation, drug delivery, wound healing, and antibacterial procedures-due to its good biocompatibility, low toxicity, biodegradability, and adhesion. Chitosan-based nanoparticles (NPs) have attracted extensive attention with respect to vaccine adjuvants and delivery systems due to their excellent properties, which can effectively enhance immune responses. Here, we list the classifications and mechanisms of action of vaccine adjuvants. At the same time, the preparation methods of chitosan, its NPs, and their mechanism of action in the delivery system are introduced. The extensive applications of chitosan and its NPs in protein vaccines and nucleic acid vaccines are also introduced. This paper reviewed the latest research progress of chitosan-based NPs in vaccine adjuvant and drug delivery systems.

Optimization of the incubation parameters for biogenic synthesis of WO3 nanoparticles using Taguchi method

Green synthesis of metal nanoparticles is gathering attention due to eco-friendly processing. Tungsten oxide (WO₃) nanoparticles have immense applications as semiconductors, antimicrobials and photo thermal materials but their synthesis using biological systems is hitherto unpublicized. The paper discusses synthesis of WO₃ nanoparticles using Stenotrophomonas maltophilia and the optimization of physico-chemical parameters of incubation which influence the growth and metabolism of the bacterium and consequently the size of the WO₃ nanoparticles. The biogenic synthesis of WO₃ nanoparticles was confirmed by ATR-FTIR and X-ray diffraction analysis. Taguchi and analysis of variance method was applied to optimize the physico-chemical parameters (pH, temperature, time, aeration rate and concentration), considering particle size and poly dispersity index (PDI) of the nanoparticles as the experimental responses. Under the design of experiments technique, Taguchi's L27 array was selected to determine the optimal process parameters which could significantly reduce the particle size and PDI of WO₃ nanoparticles. Statistical analysis by signal-to-noise ratio, regression analysis and ANOVA (95% confidence level) on experimental responses confirmed pH and aeration as most influential while temperature and time as least influential parameters. pH 8, Temperature 40 °C, aeration 200 RPM, time 3 days and concentration of sodium tungstate at 1 mM (p3t3r3d3c1) was the most effective level and parameters combination for smallest particle size and PDI of WO₃ nanoparticles. Regression models developed for particle size and PDI exhibited a linear regression of 97.80% and 90.89% respectively, while the confirmation test validated the size and PDI of the experimental values against predicted results. SEM image of WO₃ nanoparticles illustrated the same particle size as that predicted, further validating the model. The study can be applied to optimize any process parameters in the industry or on biological systems.

Recent development in nanoencapsulation and delivery of natural bioactives through chitosan scaffolds for various biological applications

Nowadays, nano/micro-encapsulation as a pioneering technique may significantly improve the bioavailability and durability of Natural bioactives. For this purpose, chitosan as a bioactive cationic natural polysaccharide has been frequently used as a carrier because of its distinct chemical and biological properties, including polycationic nature, biocompatibility, and biodegradability. Moreover, polysaccharide-based nano/micro-formulations are a new and extensive trend in scientific research and development in the disciplines of biomedicine, bioorganic/ medicinal chemistry, pharmaceutics, agrochemistry, and the food industry. It promises a new paradigm in drug delivery systems and nanocarrier formulations. This review aims to summarize current developments in approaches for designing innovative chitosan micro/nano-matrix, with an emphasis on the encapsulation of natural bioactives. The special emphasis led to a detailed integrative scientific achievement of the functionalities and abilities for encapsulating natural bioactives and mechanisms regulated in vitro/in vivo release in various biological/physiological environments.

How the external solvent in biocompatible reverse micelles can improve the alkaline phosphatase behavior

In the last decade, the nature of the nonpolar solvents that can be part of reverse micelles (RMs) has been the topic of several investigations to improve their applications. In this sense, the hydrolysis of 1-naphthyl phosphate catalyzed by the enzyme alkaline phosphatase (AP) was used as a probe to investigate the effect of the change of the external solvent on RMs formulated with the anionic surfactant sodium diethylhexyl sulfosuccinate (AOT). As external nonpolar solvents, two biocompatible lipophilic esters, isopropyl myristate and methyl laurate, and the traditional nonpolar solvents, n-heptane and benzene, were used. The results were compared among the RMs investigated and with the reaction in homogeneous media. Thus, the effect of the nanoconfinement as well as the impact of the replacement of a conventional external nonpolar solvent by biocompatible solvents were analyzed. The results indicate that the catalytic efficiency in the AOT RMs is larger than that in homogeneous media, denoting a different hydration level over the AP enzyme, which is directly related to the different degrees of nonpolar solvent penetration to the RM interface. Our findings demonstrated that toxic solvents such as n-heptane and benzene can be replaced by nontoxic ones (isopropyl myristate or methyl laurate) in AOT RMs without affecting the performance of micellar systems as nanoreactors, making them a green and promising alternative toward efficient and sustainable chemistry.

Design, fabrication and drug release potential of dual stimuli-responsive composite hydrogel nanoparticle interfaces

Nanocomposite hydrogel particles grasp considerable attention in nanotechnology and nanomedicine as one of the potential drug delivery platforms. However, prevail a coveted drug delivery strategy with sustain and stimuli-drug release is still challenging. Herein, poly (N-(4-aminophenyl) methacrylamide))-carbon nano-onions (PAPMA-CNOs = f-CNOs)/diclofenac-complex integrated chitosan (CS) nanocomposite hydrogel nanoparticles (CNPs) were fabricated using an ionic gelation strategy. CNPs possess several conducive physicochemical properties, including spherical morphology and uniform particle distribution.In vitro drug release from CNPs was vetted in different pHs of gastrointestinal (GI) tract environment at a temperature range of 37-55 °C and found dual (pH and thermo)-responsive controlled drug release. Under pH 7.4, CNPs exhibited the highest drug release at 55 °C in 15 days. The drug release results disclose that the structure of CNPs was disassembled at 55 °C to release the encapsulated drug molecules in a controlled fashion. The CNPs also displayed good cell viability against human fibroblast cells. Thus, all the results together unveil that CNPs would thrive as a promising pH and temperature-triggered drug delivery platform for the GI tract and colon targeted drug delivery.

A comparative study of antimicrobial activity of differently-synthesized chitosan nanoparticles against bovine mastitis pathogens

The greatest concern in dairy farming nowadays is bovine mastitis (BM), which results mainly from bacterial colonization of the mammary gland. Antibiotics are the most widely used strategy for its prevention and treatment, but overuse has led to growing antimicrobial resistance. Pathogens have also developed other mechanisms to persist in the udder, such as biofilm formation and internalization into bovine epithelial cells. New therapies are therefore needed to reduce or replace antibiotic therapies. In a previous study, we found that chitosan nanoparticles (Ch-NPs) have considerable potential for the treatment of BM. The aim of the present study was to evaluate the antimicrobial activity of differently-synthesized Ch-NPs against BM pathogens and their toxicity in bovine cells in vitro, to further explore the attributes of Ch-NPs for the prevention and treatment of intramammary infections. We also looked into their ability to inhibit biofilm formation and prevent the internalization of S. aureus into mammary epithelial cells. Finally, since an interesting approach for BM prevention is to enhance the host's immune response, we studied whether Ch-NPs could promote the release of pro-inflammatory cytokines in mammary epithelial cells. The results reveal that the bactericidal effect of Ch-NPs on BM pathogens and their ability to inhibit biofilm formation are size-dependent, with smaller particles being more efficient. In contrast, their effect on the viability of the cell lines is not size-dependent and all samples tested were non-toxic. The smallest Ch-NPs successfully prevented the internalization of S. aureus into the cells, but did not promote the production of pro-inflammatory cytokines. These findings make it possible to conclude that Ch-NPs are a great bactericidal agent which can prevent the main mechanisms developed by BM pathogens to persist in the udder.

Template-mediated self-assembly of magnetite-gold nanoparticle superstructures at the water-oil interface of AOT reverse microemulsions

HYPOTHESIS

Bimetallic magnetite-gold nanostructures are interesting candidates to combine and enhance individual properties of each metal element in catalytic and analytical applications. Microemulsions have been employed in templated synthesis of nanoparticles, and their combination with different types of nanoparticles can further mediate interactions at the water-oil interface, providing new forms of hybrid nanostructures.

EXPERIMENTS

Reverse water-in-oil microemulsions of droplet sizes below 50 nm were prepared from ternary mixtures of Aerosol-OT (AOT) as surfactant, incorporating 4 nm sized superparamagnetic nanoparticles (MNPs) to the hexane-pentanol oil phase and 5 nm sized polyethyleneimine-stabilized gold nanoparticles (Au(PEI)-NPs) to the water phase. The resulting isotropic L₂ phase, Winsor phases and organized nanostructures were investigated using conductometry, calorimetry, UV-Vis spectroscopy, cryo-SEM and HRTEM.

FINDINGS

Droplet-droplet interactions, morphology and surfactant film properties of AOT microemulsions could be modulated in different ways by the presence of the different nanoparticles from each liquid phase. Additionally, phase separation into Winsor phases allows the formation upon solvent evaporation of films with bimetallic heterostructures on the micrometer scale. This demonstrates a new way of nanoparticle templated assembly at liquid interfaces by assisted interactions between microemulsions and nanoparticles, as a promising strategy to obtain thin films of small, isotropic nanoparticles with hierarchical ordering.

Influence of the AOT Counterion Chemical Structure on the Generation of Organized Systems

The impact of the imidazolium counterion structure on the organized systems formed by the surfactant 1,4-bis-2-ethylhexylsulfosuccinate, AOT, both in aqueous solutions and in nonpolar solvents is investigated. With this in mind, we investigated if the ionic liquid-like (IL-like) surfactant 1-ethyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, emim-AOT, forms direct micelles or vesicles in water. Dynamic light scattering, zeta potential, conductivity, fluorescence spectroscopy, and UV-visible spectroscopy measurements were performed to characterize the organized systems in aqueous solutions. We also studied the self-aggregation of emim-AOT, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, bmim-AOT, and of 1-hexyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, hmim-AOT, in nonpolar solvents. The results obtained showed that the IL-like surfactant emim-AOT forms direct micelles in water, as sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) does. However, emim-AOT aggregates are larger, have a lower surface charge, are more stable, and have a more polar and less fluid micellar interface than Na-AOT micelles. It was also observed that emim-AOT and hmim-AOT form reverse micelles in nonpolar solvents. The size of the imidazolium cations dramatically influences the size of the reverse micelles and their ability to solubilize water.

Simultaneous delivery of anti-miRNA and docetaxel with supramolecular self-assembled "chitosome" for improving chemosensitivity of triple negative breast cancer cells

At present, treating of triple negative breast cancer (TNBC) mainly depends on chemotherapy with more toxic side effects, but the effect is limited and it is highly prone to drug resistance. Gene therapy using anti-microRNAs maybe one of alternative therapeutic strategies. Due to the poor cell permeability and significant in vivo decomposition rate of anti-microRNAs, which limits their clinical application, we developed a core-shell supramolecular nanovector of "chitosome" that were self-assembled from the synthetic amphiphilic chitosan derivatives. The constructed chitosomes could co-load hydrophilic anti-miR-21 and hydrophobic docetaxel (DTX) into one combo nanocarrier with entrapment efficiency of more than 80%, as well as spherical morphology and average particle size of 90 nm. In comparison with the naked ones, anti-miR-21 encapsulated with chitosomes showed significantly increased cellular transfection and stability against degradation by nuclease in serum. Compared with DTX or anti-miR-21 formulations used alone, the co-delivery of the two drugs with the combo chitosome obtained improved chemosensitivity of TNBC cells to DTX treatment through their synergistic mechanisms. Taken together, the developed chitosome could be a promising candidate for simultaneous delivery of insoluble chemotherapeutic drugs and gene agents for TNBC therapy. Graphical abstract.

Characterization of Reverse Micelles Formulated with the Ionic-Liquid-like Surfactant Bmim-AOT and Comparison with the Traditional Na-AOT: Dynamic Light Scattering, 1H NMR Spectroscopy, and Hydrolysis Reaction of Carbonate as a Probe

The present study investigated how the presence of butylmethylimidazolium cation (bmim⁺) alters the interfacial properties of reverse micelles (RMs) created with the ionic liquid-like surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT), in comparison to sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) RMs, employing dynamic light scattering (DLS) and ¹H NMR techniques. Moreover, through the hydrolysis reaction of bis(4-nitrophenyl)carbonate inside both RMs as reaction probe, interfacial properties changes were explored in more detail. The kinetic solvent isotope effect was also analyzed. Micellar systems were formed using n-heptane as external nonpolar solvent and water as the polar component. According to the DLS studies, water is encapsulated inside the organized media; however, a different tendency is observed depending on the cationic component of the surfactant. For Na-AOT system, the results suggest that the micellar shapes are probably spherical, while in the case of bmim-AOT, a transition from ellipsoidal to spherical micelles could be occurring when water is added. ¹H NMR data show that water is structured differently when Na⁺ cation is replaced by bmim⁺; in bmim-AOT RMs, the interaction of water with the surfactant is weaker and the water hydrogen-bonding network is less disturbed than in Na-AOT RMs. Kinetic studies reveal that the hydrolysis reaction in bmim-AOT RMs was much more favorable in comparison to Na-AOT RMs. In addition, when water content decreases in bmim-AOT RMs, the hydrolysis reaction rate increases and the solvent isotope effect remains constant, while for Na-AOT solutions, both the reaction rate and the solvent isotope effect decrease. Our results indicate that bmim⁺ cation would be located in the surfactant layer in such a way the negative charge density in the interface is less than that in Na-AOT RMs, and the reaction is more favorable. Additionally, as ¹H NMR studies reveal, the interfacial water molecules would be more available in bmim-AOT RMs to participate in the nucleophilic attack. Therefore, the present study evidences how the replacement of Na⁺ counterion by bmim⁺ alters the composition of the interface of AOT RMs.

Microfluidics combined with ionic gelation method for production of nanoparticles based on thiol-functionalized chitosan to adsorb Hg (II) from aqueous solutions

This work aimed at producing nanoparticles (NPs) based on thiol-functionalized chitosan (CS) using capillary microfluidic (MF) device combined with ionic gelation method to adsorb mercury ion [Hg (II)] from aqueous solutions. In this line, CS was functionalized with epichlorohydrin/cysteaminium chloride (2.73 M ratio) followed by fabricating NPs via MF and bulk mixing (BM) methods. To characterize the morphology, zeta potential, functionality, structure, and magnetic property of the samples, a series of tests such as SEM, TEM, DLS, FTIR, XRD, and VSM were carried out, respectively. The obtained results showed that MF technique was able to produce NPs with a diameter as small as 18 ± 3 nm, and a uniform shape compared to BM method. Thiol groups (-SH) functionalization on CS surface was confirmed by appearing a characteristic peak at 2579 cm^-1. Also, the XRD patterns indicated the appropriate synthesis of Fe₃O₄ (magnetite), and no change in the structure of CS NPs in the presence of magnetite. Moreover, adding the magnetite to thiol-functionalized CS NPs led to suitable saturation magnetization about 26 emu/g to facilitate their separation using a magnetic field. To evaluate the performance of the nanoadsorbent, it has been exposed to Hg (II) in an aqueous solution which in turn the parameters optimization for the adsorption was done via Box-Behnken design (BBD) method, exhibiting the effect of adsorbent dose and the initial concentration of Hg (II) was much more significant than that of pH. Different concentrations of total dissolved solids up to 1000 mg/L had no adverse impact on the adsorption process confirmed by EDAX spectra. The least value of RMSE (5.023) and χ² (0.3) were observed for Redlich-Peterson, Radke-Prausnitz, and UT isotherms. Maximum adsorption capacities calculated using Langmuir and UT models were 1192 mg/g and 1126 mg/g, respectively. Thermodynamic studies demonstrated that the nature of the adsorption process was spontaneous and endothermic. Recovery of nanoadsorbent was successfully carried out using HCl 0.5 mol/L. The adsorption studies revealed that the prepared nanoadsorbent is promising candidate used in mercury removal from a real wastewater potentially.

Chitosan nanoparticles enhance the antibacterial activity of the native polymer against bovine mastitis pathogens

Staphylococcus is the most commonly isolated genus from animals with intramammary infections, and mastitis is the most prevalent disease that affects dairy cows in many countries. These pathogens can live in biofilms, a self-produced matrix, which allow them evade the innate immune system and the antibiotic therapy, thereby producing persistent infections. The aim of this study was to explore the antimicrobial potential of chitosan nanoparticles (Ch-NPs) obtained by the reverse micellar method. We found that the nanoformulation developed presents antimicrobial activity against mastitis pathogens in a dose-dependent manner. Moreover, different experiments corroborated that the antimicrobial effectiveness of Ch-NP was greater than that shown by the native polymer used in the preparation of these nanocomposites. Ch-NPs caused membrane damage to bacterial cells and inhibited bacterial biofilm formation, without affecting the viability of bovine cells. These findings show the great potential of Ch-NPs as therapeutic agent for bovine mastitis treatment.

Interfacial properties modulated by the water confinement in reverse micelles created by the ionic liquid-like surfactant bmim-AOT

The behavior of the interfacial water entrapped in reverse micelles (RMs) that were formed by the ionic liquid-like surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT) was investigated with the use of UV-Vis absorption spectroscopy and nuclear magnetic resonance (NMR) relaxometry. The solvatochromism of two molecular probes, namely, 1-methyl-8-oxyquinolinium betaine (QB) and N,N,N',N'-tetramethylethylenediamine copper(ii)acetylacetonate tetraphenylborate ([Cu(acac)(tmen)][B(C6H5)4]), was investigated. As a comparison, the analog RMs formed by sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) were also explored. By varying the water content inside the RMs and consequently the different magnitude of the water-surfactant interactions at the interface, interesting properties were observed by comparing bmim-AOT and Na-AOT RMs. From the solvatochromic behavior of ([Cu(acac)(tmen)][B(C6H5)4]), we found that the interface in bmim-AOT RMs shows a smaller electron donating capacity than that in Na-AOT RMs. QB revealed that the interfacial region is a weaker hydrogen bond donor and less polar than the corresponding Na-AOT RMs. NMR experiments showed that the molecular motion of water in bmim-AOT RMs is less restricted than that of the water molecules confined in Na-AOT RMs. In summary, the results show how the nature of the bmim+ cation affects the interaction between the entrapped water and the RM interface, greatly modifying the interfacial water structure in comparison with the results known for Na-AOT.

Catanionic Reverse Micelles as an Optimal Microenvironment To Alter the Water Electron Donor Capacity in a SN2 Reaction

The effect of interfacial water entrapped in two types of catanionic reverse micelles (RMs) on the kinetic parameters of the S_N2 reaction between dimethyl-4-nitrophenylsulfonium trifluoromethanesulfonate (S⁺) and n-butylamine (BuNH₂) was explored. Two catanionic surfactants, composed of a mixture of oppositely charged ionic surfactants without their original counterions, were used to create the RMs. Thus, benzyl- n-hexadecyldimethylammonium 1,4-bis(2-ethylhexyl) sulfosuccinate (BHD-AOT) and cetyltrimethylammonium 1,4-bis(2-ethylhexyl) sulfosuccinate (CTA-AOT) were formed. Also, the well-known anionic surfactant sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (Na-AOT) was employed as a comparison. Our results showed an important catalytic-like effect of all RMs investigated in comparison with a water-benzene mixture, and the rate constant values depend on the type of surfactant used. Faster reaction in BHD-AOT RMs than in CTA-AOT and Na-AOT RMs was observed. This behavior was attributed to the strong interaction (by hydrogen bonding with AOT anion and ion-dipole interaction with BHD⁺) between the entrapped water and the BHD-AOT interface, which reduces the solvation capacity of water on S⁺. In CTA-AOT (and Na-AOT) RMs, the water-interface interaction is weaker and the electron pairs of water can solvate S⁺ ions. In summary, the chemical structure of the counterion on the catanionic surfactant alters the interfacial region, allowing the progress of a reaction inside the RMs to be controlled.

Combination of a protic ionic liquid-like surfactant and biocompatible solvents to generate environmentally friendly anionic reverse micelles

imim–DEHP, a versatile protic IL-like surfactant to formulate aqueous RMs in biocompatible non-polar solvents.

Fabrication and characterization of chitosan conjugated eurycomanone nanoparticles: In vivo evaluation of the biodistribution and toxicity in fish

Chitosan nanoparticles (CNPs) have been proven considerable delivery agents due to their remarkable physicochemical properties. Present study reports the fabrication of CNPs by ionic gelation process and their characterization by different approaches. The constructed nanoparticles were successfully conjugated with eurycomanone with significant entrapment efficiency. Particle size of chitosan and chitosan conjugated eurycomanone nanoparticles were 126.2nm and 130nm respectively. Scanning electron microscopy showed that the particles were spherical in shape and well dispersed. Cross-linking between CNPs and eurycomanone (CENPs) were confirmed by Fourier-transform infrared (FTIR) spectroscopy. Fluorescent nanoparticles were prepared by using Rhodamine-6G dye, characterised by SEM and confirmed for conjugation by FTIR. Biodistribution of CENPs showed the presence of fluorescent nanoparticles in liver, kidney, testes and brain of C. magur. The toxicity of CENPs was evaluated by comparing the histological sections of catfish testes collected from treated and control group. No signs of toxicity were seen in testes after the delivery of CENPs. Molecular docking study revealed high spontaneous binding ability of chitosan with eurycomanone and aromatase enzyme. The study reports that CNPs can act as a stabilizing agent for eurycomanone formulation and could be a promising approach to increase the reproductive performance of the fishes.

Micropolarity and Hydrogen-Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy

In the present work we show how two biocompatible solvents, methyl laurate (ML) and isopropyl myristate (IPM), can be used as a less toxic alternative to replace the nonpolar component in a sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) formulation. In this sense, the micropolarity and the hydrogen-bond ability of the interface were monitored through the use of the solvatochromism of a molecular probe (1-methyl-8-oxyquinolinium betaine, QB) and Fourier transform infrared spectroscopy (FTIR). Our results demonstrate that the micropolarity sensed by QB in ML RMs is lower than in IPM RMs. Additionally, the water molecules form stronger H-bond interactions with the polar head of AOT in ML than in IPM. By FTIR was revealed that more water molecules interact with the interface in ML/AOT RMs. On the other hand, for AOT RMs generated in IPM, the weaker water-surfactant interaction allows the water molecules to establish hydrogen bonds with each other trending to bulk water more easily than in ML RMs, a consequence of the dissimilar penetration of nonpolar solvents into the interfacial region. The penetration process is strongly controlled by the polarity and viscosity of the external solvents. All of these results allow us to characterize these biocompatible systems, providing information about interfacial properties and how they can be altered by changing the external solvent. The ability of the nontoxic solvent to penetrate or not into the AOT interface produces a new interface with attractive properties.