Increasing Alkyl Chain Length Research Articles

Synthesis and properties of amide-based cationic gemini surfactants with semi-rigid spacer

Abstract A series of novel gemini surfactants (m-E2Ph-m) with ester groups and a benzene ring as rigid spacer were synthesized and characterized by IR, 1H NMR and Mass spectrometry. The effect of hydrophobic chain length on the surface properties and aggregation behavior of the gemini surfactants were investigated by the measurements of surface tension, electrical conductivity, fluorescence. The critical micelle concentration (CMC) of these surfactants decreases with increasing alkyl chain length. The thermodynamic parameters exhibited that the micellization was a spontaneous and exothermic process in environment. The micellization process became more beneficial with the increase of alkyl chain length and the decrease of temperature.

First mesomorphic and DFT characterizations for 3- (or 4-) n-alkanoyloxy benzoic acids and their optical applications

New liquid crystalline hydrogen bonded 3- (or 4)-n-alkanoyloxy benzoic acids were synthesized and probed theoretically and experimentally. The molecular structures of these compounds were elucidated by proton NMR, carbon-13 NMR and elemental analyses. Differential scanning calorimetry (DSC) was used to investigate the thermal and mesomorphic properties of all the symmetrical dimers that bearing identical alkanoyloxy chains. Moreover, polarized optical microscopy (POM) was used to determine their mesophases. The findings show that all the designed symmetrical dimers exhibit the smectic mesophase with relative thermal stability that depends on the length of their terminal side chain. Additionally, the experimental findings of the mesomorphic behavior are further supported by DFT calculations. The alkanoyloxy benzoic acid para-derivatives (In) were shown to be more stable than their meta-substituted (IIn) analogues due to stronger hydrogen bonding interactions. The computed reactivity parameters showed that the position of ester moiety has a significant impact on the acids reactivity. The absorbance spectra of both the 3- (or 4)-n-alkanoyloxy benzoic acids revealed a blue shift with the increment of the of alkyl chain size; however, the energy band gaps of 3-n-alkanoyloxy benzoic derivatives were found to be slightly higher than those of the 4-n-alkanoyloxy benzoic acids. Moreover, the photoluminescence spectrum of the prepared materials is rather broad, and exhibited a red shift as the alkyl chain length increases. The fluorescence lifetime shown to rise as alkyl chain length grows longer, and 3-n-alkanoyloxy benzoic acids have slightly longer lifetime compared to their 4-n-alkanoyloxy benzoic analogues.

Self-aggregation of cationic gemini surfactants with amide groups in the spacer and variable alkyl chain length

AbstractSynthesis, aggregation parameters and antimicrobial activity of novel cationic gemini surfactants with two amide groups in gemini spacer structure and a variable number of carbon atoms in alkyl tails ranging from 12 to 15 are reported. The critical micelle concentration of gemini surfactants was determined using surface tension and electrical conductivity methods. The cmc values were found in the range 0.83 to 0.06 mM. The interfacial area, micelle ionisation degree and the Gibbs free energy per molecule and alkyl chain were calculated from the surface tension and conductivity curves. Particle size analysis using the dynamic light scattering method confirmed the formation of small spherical micelles 6–7 nm large in size for gemini surfactants with 12 and 13 carbon atoms in the alkyl chain. A large size above 50 nm was found for the aggregates composed of long-chain gemini molecules with 14 and 15 carbon atoms. The zeta potential of gemini surfactants shows a continuous increase with the increasing alkyl chain length. Micelle aggregation number of gemini surfactants correlates well with the hydrodynamic size data. Small aggregation number values were found for short-chain gemini molecules with 12 and 13 carbon atoms in the alkyl chain. Long-chain gemini molecules with 14 and 15 carbon atoms exhibit aggregate growth represented by an increase in the aggregation number values while maintaining the spherical or spheroidal shape of micelles. The investigations of antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria and yeast indicate the increasing antimicrobial efficiency towards the short-chain surfactant with 12 carbon atoms in the alkyl chain. A possible cut-off effect presence is proposed to explain the dependence of antimicrobial activity on the surfactant alkyl tail length.

The effects of structural variations in neutral phosphorus extractants on UO22+ extraction behavior and radiation stability: Experimental and theoretical insights

In the present work, the effects of four neutral phosphorus extractants (TBP, TAP, THP, TEHP) with different molecular structures on the extraction behaviors towards U(Ⅵ) and radiation stability were systematically studied. The results of the batch extraction and the γ-radiolysis experiments manifested that the extraction performance and radiation stability of the four extractants followed the order of TEHP > THP > TAP > TBP. Moreover, DFT calculations and Multiwfn software were utilized to analyze the properties of the extractants. The electrostatic potentials (ESP) and frontier molecular orbital of extractants indicated that the nucleophilic ability was ranked as TEHP > THP > TAP > TBP. The analyses of quantum theory of atoms in molecules (QTAIM) and Wiberg indices (WBIs) revealed that the UO22+ ions exhibited stronger complexation ability with O atoms in TEHP compared to the other three extractants. The bonds between UO22+ ions and extractants were primarily ionic in nature. From the energetic perspective, the thermodynamic energy demonstrated that the Gibbs free energy of TEHP in aqueous solution was the most negative, implying that it should be easier to combine with UO22+. This work elucidates that the increase of alkyl chain length and the presence of branched chains can enhance the extraction performance and radiation stability of neutral phosphorus extractants. It not only lays the theoretical foundation for designing novel organic phosphorous extractants with superior extraction performance and high radiation stability, but also provides scientific basis for the extraction process of uranium in spent nuclear fuel reprocessing.

Occurrence, placental transfer, and health risks of emerging endocrine-disrupting chemicals in pregnant women

Previous studies demonstrated that many environmental chemicals can cross the human placental barrier. However, the risk regarding gestational exposure of emerging endocrine-disrupting chemicals (EDCs) is unclear. In this study, the occurrence of 24 EDCs, such as bisphenol A analogs, parabens, triclocarban, and triclosan, was investigated in serum and urine samples from Chinese pregnant women. Some metabolites were determined in matched serum–urine pairs (n = 75) to perform a comprehensive assessment of exposure. The placental transfer efficiency (PTE) of the detected chemicals was determined in matched maternal–cord serum pairs (n = 110). The mean PTEs of the chemicals showed a large variation from 43.1% to 171.0%. The potential effects of physicochemical properties, molecular structures, and biological factors on PTE were investigated using multiple linear regression models and molecular docking. We found that the PTE of methyl paraben, ethyl paraben, and propyl paraben was associated with their increasing alkyl chain lengths. Furthermore, a comprehensive exposure assessment of EDCs showed that 62.7% of pregnant women had a health index > 1, which indicted potential health risks during pregnancy. However, toxicity and the underlying mechanisms of these EDCs remain to be further studied.

Insights into modeling refractive index of ionic liquids using chemical structure-based machine learning methods

Ionic liquids (ILs) have drawn much attention due to their extensive applications and environment-friendly nature. Refractive index prediction is valuable for ILs quality control and property characterization. This paper aims to predict refractive indices of pure ILs and identify factors influencing refractive index changes. Six chemical structure-based machine learning models called eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), Categorical Boosting (CatBoost), Convolutional Neural Network (CNN), Adaptive Boosting-Decision Tree (Ada-DT), and Adaptive Boosting-Support Vector Machine (Ada-SVM) were developed to achieve this goal. An enormous dataset containing 6098 data points of 483 different ILs was exploited to train the machine learning models. Each data point’s chemical substructures, temperature, and wavelength were considered for the models’ inputs. Including wavelength as input is unprecedented among predictions done by machine learning methods. The results show that the best model was CatBoost, followed by XGBoost, LightGBM, Ada-DT, CNN, and Ada-SVM. The R2 and average absolute percent relative error (AAPRE) of the best model were 0.9973 and 0.0545, respectively. Comparing this study’s models with the literature shows two advantages regarding the dataset’s abundance and prediction accuracy. This study also reveals that the presence of the –F substructure in an ionic liquid has the most influence on its refractive index among all inputs. It was also found that the refractive index of imidazolium-based ILs increases with increasing alkyl chain length. In conclusion, chemical structure-based machine learning methods provide promising insights into predicting the refractive index of ILs in terms of accuracy and comprehensiveness.

Physicochemical evaluation of interaction behavior of a series of biocompatible gemini surfactants with hemoglobin: Insights from spectroscopic and computational studies

In this study, we investigated the interaction behavior of biodegradable, cationic, oxy-diester functionalized gemini surfactants N1,N1,N14,N14-tetramethyl-2,13-dioxo-N1,N14-dialkyl-3,6,12-tetraoxateradecane-1,14-diaminium dichloride (in short Cm-E2O2-Cm, m = 12, 14 or 16 is the number of carbon atoms in the alkyl chain) with one of the most important proteins in red blood cells viz. hemoglobin. We employed a variety of in-vitro and in-silico methodologies, such as fluorescence, UV–vis, FT-IR and circular dichroism spectroscopies, DFT, molecular docking, and molecular dynamics simulations, to study these interactions. Our results show that the chain length of the surfactants have distinct implications for the interaction behavior, as evidenced by the estimated physical parameters, such as Kb and ∆G. The order of Kb values (0.24 × 103 < 3.11 ×103 < 5.85 × 103 M-1) is in accordance with the increasing alkyl chain length of the surfactants. The negative Gibbs free energy change values and their order, − 13.58 < −19.93 < −21.49, further support the spontaneity of interactions and the effect of alkyl chain length. Theoretical insight into the environment at the quantum mechanical level, binding site, and energy stability of the protein-surfactant interactions were produced by computational methods. This research contributes significantly to the field of knowledge concerning surfactants' effects on protein structure and behavior.

Synthesis and Evaluation of Interfacial Properties and Carbon Capture Capacities of the Imidazolium-Based Ionic Liquid Surfactant.

Ionic liquid as a chemical flooding agent has broad application prospect in enhancing oil recovery. In this study, a bifunctional imidazolium-based ionic liquid surfactant was synthesized, and its surface-active, emulsification capacity, and CO2 capture performance were investigated. The results show that the synthesized ionic liquid surfactant combines the characteristics of reducing interfacial tension, emulsification, and CO2 capture. The IFT values for [C12mim][Br], [C14mim][Br], and [C16mim][Br] could decrease from 32.74 mN/m to 3.17, 0.54, and 0.051 mN/m, respectively, with increasing concentration. In addition, the emulsification index values are 0.597 for [C16mim][Br], 0.48 for [C14mim][Br], and 0.259 for [C12mim][Br]. The surface-active and emulsification capacity of ionic liquid surfactants improved with the increase in alkyl chain length. Furthermore, the absorption capacities reach 0.48 mol CO2 per mol of ionic liquid surfactant at 0.1 MPa and 25 °C. This work provides theoretical support for further CCUS-EOR research and the application of ionic liquid surfactants.

Coarse-grain molecular dynamics simulation framework to unravel the interactions of surfactants on silica surfaces for oil recovery

A coarse-grained molecular dynamics (CG-MD) framework, based on the MARTINI 3.0 model, was developed to characterise the interactions between surfactants and oil-silica substrates to resemble chemical enhanced oil recovery (EOR) processes. Previous computational studies, at the atomistic scale, addressed interactions between surfactants and oil over diverse surfaces. Even though simulations provided significant information involved throughout different stages of oil extraction from surfaces, atomistic scale simulations fail when approaching the time and size scale required to address the surfactant phase behaviour that can also impact the oil detachment. Our coarse-grained model aims to overcome the lack of computer approaches that can tackle the surfactant self-assembly and the formation of ordered structures in the removal of oil from silica substrates. A new MARTINI 3.0 coarse-grain framework to model silica surfaces and aqueous solutions of CiEj and C16TAB surfactants is presented. Coarse-grained simulations entailing a silica surface, covered by dodecane or eicosane were brought in contact with aqueous solutions of C16TAB and four nonionic CiEj (C8E6, C8E12, C12E6, C16E12) surfactants to resemble EOR processes with a size/time scale several orders of magnitude larger than previous simulations. The impact of concentration and hydrophilic-lipophilic balance (HLB) of surfactants on the detachment of dodecane and eicosane from the silica surface was evaluated by visual inspection of the simulation snapshots and the evolution of the solvent accessible surface areas (SASA). In contrast with previous atomistic simulations, nonionic surfactants seem the best candidates for an optimal oil removal from silica-based surfaces whereas the presence of charged moieties hinders the process. Diluted nonionic CE aqueous solutions were shown to be the most effective solutions, unlike more concentrated ones. When compared with dodecane, eicosane was less prone to be removed from the silica surface due to the increased alkyl chain length. Our study demonstrates that not only the surfactant nature but also the phase behaviour, clearly impact the detachment of oil from silica surfaces. This is an important aspect to consider for a proper choice of surfactants in EOR processes, that is only attainable through a coarse-grained framework.

Fabrication of ultrafiltration membranes with improved antifouling and antibacterial capability by surface modification of quaternary ammonium

To minimize the organic/biological contamination, polymeric membranes with tertiary amine groups were synthesized and its surface was modified to obtain three types of quaternary ammonium modified ultrafilters. The antifouling and antibacterial properties of all prepared ultrafilters were studied. The performances differences of ultrafiltration membranes with different alkyl chain lengths of quaternary ammonium salts were explored. The results show that the increase of alkyl chain length of quaternary ammonium salts and the introduction of hydroxyl groups can effectively improve the permeability and anti-pollution performance of ultrafiltration membranes. After one cycle of Bovine serum albumin solution filtration test, the flux recovery ratio of the modified membrane is twice as much as that of the initial membrane, while the flux recovery ratio of the initial ultrafiltration membrane is only 36.6%. At the same time, the modified membrane has excellent antibacterial properties and water flux stability, which is conducive to the long-term use of the membrane.

Liquid Crystalline Mixtures with Induced Polymorphic Smectic Phases Targeted for Energy Investigations

In this study, 4-Biphenyle-4′-alkyloxybenzenamines were synthesized as a homologous series of liquid crystals based on the biphenyl moiety. Their mesomorphic and optical properties were examined for both pure and mixed components. Elemental analysis, NMR, and FT-IR spectroscopy were used to determine the molecular structures of the developed materials. Using differential scanning calorimetry (DSC), the mesophase transitions were studied, and polarized optical microscopy was used to identify the textures of the mesophases (POM). The obtained results showed that all compounds are dimorphic and only have smectic B (SmB) and smectic A (SmA) phases for all terminal side chains, which are enantiotropic. With variably proportionated terminal side chains and a focus on the mesomorphic temperature range, binary phase diagrams were constructed and an induced smectic C phase was achieved (SmC). It was found that terminal chain length affects both conformation and steric impact in the mixed states. The absorption and fluorescence emission spectra of pure as well as their binary mixtures liquid crystalline films were recorded to investigate the optical and photophysical properties. It was noted that, with the increase in alkyl chain length, the energy bandgap increases from 3.24 eV (for C6H13) to 3.37 eV (for C16H33) and charge carrier lifetime decreases, ascribing to the increase in stearic hindrance causing, consequently, the faster decay of charge carriers.

Regulating the Alkyl Chain Length of Quaternary Ammonium Salt to Enhance the Inkjet Printing Performance on Cationic Cotton Fabric with Reactive Dye Ink.

Cationic modification of cotton fabric was an effective way to improve the inkjet printing performance with reactive dye ink. However, there were few research studies that focused on the effect of the cationic agent structure, especially the alkyl chain length of the quaternary ammonium salt (QAS) cationic modifier, on the K/S value, dye fixation, and diffusion of inkjet-printed cotton fabric. In our work, different alkyl chain lengths of QAS were synthesized, and the inkjet printing performance of cationic cotton fabrics treated with different QASs was investigated. Compared with untreated cotton fabric, the K/S value and dye fixation of cationic cotton fabric treated with different QASs improved by 10.7 to 69.3% and 16.9 to 27.7%, respectively. With the increase in alkyl chain length of QAS, the interaction force between anionic reactive dyes and cationic QAS gradually increased mainly due to the fact that more N-positive ions on the quaternary ammonium group were exposed under the action of steric hindrance of alkyl chain length through the XPS spectrum. The electrostatic attraction between cationic cotton and reactive dye contributed to the diffusion of reactive dye into the fiber interior and enhanced the reaction probability of nucleophilic substitution reaction between monochlorotriazine reactive dye and the hydroxyl group of cotton fabric. The antibacterial result of the inkjet-printed cotton fabric indicated that when the alkyl chain length of QAS was higher than 8, the cationic cotton fabric obtained good antibacterial property.

Binary Mixtures of n-Tridecane with n-Alkylcyclohexanes: Density, Viscosity, and Speed of Sound within the Temperature Range (288.15 to 333.15) K

Measurements of the densities, viscosities, and speeds of sound of binary mixtures of n-tridecane and n-alkylcyclohexanes (methyl-, ethyl-, butyl-, pentyl-, heptyl-, octyl-, decyl-, and dodecylcyclohexanes) are reported at various mole fractions. Mixture densities, viscosities, and speeds of sound increased with a decrease in temperature and an increase in the component with the higher property value. Excess molar volumes (VmE’s) decreased with increasing alkyl chain length on the n-alkylcyclohexanes. The excess speeds of sound (cE’s) decreased as the n-alkyl chain length decreased until a minimum was reached for ethylcyclohexane, and then it increased for methylcyclohexane. For all molecules tested except methylcyclohexane, VmE’s and excess isentropic compressibilities (KsE’s) had the same sign, suggesting that the amount of space taken up by the molecules was influencing compressibility. Methylcyclohexane, however, had the largest positive VmE, but its excess compressibility was negative and close to zero. Its extra space was not more compressible. The VmE’s, cE’s, and viscosity deviations for n-tridecane mixtures fell between those reported for n-dodecane and n-hexadecane. These data and trends can be used by fuel researchers who are formulating mixtures to represent various fuels.

Effects of CO2-philic nonionic polyether surfactants on miscibility behaviors of CO2–hydrocarbon systems: Experimental and simulation approach

Accomplishing the high miscibility of CO2 and crude oil under reservoir conditions is critical for achieving the most efficient recovery process by CO2 injection into low-porosity and low-permeability reservoirs. In this study, the effects of nonionic polyether surfactants on improving the miscibility of CO2–hydrocarbon systems were investigated. The influence of polyether structure on the reduction of miscibility pressure between CO2 and hydrocarbons was evaluated by experiments. The results showed that the miscibility pressure of CO2 and C16 could be reduced by 4.8% to 10.2% after adding 0.04 mol polyethers with different structures per kg CO2. The capability of polyethers to improve oil–gas miscibility exhibited a first growing then diminishing trend with increasing polyoxypropylene chain length and decreased with increasing alkyl chain length. Moreover, the microscopic influence mechanism of polyether on the miscible processes of CO2–hydrocarbon systems was investigated by molecular dynamics simulations. The miscible degree parameter was defined in the simulation to quantitatively estimate oil–gas miscibility. The distributions of different molecules and potential interactions during the miscible process were analyzed. The simulation results showed that the solubilization of CO2 molecules among polyoxypropylene chains in the oil phase caused by the local aggregation of nonionic polyether surfactants enhanced the vdW interactions between hydrocarbons and CO2 and then improved the oil–gas miscibility. Furthermore, simulation results suggested that the number of polyoxypropylene groups in the nonionic polyether surfactant should be maintained at 8 to achieve the highest amount of CO2 solubilization and the best potential in improving the oil–gas miscibility. The study results provide guidance for understanding the miscible behavior among CO2, additives, and hydrocarbons, as well as designing the appropriate additive structures for improving oil–gas miscibility.

Alkyl chain length of quaternized SBA-15 and solution conditions determine hydrophobic and electrostatic interactions for carbamazepine adsorption

Santa Barbara Amorphous-15 (SBA) is a stable and mesoporous silica material. Quaternized SBA-15 with alkyl chains (QSBA) exhibits electrostatic attraction for anionic molecules via the N+ moiety of the ammonium group, whereas its alkyl chain length determines its hydrophobic interactions. In this study, QSBA with different alkyl chain lengths were synthesized using the trimethyl, dimethyloctyl, and dimethyoctadecyl groups (C1QSBA, C8QSBA, and C18QSBA, respectively). Carbamazepine (CBZ) is a widely prescribed pharmaceutical compound, but is difficult to remove using conventional water treatments. The CBZ adsorption characteristics of QSBA were examined to determine its adsorption mechanism by changing the alkyl chain length and solution conditions (pH and ionic strength). A longer alkyl chain resulted in slower adsorption (up to 120 min), while the amount of CBZ adsorbed was higher for longer alkyl chains per unit mass of QSBA at equilibrium. The maximum adsorption capacities of C1QSBA, C8QSBA, and C18QSBA, were 3.14, 6.56, and 24.5 mg/g, respectively, as obtained using the Langmuir model. For the tested initial CBZ concentrations (2–100 mg/L), the adsorption capacity increased with increasing alkyl chain length. Because CBZ does not dissociate readily (pKa = 13.9), stable hydrophobic adsorption was observed despite the changes in pH (0.41–0.92, 1.70–2.24, and 7.56–9.10 mg/g for C1QSBA, C8QSBA, and C18QSBA, respectively); the exception was pH 2. Increasing the ionic strength from 0.1 to 100 mM enhanced the adsorption capacity of C18QSBA from 9.27 ± 0.42 to 14.94 ± 0.17 mg/g because the hydrophobic interactions were increased while the electrostatic attraction of the N+ was reduced. Thus, the ionic strength was a stronger control factor determining hydrophobic adsorption of CBZ than the solution pH. Based on the changes in hydrophobicity, which depends on the alkyl chain length, it was possible to enhance CBZ adsorption and investigate the adsorption mechanism in detail. Thus, this study aids the development of adsorbents suitable for pharmaceuticals with controlling molecular structure of QSBA and solution conditions.

Diffusion Measurements To Understand Dynamics and Structuring in Solutions Involving a Homologous Series of Ionic Liquids.

The self-diffusion coefficients of each of the components in mixtures containing pyridine and each of the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides in acetonitrile were determined using NMR diffusometry (i. e., Pulsed Gradient Spin Echo). The nature of solvation was found to change significantly with the proportion of salt in the mixtures. Increased diffusion coefficients (when corrected for viscosity) for the molecular components were observed with increasing proportion of ionic liquid and with increasing alkyl chain length on the cation. Comparison of the molecular solvents suggests increased interactions in solution of the pyridine with other components of the mixture, consistent with the proposed interactions shown previously to drive changes in reaction kinetics. Discontinuities were seen in the diffusion data for each species in solution across different ionic liquids between the hexyl and octyl derivatives, suggesting a change in the structuring in solution as the alkyl chain on the cation changes and demonstrating the importance of such when considering homologous series.

Synthesis and properties of alkyl glyceryl ether sulfonate

Abstract In this work, alkyl glyceryl ether sulfonates with two alkyl chain lengths were synthesised by etherification and sulfonation. The structures of these sulfonates were characterised by FTIR, 1H NMR and MS. Their characterisations were investigated for their surface properties and thermodynamic properties by surface tension, conductivity and fluorescence methods. The critical micelle concentration (CMC) of surfactants increases with increasing temperature and decreases with increasing alkyl chain length. The micellation process of alkyl glyceryl ether sulfonates is spontaneous and driven by entropy.

BMIm][BARF] imidazolium salt solutions in alkyl carbonate solvents: Structure and interactions

Solutions of weakly coordinating ionic liquids (ILs) in alkyl carbonates are gaining growing attention, as the latter are “green” solvents with high solvation power, but the phase behavior and structure of ILs in organic polar solvents are still poorly understood. Here, we study the interactions and nanoscale structure of 1‑butyl‑3-methylimidazolium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [BMIm][BARF], in three symmetrical alkyl carbonate solvents with increasing alkyl chain-length. Electrical conductivity and nuclear magnetic resonance measurements showed that [BMIm][BARF] was mostly undissociated in these solvents, especially at lower IL concentration. Small angle X-ray scattering patterns evidenced the presence of rod-like nanostructures in the IL/solvent mixtures. At higher IL concentration, [BMIm][BARF] is increasingly more dissociated in solvents with lower dielectric constant, as confirmed by analysis of the solvents’ carbonyl stretching band via Fourier transform infrared spectroscopy. This trend is opposite to that exhibited by BMIm ILs with less bulky counterions. The bulky BARF− is weakly coordinating and has no ability to give strong H-bonding, thus short-range anisotropic van der Waals forces are likely key in the interaction of the ion pairs. The slower self-diffusion of the ions in alkyl carbonates with lower dielectric constants might partially hinder close contact needed for self-assembly into local nano-sized structures. Overall, our results shed light on interactions and self-organization in imidazolium salt-alkyl carbonate mixtures, with potential impact in applicative fields spanning from batteries, catalysis and extraction, up to bio-applications (antimicrobial and bioengineering).

Chronic Exposure to Low Levels of Parabens Increases Mammary Cancer Growth and Metastasis in Mice.

Methylparaben (MP) and propylparaben (PP) are commonly used as food, cosmetic, and drug preservatives. These parabens are detected in the majority of US women and children, bind and activate estrogen receptors (ER), and stimulate mammary tumor cell growth and invasion in vitro. Hemizygous B6.FVB-Tg (MMTV-PyVT)634Mul/LellJ female mice (n = 20/treatment) were exposed to MP or PP at levels within the US Food and Drug Administration's "human acceptable daily intake." These paraben-exposed mice had increased mammary tumor volume compared with control mice (P < 0.001) and a 28% and 91% increase in the number of pulmonary metastases per week compared with the control mice, respectively (P < 0.0001). MP and PP caused differential expression of 288 and 412 mammary tumor genes, respectively (false discovery rate < 0.05), a subset of which has been associated with human breast cancer metastasis. Molecular docking and luciferase reporter studies affirmed that MP and PP bound and activated human ER, and RNA-sequencing revealed increased ER expression in mammary tumors among paraben-exposed mice. However, ER signaling was not enriched in mammary tumors. Instead, both parabens strongly impaired tumor RNA metabolism (eg, ribosome, spliceosome), as evident from enriched KEGG pathway analysis of differential mammary tumor gene expression common to both paraben treatments (MP, P < 0.001; PP, P < 0.01). Indeed, mammary tumors from PP-exposed mice had an increased retention of introns (P < 0.05). Our data suggest that parabens cause substantial mammary cancer metastasis in mice as a function of their increasing alkyl chain length and highlight the emerging role of aberrant spliceosome activity in breast cancer metastasis.

Effects of alkyl chain length on the interfacial, antibacterial, and antioxidative properties of erythorbyl fatty acid esters

Erythorbyl fatty acid esters (EFEs) are promising multifunctional food emulsifiers with antibacterial and antioxidative activities. Variations in the alkyl chain of EFEs may alter the physicochemical properties, affecting their multifunctional characteristics. Herein, the effect of alkyl chain length of EFEs on the multifunctionality was investigated by comparing the interfacial, antibacterial, and antioxidative activities of homologous series of EFEs with different saturated fatty acids (C10:0-C18:0). Interfacial tension measurement indicated that critical micelle concentration (CMC) decreased with increasing alkyl chain length, and erythorbyl myristate (EM, C14:0) with CMC of 1.2 mM and γCMC of 1.4 mN/m had the best interfacial properties among EFEs. The alkyl chain length of EFEs significantly influenced the antibacterial activity and EM showed the highest activity with minimum inhibitory concentrations ranging from 0.09 to 0.6 mM against Gram-positive bacteria. All EFEs exhibited radical scavenging activity and lipid oxidation inhibitory activity in oil-in-water emulsions, while the optimal alkyl chain for the antioxidative activity was observed in erythorbyl palmitate (C16:0). These findings will contribute to the practical applications of EFEs in food industry and the systematic investigation on the structure-properties relationships of other amphiphilic compounds.