Hexaethylene Glycol Research Articles

Molecular Dynamics Calculation of Interfacial Tension in a Two-Phase Liquid Hydrocarbon–Water–Surfactant System: From Rarefied to Superdense Surfactant Monolayer

A method is proposed for calculating low interfacial tension (IFT) based on molecular dynamics simulation of systems with superdense packing of surfactant molecules at the water–liquid hydrocarbon interface. The interfacial tension was calculated by the molecular dynamics method using the all-atom and coarse-grained models in water–alkane (decane, dodecane) two-phase systems in the presence of various individual surfactants. The following ionic and nonionic surfactants were considered: sodium dodecyl sulfate (SDS), cetyltrimethylammonium chloride (CTAC), sodium dodecylbenzenesulfonate (SDBS), sodium decet-6 sulfate C10E6SO4Na, hexaethylene glycol monodecyl ether (C10E6), triethylene glycol monononadecyl ether (C19E3), and octapropoxypentaethylene glycol monododecyl ether (C12P8E5). It was shown that the interfacial tension decreases to zero when surfactant adsorption increases to the limiting values.

Molecular Dynamics Study of the Green Solvent Polyethylene Glycol with Water Impurities.

Polyethylene glycol (PEG) is one of the environmentally benign solvent options for green chemistry. It readily absorbs water when exposed to the atmosphere. The Molecular Dynamics (MD) simulations of PEG200, a commercial mixture of low molecular weight polyethyelene glycol oligomers, as well as di-, tetra-, and hexaethylene glycol are presented to study the effect of added water impurities up to a weight fraction of 0.020, which covers the typical range of water impurities due to water absorption from the atmosphere. Each system was simulated a total of four times using different combinations of two force fields for the water (SPC/E and TIP4P/2005) and two force fields for the PEG and oligomer (OPLS-AA and modified OPLS-AA). The observed trends in the effects of water addition were qualitatively quite robust with respect to these force field combinations and showed that the water does not aggregate but forms hydrogen bonds at most between two water molecules. In general, the added water causes overall either no or very small and nuanced effects in the simulation results. Specifically, the obtained water RDFs are mostly identical regardless of the water content. The added water reduces oligomer hydrogen bonding interactions overall as it competes and forms hydrogen bonds with the oligomers. The loss of intramolecular oligomer hydrogen bonding is in part compensated by oligomers switching from inter- to intramolecular hydrogen bonding. The interplay of the competing hydrogen bonding interactions leads to the presence of shallow extrema with respect to the water weight fraction dependencies for densities, viscosities, and self-diffusion coefficients, in contrast to experimental measurements, which show monotonous dependencies. However, these trends are very small in magnitude and thus confirm the experimentally observed insensitivity of these physical properties to the presence of water impurities.

Chiral hybrid aza-oxa-terpene-based macrocycles as selective extractants for Pd(II) and Au(III)

A series of novel hybride chiral macrocyclic compounds is described. The macrocyclic core of the new compounds is decorated with monoterpene fragments and includes 2 imine nitrogens and 2 tertiary amine nitrogens of the N,N-piperazine linkage as well as several repeating ethyleneoxy units resembling those of crown ethers. The macrocyclic compounds are prepared in moderate preparative yield (16–31%) upon treatment of a mixture of bis(α-amine oximes) and α,ω-dichloro derivatives of tri-, tetra- and hexa-ethylene glycol with sodium methylsulfinylmethylide. Chemical structure of the new macrocycles was established by a complex of spectroscopic techniques and X-ray analysis. The new macrocyclic compounds demonstrate remarkable selectivity with respect to Pd(II) and Au(III) and are able to efficiently extract these metals from acidic media containing a complex mixture of alkali metals, 3d-elements and noble metals. The features of conformational behavior, the ability to form complexes and the selectivity of extraction were studied using quantum chemical calculations at the DFT level. Based on the data obtained, a consistent scheme has been formulated to explain the features of extraction and the extraction selectivity of individual macrocycles.

Non-targeted analysis based on quantitative prediction and toxicity assessment for emerging contaminants in tire particle leachates

Non-targeted analysis (NTA) has great potential to screen emerging contaminants in the environment, and some studies have conducted in-depth investigation on environmental samples. Here, we used a NTA workflow to identify emerging contaminants in used tire particle (TP) leachates, followed by quantitative prediction and toxicity assessment based on hazard scores. Tire particles were obtained from four different types of automobiles, representing the most common tires during daily transportation. With the instrumental analysis of TP leachates, a total of 244 positive and 104 negative molecular features were extracted from the mass data. After filtering by a specialized emerging contaminants list and matching by spectral databases, a total of 51 molecular features were tentatively identified as contaminants, including benzothiazole, hexaethylene glycol, 2-hydroxybenzaldehyde, etc. Given that these contaminants have different mass spectral responses in the mass spectrometry, models for predicting the response of contaminants were constructed based on machine learning algorithms, in this case random forest and artificial neural networks. After five-fold cross-validation, the random forest algorithm model had better prediction performance (MAECV = 0.12, Q2 = 0.90), and thus it was chosen to predict the contaminant concentrations. The prediction results showed that the contaminant at the highest concentration was benzothiazole, with 4,875 μg/L in the winter tire sample. In addition, the joint toxicity assessment of four types of tires was conducted in this study. According to different hazard levels, hazard scores increasing by a factor 10 were developed, and hazard scores of all the contaminants identified in each TP leachate were summed to obtain the total hazard score. All four tires were calculated to have relatively high risks, with winter tires having the highest total hazard score of 40,751. This study extended the application of NTA research and led to the direction of subsequent targeting studies on highly concentrated and toxic contaminants.

Impact of Oligoether Side-Chain Length on the Thermoelectric Properties of a Polar Polythiophene.

Conjugated polymers with oligoether side chains make up a promising class of thermoelectric materials. In this work, the impact of the side-chain length on the thermoelectric and mechanical properties of polythiophenes is investigated. Polymers with tri-, tetra-, or hexaethylene glycol side chains are compared, and the shortest length is found to result in thin films with the highest degree of order upon doping with the p-dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). As a result, a stiff material with an electrical conductivity of up to 830 ± 15 S cm-1 is obtained, resulting in a thermoelectric power factor of about 21 μW m-1 K-2 in the case of as-cast films. Aging at ambient conditions results in an initial decrease in thermoelectric properties but then yields a highly stable performance for at least 3 months, with values of about 200 S cm-1 and 5 μW m-1 K-2. Evidently, identification of the optimal side-chain length is an important criterion for the design of conjugated polymers for organic thermoelectrics.

Free energy decompositions illuminate synergistic effects in interfacial binding thermodynamics of mixed surfactant systems.

Recent vibrational sum frequency generation spectroscopic experiments [Sengupta et al., J. Phys. Chem. Lett. 13, 11391-11397 (2022)] demonstrated synergistic interfacial adsorption effects between the anionic dodecyl sulfate (DS-) and the polar, but charge-neutral hexaethylene glycol monododecyl ether (C12E6), surfactants. In this study, the interfacial adsorption thermodynamics underlying these synergistic effects are analyzed through free energy decompositions. A general decomposition method utilizing alchemical intermediate states is outlined. Combining free energy decompositions with the potential distribution theorem illuminates the statistical interpretations of correlated effects between different system components. This approach allows for the identification of the physical effects leading to synergistic adsorption thermodynamics of DS- binding to the air-C12E6-water interface. The binding properties are found to result from a combination of effects predominantly including energetic van der Waals stabilization between DS- and C12E6, as well as competing energetic and entropic effects due to changes in the interfacial water structure as a result of introducing a C12E6 monolayer into the bare air-water interface.

Adsorption of flexible linker for siRNA on carbon nanotube using pyrene anchor: Molecular dynamics simulation

Carbon nanotubes are considered an effective nanoplatform for drug delivery, including therapeutic nucleic acids such as small interfering RNAs (siRNAs), which are used in cancer therapy. In this work, a noncovalent immobilization of a single-stranded oligonucleotide (with 17 nucleotides in length) on the single-walled carbon nanotube (SWNT) surface using a pyrene molecule as an anchor is simulated by molecular dynamics method. This oligonucleotide design supposes the following binding with siRNA ends to provide its keeping near the nanotube surface. In the model, the pyrene molecule is covalently conjugated to the oligonucleotide through an hexaethylene glycol oligomer (EG)6 and attached to the SWNT’s surface by means of π-π stacking interaction. Structures of the complex and the binding energy of pyrene in the complex with SWNT are determined. Two possible orientations of the oligonucleotide arrangement relative to SWNT were considered: mutually perpendicular orientation and arrangement of an oligonucleotide along the nanotube. In both cases, the pyrene-terminated flexible polyethylene glycol linker plays an important role in keeping the oligonucleotide near the nanotube surface and provides sufficiently rapid adsorption of the biopolymer on SWNT, which is important for the creation of new drug delivery systems into the cell and for biosensor design.

Interface Adsorption versus Bulk Micellization of Surfactants: Insights from Molecular Simulations.

Surfactants play essential roles in many commonplace applications and industrial processes. Although significant progress has been made over the past decades with regard to model-based predictions of the behavior of surfactants, important challenges have remained. Notably, the characteristic time scales of surfactant exchange among micelles, interfaces, and the bulk solution typically exceed the time scales currently accessible with atomistic molecular dynamics (MD) simulations. Here, we circumvent this problem by introducing a framework that combines the general thermodynamic principles of self-assembly and interfacial adsorption with atomistic MD simulations. This approach provides a full thermodynamic description based on equal chemical potentials and connects the surfactant bulk concentration, the experimental control parameter, with the surfactant surface density, the suitable control parameter in MD simulations. Self-consistency is demonstrated for the nonionic surfactant C12EO6 (hexaethylene glycol monododecyl ether) at an alkane/water interface, for which the adsorption and pressure isotherms are computed. The agreement between the simulation results and experiments is semiquantitative. A detailed analysis reveals that the used atomistic model captures well the interactions between surfactants at the interface but less so their adsorption affinities to the interface and incorporation into micelles. Based on a comparison with other recent studies that pursued similar modeling challenges, we conclude that the current atomistic models systematically overestimate the surfactant affinities to aggregates, which calls for improved models in the future.

Synthesis and chemical properties of π‐conjugated polyphenylenes bearing o‐diaminobenzene and cis‐platin units

Abstractπ‐Conjugated polyphenylenes (PPs) consisting of 2,3‐diaminobenzene‐1,4‐diyl and 9,9‐bis(hexaethylene glycol monomethyl ether)fluorene‐2,7‐diyl (polymer‐1) or 9,9‐bis(6‐N,N,N‐trimethylammoniumhexyl bromide)fluorene‐2,7‐diyl (polymer‐2) units were synthesized via the Suzuki−Miyaura polycondensation. The reactions of polymers 1 and 2 with K2PtCl4 yielded the corresponding PPs polymer‐1(Pt) and polymer‐2(Pt), respectively, bearing cis‐platin skeletons. GPC measurements revealed that the Mn values of polymers 1 and 2 were 21,500 and 4800 and Mw values were 30,600 and 5200, respectively. Polymers 1(Pt) and 2(Pt) exhibited photoluminescence (PL) in solution, whose quantum yields of PL were improved compared to those of polymers 1 and 2. The emission wavelength of polymer‐1 in solution shifted to longer wavelengths with increasing solvent dielectric constants. The solvatochromic behavior of the polymer was investigated by the Lippert−Mataga method using the PL data. Cyclic voltammetry analysis indicated that the amino groups of polymers 1 and 2 underwent electrochemical oxidation in a two‐step process, and the Pt metal centers of polymers 1(Pt) and 2(Pt) were redox active.

On the Behavior of the Ethylene Glycol Components of Polydisperse Polyethylene Glycol PEG200.

Molecular dynamics (MD) simulations are reported for [polyethylene glycol (PEG)200], a polydisperse mixture of ethylene glycol oligomers with an average molar weight of 200 g·mol-1. As a first step, available force fields for describing ethylene glycol oligomers were tested on how accurately they reproduced experimental properties. They were found to all fall short on either reproducing density, a static property, or the self-diffusion coefficient, a dynamic property. Discrepancies with the experimental data increased with the increasing size of the tested ethylene glycol oligomer. From the available force fields, the optimized potential for liquid simulation (OPLS) force field was used to further investigate which adjustments to the force field would improve the agreement of simulated physical properties with experimental ones. Two parameters were identified and adjusted, the (HO)-C-C-O proper dihedral potential and the polarity of the hydroxy group. The parameter adjustments depended on the size of the ethylene glycol oligomer. Next, PEG200 was simulated with the OPLS force field with and without modifications to inspect their effects on the simulation results. The modifications to the OPLS force field significantly decreased hydrogen bonding overall and increased the propensity of intramolecular hydrogen bond formation at the cost of intermolecular hydrogen bond formation. Moreover, some of the tri- and more so tetraethylene glycol formed intramolecular hydrogen bonds between the hydroxy end groups while still maintaining strong intramolecular interactions with the ether oxygen atoms. These observations allowed the interpretation of the obtained RDFs as well as structural properties such as the average end-to-end distances and the average radii of gyration. The MD simulations with and without the modifications showed no evidence of preferential association of like-oligomers to form clusters nor any evidence of long-range ordering such as a side-by-side stacking of ethylene glycol oligomers. Instead, the simulation results support the picture of PEG200 being a random mixture of its ethylene glycol oligomer components. Finally, additional MD simulations of a binary mixture of tri-and hexaethylene glycol with the same average molar weight as PEG200 revealed very similar structural and physical properties as for PEG200.

Surfactant induced gelation of TEMPO-oxidized cellulose nanofibril dispersions probed using small angle neutron scattering.

In this work, we studied TEMPO-oxidized cellulose nanofibril (OCNF) suspensions in the presence of diverse surfactants. Using a combination of small angle neutron scattering (SANS) and rheology, we compared the physical properties of the suspensions with their structural behavior. Four surfactants were studied, all with the same hydrophobic tail length but different headgroups: hexaethylene glycol mono-n-dodecyl ether (C12EO6, nonionic), sodium dodecyl sulfate (SDS, anionic), cocamidopropyl betaine (CapB, zwitterionic), and dodecyltrimethylammonium bromide (DTAB, cationic). Contrast variation SANS studies using deuterated version of C12EO6 or SDS, or by varying the D2O/H2O ratio of the suspensions (with CapB), allowed focusing only on the structural properties of OCNFs or surfactant micelles. We showed that, in the concentration range studied, for C12EO6, although the nanofibrils are concentrated thanks to an excluded volume effect observed in SANS, the rheological properties of the suspensions are not affected. Addition of SDS or CapB induces gelation for surfactant concentrations superior to the critical micellar concentration (CMC). SANS results show that attractive interactions between OCNFs arise in the presence of these anionic or zwitterionic surfactants, hinting at depletion attraction as the main mechanism of gelation. Finally, addition of small amounts of DTAB (below the CMC) allows formation of a tough gel by adsorbing onto the OCNF surface.

Fluorescence turn‐off and turn‐on sensors of Zn2+ based on π‐conjugated poly(aryleneethynylene)s comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐dialkylfluorene units

Abstractπ‐Conjugated poly(aryleneethynylene)s, polymer‐1 comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐dihexylfluorene units and polymer‐2 comprising alloxazine‐6,9‐diyl and 2,7‐diethynylene‐9,9‐bis(hexaethylene glycol monomethyl ether)fluorene units, were synthesized via Pd‐complex‐catalyzed condensation reactions. The Mn values of polymers 1 and 2 were 5200 and 8100, and Mw values were 24,900 and 69,700, respectively. The onset wavelengths of the polymers were longer wavelength than that of the monomer in the UV–vis spectra, confirming the π‐conjugated system along the polymer chain. The photoluminescence (PL) of the polymers decreased with the addition of Zn2+ until an equimolar amount and then increased upon the addition of an excess amount of Zn2+, which enabled the detection of Zn2+ over a wider concentration range (10−6–10−4 M) than those of the previously reported Zn2+ sensors. The PL intensity upon the addition of excess Zn2+ was greater in polymer‐2 than in polymer‐1 because the Zn2+‐alloxazine complex in polymer‐2 was stabilized by its interaction with the oligoether side chain. The difference in the PL response of the polymers to metal ions such as Cu+, Cu2+, and Zn2+ was analyzed using the Stern–Volmer and Benesi–Hildebrand methods.

A DFT study on the reaction pathway involved in the metal‐ion‐templated synthesis of benzo‐21‐crown‐7(B21C7) from catechol and hexaethylene glycol ditosylate in the presence of base

AbstractThis present work explores the mechanism of the alkali metal‐ion (Na+ and K+) aided benzo‐21‐crown‐7(B21C7) formation from catechol and hexaethylene glycol di‐p‐toluenesulfonate in the presence of base [Correction added on 29 December 2022, after first online publication: benzo‐21‐crown‐7(f) has been corrected to benzo‐21‐crown‐7(B21C7).]. The density functional theory (DFT)‐based studies (in gas‐phase and in acetonitrile) have identified two SN2 steps along the reaction path, where each step is characterized by an energy barrier due to the presence of a transition state (TS). The metal‐ion template effect eases the binding between the catechol oxygen and the carbon atom holding the tosyl leaving group. This metal‐ion framework facilitates the cyclization process, which is responsible for the better yield of the crown ether. In case of K+‐coordinated system in solution, the TS dipole moment value for this step is 10 Debye higher than the corresponding reactant, whereas for Na+‐coordinated system, this difference is much smaller (~7.5 Debye). A comparison of the barrier heights of this intramolecular SN2 step in acetonitrile shows a higher value for Na+ ion system (30 kcal/mol) than that of K+‐coordinated system (22 kcal/mol). Expectedly, a higher rate constant for the cyclization has been found from the kinetics study of the latter, which is in‐line with the reported experimental results. Additionally, we have also explored the consequences of the involvement of a second metal ion in the process, a possibility, which was predicted earlier for large ring‐sized crown ethers.

Observation of Strong Synergy in the Interfacial Water Response of Binary Ionic and Nonionic Surfactant Mixtures.

Interfacial vibrational footprints of the binary mixture of sodium dodecyl sulfate (SDS) and hexaethylene glycol monododecyl ether (C12E6) were probed using heterodyne detected vibrational sum frequency generation (HDVSFG). Our results show that in the presence of C12E6 at CMC (70 μM) the effect of SDS on the orientation of interfacial water molecules is enhanced 10 times compared to just pure surfactants. The experimental results contest the traditional Langmuir adsorption model predictions. This is also evidenced by our molecular dynamics simulations that show a remarkable restructuring and enhanced orientation of the interfacial water molecules upon DS- adsorption to the C12E6 surface. The simulations show that the adsorption free energy of DS- ions to a water surface covered with C12E6 is an enthalpy-driven process and more attractive by ∼10 kBT compared to the adsorption energy of DS- to the surface of pure water.

Zeptoliter DNA Origami Reactor to Reveal Cosolute Effects on Nanoconfined G-Quadruplexes.

Cellular environments such as nanoconfinement and molecular crowding can change biomolecular properties. However, in nanoconfinement, it is extremely challenging to investigate effects of crowding cosolutes on macromolecules. By using optical tweezers, here, we elucidated the effects of hexaethylene glycol (HEG) on the mechanical stability of a telomeric G-quadruplex (GQ) in a zeptoliter DNA origami reactor (zepto-reactor). When HEG molecules were introduced in the GQ-containing zepto-reactor at different positions, we found that the GQ species split into two equilibrated populations, reflecting diverse effects of the oligoethylene glycol on the GQ via either a long-range dehydration effect or direct interactions. When the number of HEG molecules was increased, the stability of the GQ unexpectedly decreased, suggesting that the direct destabilizing interaction between the GQ and HEG is dominating over the long-range stabilizing dehydration effects of the HEG in hydrophilic nanocavities. These findings indicate that a nanoconfined environment can alter regular effects of cosolutes on biomacromolecules.

Simulation of surfactant adsorption at liquid-liquid interface: What we may expect from soft-core models?

The present work attempts to systematically explore the surfactant sorption at liquid-liquid interfaces with coarse-grained models targeting thermodynamic properties of reference liquid solutions. We employ dissipative particle dynamics with soft-core forcefield tested against experimental data on micellization of surfactants in water, and the previous results are reproduced in this work. We consider three different nonionic surfactants: hexaethylene glycol monododecyl ether (C12E6), 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol) known as Triton X-100 (TX-100), and two alkyl glucoside surfactants (CnG1) with n-alkane tail fragments and a saccharide hydrophilic head at decane-water and toluene-water interfaces. For TX-100, we composed a model based on the literature forcefield and found good agreement with the experimental critical micelle concentrations (CMCs). The head-head interactions are of different origins for different surfactant groups: entropic repulsion between ethylene oxide chains of C12E6 and TX-100, and more chemically specific and complex interactions between the maltose heads of alkyl glucosides. We interpret our results with the Redlich-Peterson equation of monolayer adsorption in order to relate the adsorption to the bulk concentration of the surfactant and the interfacial tension. The densities of the adsorbed monolayer at CMC mostly agree with the experimental data, and a reasonable agreement was obtained for the interfacial tension at CMC. At the same time, we found significant discrepancies between the simulated and experimental adsorption isotherms. We explain them by the oversimplified forcefield: when the parameters are fitted to the free energies of bulk solutions, they may not correctly reproduce the interfacial free energies.

Sensing performance of metal-ion sensors based on polyfluorenes bearing N1-Alkylcytosine, oligoether, and alkylammonium side chains

π-Conjugated polyfluorenes bearing 6- N 1 -cytosinehexyl and hexaethylene glycol monomethyl ether side chains ( polymer-1 ) and 3- N 1 -cytosinepropyl and 3- N , N , N -trimethylammoniumpropyl bromide side chains ( polymer-2 ) were synthesized via the Suzuki-Miyaura coupling reactions. GPC measurements suggested that the M n values of polymers 1 and 2 were 22,900 and 8,510, whereas their M w values were 32,100 and 8,740, respectively. The metal-ion sensing behaviors of the polymers for Na + , Cu + , Cu 2+ , Fe 3+ , Pd 2+ , and Ag + , in an organic solvent and water were investigated by monitoring the decrease in the photoluminescence (PL) intensity upon the addition of a metal ion. The sensing performance of polymers depends on the polymer structure. Polymer-1 could detect Cu + , Cu 2+ , and Pd 2+ at the micro-molar level. The Benesi–Hildebrand method using PL quenching data was available to investigate the association behavior between the cytosine groups of the polymers and metal salts. The mechanism of PL quenching with polymer metal complexation was also discussed. • A Polyfluorene bearing N 1 -alkylcytosine and oligoether side chains was obtained. • The metal complexes of the polymer interacted with oligoether side chain. • Polymer photoluminescence was decreased upon the addition of metal ions. • The polymer acted as a highly sensitive sensor for metal salts.

Characterization of the composition of plant protection products in different formulation types employing suspect screening and unknown approaches

BACKGROUNDPlant protection products (PPPs) are used extensively in agriculture to control crops. These PPPs, which may be found in different types of formulations, are composed of a designated pesticide (active principle) and other inactive ingredients as co‐formulants. They perform specific functions in the formulation, as solvents, preservatives or antifreeze agents, among others.RESULTSA research technique based on ultra‐high‐performance liquid chromatography (UHPLC) coupled to a Quadrupole‐Orbitrap mass analyzer was successfully applied to characterize the composition of six different PPPs in terms of the presence of co‐formulants and types of formulations: emulsifiable concentrate (EC), emulsion in water (EW), suspension concentrate and water‐dispersible granule. These PPPs (FLINT MAX, MASSOCUR 12.5 EC, IMPACT EVO, TOPAS, LATINO and IMPALA STAR) had antifungal activity, containing one triazole compound as active principle (tebuconazole, penconazole, myclobutanil, flutriafol or fenbuconazole, respectively). Non‐targeted approaches, applying suspect and unknown analysis, were carried out and ten compounds were identified as potential co‐formulants. Six (glyceryl monostearate, 1‐monopalmitin, dimethyl sulfoxide, N,N‐dimethyldecanamide, hexaethylene glycol and 1,2‐benzisothiazol‐3(2H)‐one) were confirmed by injecting analytical standards. Finally, these compounds were quantified in the PPPs.CONCLUSIONThe current study allowed for detecting co‐formulants in a wide range of concentrations, between 0.04 (dimethyl sulfoxide) and 19.00 g L−1 (glyceryl monostearate), highlighting the feasibility of the proposed analytical methodology. Moreover, notable differences among the types of formulations of PPPs were achieved, revealing that EC and EW were the formulations that contained the largest number of co‐formulants (four out of six detected compounds). © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pseudomorphic synthesis of bimodal porous silica microspheres for size-exclusion chromatography of small molecules

In this work, mesoporous silica microspheres with bimodal porous structures for size exclusion chromatography (SEC) supports were synthesized via a pseudomorphic transformation method by using 3.5 and 5 μm commercial silica particles as sources and cetyltrimethylammonium bromide (CTAB) as a template. The effects of the synthetic conditions on the pore size distribution were examined, including the temperature, reaction time and the molar ratio of SiO2:NaOH. Bimodal porous silicas (BPSs) with pore sizes of 3.01 and 12.80 nm were obtained with SiO2:NaOH:CTAB:H2O=1:0.1:0.1:20 at 80 °C for 24 h. The BPSs were bonded with diol groups to produce a stationary phase for SEC. The column performance was evaluated with three types of samples, namely, dextran (70 KDa-62 Da), polyethene glycol (PEG) (20 KDa-32 Da) and three biomolecules (36 KDa-1.36 KDa). The column that was packed with a 3.5 μm stationary phase showed excellent resolution for molecular weights of less than 1 KDa with high column efficiency. Carbohydrate samples (dextran (MW=1296), dextran (MW=972), sucrose (MW=342), glucose (MW=180) and glycerol (MW=92)) were separated. Heptaethylene glycol, hexaethylene glycol, pentaethylene glycol, tetraethylene glycol, triethylene glycol, and diethylene glycol were resolved in a PEG200 sample. In summary, this work shows the advantages of bimodal mesopores in SEC for small molecules less than 1 kDa. In the pseudomorphic synthesis, the pore size can be regulated by template micelles. Thus, the development SEC supports with high accuracy for a specified molecular weight range is expected since the pore size can be regulated by the surfactant template.

Highly fluorescent polyethylene glycol-ascorbic acid complex for imaging and antimicrobial therapeutics

In this report, a facile and eco-friendly method was developed to synthesize a potent antimicrobial agent, effective against fungus, bacteria, and virus. The biocompatible FDA approved polymer, polyethylene glycol (PEG), has been modified by ascorbic acid to form fluorescent polyethylene glycol-ascorbic acid complex (FL PEG AA). The flourescence of FL PEG AA complex could be tuned from green to red in the visible range with varying ascorbic acid(AA) concentrations. The Density Functional Theory (DFT) and the Time-Dependent Density Functional Theory (DT-DFT) on ascorbic acid–monoethylene glycol and ascorbic acid–hexaethylene glycol studies were performed to understand the electronic and bonding nature of FL PEG-ascorbic acid (FL PEG AA) system. The emission of FL PEG AA can be ascribed to the integrated core of FL PEG AA through strong hydrogen-bonding interactions. The fluorescence of FL PEG AA was successfully applied to understand its cellular uptake by breast cancer cells. The FL PEG AA complex showed significant inhibition of growth, when tested against fungus (Candida albicans), bacteria: gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) and the virus (Bacteriophage lambda). The antimicrobial activity of the FL PEG AA system supports the application of this novel formulation as a potent antimicrobial agent. Due to its viscous physical nature, the FL PEG AA complex could be applied as a coating agent or aerosol spray.