Molecules In Aqueous Solution Research Articles

Agglomeration of Coniferyl Alcohol Molecules in Aqueous Solutions under Normal and Supercritical Conditions

Agglomeration of Coniferyl Alcohol Molecules in Aqueous Solutions under Normal and Supercritical Conditions

Peculiarities of structure in aqueous electrolyte solutions and specificity of hydration effects

A new approach to the hydration theory in aqueous solutions of electrolytes is developed. We show that the formation energy of one polarization complex is less than the thermal noise energy, as a result, polarization complexes are not stable. The notion of the effective polarization complex is introduced. It is connected with the concept of contraction of aqueous electrolyte solutions and certifies that the effective hydration number z does not exceed 3÷4. This value agrees with the estimates obtained from the self-diffusion coefficients of ions and water molecules in aqueous solutions of electrolytes. We propose new theories for the kinematic shear viscosity of electrolyte solutions and self-diffusion of ions and water molecules in them. They have nothing in common with the activation approach, with the existence of voids in the water structure and with the quasi-Brownian character of ions displacements. We show that the kinematic shear viscosity is described by the formula which is typical for pure water and other argon-like liquids. The special attention is focused on the determination of a particle radii. The self-diffusion coefficients of water molecules and ions are considered to be the sums of two contributions, one of which has Einstein-like type and another is responsible for the collective drift in the fluctuation hydrodynamic field. We show that values of the self-diffusion and shear viscosity coefficients are inherently consistent with each other.

Stabilizing MXene by Hydration Chemistry in Aqueous Solution

AbstractMXenes attract interest in diverse fields but suffer from fast structural degradation by attacking of dissolved oxygen and water molecules in aqueous solution. This drawback hinders the long‐term storage, applications and understanding of the chemical nature of MXenes. Herein, we report a cost‐effective and environmentally sustainable way for long‐term storage of MXenes in aqueous solution by hydration chemistry of nontoxic inorganic salts. The attacking of MXene by free water and dissolved oxygen molecules is inhibited by decreasing the water activity, which simultaneously lowers the dissolved oxygen concentration, of saline solution. As a result, the storage life of MXene can be prolonged to up to 400 days at ambient conditions without loss of intrinsic surface chemistry and bulk carrier properties. Over 90 % of salt protectant can be recycled by simply evaporating the final waste liquor after fully extracting the MXene to minimize the waste discharge and processing cost. This work offers a commercializable approach with high cost‐effectiveness, processing sustainability and environmental benefit for extending the shelf life of MXenes.

Stabilizing MXene by Hydration Chemistry in Aqueous Solution.

MXenes attract interest in diverse fields but suffer from fast structural degradation by attacking of dissolved oxygen and water molecules in aqueous solution. This drawback hinders the long-term storage, applications and understanding of the chemical nature of MXenes. Herein, we report a cost-effective and environmentally sustainable way for long-term storage of MXenes in aqueous solution by hydration chemistry of nontoxic inorganic salts. The attacking of MXene by free water and dissolved oxygen molecules is inhibited by decreasing the water activity, which simultaneously lowers the dissolved oxygen concentration, of saline solution. As a result, the storage life of MXene can be prolonged to up to 400 days at ambient conditions without loss of intrinsic surface chemistry and bulk carrier properties. Over 90 % of salt protectant can be recycled by simply evaporating the final waste liquor after fully extracting the MXene to minimize the waste discharge and processing cost. This work offers a commercializable approach with high cost-effectiveness, processing sustainability and environmental benefit for extending the shelf life of MXenes.

Carbamoyl phosphate and its substitutes for the uracil synthesis in origins of life scenarios

The first step of pyrimidine synthesis along the orotate pathway is studied to test the hypothesis of geochemical continuity of protometabolic pathways at the origins of life. Carbamoyl phosphate (CP) is the first high-energy building block that intervenes in the in vivo synthesis of the uracil ring of UMP. Thus, the likelihood of its occurrence in prebiotic conditions is investigated herein. The evolution of carbamoyl phosphate in water and in ammonia aqueous solutions without enzymes was characterised using ATR-IR, 31P and 13C spectroscopies. Carbamoyl phosphate initially appears stable in water at ambient conditions before transforming to cyanate and carbamate/hydrogenocarbonate species within a matter of hours. Cyanate, less labile than CP, remains a potential carbamoylating agent. In the presence of ammonia, CP decomposition occurs more rapidly and generates urea. We conclude that CP is not a likely prebiotic reagent by itself. Alternatively, cyanate and urea may be more promising substitutes for CP, because they are both “energy-rich” (high free enthalpy molecules in aqueous solutions) and kinetically inert regarding hydrolysis. Energy-rich inorganic molecules such as trimetaphosphate or phosphoramidates were also explored for their suitability as sources of carbamoyl phosphate. Although these species did not generate CP or other carbamoylating agents, they exhibited energy transduction, specifically the formation of high-energy P–N bonds. Future efforts should aim to evaluate the role of carbamoylating agents in aspartate carbamoylation, which is the following reaction in the orotate pathway.

A highly sensitive and multi-responsive Tb-MOF fluorescent sensor for the detection of Pb2+, Cr2O72−, B4O72−, aniline, nitrobenzene and cefixime

A terbium metal organic framework (Tb-MOF), namely {[Tb(dppa)(H2O)2]·dima·H2O·0.5O}n (1), (H4dppa = 5-(3′4′-dicarboxylphenoxy)isophthalic acid, dima = dimethylamine, which is formed by the decomposition of DMF in aqueous solution at high temperature.) was prepared and characterized. Tb-MOF is connected by (dppa)4- ligands via μ4:η1,η2,η2,η2 coordination mode to form a two-dimensional wavy network, which is extended to three-dimensional supramolecular structures based on hydrogen bonding. Tb-MOF has excellent fluorescence properties, which can be used for fluorescence recognition and quantitative determination of cation and anion, antibiotics and small organic molecules in aqueous solution with high sensitivity and good selectivity. Tb-MOF showed enhanced fluorescene for Pb2+ and B4O72− ions, while quenching fluorescence for Cr2O72− ion. Noticeably, this is the first time that Pb2+ and B4O72− ions have been detected by a MOF-based fluorescence sensor using a fluorescence enhancement mechanism. More interestingly, Tb-MOF can quantitatively detect aniline (ANI) in aqueous solution by ratiometric fluorescence sensing. In addition, Tb-MOF has great selectivity and sensitivity for detecting of nitrobenzene (NB) and cefixime (CEF). In particular, when NB concentration is 50 μM, the fluorescence quenching rate of Tb-MOF reaches 99.6%. Therefore, this paper introduces a highly sensitive and multi-responsive Tb-MOF sensor, which can be used to detect Pb2+, B4O72−, Cr2O72−, ANI, NB and CEF with fast response speed and good selectivity.

Pluronic-loaded Silver Nanoparticles/Photosensitizers Nanohybrids: Influence of the Polymer Chain Length on Metal-enhanced Photophysical Properties.

Silver nanoparticles (AgNPs) are incredibly versatile nanostructures that more recently have been exploited to create advanced optoelectronic materials due enhancement of local magnetic field after its irradiation. However, the use of AgNPs as nanoantennas to amplify photophysical properties of close photosensitizer (PS) molecules in photodynamic therapy is still underexplored. The reason for that is the difficulty to control crucial parameters such as silver-PS distance in aqueous solution. In this scenario, here we propose a nanohybrid system where AgNP/PS distance is controlled by a thin layer of different Pluronic copolymers. The controllable distance and aqueous stability of proposed nanohybrids allow a tunable enhancement of fluorescence emission and singlet oxygen generation of some selected PS molecules. A detailed mechanism investigation demonstrated that the observed metal-enhanced photophysics is due to magnetic field enhancement close to AgNP surface (AgNP/PS distance-controlled effect) and the resonant coupling of AgNP hot electrons and HOMO-LUMO energies of the PS (AgNP/PS spectral overlap-controlled effect). These results show that the rational design in engineering new nanohybrid structures allowed photophysical improvement of PS molecules in aqueous solution in a tunable way and point out Pluronic-based AgNP/PS nanohybrids as a smart material for further developments aiming at theranostic applications in photodynamic therapy.

Studies of intrinsic volumes of ethylene glycol and polyethylene glycol–300 molecules in aqueous solutions at 298.15 K: Application of Tammann–Tait–Gibson (TTG) equation of state

Systemic density (ρ) measurements have been carried–out for aqueous solutions of polyethylene glycols (PEG's) with the molar mass 200, 300, 400 and 600 D at (288.15, 293.15, 298.15, 303.15 and 308.15) K and at ambient pressure of 0.1 MPa in dilute solute concentration region (0.0119–0.4941 mol⋅kg−1). The ρ data are used to obtain the apparent molar volume (Vϕ) and partial molar volume (V¯2) of studied PEG's in aqueous solutions at finite concentration as well as at infinitely dilute solutions (Vϕ0) at studied temperatures. The coefficient of thermal expansion (α) for solutions, apparent molar expansivity (Eϕ) and limiting apparent molar expansivity (Eϕ0) for solutes are calculated at 293.15, 298.15 and 303.15 K. The densities of studied PEG's in carbon tetrachloride (CCl4) medium are also measured at 298.15 K. The transfer volume (ΔtrVϕ0) for PEG from pure liquid state to CCl4 and to water as solvent are estimated. The literature data of sound velocity (u), coefficient of thermal expansion (α) and specific heat capacity (CP) for solutions have been utilized to obtain thermodynamic properties like adiabatic compressibility (βad) and isothermal compressibility (βT) in case of aqueous solutions of ethylene glycol (EG) and PEG–300 at 298.15 K. The data are further utilized to obtain apparent molar adiabatic compressibility (KϕS) and apparent molar isothermal compressibility (KϕT) for EG and PEG–300 solute molecules at finite and at infinitely dilute solute concentration (KϕS0 and KϕT0, respectively). Further, the data of KϕT, α and CP data have been utilized to estimate internal pressure Pi (=∂U∂VT) of solutions containing EG and PEG–300 molecules as a function of concentration. The intrinsic volumes (Vint.) of these molecules have been calculated by applying Tammann–Tait–Gibson (TTG) equation of state. It is being observed that intrinsic volume differs appreciably from the value based upon EG and PEG–300 in a liquid state as a standard state. The excess volume change (V¯20E=V¯20-V¯int.0) values are found to be −16.1 and −63.8⋅10–6 m3⋅mol−1 for EG and PEG–300, respectively. Similar calculations made for PEG–300 in CCl4 medium also yield excess volume change of −60⋅10–6 m3⋅mol−1 magnitude. These results are explained on the basis of three dimensional hydrogen bonded structure of EG and the linkage ▪ interaction with solvent water having a presence of helical segments. The inferences drawn will be of help to understand the weak denaturing interactions of glycols in protein denaturation studies.

Colloidal Assemblies Composed of Polymeric Micellar/Emulsified Systems Integrate Cancer Therapy Combining a Tumor-Associated Antigen Vaccine and Chemotherapeutic Regimens

Integrative medicine comprising a tumor-associated antigen vaccine and chemotherapeutic regimens has provided new insights into cancer therapy. In this study, the AB-type diblock copolymers poly(ethylene glycol)–polylactide (PEG–PLA) were subjected to the dispersion of poorly water-soluble molecules in aqueous solutions. The physicochemical behavior of the chemotherapeutic agent DBPR114 in the PEG–PLA-polymeric aqueous solution was investigated by dynamic light scattering (DLS) technology. In vitro cell culture indicated that replacing the organic solvent DMSO with PEG–PLA polymeric micelles could maintain the anti-proliferative effect of DBPR114 on leukemia cell lines. A murine tumor-associated antigen vaccine model was established in tumor-bearing mice to determine the effectiveness of these formulas in inducing tumor regression. The results demonstrated that the therapeutic treatments effectively reinforced each other via co-delivery of antitumor drug/antigen agents to synergistically integrate the efficacy of cancer therapy. Our findings support the potential use of polymeric micellar systems for aqueous solubilization and expansion of antitumor activity intrinsic to DBPR114 and tumor-associated antigen therapy.

Abstract 284: Design, synthesis and biological evaluation of novel water-soluble salts of the antimitotic prodrugs 4-(3-alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides selectively bioactivated by cytochrome p450 1A1 in breast cancer cells

Abstract One of the predominant problems in drug development is the solubility of new molecules in aqueous solutions. New potent antimitotics developed in our research group do not avoid this issue. Our molecules are poorly soluble in aqueous solution which represent a significant impediment for biopharmacological and pharmacodynamical studies. To circumvent that difficulty, salt formation is a widely used strategy to improve hydrosolubility. Moreover, it is estimated that approximately 50% of the drugs used in clinics are administered as salt formulations. It is in that context that we studied the salt formation of our new family of poorly hydrosoluble antimitotics prodrugs referred to as 4-(3-alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides (PAIB-SAs) that are selectively bioactivated by cytochrome p450 1A1 (CYP1A1) in breast cancers. We propose that this will significantly increase their aqueous solubility without altering their selectivity and their anticancer activity. The synthesis of the various salts of PAIB-SAs prepared was based on varying the counterion bound onto the sulfonamide group of the most promising compounds. These salts were synthesized using classical organic chemistry and their maximum aqueous solubility was measured. Their antiproliferative activity was then assessed in vitro using the sulforhodamine B colorimetric assay on MCF7 and MDA-MB-468 human breast cancer cells expressing CYP1A1, and MDA-MB-231 cells devoid of CYP1A1. The bioactivation of PAIS-SAs salts into its cytotoxic metabolites by CYP1A1 Supersomes was assessed by UHPLC. The effect of PAIB-SA salts on cell cycle progression and on microtubule integrity were also assessed by flow cytometry and by immunofluorescence, respectively. We hereby report the synthesis of 18 new salts of PAIB-SAs using either sodium, potassium or lithium as the cation of 6 most promising PAIB-SAs and their biological evaluation. Our results evidenced that the new PAIB-SA salts are highly soluble in water comparatively to their neutral counterparts. They also exhibited high selective cytocidal activity toward MCF7 and MDA-MB-468 expressing CYP1A1 as compared to MDA-MB-231 lacking CYP1A1. They are bioactivated by N-dealkylation by CYP1A1 into potent antimitotic agents. They arrested the cell cycle progression in the G2/M phase and disrupted the microtubule dynamics assembly. In conclusion, we have significantly increased the hydrosolubility of PAIB-SAs by designing new salts. PAIB-SAs water-soluble salts showed similar antiproliferative efficacy and CYP1A1 bioactivation to their neutral counterparts. This important achievement will allow us to optimize our galenic formulations in view of further biopharmaceutical and pharmacodynamical studies. Citation Format: Vincent Ouellette, Atziri Corin Chavez Alvarez, Sébastien Fortin. Design, synthesis and biological evaluation of novel water-soluble salts of the antimitotic prodrugs 4-(3-alkyl-2-oxoimidazolidin-1-yl)-N-phenylbenzenesulfonamides selectively bioactivated by cytochrome p450 1A1 in breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 284.

Molecular Dynamics of Decane Solubilization and Diffusion of Aggregates Consisting of Surfactant and Decane Molecules in Aqueous Solutions

Molecular Dynamics of Decane Solubilization and Diffusion of Aggregates Consisting of Surfactant and Decane Molecules in Aqueous Solutions

Hydrogen Complexes of 1,2-Naphthoquinone with Water Molecules in Aqueous Solution and Their Influence on Shifts of Absorption Bands

Hydrogen Complexes of 1,2-Naphthoquinone with Water Molecules in Aqueous Solution and Their Influence on Shifts of Absorption Bands

SERS substrate with wettability difference for molecular self-concentrating detection

The surface-enhanced Raman spectroscopy (SERS) has attracted much attention due to the powerful capability of quantificational analysis. Nowadays, most of the enhancement effect by SERS substrate is provided by the ‘hot spots’ occupying relatively small space. When the amount of analyte is too low, it is difficult to ensure that all the probe molecules can be placed into the ‘hot spots’, which is a headache in SERS quatification. In order to solve this problem, we have developed a structure of CuO nanowires/Ag nanoparticles with wettability capacity difference, which can aggregate molecules in water and oil simultaneously under two different mechanisms. The limit of detection and enhancement factor of this structure are estimated as 10−15 M and 1.55 × 1011 respectively (for rhodamine 6G, R6G). In a proof-in-principle experiment of sewage detection, it successfully achieved the aggregation and additional enhancement of both the R6G molecules in aqueous solution and thiuram molecules in toluene, realizing efficient and accurate Raman detection.

More Than 50-Fold Enhanced Nonlinear Optical Response of Porphyrin Molecules in Aqueous Solution Induced by Mixing Base and Organic Solvent

The difference absorption spectrum (DAS) of porphyrin molecules (tetraphenyl-porphyhrin sulfonic acid, TPPS) in aqueous solution induced by continuous wave laser irradiation has been reported previously. It was interpreted that the DAS was caused by the formation of TPPS aggregates induced by laser irradiation. However, transient spectra similar in their shape have already been reported and are attributed to the excited-state absorption and saturable absorption (SA) effects due to the triplet state formation in TPPS. In the present study, we investigated the triplet quenching effect by O2 on the DAS of TPPS aqueous solution and revealed that it originated from the triplet state formation. We also found that mixing the appropriate amount of MeOH and NaOH in TPPS aqueous solution increased its absorbance change by more than 50 times. This may be due to the decrease in dissolved oxygen concentration by mixing them. This result suggests the possibility of controlling the performance of NLO materials by adjusting the solvent mixture ratio and base/acid concentration.

All-dielectric chiral-field-enhanced Raman optical activity

Raman optical activity (ROA) is effective for studying the conformational structure and behavior of chiral molecules in aqueous solutions and is advantageous over X-ray crystallography and nuclear magnetic resonance spectroscopy in sample preparation and cost performance. However, ROA signals are inherently minuscule; 3–5 orders of magnitude weaker than spontaneous Raman scattering due to the weak chiral light–matter interaction. Localized surface plasmon resonance on metallic nanoparticles has been employed to enhance ROA signals, but suffers from detrimental spectral artifacts due to its photothermal heat generation and inability to efficiently transfer and enhance optical chirality from the far field to the near field. Here we demonstrate all-dielectric chiral-field-enhanced ROA by devising a silicon nanodisk array and exploiting its dark mode to overcome these limitations. Specifically, we use it with pairs of chemical and biological enantiomers to show >100x enhanced chiral light–molecule interaction with negligible artifacts for ROA measurements.

Accelerating cryoprotectant diffusion kinetics improves cryopreservation of pancreatic islets

Cryopreservation offers the potential to increase the availability of pancreatic islets for treatment of diabetic patients. However, current protocols, which use dimethyl sulfoxide (DMSO), lead to poor cryosurvival of islets. We demonstrate that equilibration of mouse islets with small molecules in aqueous solutions can be accelerated from > 24 to 6 h by increasing incubation temperature to 37 °C. We utilize this finding to demonstrate that current viability staining protocols are inaccurate and to develop a novel cryopreservation method combining DMSO with trehalose pre-incubation to achieve improved cryosurvival. This protocol resulted in improved ATP/ADP ratios and peptide secretion from β-cells, preserved cAMP response, and a gene expression profile consistent with improved cryoprotection. Our findings have potential to increase the availability of islets for transplantation and to inform the design of cryopreservation protocols for other multicellular aggregates, including organoids and bioengineered tissues.

A polarizable three-layer frozen density embedding/molecular mechanics approach.

We present a novel multilayer polarizable embedding approach in which the system is divided into three portions, two of which are treated using density functional theory and their interaction is based on frozen density embedding (FDE) theory, and both also mutually interact with a polarizable classical layer described using an atomistic model based on fluctuating charges (FQ). The efficacy of the model is demonstrated by extending the formalism to linear response properties and applying it to the simulation of the excitation energies of organic molecules in aqueous solution, where the solute and the first solvation shell are treated using FDE, while the rest of the solvent is modeled using FQ charges.

Elastomeric Silicone Sponges for Bleach Delivery

Topical disinfection protocols to inactivate organisms, particularly on high contact surfaces, have become increasingly important. A classical oxidative agent, sodium hypochlorite (bleach), has many benefits, but can be problematic during applications because of its ability to oxidize the organic polymers in which it is contained. We demonstrate that bleach-containing elastomeric sponges are readily created in one step at room temperature from thiopropyl-modified silicone oils; sodium hypochlorite induces disulfide cross-linking and a foam structure due, in part, to the concomitant formation of sulfonates. No surfactants are required. The morphology of the bleach-containing silicone sponge is tunable by the aqueous bleach solution concentration and the water/silicone ratio used. The resulting silicone sponge contains excess bleach that can be released gradually, as shown by its ability to oxidize organic molecules in aqueous solution, either directly or after dehydration/rehydration; the latter process provides a way to store the bleach-containing material in dry form. Such foams exhibit enhanced sustainability as, we show, they can be converted back to thiopropylsilicone oils by reduction using hydrosilicones. The resulting oils can be re-cross-linked, completing the life cycle.

The high active SERs substrate prepared by self assembling Ag nanoparticles on PPy@PEDOT:PSS film to detect the sodium formaldehyde sulfoxylate molecules

Abstract The Ag/PPy@PEDOT:PSS film was used as a Surface-enhanced Raman scattering (SERs) substrate to directly detect the low concentration of sodium formaldehyde sulfoxylate (SFDS) molecules in solution. We prepared the PPy@PEDOT:PSS film by electrochemical potentiostatic (ECP) method and then directly grew Ag nanoparticles on its surface to prepare the SERs substrate of Ag/PPy@PEDOT:PSS film. The results showed that with the increase of depositional time of Ag nanoparticles, accordingly, the size and density of Ag nanoparticles could be increased on the film surface, and their SERs effect was also enhanced gradually; this SERs substrate could sensitively detect the SFDS molecules in aqueous solution. Moreover, the minimum detection limit was up to 1 ng/mL. This preparing and detecting method of SERs substrates provides a new way for the preparation of high sensitivity SERs substrate and for direct and rapid detection of low concentration of SFDS molecules in food and drug.

Cholesterol Molecules Alter the Energy Landscape of Small Aβ1–42 Oligomers

Small amyloid-β (Aβ) oligomers are believed to be key pathogenic species in Alzheimer's disease (AD). One suggested toxicity mechanism is the detergent model where oligomers remove lipid molecules from the bilayer. Senile plaques of AD patients also accumulate a 1:1 ratio of cholesterol/Aβ. What are the dominant structures of small Aβ42 oligomers with cholesterol molecules in aqueous solution? Here, we answer this question by performing atomistic replica exchange molecular dynamics simulations of Aβ42 dimers and trimers. Our simulations demonstrate that the interactions with cholesterol molecules change completely the energy landscape of small Aβ42 oligomers. This result shows that simulations in the bulk solution cannot recapitulate aggregation in the brain extracellular space.