Behavior Of Aqueous Solutions Research Articles

Synthesis by design and application to desalination of VO2/CTAB-Ti3C2 capacitive deionization electrode

As an emerging technology in capacitive deionization (CDI), flow-electrode capacitive deionization (FCDI) has attracted much attention due to its unlimited electrosorption capacity and continuous operation. Like CDI, carbon is generally chosen as the electrode material for FCDI at this stage, but conventional carbon materials have limited desalination capacity due to the double electric layer. The two-dimensional layered material MXene has been gradually applied to CDI due to its unique structure and physicochemical properties. However, the van der Waals forces exist between the MXene layers, and the layered structure of MXene is susceptible to stacking, while exhibiting an obvious swelling behavior in aqueous solution, thus affecting its desalination performance. Herein, we report a designed VO2/CTAB-Ti3C2 heterostructure synthesised by a simple hydrothermal method. The addition of VO2 can alleviate the lamellar structure buildup of Ti3C2 and improve the desalination performance of Ti3C2. On the other hand, Ti3C2 can be used as a conductive substrate for VO2, which improves the charge transfer rate of VO2, prevents VO2 agglomeration, and provides more contact surfaces for ion intercalation. Compared with the pure VO2 and Ti3C2 electrodes, the composite electrode has a good desalination performance, and its desalination reaches 1041.5 mg g−1 at 1.2 V. Therefore, this VO2/CTAB-Ti3C2 hybrid material is expected to be used as an electrode material for flow capacitive deionization.

Four-Component Statistical Copolymers by RAFT Polymerization.

This manuscript serves as the starting point for in-depth research of multicomponent, statistical, methacrylate-based copolymers that potentially mimic the behavior of proteins in aqueous solutions. These synthetic macromolecules are composed of specially chosen comonomers: methacrylic acid (MAA), oligoethylene glycol methyl ether methacrylate (OEGMA475), 2-(dimethylamino)ethyl methacrylate (DMAEMA) and benzyl methacrylate (BzMA). Monomer choice was based on factors such as the chemical nature of pendant functional groups, the polyelectrolyte/polyampholyte and amphiphilic character and the overall hydrophobic-hydrophilic balance (HLB) of the obtained quaterpolymers. Their synthesis was achieved via a one-pot reversible addition fragmentation chain transfer (RAFT) polymerization in two distinct compositions and molecular architectures, linear and hyperbranched, respectively, in order to explore the effects of macromolecular topology. The resulting statistical quaterpolymers were characterized via 1H-NMR and ATR-FTIR spectroscopies. Their behavior in aqueous solutions was studied by dynamic (DLS) and electrophoretic light scattering (ELS) and fluorescence spectroscopy (FS), producing vital information concerning their self-assembly and the structure of the formed aggregates. The physicochemical studies were extended by tuning parameters such as the solution pH and ionic strength. Finally, the quaterpolymer behavior in FBS/PBS solutions was investigated to test their colloid stability and biocompatibility in an in vivo-mimicking, biological fluid environment.

Integrating low salinity water, surfactant solution, and functionalized magnetite nanoparticles with natural acidic groups for enhanced oil recovery: Interfacial tension study

In recent years, nanoparticles (NPs) have become a popular choice for improving oil recovery through enhanced oil recovery (EOR) methods. NPs can enhance oil recovery by reducing interfacial tension (IFT), altering wettability, and decreasing the mobility ratio. In this study, magnetic NPs with acidic groups (tartaric acid and malic acid), which are natural acids found in fruits such as grapes and apples, were synthesized and functionalized to reduce the IFT between oil and water. Various characterizations tests, including zeta potential (ZP), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray analysis (EDAX), were used to determine the properties of NPs. Afterwards, the IFT behaviour of crude oil and aqueous solutions, containing surfactant sodium dodecyl sulfate (SDS), two types of salts namely sodium chloride (NaCl) and sodium sulfate (Na2SO4), and functionalized magnetite NPs with tartaric acid and malic acid were investigated. Two crude oils were used in this study: light (A) and heavy (B). The results showed that increasing salt concentration decreases the IFT for crude oils down to an optimum point (20000 ppm for both salts), after which the IFT increases with increasing salt concentration. The presence of functionalized Fe3O4@Tartaric acid NPs (300 ppm) in the aqueous solutions containing salts at their optimum concentration (20000 ppm) and SDS (300 ppm) can decrease the IFT more significantly than that of Fe3O4 and Fe3O4@Malic acid for both crude oils. This is due to higher stability and higher ZP of functionalized Fe3O4@Tartaric acid NPs compared to Fe3O4@Malic. The IFT for oil A decreases from 20.8 mN/m to 2.87 mN/m for light crude oil and from 32.96 mN/m to 1.91 mN/m for heavy crude oil. The IFT for heavy crude oil was more reduced than that of light crude oil, which was due to the presence of asphaltene, resin, and other surface-active agents in heavy crude oil, which can act as a natural surfactant in oil and help reducing the IFT.

Range and sensitivity of 17O nuclear spin-lattice relaxation as a probe of aqueous electrolyte dynamics.

The study of electrolytic solutions is of relevance in many research fields, ranging from biophysics, materials, and colloid science to catalysis and electrochemistry. The dependence of solution dynamics on the nature of electrolytes and their concentrations has been the subject of many experimental and computational studies, yet it remains challenging to obtain a full understanding of the factors that govern solution behavior. Here, we provide additional insights into the behavior of aqueous solutions of alkali chlorides by combining 17O relaxation data with diffusion and viscosity data and contrast their behavior with 1H nuclear magnetic resonance relaxation data. The main findings are that 17O relaxation correlates well with viscosity data but not with diffusion data, while 1H relaxation correlates with neither. Certain ionic trends match known ion-specific series behavior, especially at high concentrations. Notably, we also examine the ranges of the interactions and conclude that the majority of the effects are tied to local water reorientation dynamics.

The Use of an Advanced Intelligent-Responsive Polymer for the Study of Dynamic Water-Carbon Dioxide Alternating Displacement.

Addressing the issue of inadequate temperature tolerance in traditional polymers, in this study, we successfully executed a one-step synthesis of intelligent-responsive polymers which have excellent adaptability in water-gas alternating displacement scenarios. Utilizing the fatty acid method, we produced OANND from oleic acid (OA) and N,N-dimethyl-1,3-propanediamine (NND). Upon testing the average particle size in the aqueous solution both prior and subsequent to CO2 passage, it became evident that OANND assumes the form of a small-molecule particle in the aqueous phase, minimizing damage during formation. Notably, upon CO2 exposure, it promptly organizes into stable micelles with an average size of 88 nm and a relatively uniform particle distribution. This unique characteristic endows it with a rapid CO2 response mechanism and the ability to form a highly resilient gel. In the exploration of viscoelastic fluids, we observed the remarkable behavior of the AONND aqueous solution when CO2/N2 was introduced. This system displayed repeatable transitions between aqueous and gel states, with the highest viscosity peaking at approximately 3895 mPa·s, highlighting its viscosity reversibility and reusability properties. The rheological property results that we obtained indicate that an elongated micellar structure is present in the solution system, with the optimal concentration ratio for its formation determined as 0.8, which is the molar ratio of the OANND-NaOA system. In the sealing performance tests, a 1.0 wt% concentration of the gel system exhibited excellent injectability properties. At 80 °C, this gel effectively reduced the permeability of a sand-filled model to 94.5% of its initial value, effectively sealing potential leakage paths or gas fluxes. This remarkable ability to block leakage paths and reduce seepage capacity highlights the material's superior blocking effect and erosion resistance properties. Furthermore, even at a temperature of 90 °C and an injection pore volume (PV) of 3, this plugging system could reduce the permeability of a high-permeability sand-filled model to over 90% of its initial value.

Adsorption Layer Properties and Foam Behavior of Aqueous Solutions of Whey Protein Isolate (WPI) Modified by Vacuum Cold Plasma (VCP)

For years, cold plasma processing has been used as a non-thermal technology in industries such as food. As interfacial properties of protein play a remarkable role in many processes, this study investigates the effect of cold plasma on the foaming and interfacial behavior of WPI. The objective of this study is to evaluate the effect of different gases (air, 1:1 argon–air mixture, and sulfur hexafluoride (SF6)) used in low-pressure cold plasma (VCP) treatments of whey protein isolate (WPI) on the surface and foaming behavior of aqueous WPI solutions. Dynamic surface dilational elasticity, surface tension isotherms, surface layer thickness, and the foamability and foam stability were investigated in this study. VCP treatment did not significantly affect the adsorption layer thickness. However, an increase in induction time, surface pressure equilibrium value, and aggregated size is observed after SF6VCP treatment, which can be attributed to the reaction of WPI with the reactive SF6 species of the cold plasma. The surface dilational elastic modulus increased after VCP treatment, which can be related to the increased mechanical strength of the protein layer via sulfonation and aggregate formation. VCP treatment of WPI increases the foam stability, while the average diameter of foam bubbles and liquid drainage in the foam depends on the gas used for the cold plasma.

Self-Assembly of Amphiphilic PDI and NDI Derivatives with Opposite Thermoresponsive Fluorescent Behaviors in Aqueous Solution.

This work presents a study of the thermally induced aggregation of perylene diimide (PDI) and naphthalene diimide (NDI) derivatives modified with oligo ethylene glycol (OEG) chains in aqueous solution. Water-soluble and flexible OEG side chains were introduced into the π-core of glutamate-modified NDI and PDI structures, and the aggregation process was modulated by heating or cooling in water. Interestingly, a rare opposite temperature response of fluorescent behavior from the two amphiphilic chromophores was revealed, in which the PDI exhibited fluorescent enhancement, while fluorescent quenching upon temperature increase was observed from the NDI assembly. The mechanism of thermally induced aggregation is clearly explained by studies with various spectroscopic techniques including UV-visible, fluorescence, 1H NMR, 2D NMR spectroscopy, and SEM observation as well as control experiments operated in DMSO solution. It is found that although similar J-aggregates were formed by both amphiphilic chromophores in aqueous solution, the temperature response of the aggregates to temperature was opposite. The degree of PDI aggregation decreased, while that of NDI increased upon temperature rising. This research paves a valuable way for understanding the complicated supramolecular behaviors of amphiphilic chromophores.

Water-soluble dye – ZnII octacarboxy substituted tetrapyrazinoporphyrazine: Spectral-luminescence study of behavior in aqueous solutions

ZnII complex of octacarboxy substituted tetrapyrazinoporohyrazine, ZnTPyzPA(COOH)8, was prepared by mild alkaline hydrolysis of the corresponding octaethyl ester, ZnTPyzPA(COOEt)8, which was synthesized by template cycloteramerization of 5,6-di(ethoxycarbonyl)pyrazine-2,3-dicarbonitrile in the presence zinc(II) acetate in o-dichlorobenzene. Both complexes were characterized by IR, UV–vis, NMR spectroscopy (1H, 13C). Conformational analysis performed by DFT method in agreement with spectral study indicates that one of COOH group in each pyrazine ring participates in intramolecular hydrogen bonding with the adjacent pyrazine nitrogen atom. Unlike octacarboxy substituted ZnII phthalocyanine, ZnTPyzPA(COOH)8 remains non-aggregated not only in the octaanionic form present in the basic medium but also in tetraanioinic form existing in acid aqueous solutions since intramolecular H-bonding prevents intermolecular interactions. However, the fluorescence is almost completely quenched for tetraanion which can be related to the proton transfer in the excited state from carboxylic group to the pyrazine nitrogen. Aggregation is observed only for non-ionized form of ZnTPyzPA(COOH)8 existing in strongly acidic medium (1 M HCl solution, pH < 1).

Structure and self-diffusivity of mixed-cation electrolytes between neutral and charged graphene sheets.

Graphene-based applications, such as supercapacitors or capacitive deionization, take place in an aqueous environment, and they benefit from molecular-level insights into the behavior of aqueous electrolyte solutions in single-digit graphene nanopores with a size comparable to a few molecular diameters. Under single-digit graphene nanoconfinement (smallest dimension <2nm), water and ions behave drastically different than in the bulk. Most aqueous electrolytes in the graphene-based applications as well as in nature contain a mix of electrolytes. We study several prototypical aqueous mixed alkali-chloride electrolytes containing an equimolar fraction of Li/Na, Li/K, or Na/K cations confined between neutral and positively or negatively charged parallel graphene sheets. The strong hydration shell of small Li+ vs a larger Na+ or large K+ with weaker or weak hydration shells affects the interplay between the ions's propensity to hydrate or dehydrate under the graphene nanoconfinement and the strength of the ion-graphene interactions mediated by confinement-induced layered water. We perform molecular dynamics simulations of the confined mixed-cation electrolytes using the effectively polarizable force field for electrolyte-graphene systems and focused on a relation between the electrochemical adsorption and structural properties of the water molecules and ions and their diffusion behavior. The simulations show that the one-layer nanoslits have the biggest impact on the ions' adsorption and the water and ions' diffusion. The positively charged one-layer nanoslits only allow for Cl- adsorption and strengthen the intermolecular bonding, which along with the ultrathin confinement substantially reduces the water and Cl- diffusion. In contrast, the negatively charged one-layer nanoslits only allow for adsorption of weakly hydrated Na+ or K+ and substantially break up the non-covalent bond network, which leads to the enhancement of the water and Na+ or K+ diffusion up to or even above the bulk diffusion. In wider nanoslits, cations adsorb closer to the graphene surfaces than Cl-'s with preferential adsorption of a weakly hydrated cation over a strongly hydrated cation. The positive graphene charge has an intuitive effect on the adsorption of weakly hydrated Na+'s or K+'s and Cl-'s and a counterintuitive effect on the adsorption of strongly hydrated Li+'s. On the other hand, the negative surface charge has an intuitive effect on the adsorption of both types of cations and only mild intuitive or counterintuitive effects on the Cl- adsorption. The diffusion of water molecules and ions confined in the wider nanoslits is reduced with respect to the bulk diffusion, more for the positive graphene charge, which strengthened the intermolecular bonding, and less for the negative surface charge, which weakened the non-covalent bond network.

Hydration numbers of biologically relevant divalent metal cations from abinitio molecular dynamics and continuum solvation methods.

Hydration and, in particular, the coordination number of a metal ion is of paramount importance as it defines many of its (bio)physicochemical properties. It is not only essential for understanding its behavior in aqueous solutions but also determines the metal ion reference state and its binding energy to (bio)molecules. In this paper, for divalent metal cations Ca2+, Cd2+, Cu2+, Fe2+, Hg2+, Mg2+, Ni2+, Pb2+, and Zn2+, we compare two approaches for predicting hydration numbers: (1) a mixed explicit/continuum DFT-D3//COSMO-RS solvation model and (2) density functional theory based abinitio molecular dynamics. The former approach is employed to calculate the Gibbs free energy change for the sequential hydration reactions, starting from [M(H2O)2]2+ aqua complexes to [M(H2O)9]2+, allowing explicit water molecules to bind in the first or second coordination sphere and determining the most stable [M(H2O)n]2+ structure. In the latter approach, the hydration number is obtained by integrating the ion-water radial distribution function. With a couple of exceptions, the metal ion hydration numbers predicted by the two approaches are in mutual agreement, as well as in agreement with the experimental data.

Synthesis and behavior in aqueous solution of carboxymethyl pullulan-graft-poly(N-isopropylacrylamide-co-methacrylamide)

Stimuli-responsive polymers are fascinating materials because they mimic the behavior of living systems. This ability to respond to the action of certain stimuli makes them interesting both from the point of view of the theoretical study of their behavior in solution and of biomedical applications. In this regard, semitelechelic oligomers of N-isopropylacrylamide-co-methacrylamide (thermosensitive) with amine end groups were grafted onto previously synthesized carboxymethyl pullulan (sensitive to pH). The oligomers as well as the graft copolymer were characterized in terms of composition, molecular mass, number of grafts on the pullulan macromolecule, grafting density, and Kuhn segment length. Thermoresponsiveness of the grafted copolymer was studied in wide concentration and pH ranges. The onset temperature of phase separation proved to be independent of concentration and influenced by pH in highly basic solutions.The time of the copolymer response to abrupt change in temperature was analyzed.

Amphiphilic block copolymers of poly(N-vinyl pyrrolidone) and poly(isobornyl methacrylate). Synthesis, characterization and micellization behaviour in selective solvents

Block copolymers of N-vinyl pyrrolidone (NVP) and isobornyl methacrylate (IBMA), PIBMA-b-PNVP, were prepared employing the RAFT polymerization technique. IBMA was polymerized first followed by the polymerization of NVP in the presence of a suitable fluoroalcohol to accelerate the crossover reaction. The copolymers were characterized by Size Exclusion Chromatography (SEC) and NMR spectroscopy. The thermal stability of these copolymers was studied via Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), showing unique characteristics compared to the respective PIBMA and PNVP homopolymers. The micellization behavior was studied in THF, which is a selective solvent for the PIBMA blocks. The corresponding statistical copolymers, PNVP-stat-PIBMA were also examined to elucidate the effect of the macromolecular architecture on the micellar properties. Furthermore, the self-assembly behavior in aqueous solutions was studied for the PIBMA-b-PNVP block copolymers. Water is a selective solvent for the PNVP blocks. Static (SLS) and dynamic light scattering (DLS) were employed to study the micellar assemblies. The encapsulation of the hydrophobic compound curcumin within the micellar core of the micellar structures in aqueous solutions was investigated by UV–Vis spectroscopy and DLS measurements.

Effect of End Groups on the Cloud Point Temperature of Aqueous Solutions of Thermoresponsive Polymers: An Inside View by Flory-Huggins Theory.

In an effort to gain insight into the origin of the effects of end groups on the cloud point temperature (Tcp) as a function of the polymer molar mass of thermoresponsive polymers with lower critical solution behavior in dilute aqueous solutions, we use the Flory-Huggins (FH) theory amended for end groups. The theory was applied to available experimental data sets of poly(N-isopropylacrylamide) (PNIPAM), poly(4-vinylbenzyl methoxytris(oxyethylene) ether) (PTEGSt), and poly(α-hydro-ω-(4-vinylbenzyl)tetrakis(oxyethylene) ether) (PHTrEGSt). The theory relates the variations in TcpM,ϕcp for different end groups to the effective FH χ parameter of the end groups and explains the qualitative notion that the influence of the end groups is related to the hydrophobicity/hydrophilicity of the end groups relative to that of the so called intrinsic TcpM,ϕcp response of a polymer without end groups. The limits to the applicability of the FH theory are established, and a set of possible theoretical improvements is considered. The ultimate scrutiny of the simple FH theory and suggested improved theories must await the measurement of truly thermodynamic cloud points; the available cloud points are merely estimations of the thermodynamic cloud point, for which the deviation to the true cloud point cannot be established with sufficient accuracy.

The influence of herbicidal anions on chemical shifts in NMR, phytotoxicity and surface properties of pyrrolidinium surface-active ionic liquids

Abstract Six surface-active ionic liquids (SAILs) with herbicidal anions were synthetized (with a yield of ≥ 88 %) and their structure was confirmed by NMR spectra. Subsequently, their surface properties, phytotoxicity and bulk aggregation behavior in aqueous solution investigated. The compounds studied have an amphiphilic structure and, due to the presence of two long alkyl chains in the cation, they displayed surface activity (CMC values, ranging from 0.13 mmol L−1 to 1.36 mmol L−1). Our results provide explanations for the role of counterions in the physical and chemical properties of SAILs. Indeed, the aromatic anion affects the hydrophilic charge of the surface-active compounds. The SAILs containing the [MCPA]− and [MCPP]− anions were the most phytotoxic to representatives of dicotyledonous plants compared to the other compounds. By analysis of the structure of SAILs, we demonstrate that counterions play an important role in self-assembly and adsorption processes in aqueous solutions, and therefore, in the potential biological application of these compounds.

Development of a Versatile Lipid Core for Nanostructured Lipid Carriers (NLCs) Using Design of Experiments (DoE) and Raman Mapping.

The objective of this study was to develop a versatile lipid core for the 'brick-dust type of drugs' (poorly water-soluble and poorly lipid-soluble drugs). In the first step, excipients of different polarities were classified according to their behavior in aqueous solutions. Subsequently, binary mixtures were prepared with cetyl palmitate (Crodamol™ CP pharma, Campinas, São Paulo, Brazil) as the solid lipid, and its miscibility with other excipients was evaluated using Raman mapping and classical least squares (CLS). Based on the results, the excipients Crodamol™ CP pharma (hydrophobic), Super Refined™ DMI (dimethyl isosorbide; hydrophilic, Mill Hall, PA, USA), and Super Refined™ Lauryl Lactate (lauryl lactate, medium polarity, Mill Hall, PA, USA) were chosen to compose the lipid core. The ideal proportion of these excipients was determined using a mixture design and the standard deviation (STD) of image histograms as the response variables. After statistical evaluation of the DoE results, the final composition was determined, and drugs with different logP (0 to 10) and physicochemical characteristics were evaluated in the optimized mixture. The drugs butamben (Sigma-Aldrich Co., Spruce Street, St. Louis, MO, USA), tacrolimus (NutriFarm, São Paulo, Brazil), atorvastatin calcium, and resveratrol (Botica da Terra, Campinas, Brazil) presented a homogeneous distribution in the optimized lipid core, indicating that this is a promising system to be used in nanostructured lipid carrier (NLC) formulations of such types of drugs.

Theoretical multiscale study on the properties, aqueous solution behavior and biological impact of zinc oxide nanoparticles

The aim of this theoretical study is to describe the relationship between the structure and the physicochemical properties of zinc oxide nanoparticles (ZnO NPs) and Mn doped ZnO NPs to assess their toxicological impact. In order to do so, a multiscale modelling approach is applied. Different nanoparticles, as well as the mechanism(s) of nanoparticle aggregation and growing, are characterized in terms of size and shape considering electronic, surface, structural and topological properties via quantum mechanics simulations. To evaluate the toxicology impact of ZnO NPs in human health safety and their possible environmental impact, classical molecular dynamics simulations were carried out to study the interaction between the nanomaterials and biological target systems: a set of selected human proteins and model plasma membranes. Likewise, the simulation of nanoparticles dispersion in aqueous media along with water adsorption on their surfaces was conducted.The mayor findings may be summarized as: (i) the ZnO NPs from 12 to 96 (ZnO) units are characterized and their interaction energies, HOMO-LUMO gaps, superficial areas and volumes are reported; (ii) the (ZnO)12 NP and Zn11MnO12 NP are further characterized via their topological properties, vibrational spectra, PDOS and non-covalent interactions; (iii) the doping with Mn atoms is favourable. The interaction energies, HOMO-LUMO orbitals and gaps, PDOS, atomic charges, superficial areas and volumes are reported for NPs doped with up to 5 Mn atoms; (iv) high water affinity for ZnO NPs is reported with both quantum and classical calculations, v) (ZnO)12 NPs do not penetrate the cell membrane and (vi) the affinity energy of both ZnO and Mn doped NPs for human proteins is moderate.The reported results provide in-depth whole-chain studies of zinc oxide nanoparticles, which have been successfully applied for different technologies.

The Effect of Block Ratio and Structure on the Thermosensitivity of Double and Triple Betaine Block Copolymers.

AB-type and BAB-type betaine block copolymers composed of a carboxybetaine methacrylate and a sulfobetaine methacrylate, PGLBT-b-PSPE and PSPE-b-PGLBT-b-PSPE, respectively, were synthesized by one-pot RAFT polymerization. By optimizing the concentration of the monomer, initiator, and chain transfer agent, block extension with precise ratio control was enabled and a full conversion (~99%) of betaine monomers was achieved at each step. Two sets (total degree of polymerization: ~300 and ~600) of diblock copolymers having four different PGLBT:PSPE ratios were prepared to compare the influence of block ratio and molecular weight on the temperature-responsive behavior in aqueous solution. A turbidimetry and dynamic light scattering study revealed a shift to higher temperatures of the cloud point and micelle formation by increasing the ratio of PSPE, which exhibit upper critical solution temperature (UCST) behavior. PSPE-dominant diblocks created spherical micelles stabilized by PGLBT motifs, and the transition behavior diminished by decreasing the PSPE ratio. No particular change was found in the diblocks that had an identical AB ratio. This trend reappeared in the other set whose entire molecular weight approximately doubled, and each transition point was not recognizably impacted by the total molecular weight. For triblocks, the PSPE double ends provided a higher probability of interchain attractions and resulted in a more turbid solution at higher temperatures, compared to the diblocks which had similar block ratios and molecular weights. The intermediates assumed as network-like soft aggregates eventually rearranged to monodisperse flowerlike micelles. It is expected that the method for obtaining well-defined betaine block copolymers, as well as the relationship of the block ratio and the chain conformation to the temperature-responsive behavior, will be helpful for designing betaine-based polymeric applications.

The physicochemical and DNA binding studies of ceftazidime pentahydrate and cefotaxime sodium in aqueous medium

Abstract Ceftazidime pentahydrate (CP) and cefotaxime sodium (CS) are semisynthetic cephalosporin antibiotics and are used to treat a variety of diseases worldwide. In order to explore the efficiency of a medicinal compound, it is important to have a deep understanding of its solution and physiochemical behaviour along with its interaction with biological molecules. In this regard, the solution of two drugs i.e., ceftazidime pentahydrate (CP) and cefotaxime sodium (CS) were investigated in detail. The physicochemical properties of drugs solutions and their interaction with deoxyribonucleic acid (DNA) were studied in water under varying experimental parameters. In the present study the physicochemical properties such as density, viscosity, surface tension, and conductance of aqueous solution, having various molar concentrations, of CP and CS were traced out at different temperatures. Five various concentrations (0.05, 0.1, 0.15, 0.2, and 0.3 mol dm−3) of each drug in an aqueous medium were prepared separately, and the physicochemical properties of each solution, were studied individually at temperatures such as 293, 303, 313, 323, and 333 K respectively. Most of these parameters have shown different behaviour with varying concentration of solution and temperature of the medium. In addition, these drugs showed a spontaneous surface-active and association behaviour in aqueous solutions and drug DNA solution. The flow behaviour, surface properties, volumetric behaviour and solute–solvent interaction of this drug were prominently influenced by experimental variables. UV-Visible spectroscopy was also used to study the interaction of these drugs with DNA in aqueous media in detail. Calculated values of binding constants (K b) for all drug–DNA are positive, indicating constructive binding and interactions between the molecules. In addition the binding efficiency of ceftazidime pentahydrate was found more than that of cefotaxime sodium. The interaction of drug–DNA was not only affected by the nature of the drug but also by the drug-to-DNA ratio and nature of the medium used.

The Importance of AI Algorithm Combined with Tunable LCST Smart Polymers in Biomedical Applications

Smart polymers, also known as stimulus-responsive polymers or environmentally sensitive polymers, are a class of polymers that exhibit changes in their physical and chemical properties in response to various external stimuli, including small physical and chemical changes in the environment. These stimuli can trigger changes in the properties of the smart polymer, such as phase, shape, optics, mechanics, electric field, surface energy, reaction rate, permeability, and perception. Due to the biological sluggishness of conventional smart polymers, different manifestations of polymers are realized through the combination of AI technologies, including water solubility, adsorption on the surface of the carrier, or part of the cross-linked polymer system. While the definition of smart polymers can include two-phase transition processes such as glass transition and melting, the focus of research in the field of smart polymer systems is their behavior in polymer aqueous solutions, interfaces, and hydrogels. In this paper, a noteworthy smart polymer Low critical solution temperature (LCST) polymer is analyzed based on the combination of AI algorithm and deep learning. By carefully designing and modifying the structure of the polymer, the researchers can adjust the LCST to approximate the physiological temperature, making it suitable for potential biomedical applications. Looking ahead, an important development direction is the creation of LCST-type polymers that exhibit a variety of responses to different stimuli, while also improving their biodegradability. Incorporating AI into the design and modification of these polymers could facilitate the development of advanced smart materials with enhanced properties and functionality, opening up new possibilities in areas such as biotechnology, drug delivery, and response materials.

Effect of inhomogeneous structure on the water desalination performance of graphitic carbon nitride nanochannels: A molecular dynamics study

The transport behaviors of aqueous solution in two-dimensional (2D) nanomaterial-based separation membranes are correlated with the structure of the nanoconfined geometry. However, little is known about the impact of asymmetric structures on the transport behavior of aqueous solutions in membranes. In this work, we use molecular dynamics (MD) simulations to investigate the transport behaviors of aqueous solution in non-parallel stacked graphitic carbon nitride (g-C3N4) nanochannels. Interestingly, the non-parallel stacking of g-C3N4 could lead to the local aggregation of water, resulting in an inhomogeneous density distribution within the nanochannel. The high-density region in g-C3N4 nanochannel significantly disrupted the continuum fluid of water. Moreover, the inhomogeneous density distribution of water could impede ion transport in the non-parallel g-C3N4 nanochannel. It was found that ions cannot maintain compact hydration structures in the high-density region. This work reveals the unique properties of slightly tilted membrane structures, providing novel perspective for the design of next-generation nanofluidic devices.