Solution Temperature Research Articles

Phase Behavior Determines Morphology of Amylose Crystallized From Aqueous Solutions

ABSTRACTBackground and ObjectivesHere, we present a simplified system comprising amylose of varying degrees of polymerization in water, with the goal of probing the temperature–concentration phase diagram to determine if a miscibility gap leading to liquid−liquid phase separation might serve as a model for starch granule initiation and, if so, under what conditions.FindingsA miscibility gap in the cooling‐rate‐dependent phase behavior is demonstrated for the amylose−water system, with its temperature and concentration depending on the degree of polymerization (DP) of the starch. Liquid–liquid phase separation within this miscibility gap followed by crystallization of the polymer‐rich phase produced spherulites. If crystallization preceded liquid–liquid phase separation, a precipitate or gel was formed. The upper critical solution temperature appeared between 60°C and 70°C, and the miscibility gap was observed between 5% and 30%–50% w/w starch, depending on DP for DP ≥ 68. For DP 29, the miscibility gap occurred at concentrations ≥ 20% w/w.ConclusionsA cooling‐rate‐dependent miscibility gap in the temperature–concentration phase diagram has been observed in aqueous amylose solutions under reasonable ambient conditions of temperature and starch concentration, allowing phase separation to occur within plastids in vivo.Significance and NoveltyThis work provides a biophysical complement to the biochemistry associated with starch granule initiation.

Close‐to‐Equilibrium Crystallization for Large‐Scale and High‐Quality Perovskite Single Crystals

AbstractThe growth of large semiconductor crystals is crucial for advancing modern electronics and optoelectronics. While various crystal growth techniques have been developed for lead halide perovskites, a significant challenge remains: as crystal size increases, performance tends to deteriorate dramatically. This study addresses the inherent limitations of perovskite crystal growth by designing a novel strategy for near‐equilibrium growth system to maintain optimal conditions throughout the process. The system consists of three independent units: a solution supply unit, a crystal growth unit, and a solution recycling unit, which together ensure a constant solution concentration and temperature. By systematically optimizing temperature control and solution feeding rates, large and high‐quality FAPbBr3 single crystals, including a notable crystal measuring 51 × 45 × 10 mm3 are successfully produced. This crystal demonstrates a mobility‐lifetime product of 2.83 × 10⁻2 cm2 V⁻¹ and an ultralow detection limit of 319.22 pGyair, significantly surpassing existing perovskite crystals of similar size. The approach can serve as a universal platform for the controlled synthesis of all kinds of perovskite single crystals, laying the foundations for their use in various optoelectronic applications.

Response Surface Optimisation of Carbon Dioxide Adsorption Onto Palm Shell Activated Carbon Functionalised With Natural Amino Acids

ABSTRACTAmino acids have shown promising results for carbon dioxide (CO2) capture when functionalised on solid materials; however, the functionalisation often relies on commercial synthetic amino acids. This study investigated the optimal CO2 adsorption performance of amino acid–functionalised material synthesised from palm shell–based activated carbon and natural amino acids, specifically egg white (EW) solution, in a continuous adsorption column. The process conditions of the column were optimised using response surface methodology. Four parameters, namely, the gas flow rate, adsorption temperature, CO2 concentration and EW concentration in the impregnation solution, were identified as significantly affecting CO2 adsorption performance. Good agreements were obtained between the predicted and experimental data, with the coefficients of determination ranging from 0.9639 to 0.9784. A maximum CO2 adsorption capacity of 1.1793 mmol/g was achieved under optimal process conditions: a gas flow rate of 200 mL/min, an adsorption temperature of 25°C, a CO2 concentration of 25 vol.%, and an EW concentration of 15 wt.%. The validation results further confirmed the reliability of the developed model equation in predicting the maximum CO2 adsorption capacity at a fixed 15 vol.% CO2 concentration, with low estimation error. The comparable results obtained using EW waste in this study represent a significant finding in the potential for waste valorisation, aligning with Sustainable Development Goal (SDG) 12 of the United Nations Sustainable Development Goals, as well as contributing to climate action as outlined in SDG 13.

Facile nucleophilic substitution approach for the spectrofluorimetric assay of natamycin based on diarylpyrrolone formation, evaluation of method greenness

An ecofriendly, effective, and selective spectrofluorimetric approach for natamycin analysis was developed using fluorescamine as a fluorogenic probe. Natamycin is the only topical ocular antifungal medication that is presently on the market for treating keratitis, conjunctivitis, and blepharitis caused by yeast and other fungi. Owing to its primary aliphatic amino group, natamycin can easily interact with fluorescamine resulting in the formation of the highly fluorescent diaryl pyrrolone derivative. The derivatization reaction was completed within very short time at room temperature in borate buffer solution (pH 7.6). The fluorescence intensity of the reaction product was monitored at 465 nm after exciting at 390 nm. The linearity range of the spectrofluorimetric method was 0.25–4.0 µg/mL of natamycin with limit of detection (LOD) of 0.082 µg/mL. The method was applied for the determination of the cited drug in pharmaceutical eye drops and artificial aqueous humor with high percentage recoveries and low relative standard deviations. In addition, the involved analytical procedure was green based on the results of the ecology scale scores.

Removal of dyes from aqueous solution using a magnetic graphene oxide nanocomposite: kinetic, isothermal, and thermodynamic characterization

The efficacy of utilizing graphene-magnetite nanocomposite for methylene blue and crystal violet adsorption treatment from aqueous samples was investigated in this study. The nanocomposite properties were evaluated by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and vibrating quantum magnetometry. Some adsorption parameters such as adsorption capacity, contact time, stirring rate, temperature, and pH of the aqueous solution were explored in the research too. Moreover, it was found that adsorption followed a pseudo-second-order kinetic model with an R2 value of 0.999 resulting in a maximum adsorption capacity of 240 mg/g for methylene blue and 203 mg/g for crystal violet respectively. Besides, different well-known isotherm models fit the equilibrium data well. Assessments of thermodynamic parameters showed that the removal of both dyes by GO-Fe3O4 nanocomposite is spontaneous. Also, the reuse ability of GO-Fe3O4 nanocomposite was studied and the result was shown to be recycled suitably and possessed adsorptive properties so that it can be developed as an inexpensive and alternative adsorbent for dye wastewater treatment.

Formulation of thiosemicarbazide based epoxy resin as inhibitor for corrosion of mild steel in 1M HCl: electrochemcial and theoretical studies

ABSTRACT The study presents the development of a new pentafunctional epoxy resin, pentaglycidylthiosemicarbazide (PGTSC), synthesised through a simple condensation process. The molecular structure of PGTSC was characterised using FTIR and 1H NMR spectroscopy. Viscosity measurements indicated that PGTSC's viscosity is significantly influenced by solution concentration and temperature, demonstrating its improved inhibition performance. Electrochemical tests showed that PGTSC achieves a maximum corrosion inhibition efficiency of 92% at a concentration of 10−3 M, with a notable reduction in corrosion current density from 608.60 µA/cm² to 36.67 µA/cm² in 1.0 M HCl. The polarisation studies revealed a mixed-type inhibition mechanism affecting both anodic and cathodic reactions, and the polarisation resistance increased, enhancing the protective properties of steel. The findings were corroborated by additional studies, including PDP, EIS, SEM observations, and computational DFT, MD, and MC calculations support the experimental findings and were in good agreement.

Facile Synthesis of Bioactive Silver Nanocomposite Hydrogels with Electro-Conductive and Wound-Healing Properties

Bioactive metal and metal oxide-based nanocomposite hydrogels exhibit significant antibacterial properties by interacting with microbial DNA and preventing bacterial replication. They offer potential applications as coating materials for human or animal skin injuries to prevent microbial growth and promote healing. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method and incorporated into a polymer network to fabricate silver nanocomposite hydrogels (AgNCHGs) through a simple free radical polymerization method. N-isopropylacrylamide (NIPA), which has lower critical solution temperature (LCST) at about body temperature, or acrylamide (AAm) was used as the main monomer, while one or more ionic co-monomers, such as acrylic acid (AAc) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), were incorporated to obtain AgNCHGs. AgNPs were introduced into the hydrogel network via three different approaches. In the first method, the synthesized hydrogel was immersed in a silver nitrate (AgNO3) solution and reduced in situ using sodium borohydride (NaBH4) as a reducing agent. The second method involved mixing AgNO3 with gel precursors before reduction with NaBH4 to form AgNPs within the hydrogel. The final approach synthesized the AgNCHGs directly in a dispersion of pre-fabricated AgNPs. The incorporation of AgNPs in different AgNCHGs was confirmed through various characterization techniques. Varying temperature and pH conditions can trigger the release of bioactive AgNPs from the hydrogels. Furthermore, the antimicrobial and wound-healing properties of the AgNCHGs were evaluated against bacteria and fungi, demonstrating their potential in biomedical applications. In addition, AgNCHGs exhibit excellent electrical conductivity. The electrical conductivity of the hydrogels can be finely tuned by adjusting the concentration of AgNPs, making these materials promising candidates for energy, sensor, and stretchable electronics applications. This study presents facile synthesis methods of AgNCHGs, which integrate bioactivity, wound healing, and electrical conductivity in the same matrix, addressing a significant challenge in designing multifunctional hydrogels for next-generation technologies.

Formation of a nitrobenzoxadiazole-based yellow fluorophore for the selective spectrofluorimetric determination of the antifungal drug pimaricin in ophthalmic pharmaceutical formulations

Pimaricin (PMR) is a polyene antifungal drug commonly used as the primary medicine for treating fungal keratitis. In this study, a selective and novel spectrofluorimetric method was designed, optimized, and validated to determine pimaricin in its ophthalmic preparations. The method based on the formation of a nitrobenzoxadiazole-based yellow fluorophore upon the reaction of pimaricin with 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl). The fluorescence intensity of the fluorophore was measured at the emission wavelength of 538.5 nm (excitation = 473.5 nm). The factors affecting the reaction (reagent volume, alkalinity, reaction temperature, heating time, volume and type of buffer solution, and the dilution solvent) were investigated and optimized. The calculated linear range was 0.25–1.5 µg/mL, and the limits of detection and quantitation for the method were 0.047 and 0.143 µg/mL, respectively. The selectivity of the method for PMR in the presence of the pharmaceutical additive benzalkonium chloride was proved. The established method was successfully applied to determine PMR in its pharmaceutical ophthalmic preparation (Natamycin® ophthalmic drops) with an accuracy of 103.79 ± 1.83%. The proposed method is practical and valuable for its routine application in quality control laboratories for analysis of PMR in its ophthalmic pharmaceutical preparation.

Cu(I)-Induced G-quartets: Robust Supramolecular Polymers Exhibiting Heating-Induced Aqueous Phase Transitions into Gel or Precipitate.

Certain proteins and synthetic covalent polymers experience aqueous phase transitions, driving functional self-assembly. Herein, we unveil the ability of supramolecular polymers (SPs) formed by G4.Cu+ to undergo heating-induced unexpected aqueous phase transitions. For the first time, guided by Cu+, guanosine (G) formed a highly stable G-quartet (G4.Cu+)/G-quadruplex as a non-canonical DNA secondary structure with temperature tolerance, distinct from the well-known G4.K+. The G4.Cu+ self-assembled in water through p-p stacking, metallophilic and hydrophobic interactions, forming thermally robust SPs. This enhanced stability is attributed to the stronger coordination of Cu+ to four carbonyl oxygens of G-quartet and the presence of Cu+---Cu+ attractive metallophilic interactions in Cu+-induced G-quadruplex, exhibiting a significantly higher interaction energy than K+ as determined computationally. Remarkably, the aqueous SP solution exhibited heating-induced phase transitions-forming a hydrogel through dehydration-driven crosslinking of SPs below cloud temperature (Tcp) and a hydrophobic collapse-induced solid precipitate above Tcp, showcasing a lower critical solution temperature (LCST) behavior. Notably, this LCST behavior of G4.Cu+ SP originates from biomolecular functionality rather than commonly exploited thermo-responsive oligoethylene glycols with supramolecular assemblies. Furthermore, exploiting the redox reversibility of Cu+/Cu2+, we demonstrated control over the assembly and disassembly of G-quartets/G-quadruplex and gelation reversibly.

Rapid Iron-Mediated Aqueous-Phase Reactions of Organic Peroxides from Monoterpene-Derived Criegee Intermediates and Implications for Aerosol and Cloud Chemistry.

Fenton-like reactions between organic peroxides and transition-metal ions in the atmospheric aqueous phase have profound impacts on the chemistry, composition, and health effects of aerosols. However, the kinetics, mechanisms, and key influencing factors of such reactions remain poorly understood. In this study, we synthesized a series of monoterpene-derived α-acyloxyalkyl hydroperoxides (AAHPs), an important class of organic peroxides formed from Criegee intermediates during the ozonolysis of alkenes, and investigated their Fenton-like reactions with iron ions in the aqueous phase. We found that the AAHPs are essentially chemically inert to Fe3+ but highly reactive toward Fe2+. The aqueous-phase reaction rate constant between AAHPs and Fe2+ (kIIAAHP+Fe(II)) was determined to range between 11.0 ± 0.8 and 150.0 ± 3.3 M-1 s-1, depending positively on the solution pH (1-3), water content (50%-90%), and temperature (8-25 °C). Meanwhile, the kIIAAHP+Fe(II) value is linearly correlated to the O/C ratio of AAHPs, which allows for the estimation of the Fenton-like reactivity of AAHPs based on their oxygenation level. In addition, the decomposition of AAHPs via Fenton-like reactions with Fe2+ predominantly yields alkoxy (RO) radicals with the production yield of OH radicals smaller than 16%. Similar to synthesized AAHPs, several abundant peroxides including the pinonic acid-derived AAHP exhibit high Fenton-like reactivity toward Fe2+ but low reactivity toward Fe3+ in dissolved α-pinene secondary organic aerosol. A quantitative analysis based on the measured kinetics suggests that Fenton-like reactions are important and even dominant drivers behind the transformation of AAHPs in the atmosphere, which would significantly affect atmospheric multiphase chemistry and aerosol health impacts.

Synthesis and Application of a Temperature Sensitive Poly(Acrylamide‐Co‐N‐Isopropylacrylamide‐Co‐Sodium P‐Styrene Sulfonate) as a New Water‐Based Drilling Fluid Plugging Agent

ABSTRACTIn the process of oil and gas production, the failure of drilling fluid caused it to invade the formation, leading to wellbore instability. N‐isopropylacrylamide (NIPAM), acrylamide (AM), and sodium p‐styrene sulfonate (SSS) were used as raw materials, and the P(NIPAM/AM/SSS) (abbreviated as NAS) temperature‐sensitive plugging agent was synthesized by inverse emulsion polymerization. The optimum synthesis conditions were obtained using a redox initiation system. Infrared measurements and UV–visible analysis showed that the target product was successfully prepared, and NAS exhibited a lower critical solution temperature (LCST) of 55°C, with sensitive temperature‐responsive behavior. Rheological and filtration tests, along with high‐temperature and high‐pressure (HTHP) sand tray tests, demonstrated that the temperature‐sensitive plugging agent effectively plugged the formation. Particle size analysis and Zeta potential analysis indicated that the addition of the temperature‐sensitive plugging agent increased the electrostatic stability of bentonite‐based slurry and polymer. Contact angle measurements and micro‐morphology of the mud cake revealed that a hydrophilic‐hydrophobic transition occurred at high temperatures in NAS, forming a dense hydrophobic film on the surface of the mud cake. This film effectively sealed cracks and micropores, reduced the invasion of free water, and improved wellbore stability.

Physiochemical synthesis of hydroxyapatite adsorbents from chicken and camel bone waste for removing Cd and Pb ions from polluted water

The utilization of waste resources to synthesize functional materials is crucial for achieving environmentally sustainable development. In this context, the current investigation aims to develop a new material using waste chicken and camel bones as adsorbents for the removal of Pb2+ and Cd2 from polluted water. The Hydroxyapatite (HA) adsorbents of chicken (HB) and camel (CB) bones were prepared via chemical treatment with NaOH, HNO3, H2O2, and ethanol, and also those followed by carbonization. The physicochemical and microscopic characteristics of the adsorbents were analyzed via SEM, XRD, FT-IR, and BET surface area analyses. Adsorption studies of Pb2+ and Cd2+ were performed in a batch style that included initial metal concentration, pH, pHpzc, solution temperature, contact time, and adsorbent dose. The results revealed that the bone chemically activated with 0.1 M NaOH had greater adsorption of Cd2+ ion (99.7% for HB and 99.89% for CB) and Pb2+ ions (99.85% for HB and 99.79% for CB) than the other activators did. Adsorption isotherms, adsorption kinetics, and thermodynamic models have been used to confirm the fit conditions that improve the adsorption technique. Maximum adsorption removal percentages for Pb2+ and Cd2+ were obtained under constant operation conditions (initial metal concentration 10 ppm, pH 6, adsorbent dose 0.05 g, contact time 30 min and solution temperature 328 K. Adsorption of Pb2+ and Cd2+ obeyed a pseudo-second-order model and fit well with the Langmuir isotherm.The metals adsorption using the prepared adsorbent was a spontaneous and exothermic process. Overall, the prepared adsorbents from chicken and camel bone waste are highly effective and promising as low-cost materials for the remediation of heavy metals-contaminated waters.

When a Small Amount of Comonomer Is Enough: Tailoring the Critical Solution Temperature of LCST-Type Thermoresponsive Random Copolymers by PEG Methyl Ether Methacrylate with 1100 g/mol Molecular Weight.

Tuning the critical solution temperature (CST) of thermoresponsive polymers is essential to exploit their immense potential in various applications. In the present study, the effect of PEG-methyl ether methacrylate with a higher molecular weight of 1100 g/mol (mPEGMA1100) as a comonomer was investigated for its suitability for the CST adjustment of LCST-type polymers. Accordingly, a library of mPEGMA1100-based copolymers was established with varying compositions (XmPEGMA1100) using four main comonomers, namely di(ethylene glycol) ethyl ether acrylate, N-isopropyl acrylamide and methacrylamide, and mPEGMA300, with different CST values (cloud points, TCP, and clearing points, TCL, by turbidimetry). It was found that less than 20 mol% of the mPEGMA1100 in the copolymers is practically sufficient for tuning the CST in the entire measurable temperature range, i.e., up to 100 °C, regardless of the CST of the homopolymer of the main comonomer (CST0). Moreover, a predictive asymptotic model was developed based on the measured CST values, which strikingly revealed that the CSTs of mPEGMA1100-containing copolymers depend only on the two main parameters of these copolymers, XmPEGMA1100 and the CST of the homopolymer of the main comonomer (CST0), that is, CST = f(CST0, XmPEGMA1100). The revealed two-parameter relationship defines a surface in 3D plotting, and it is applicable to determine the CST of copolymers in advance for a given composition or to define the suitable composition for a required CST value. These unprecedented results on the dependence of CSTs on two major well-defined parameters enable to design a variety of novel macromolecular structures with tailored thermoresponsive properties.

The Synthesis of Functionalized W5O14 Nanorods for the Adsorption of Bismarck Brown R from Wastewater

In this research, a tungsten oxide was prepared via a green (biogenic) synthesis route where sodium tungstate dihydrate and Punica granatum peel extract were used as a precursor and a reducing/capping agent, respectively. The characterization of the prepared tungsten oxide was performed through various spectroscopic and microscopic techniques. The characterization results revealed the preparation of highly crystalline and nanorod-shaped (length = 123 nm and width = 31.3 nm) tungsten oxide with a probable chemical formula of W5O14. Various functional groups on the W5O14 surface were also reported. The prepared nanorods were further used for the removal of Bismarck Brown R (BBR) dye from water in a batch manner. By varying the dose of nanorods (0.5–3.0 g L−1), BBR solution pH (2−10), contact time (15–120 min), BBR concentration in solution (10–60 mg L−1), and temperature of BBR solution (30, 40, and 50 °C), the optimized condition for maximum adsorption efficiency was measured. The results revealed that 2.0 g L−1 amount of nanorods of tungsten oxide were used to remove ~98% of BBR dye from its 10 mg L−1 at 30 °C and 7.0 pH. The temperature-dependent adsorption data were fitted to different types of non-linear isotherm models (e.g., Langmuir and Freundlich) to assess the adsorption potential and adsorption mechanisms in relation to temperature impacts. The synthesized nano-adsorbent fits the Langmuir as well as the Freundlich isotherm model with a maximum adsorption capacity of 17.84 mg g−1. Pseudo-first-order, pseudo-second-order, and Elovich kinetic models were used for the study of adsorption kinetics. BBR adsorption onto the W5O14 nanorods follows the pseudo-second-order rates. The present adsorption is governed by physico-chemical adsorption with predominant chemical interactions.

Benchmarking residue-resolution protein coarse-grained models for simulations of biomolecular condensates.

Intracellular liquid-liquid phase separation (LLPS) of proteins and nucleic acids is a fundamental mechanism by which cells compartmentalize their components and perform essential biological functions. Molecular simulations play a crucial role in providing microscopic insights into the physicochemical processes driving this phenomenon. In this study, we systematically compare six state-of-the-art sequence-dependent residue-resolution models to evaluate their performance in reproducing the phase behaviour and material properties of condensates formed by seven variants of the low-complexity domain (LCD) of the hnRNPA1 protein (A1-LCD)-a protein implicated in the pathological liquid-to-solid transition of stress granules. Specifically, we assess the HPS, HPS-cation-π, HPS-Urry, CALVADOS2, Mpipi, and Mpipi-Recharged models in their predictions of the condensate saturation concentration, critical solution temperature, and condensate viscosity of the A1-LCD variants. Our analyses demonstrate that, among the tested models, Mpipi, Mpipi-Recharged, and CALVADOS2 provide accurate descriptions of the critical solution temperatures and saturation concentrations for the multiple A1-LCD variants tested. Regarding the prediction of material properties for condensates of A1-LCD and its variants, Mpipi-Recharged stands out as the most reliable model. Overall, this study benchmarks a range of residue-resolution coarse-grained models for the study of the thermodynamic stability and material properties of condensates and establishes a direct link between their performance and the ranking of intermolecular interactions these models consider.

Protection of Enzymes Against Heat Inactivation by Enzyme-Polymer Conjugates.

Along with the quick advancements in enzyme technology, inactivation has emerged as the key barrier for enzymes to be fully utilized as biocatalysts. Here, a novel strategy is presented for the preservation of the enzymatic activity even after heat treatment by grafting enzymes onto the thermal responsive block copolymer via an activated ester-amine reaction. A new water-soluble activated ester monomer, acrylic polyethylene glycol (PEG) functionalized 3-fluoro-4-hydroxybenzoate is synthesized. This activated ester monomer and 2-methoxyethoxyethyl methacrylate (MEEMA) as copolymer monomers are first used to synthesize water-soluble polymers bearing activated ester for post-polymerization modification with amines. Two model enzymes containing amine residues, urease, and papain, are grafted onto the resulting thermal responsive polymers to obtain PMEEMA-co-Enzyme, respectively. The obtained particles of polymer-enzyme conjugates flocculate above the low critical solution temperature (LCST)and redissolve when cooled below that temperature. The activity of the conjugated enzymes has been studied after high temperatures treatment and compared to that of free enzymes. The enzymatic activity assays show that the thermosensitive polymer can act as a stabilizer under high-temperature conditions after multipoint grafting with the enzyme, thus protecting the enzyme from thermal inactivation.

Modeling and Elucidating the Behavior of a Thermoresponsive LCST Ionic Liquid.

Desalination of seawater by forward osmosis is a technology potentially able to address the global water scarcity problem. The major challenge limiting its widespread practical application is the design of a draw solute that can be separated from water by an energetically efficient process and then reused for the next cycle. Recent experiments demonstrate that a promising draw solute for forward-osmosis desalination is tetrabutylphosphonium 2,4,6-trimethylbenzenesulfonate ([P4444][TMBS]). When mixed with water, this ionic liquid (IL) is thermoresponsive and exhibits a lower critical solution temperature (LCST), above which it phase-separates into an IL-rich phase and a water-rich phase. Elucidating the physical mechanism of the liquid-liquid phase separation, as well as rationally designing optimized derivatives, necessitates an accurate model to describe this and related ILs. In this paper, we resort to explicit-solvent all-atom molecular dynamics simulations and adopt AMBER-based force-field parameters for the cation whose partial charges were assigned by the RESP fitting procedure. Utilizing the same methodology, we parametrize the anion. The simulations' results indicate the IL/water mixture, at the experimental critical composition, can unambiguously phase-separate only when the partial charges of the ions are scaled down. Nevertheless, the best-performing charge scaling factor is found to be 0.95, a value much milder than those reported for ILs in neat phases. This can be explained by a diminished charge transfer, or induced dipoles, within the ions when the IL is in a mixture with water. With this charge scaling, the simulations reproduce well the LCST composition-temperature phase diagram, albeit overestimation of the critical temperature by 10 K. In particular, very good agreement is obtained for the composition of the two segregated phases. Estimation of viscosity points to IL/water mixture that is almost twice as viscous in simulations than that reported experimentally. Furthermore, we analyze changes in energy between different components in the mixture and find that the driving force for phase separation is, at least, enthalpic. Structural analyses of the ions and their interactions with water molecules corroborate the importance of the latter in mediating structural organizations of the anions, as well as in strengthening the interactions between the cations.

Effect of Polymer Network Architecture on Adsorption Kinetics at Liquid-Liquid Interfaces: A Comparison Between Poly(NIPAM-co-AA) Copolymer Microgels and Interpenetrating Network Microgels.

Understanding the adsorption features of polymer microgels with different chemical compositions and structures is crucial in studying the mechanisms of respective emulsion stabilization. Specifically, the use of stimuli-responsive particles can introduce new properties and broaden the application range of such complex systems. Recently, we demonstrated that emulsions stabilized by microgels composed of interpenetrating networks (IPNs) of poly-N-isopropylacrylamide (PNIPAM) and polyacrylic acid (PAA) exhibit higher colloidal stability upon heating compared to PNIPAM homopolymer and other relevant PNIPAM-based copolymer counterparts. In the present work, using pendant drop tensiometry, we studied the evolution of water-tetradecane interfacial tension during the adsorption of PNIPAM-PAA IPN particles, comparing them with single-network P-(NIPAM-co-AA) and PNIPAM microgels. The results showed that, despite having the same chemical composition, copolymer particles exhibit completely different adsorption behavior in comparison to other microgel architectures. The observed disparity can be attributed to the nonuniform distribution of charged acrylic acid groups within the P-(NIPAM-co-AA) network obtained through precipitation polymerization. Oppositely, the presence of IPN architecture provides a uniform distribution of different monomers inside respective microgels. Additionally, hydrogen bonding between PNIPAM and PAA subchains appears to reduce the electrostatic energy barrier, enhancing the ability of IPN particles to successfully cover the liquid interface. Overall, our findings confirm the efficiency of using PNIPAM-PAA IPN microgels for the preparation of oil-in-water emulsions and their stability, even when the temperature rises above the lower critical solution temperature of PNIPAM.

Development and Characterization of Hyaluronic Acid Graft-Modified Polydopamine Nanoparticles for Antibacterial Studies.

The problem of antibiotic abuse and drug resistance is becoming increasingly serious. In recent years, polydopamine (PDA) nanoparticles have been recognized as a potential antimicrobial material for photothermal therapy (PTT) due to their excellent photothermal conversion efficiency and unique antimicrobial ability. PDA is capable of rapidly converting light energy into heat energy under near-infrared (NIR) light irradiation to kill bacteria efficiently. In order to solve the problem of PDA's tendency to aggregate and precipitate, this study improved its stability by grafting hyaluronic acid (HA) onto the surface of PDA. Using dopamine and hyaluronic acid as raw materials, hyaluronic acid (HA) was grafted onto polydopamine (PDA) nanoparticles via self-polymerization and Michael addition reactions under alkaline conditions to obtain PDA-HA-modified nanoparticles. We confirmed the successful grafting of hyaluronic acid via scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), nuclear magnetic hydrogen spectroscopy (¹H NMR), ultraviolet-visible spectroscopy (UV-vis), Raman spectroscopy (Raman), and dynamic light scattering (DLS) methods. Scanning electron microscopy (SEM) was used to observe the surface morphology and nanostructure of the grafted materials, providing information on the morphology and size distribution of the materials. Near-infrared performance experiments showed that the temperature of the PDA-HA solution increased rapidly under near-infrared light irradiation, demonstrating an excellent photothermal conversion performance. Antimicrobial properties were assessed via the colony counting method, and typical Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli were selected as model strains. The experimental groups were tested under dark conditions and near-infrared (NIR) light irradiation. PDA/HA showed significant photothermal properties under NIR light irradiation, resulting in a rapid increase in the surrounding temperature to a level sufficient to kill bacteria. Under NIR light irradiation, PDA/HA exhibited 100% antimicrobial efficacy against both S. aureus and E. coli, while antimicrobial efficacy was limited under dark conditions. This indicates that the antibacterial activity of PDA/HA is highly dependent on NIR light activation.

The molecular mechanism of temperature-dependent phase separation of heat shock factor 1.

Heat shock factor 1 (HSF1) is the critical orchestrator of cell responses to heat shock, and its dysfunction is linked to various diseases. HSF1 undergoes phase separation upon heat shock, and its activity is regulated by post-translational modifications (PTMs). The molecular details underlying HSF1 phase separation, temperature sensing and PTM regulation remain poorly understood. Here, we discovered that HSF1 exhibits temperature-dependent phase separation with a lower critical solution temperature behavior, providing a new conceptual mechanism accounting for HSF1 activation. We revealed the residue-level molecular details of the interactions driving the phase separation of wild-type HSF1 and its distinct PTM patterns at various temperatures. The mapped interfaces were validated experimentally and accounted for the reported HSF1 functions. Importantly, the molecular grammar of temperature-dependent HSF1 phase separation is species specific and physiologically relevant. These findings delineate a chemical code that integrates accurate phase separation with physiological body temperature control in animals.