A hydrogel formed by a short peptide is presented that exhibits remarkable stimuli-responsiveness and plasticity, undergoing a morphological transformation from nanofibers to nanospheres in the presence of monovalent (Li+, Na+, K+) or trivalent (Al3+, Fe3+) metal ions under physiological conditions. The nanofibrillar structure of the hydrogel was examined using transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD) studies and atomistic molecular dynamics simulations, in complement, to explain the nanostructural transitions at the microscopic level. Interestingly, exposure to divalent metal ions (Mg2+, Ca2+, Co2+, Ni2+) induces a unique shrinking (syneresis) behavior, accompanied by a morphological shift to nanoribbons. Both simulations and SAXS analysis confirm that these ions cause a contraction in the packing of gelator peptides, significantly reducing the interpeptide distance. This ion-specific adaptability confers tunable physicochemical properties and morphological plasticity. Hydrogels incorporating mono- or trivalent ions exhibit enhanced thermal stability and mechanical strength relative to ion-free counterparts, underscoring the reinforcing role of metal coordination. Strikingly, shrunken gels formed in the presence of divalent ions display even greater stiffness than freshly prepared gels in the absence of any metal ions, suggesting that syneresis acts as a postassembly strengthening mechanism. These findings highlight a versatile, stimuli-responsive soft material in which ion-peptide interactions orchestrate nanoscale morphology, mesoscale network architecture, and macroscopic mechanical performance-opening avenues for adaptive hydrogel systems in targeted biomedical, sensing, and controlled-release applications.

Ion specificity at solvent surfaces: concentration depth profiles of monovalent inorganic ions.

ABSTRACT This study investigates the formulation and functionality of composite gels made from seaweed (SW), rice protein (RP), and date insoluble fiber (DIF), focusing on the effects of pH (4, 6, and 8) and monovalent cations (K + via KCl). Three formulations, SW, SW + RP, and SW + RP + DIF, were evaluated for physicochemical, textural, and structural properties. The incorporation of rice protein decreased gel hardness but increased adhesiveness and springiness, indicating enhanced elasticity and cohesive strength. The addition of date fiber further modified the texture by increasing hardness, likely due to matrix reinforcement by fiber particles. No syneresis was observed in any formulation. The addition of K + significantly increased gel hardness and moisture content, indicating the formation of stronger, more water‐retentive networks. Rheological and microstructural analyses confirmed that K + induced the formation of brittle gels with larger pores, whereas formulations without K + produced softer, less brittle gels with more compact and uniform structures. Color properties were also influenced by the addition of rice protein and date fiber, as well as pH, reflecting compositional, and pigment effects. From a sustainable protein perspective, this study demonstrates the potential of combining seaweed, rice protein, and fiber‐rich by‐products to create functional, plant‐based gel systems. The approach supports circular economy principles by utilizing renewable ingredients and food processing residues, offering viable alternatives to synthetic gelling agents and animal‐derived proteins.

Low-polar solvent strikingly stiffens double-stranded RNA and reverses its twist-stretch coupling.

Unveiling the synergistic mechanisms of multi-ionic removal in microbial desalination cells: Ion transfer, electrochemical behavior and microbial response.

Synthesis and characterization of triple acid stationary phases for cation exchange chromatography using click chemistry and atom transfer radical polymerization.

Ion conductors with fast ion transport and reliable stability are highly desired for energy storage and conversion devices. While solid-state ion conductors with high safety and energy density are promising materials for a new generation of electrochemical devices, it remains challenging to achieve high ion conductivity, especially for multivalent ions due to the stronger steric effect and electrostatic interactions. Here, we report the well-ordered charged nanochannels with high ion density, typically fabricated by stacking montmorillonite (MMT) nanosheets, to serve as versatile solid-state ion conductors. Characterization studies and molecular dynamics simulations reveal that the “adaptive” nanochannel height of MMT membranes, combined with Coulomb interaction-induced concerted ion movement and surface-charge-governed ion transport arising from the high-packing-density cations inside the negatively charged nanochannels, jointly suppress the steric effect and strong interactions for various cations. As a result, our MMT nanochannels achieve considerably high conductivity for both monovalent (K+, Na+, and Li+) and multivalent ions (Mg2+ and Al3+), ∼80 to 210 mS cm−1 at 80 °C, higher than that of the corresponding bulk solutions and state-of-the-art ion conductors. This work provides fresh perspectives on fast ion transport in nanoconfined environments, and presents a promising route for developing next-generation ionic devices.

Boosting enhanced capacitive deionization of H2TiO3/carbon electrodes by yolk-shell construction.

Extending the applicability of modified electrodialysis metathesis for high-recovery desalination by improving concentrate separation and monovalent ion retention

Deoxyribozymes (DNAzymes) are in vitro selected catalytic DNA molecules that recruit metal ions to function. However, nearly all previous DNAzymes generated through conventional selection methods exhibit poor metal selectivity. Here, we report an acidic in vitro selection strategy for isolating truly metal-specific DNAzymes. By using Ca2+ as the target in positive selection and a mixture of competing metal ions in counter-selection, and conducting the selections under acidic conditions to suppress metal hydrolysis, we have successfully selected an acidic RNA-cleaving DNAzyme, termed aRCD-Ca2, which is only activated by Ca2+ and shows no response to all other tested metal ions, including monovalent ions and chemically similar competing divalent ions (Mg2+, Cu2+, Zn2+, Co2+, Ni2+, Mn2+ and Pb2+). This represents the first acidic DNAzyme with exclusive metal selectivity. Moreover, aRCD-Ca2 exhibits fast catalytic activity, with a k obs of 0.026 min-1 toward Ca2+. A trans-acting aRCD-Ca2TCQ was also engineered from aRCD-Ca2 that enabled highly specific and sensitive monitoring of Ca2+ dynamics in HT22 cell lysosomes through a fluorescent probe. We envision that the described acidic in vitro selection strategy can be readily adapted to obtain more new DNAzymes with high specificity for other metal ions and advance the development of nucleic acid catalysts for a wide range of applications.

Membranes selective to ions of the same charge are increasingly sought for water waste processing and valuable element recovery. However, while narrow channels are known to be essential, other membrane parameters remain difficult to identify and control. Here we show that Zr⁴⁺, Sn⁴⁺, Ir⁴⁺, and La³⁺ ions intercalated into vermiculite laminate membranes become effectively unexchangeable, creating stable channels, one to two water layers wide, that exhibit robust and tuneable ion selectivity. Ion permeability in these membranes spans five orders of magnitude, following a trend dictated by the ions’ Gibbs free energy of hydration. Unexpectedly, different intercalated ions lead to two distinct monovalent ion selectivity sequences, despite producing channels of identical width. The selectivity instead correlates with the membranes’ stiffness and the entropy of hydration of the intercalated ions. These results introduce an ion selectivity mechanism driven by entropic and mechanical effects, beyond classical size and charge exclusion.

A novel fluorescent sensor ferrocenyl salicylaldehyde Schiff base derivative SF-Fc was designed, synthesized, and characterized by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), and SC-XRD spectroscopic analyses. The sensor was highly selective to trivalent ions Al3+, Cr3+, and Fe3+ over other monovalent or divalent ions and showed fluorescence enhancement towards trivalent metal ions (Al3+, Cr3+, Fe3+) in acetonitrile (pH 6). Detection limits of probe SF-Fc for Al3+, Cr3+, and Fe3+ were 1.2 × 10-7 mol/L, 2.4 × 10-7 mol/L, and 4.9 × 10-7 mol/L, respectively. In addition, the sensor exhibited an obvious color change in the presence of Cu2+ in acetonitrile solution, indicating a direct colorimetric naked-eye detection of Cu2+ without requiring instrumental assistance. Moreover, the probe SF-Fc successfully detected trivalent metal ions in actual water samples, with satisfactory recovery rates (88.7%-108.9%) and relative standard deviation (RSD) values (0.34%-2.91%).

First principles study of titanium oxychloride as an anode material in monovalent and multivalent ion batteries

With increasing global demand for sustainable and cost-effective energy storage, it has become essential to explore electrode materials composed of abundant elements with reduced environmental impact. Organic electrode materials (OEMs), primarily built from carbon, hydrogen, nitrogen, and oxygen, offer promising alternatives to traditional inorganic cathodes. OEMs provide advantages such as reduced carbon footprint, lower cost, structural tunability, and compatibility with multivalent ions, addressing several limitations of conventional inorganic materials.Among various OEMs, conjugated polymers containing redox-active subunits have gained considerable attention, overcoming the limited cycling stability typically observed with small organic molecules dissolved in electrolyte. Beyond lithium chemistries, magnesium metal represents an attractive alternative due to its high natural abundance, inherent safety, and higher volumetric energy density compared to lithium. However, Mg battery typically exhibit sluggish kinetics, poor electrode stability, and active material dissolution. Overcoming these limitations is essential, especially for high-demand applications such as electric aviation, which require rapid discharge rates and extended cycle life.Our earlier research on organic cathodes based on perylene diimide (PDI) ladder oligomers established foundational design criteria for improved rate capability and cycling stability. Specifically, we studied short-chain helical perylene diimide (hPDI-short) oligomers comprising six subunits. Two key structural features were identified: (1) molecular contortion provided by the rigid ladder backbone promoted rapid ion transport pathways; and (2) extended conjugation length enhanced electronic conductivity, greatly improving battery performance. Despite promising results, limitations in previous synthetic approaches prevented systematic exploration of longer polymer chains, thus hindering deeper investigation into the structure-property relationships required for higher-performing OEMs.In this work, we report a high-yielding and scalable synthetic strategy enabling the controlled synthesis of longer-chain hPDI polymers. We synthesized two ladder polymers of increased lengths, designated hPDI-medium (~15 subunits) and hPDI-long (~90 subunits), enabling a systematic investigation of polymer length on electrochemical performance. This synthetic control allows detailed examination of ladder-length effects, which has been previously unexplored in polymer cathodes.Comprehensive electrochemical characterization reveals a clear correlation between polymer length and performance. Among the tested materials, hPDI-medium achieves the best balance of solubility, structural stability, rapid redox kinetics, and overall electrochemical performance. This polymer exhibits highly reversible redox activity, superior electrode integrity, and notably fast charge-discharge capability, making it particularly suitable for high-power applications. During rate testing, hPDI-medium maintains 91% capacity retention when increasing cycling rates dramatically from 1 C to 50 C in Li cells.In Li-metal battery, hPDI-medium shows exceptional performance even under extremely demanding cycling conditions, retaining over 99% of its initial capacity after 10,000 cycles at an ultrahigh rate of 77 C (10 A/g). This surpasses previous results reported for related organic cathodes, highlighting its exceptional stability and rapid charging capability. In Mg-metal batteries, where electrode instability and sluggish kinetics typically pose significant challenges, the hPDI-medium polymer effectively mitigates solubility issues and improves cycling stability. The Mg-metal cells demonstrate remarkable electrochemical stability, maintaining over 99.5% Coulombic efficiency and retaining approximately 67% of their initial capacity after 3,000 cycles at a high rate of 10 C (1.3 A/g).This work highlights the significant impact of molecular-level structural engineering on the electrochemical properties of organic cathodes, in both monovalent and divalent ion systems. By strategically adjusting polymer length and architecture, we achieve tailored OEMs capable of ultrafast-rate performance and exceptional long-term stability. The insights derived from this systematic investigation of ladder polymer cathodes not only emphasize their potential in next-generation Li and Mg battery technologies but also provide clear molecular design guidelines for developing advanced, sustainable, high-performance organic battery materials.

Limitations in current battery technologies have driven increasing interest in alternative secondary battery systems, particularly multivalent-ion systems [1]. Unlike monovalent ions, multivalent ions can transfer multiple electrons per ion, offering the potential to significantly increase energy density [2]. In recent years, significant progress has been made in developing cathode materials for aqueous multivalent-ion batteries (AMVIBs). Among these, metal-organic frameworks (MOFs), particularly Prussian Blue Analogues (PBAs) have emerged as promising candidates due to their unique open-framework structures with large diffusion channels, which facilitate fast ion transport and minimize volumetric changes during cycling [3]. PBAs have demonstrated promising performance in various systems, including magnesium- and calcium-ion batteries. Understanding the diffusion behavior of different charge carriers in terms of size and polarizing power is critical for guiding the design of next-generation battery materials.In this study, we present a comparative analysis of calcium- and magnesium-ion intercalation in CuHCF systems based on semi-empirical quantum mechanics tight-binding method GFN-xTB [4] . To investigate the ion diffusion mechanisms and energy barriers within the CuHCF framework, we employed the semi-empirical xTB method. A mesh-based scan of single-point energy calculations was carried out within one cavity of the CuHCF unit cell. The resulting energy maps reveal that calcium ions preferentially diffuse along the cyanide groups, driven by attractive electrostatic interactions between the positively charged Ca²⁺ ions and the negatively charged cyanide groups. In contrast, the energetically favorable position for magnesium ions is near the center of the cavity. Regarding the diffusion pathway, magnesium ions tend to migrate through vacancies rather than across face walls, highlighting a distinct transport mechanism compared to calcium. Our results reveal contrasting diffusion behaviors between calcium and magnesium ions in the CuHCF framework. These differences highlight the influence of size and polarizing power on ion transport mechanisms. These findings can benefit the rational design of next-generation aqueous batteries employing alternative charge carriers.Reference: C. P. Grey and J. M. Tarascon, Nature Mater, 16, 45–56 (2017). M. E. Arroyo-de Dompablo, A. Ponrouch, P. Johansson, and M. R. Palacín, Chem. Rev., 120, 6331–6357 (2020). K. Hurlbutt, S. Wheeler, I. Capone, and M. Pasta, Joule, 2, 1950–1960 (2018). S. Grimme, C. Bannwarth, and P. Shushkov, J. Chem. Theory Comput., 13, 1989–2009 (2017).

The use of produced water as a primary component in formulating polymer-based fracturing fluids is becoming a viable option due to the limited availability of fresh water in the field. Nevertheless, the practical use of production water faces several challenges due to its complex composition, which includes monovalent and divalent ions that considerably affect the fluid’s viscosity. Recent studies have shown that calcium ions substantially influence the viscosity of linear fracturing fluids, whereas magnesium ions, do not have a notable effect. However, the effects of other divalent ions commonly found in production water, such as barium and sulfate, remain underreported. In this study, the influence of barium and sulfate ions on linear fracturing fluids will be examined. The viscosity of linear gel fracturing fluids, prepared using hydroxypropyl guar (HPG) polymer with varying concentrations of barium and sulfate ions, will be investigated under different shear rates and temperatures. The results indicate that produced water contains barium and sulfate ions, which affect the rheology of the linear fracturing fluid. A concentration of 150 ppm of BaCl2 can increase the viscosity by 30%, whereas 150 ppm of Na2SO4 increases the HPG viscosity by 7% at ambient temperature (25 °C). At 70 °C, the effect of barium and sulfate ions on the increase in viscosity of the HPG linear fracturing fluid are observed to be less significant.

Abstract The design of novel two-dimensional (2D) electrode materials with high storage capacity and energy density is essential for the development of high-performance rechargeable metal ion batteries (MIBs). Herein, we study 2D metallic cobalt phosphide (CoP) as a potential anode material for various MIBs (Ca, Mg, Li, Na, and K) using density functional theory (DFT). The CoP monolayer exhibited high stability and good mechanical strength while maintaining sufficient flexibility to accommodate volumetric changes during ion intercalation/deintercalation. It exhibits strong adsorption for different metal ions required to prevent dendrite formation. The computed diffusion barrier of Li, \SI{0.29}{eV}, is the minimum among all the studied ions, indicating favorable ion mobility and fast charge discharge capability. The calculated storage capacities for divalent ions (Ca, Mg), \SI{2383}{mAh g^{-1}} and monovalent ions (Li, Na, K), \SI{1191}{mAh g^{-1}} are remarkably high, surpassing many reported 2D materials. The open circuit voltages (OCVs) obtained for both types of ions fall within the optimal range of \SIrange{0.2}{1.5}{V}, leading to an exceptionally high energy density of \SI{2526}{Wh/kg} for Ca. Our study provides significant application oriented advances and strongly recommends 2D CoP as a promising anode material for high performance MIBs.

Use of milk powders to manufacture panela cheese by a wheyless cheesemaking process.

In lipid-based mRNA pharmaceuticals applicable for vaccination, cancer therapy, and other types of therapeutics, negatively charged RNA is embedded in nanoparticles containing positively charged or ionizable lipids. The local cohesion at the lipid-RNA interface plays an important role in the stability and biological activity of the resulting nanoparticles. Ions and other buffer components in the RNA's immediate surroundings may affect RNA stability against hydrolysis and its binding strength to the oppositely charged lipid layers, which is relevant for release after cellular uptake and endosomal processing. Here, we use Langmuir monolayers at the air-water interface as well-defined experimental models to study the local molecular organization of mRNA adsorbed to lipid layers. The binding of mRNA (approximately 3900 nucleotides) in the presence of monovalent and divalent ions from the aqueous phase to monolayers consisting of cationic transfection lipids and zwitterionic phospholipids is investigated with synchrotron-based X-ray fluorescence and scattering techniques. The experiments provide detailed insights into the structure of the adsorbed layers as well as the fractions of all molecular moieties contributing to the interfacial electrostatic balance, specifically phosphates from RNA, phosphates from phospholipids in the monolayer, and elemental counterions such as chloride, potassium, and calcium. The mRNA forms discrete, 1-2 nm thick, electron-dense layers tightly bound to the lipid membrane, where cationic ions accumulate at the interface together with the mRNA. This leads to a 1.5-3-fold excess of anionic nucleotides relative to cationic lipids at the interface, which is more pronounced in the presence of divalent compared to monovalent cations. The anions that compensate for the lipid charge in the absence of RNA get displaced from the interface upon RNA adsorption. The quantitative information about local interfacial moieties obtained here may constitute a valuable basis for the evaluation of quality aspects of nanoparticles comprising mRNA in the bulk phase.

AlCl3 hydration states and complexation are not well understood both in solutions and at the air-aqueous interface despite their potential significance in natural waters and their industrial and energy-related applications. Here, we investigated Al3+ and Cl- ion behaviors in an AlCl3 aqueous bulk solution and at the air-aqueous interface using interface-selective vibrational sum frequency generation (SFG), Raman and infrared spectroscopies, molecular dynamics (MD) simulation, as well as molecular-informed reduced modeling. Our reduced modeling reveals relatively long-range effects for Al3+ as compared to monovalent ions such as Na+ indicating that the interfacial depth of trivalent ions can be significantly larger than that of monovalent ions at the air-water interface. MD simulations reveal interfacial stratification and multiple layering of the ions. Compression of the Al3+ and Cl- distributions with increasing concentrations from 0.5 to 2.5 m is also observed in the subsurface regions. Significant SSP- and PPP-polarized SFG OH spectral intensity increases are observed from 0.5 to 1.5 m and 0.5 to 2.5 m, respectively, indicative of interfacial depth increases and a change in average orientation above 1.5 m. Extensive evaluation of SFG spectra, Fresnel-corrected using several approaches, shows the same trends. The nonmonotonic trend points to a changing structure in surface and subsurface water orientation and hydrogen bonding environment generally consistent with the MD simulation of stratification and water orientation changes. Furthermore, solvent-shared ion pairing is implicated with MD simulation radial distribution analysis and consistent with infrared spectral identification of the hexaaqua aluminum ion in the solution phase. Spectral evidence of a strong Al3+ hydration shell and the acidic behavior of the Al3+ ions is obvious in the Raman and infrared spectra of the bulk solution. We show that the MD dipole potential is directly related to the MD second-order susceptibility of the interface, χSFG-MD(2), both of which correlate up to ∼35 Å with the spectral observations of increasing and then saturating intensities, suggesting that both ion stratification and interfacial depth determine the water orientations at an air-water interface of 1-3 electrolyte solutions.