Implications of specific ion effects on salt-induced proteome precipitation in organic solvent.

Modification of Whey Protein Isolate with Surfactants Based on Hofmeister Series and Interaction Parameter

The freezing point depression of ternary salt-polymer-water mixtures is examined with a particular focus on how specific ion hydration modulates polymer-solvent interactions. Using poly(ethylene glycol) (PEG) as a model hydrophilic polymer and four sodium salts (NaF, NaCl, NaI, and NaSCN) spanning the Hofmeister series, we show that the freezing point of PEG solutions follows the Flory-Huggins equation and is independent of molecular weight for PEGs larger than 1000 g mol-1. While binary salt-water systems display purely colligative behavior, ternary PEG-salt-water mixtures exhibit pronounced ion-specific effects. The addition of NaF, NaCl, and NaI produces synergistic freezing point depressions exceeding the sum of the individual PEG and salt contributions, consistent with strong ion hydration that withdraws water from the polymer hydration shell. In contrast, NaSCN yields a nearly additive response, reflecting its weak hydration and direct association with PEG chains. The effective interaction parameters and derived hydration numbers reveal a quantitative correlation between ion hydration strength and the macroscopic freezing behavior. This establishes a general thermodynamic framework that links molecular hydration to bulk phase transitions in aqueous polymer systems.

Mechanically strong poly(vinyl alcohol) hydrogels with low friction via Hofmeister series

Fine-tuning the mechanical and degradation properties of chemically crosslinked hyaluronic acid hydrogels through salt treatment.

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

This study investigated the effects of inorganic electrolytes (NaCl, NaBr, and Na2SO4) on the interfacial behavior, rheological properties, and foam performance of a ternary surfactant system composed of sodium dodecyl sulfate (SDS), dodecyl dimethyl betaine (BS-12), and a silicone surfactant (RH-288) at a mass ratio of 10 : 1 : 1. The mixed surfactant system exhibited enhanced surface activity with a critical micelle concentration close to that of RH-288 alone. Upon addition of electrolytes, a sphere-to-worm-like micellar transition was induced, significantly altering the solution's rheological behavior. Unlike NaBr and Na2SO4, NaCl promoted the formation of elongated and densely entangled worm-like micelles with long relaxation times, resulting in pronounced viscoelasticity. Although foamability slightly decreased with salt addition, foam stability markedly improved, as evidenced by reduced drainage, slower bubble coarsening, and enhanced thermal resistance up to 80 °C. Cryogenic transmission electron microscopy (cryo-TEM) confirmed the presence of worm-like micellar networks in the NaCl-containing system. The results demonstrated that anion-specific effects, interpreted by the Hofmeister series, played a critical role in modulating micellar dynamics and foam stability. Furthermore, the dynamic relaxation characteristics of the micellar network should be regarded as a key factor alongside bulk viscosity. The SDS/BS-12/RH-288 system with 0.4 mol L-1 NaCl shows great potential as a high-performance, environmentally friendly, fluorine-free foam extinguishing agent. This study can provide a suitable approach to develop fluorine-free foam extinguishing agents for forest and grassland firefighting.

Adenosine triphosphate (ATP) is an essential molecule involved in various biological reactions in vivo. It has been reported that ATP acts as a hydrotrope, dissolving the hydrophobic molecules in aqueous solution. Previously, we reported that polyphosphates, including triphosphate, significantly accelerated amyloid formation under ultrasonication. In this study, adenosine nucleotides, including AMP, ADP, and ATP, were used to investigate the mechanism of amyloid formation of α-synuclein (αSyn) under ultrasonication at various adenosine nucleotide concentrations. As a result, amyloid formation was accelerated at two distinct concentration regions of adenosine nucleotides, i.e., relatively low and high via the charge-charge interactions and salting-out effect in the Hofmeister series, respectively, at neutral pH. A similar concentration-dependent amyloid formation was also observed with polyphosphates possessing corresponding phosphate chain lengths. At acidic pH, ATP accelerated the formation of both amyloid fibrils and amorphous aggregates of αSyn, β2-microglobulin, and insulin via charge-charge interaction. Moreover, under acidic conditions, ATP might induce conformational transitions from the unfolded monomeric state to a molten globule-like state. These findings suggest that ATP functions as a salt, stabilizing compact conformers, including the native-like structure and amyloid fibril via intra- and intermolecular interactions, respectively. ATP may trigger amyloid formation by disrupting the supersaturated state above the thermodynamic solubility.

Potato starch offers the unique potential of mineral enrichment through the presence of phosphorylated amylopectin chains. This property was utilised in a straightforward dual modification of native potato starch by combining mineral enrichment with dry heat treatments (DHT). DHT itself (110–130 °C, 3–6% moisture, 2 h) affords potato starches with lower viscosity and gelatinisation temperatures and higher contents of digestible starch. Prior ion exchange with Na+, K+, Mg2+, and Ca2+ enhanced the versatility of dry heat treatments. This study demonstrates the fine-tuning of functional properties (rheology) of these novel, dual-modified starches. Of special interest are magnesium and calcium due to their nutritional value and their valency, allowing ionic cross-linking. The present study contributes to the understanding of starch–ion interactions in DHT, clearly highlighting the role of specific ion effects, as per the Hofmeister series (K+ > Na+ and Ca2+ > Mg2+), in addition to the reversible ionic cross-linking effect of divalent cations. This knowledge is of use for potential substitution of chemically modified starches in food products, serving relevant trends and needs of today’s food industry for clean-label starches.

Hofmeister effect-regulated poly(vinyl alcohol) @ cellulose nanofiber hydrogel-based SERS enhancement and sensing application.

Cells are complex chemical systems capable of sensing and responding to environmental cues by dynamically reshaping themselves, e.g., by forming arm-like protrusions such as filopodia. Recapitulating cellular behavior in artificial systems is a long-standing goal in understanding the matter-to-life transition and designing responsive soft materials. Here, we use oil-in-water emulsions that mimic cellular environmental sensing and form directional arm-like filopodia in response to external chemical cues. Our work analyzes the step-by-step process involved in the formation of artificial filopodia, and we engineer ways to direct filopodia growth through different chemical gradients. The process is driven by asymmetric surfactant partitioning across the oil-water interface, followed by ordering at the interface to form lamellar structures, which are projected out as filopodia. We observe filopodia growing away from the source of kosmotropic anions and toward the source of chaotropic anions from the Hofmeister series. Significantly, these systems also respond to amino acid gradients, similar to cells: tryptophan gradients favor growth toward the source, while lysine and arginine gradients cause growth away from the amino acid source. Our findings open new avenues for fabricating life-like materials that sense and grow in response to external signals.

Abstract Rechargeable non‐alkaline zinc–air batteries (ZABs) based on highly reversible zinc peroxide chemistry offer high energy density and superior stability under ambient air. However, the unique chemistry is closely related to the inner Helmholtz layer facilitated by the triflate anions, which has not been reported in other dilute fluorine‐free electrolytes. There is still a lack of selection criteria for anions and benchmarking two‐electron oxygen reduction reaction (2e − ORR) selectivity. Herein, the Hofmeister series was introduced to depict the hydrophobicity of anions. Integrated spectroscopic and electrochemical analyses demonstrate that chaotropic anions promote 2e − ORR selectivity by disrupting the hydrogen‐bond network and decreasing interfacial water at the electrode–electrolyte interface. As proof of concept, a fluorine‐free chaotropic electrolyte, zinc perchlorate (Zn(ClO 4 ) 2 ), is proposed to enable efficient zinc peroxide chemistry for ZABs without requiring specialized cell configuration. The ZABs using Zn(ClO 4 ) 2 electrolyte not only exhibit improved reaction kinetics and higher energy efficiency but also reduced cost compared to fluorine‐containing counterparts. This study provides new insights into electrolyte design strategies for developing low‐cost and durable ZABs based on zinc peroxide chemistry.

Rechargeable non-alkaline zinc-air batteries (ZABs) based on highly reversible zinc peroxide chemistry offer high energy density and superior stability under ambient air. However, the unique chemistry is closely related to the inner Helmholtz layer facilitated by the triflate anions, which has not been reported in other dilute fluorine-free electrolytes. There is still a lack of selection criteria for anions and benchmarking two-electron oxygen reduction reaction (2e- ORR) selectivity. Herein, the Hofmeister series was introduced to depict the hydrophobicity of anions. Integrated spectroscopic and electrochemical analyses demonstrate that chaotropic anions promote 2e- ORR selectivity by disrupting the hydrogen-bond network and decreasing interfacial water at the electrode-electrolyte interface. As proof of concept, a fluorine-free chaotropic electrolyte, zinc perchlorate (Zn(ClO4)2), is proposed to enable efficient zinc peroxide chemistry for ZABs without requiring specialized cell configuration. The ZABs using Zn(ClO4)2 electrolyte not only exhibit improved reaction kinetics and higher energy efficiency but also reduced cost compared to fluorine-containing counterparts. This study provides new insights into electrolyte design strategies for developing low-cost and durable ZABs based on zinc peroxide chemistry.

Characterization of hygroscopic behavior of single inorganic salt particles across the Hofmeister series

Chaotropic or hydrophobic effect: Distinct binding signatures of nano-ions to a non-ionic polymer.

Hofmeister and electrostatic modulation of the structure and polymorphism of rice protein fibrils.

Developing new and safe electrolyte formulations is a major challenge for the adoption of higher energy electrode chemistries in electrochemical energy storage devices. Electrolyte engineering must balance performance, affordability, and safety in new formulations. There are hundreds of possible solvents, salts and additives to tailor the electrolyte to the right application. Computational tools are a promising solution to accelerate the process through machine learning,1 thermodynamic calculations,2 and molecular dynamics.3 These techniques can be computationally expensive and, without a substantial training set, still require extensive experimental validation of their results. Experimental electrolyte dataset availability is still limited due to the absence of standardization in the field, and it is challenging to scrape the literature. Therefore, there is a need for experimental tools to generate new electrolyte datasets for powerful data analysis techniques to enable novel battery chemistries.In this presentation I will discuss our automated system for electrolyte formulation and characterization in the context of aqueous electrolyte discovery. The platform autonomously handles electrolyte components and conducts electrochemical tests including Coulombic efficiency, cyclic voltammetry and impedance spectroscopy. Here we screen possible combinations of widely used aqueous electrolyte salts including lithium acetate, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethane)sulfonimide (LiTFSI), lithium nitrate, and lithium sulfate . The chosen salts contain anions spanning a wide range of the Hofmeister series, which classifies them between chaotropic (structure breaking) and kosmotropic (structure making). It has been shown that chaotropic anions expand the Electrochemical Stability Window (ESW), specifically, increasing the potential at which OER occurs, though there is still a debate in the literature about the true impact of anions on the stability window.4,5 Moreover, enabling aqueous electrolytes depends on enabling high energy anodes. Currently, various +3 V lithium aqueous battery chemistries rely on using high concentrations of LiTFSI. Here we outline possible strategies to enable higher energy anodes such as lithium titanate while constraining our material use. We leverage our high-throughput electrolyte characterization platform to produce high quality, consistent, open-source databases of electrolyte properties that we envision will assist and accelerate the entire field’s research. Our long-term goal is to go beyond aqueous electrolytes and to use the comprehensive data generated to make fundamental advances in developing new electrolyte models that will allow researchers to quickly predict optimal formulations and device performance.1 S. C. Kim et al., Proceedings of the National Academy of Sciences, 120, e2214357120 (2023).2 A. Dave, K. L. Gering, J. M. Mitchell, J. Whitacre, and V. Viswanathan, J. Electrochem. Soc., 167, 013514 (2019).3 B. Ravikumar, M. Mynam, and B. Rai, J. Phys. Chem. C, 122, 8173–8181 (2018).4 D. Reber, R. Grissa, M. Becker, R.-S. Kühnel, and C. Battaglia, Advanced Energy Materials, 11, 2002913 (2021).5 D. Dong, C.-X. Zhao, X. Zhang, and C. Wang, Advanced Materials, n/a, 2418700.

Micelles exhibit distinct ion-specific effects depending on the polarity of their cores. Herein, we systematically investigate the specific ion effects on sulfone-functionalized polymersomes, revealing distinct ion-specific responses in nonionic micellar systems with polar cores. The influence of a series of Hofmeister salts on the colloidal stability and morphological evolution of poly(N,N-dimethyl acrylamide)-b-poly[2-(propylsulfonyl)ethyl acrylamide] (PDMAc-b-PPSEAm) polymersomes was studied. While the polymersomes show minimal cation sensitivity, they exhibit pronounced anion-specific responses correlating with anion hydration ability. Chaotropic anions drive morphological evolution toward wormlike micelles and spherical micelles by binding directly to the core-forming block and altering its hydrophilicity, with efficacy following the Hofmeister series: I- > SCN- > Br- > NO3- > Cl-. Conversely, kosmotropic anions induce precipitation of polymersomes via dehydration of the corona-forming block, with efficacy ranking as CO32- ≈ SO42- > H2PO4-.

Idiosyncratic behaviour of pegylated lipid nanoparticles used in RNA delivery: A dynamic light scattering study.

Competitive micellization and host-guest complexation of sodium dodecyl sulfate with β-cyclodextrin: Insights from the Hofmeister series.