Kosmotropic Ions Research Articles

CoFe Oxides-Coated 2D Black Phosphorus for Flame-Retardant Nanocoatings with Tunable Mechanical Strength and Efficient Elimination of Toxic Gases.

2D black phosphorus (BP) degrades irreversibly into phosphate compounds under ambient conditions, which limits its application in a variety of fields. In this study, by coating amorphous ferric-cobalt oxides (CoFeO)on BP nanosheets, a multifunctional CoFeO@2D BP is successfully developed that effectively inhibited combustion and catalyzed CO oxidation to eliminate toxic gases. Strong affinity between transition-metal cations and BP allowed the uniform growth of amorphous ferric‒cobalt oxides on the BP surface, which effectively prevented the spontaneous degradation of 2D BP. By combining CoFeO@2D BP with gelatin and kosmotropic salts, the as-obtained nanocoatings are used for surface treatment of flammable polyurethane foam (PU). Kosmotropic ions induced strong hydrophobic interactions and bundling within the gelatin chains which significantly enhanced the mechanical performance of the PU. BP accelerates the carbonization of gelatin to inhibit the combustion of PU, and CoFe oxides, which act as true active centers to accelerate the oxidation of CO, effectively inhibiting the production of harmful gas. The release rate of CO decreases by 73% and the limiting oxygen index (LOI) increases from 17% to ≈32% during PU combustion. The developed novel 2D material opens the way for multifunctional coatings with integrated durability, flame retardancy, and high smoke suppression efficiency.

Spider Silk: Rapid, Bottom‐Up Self‐Assembly of MaSp1 into Hierarchically Structured Fibers Through Biomimetic Processing

AbstractSpider dragline silk's exceptional mechanical performance, coupled with its benign production pathway, have inspired the design of diverse smart materials. Remarkably, relatively little is known about the self‐assembly process of major ampullate spidroin 1 (MaSp1) – the main protein constituent of dragline fiber – during its rapid conversion from soluble precursor protein into hierarchically structured mature silk fibers. Herein, the biomimetic potential of MaSp1 is explored using a new recombinant platform with full domain representation. MaSp1 is found to undergo efficient liquid‐liquid phase separation (LLPS) in response to kosmotropic ions, with notably higher propensity compared to MaSp2, and with MaSp1 exhibiting a more complex solubility profile relative to levels of sodium chloride. To further the understanding of silk spinning, the rapid assembly of mesoscale structures is monitored in real‐time in response to ion and pH gradients, revealing a progression from LLPS droplets toward aligned hierarchical fibers. Furthermore, using this biomimetic system, insoluble macroscopic MaSp1 fibers can be readily generated, wherein the application of mechanical deformation triggers the emergence of β‐sheet secondary structures. The insights gained from this study can have broader application in efforts to mimic the formation of biomaterials with spatially organized features across multiple length scales.

Anionic Hofmeister Effect Regulated Conductivity in Polyelectrolyte Hydrogels for High-Performance Supercapacitor.

The Hofmeister effect not only affects the stability and solubility of protein colloids but also has specific effects on the polymer molecules. Here, the impact of the Hofmeister effect on the electrochemical properties of polyelectrolyte hydrogels at room temperature and subzero temperature studied for the first time. Polyelectrolyte hydrogels exhibit an anti-polyelectrolyte effect in low concentrations of ammonium salt, while they exhibit an obvious Hofmeister effect in high concentrations of ammonium salt. Kosmotropic ions demonstrate strong interaction with water molecules or polymer chains, resulting in the reduction of conductivity of polyelectrolyte hydrogels. However, chaotropic ions exhibit weak interactions with water molecules or molecular chains, leading to an increase in conductivity. The Hofmeister effect has a more significant effect on the polyzwitterion electrolyte. The conductivity of polyzwitterion hydrogel soaked in chaotropic ion is up to 6.2 mS cm-1 at -40°C. The supercapacitor assembled by polyzwitterion electrolytes maintains a capacitance retention rate of 85% and ≈100% coulomb efficiency after 15 000 cycles at -40°C. This study elucidates the influence of the Hofmeister effect on conductivity in polyelectrolytes and expands the regulatory approach for improving the performance of energy storage devices.

Structurability of microalgae, soy and pea protein for extruded high-moisture meat analogues

Despite ecological and nutritional benefits, food ingredients derived from microalgae remain a niche market. A contributing factor to this is the lack of knowledge to exploit their techno-functional properties. This research investigated the structurability of Auxenochlorella protothecoides microalgal biomass during high moisture extrusion cooking for meat analogues. The fibrous extrudate structure weakened with increasing A. protothecoides content in the recipe. To scrutinise reasons for this phenomenon, a thorough compositional comparison of microalgal biomass and conventional raw materials from soy and pea was performed. The identified macrocompositional differences were shown to exert only a minor impact on fibrous structure formation. Thus, structurability appears to be predominately influenced by protein composition, protein properties and electrolyte environment. The proteins of the analysed microalgal biomass were 20 % smaller in molecular weight, had 18–68 % higher solubility and contained 15–50 % less hydrophobic sidechains, all of which may impede protein interaction potential and thereby network formation. Additionally, the pH of microalgae suspensions was lower, which has a negative impact on disulfide bridge formation. Moreover, the analysed microalgal biomass contained considerable amounts of kosmotropic ions that stabilise individual proteins. Denaturation, pH shift, addition of cysteine, transglutaminase and polyvalent cations were proposed as measures to improve structurability of the microalgae A. protothecoides.

Load-bearing columns inspired fabrication of ductile and mechanically enhanced BSA hydrogels

Currently, protein-based hydrogels are widely applied in soft materials, tissue engineering and implantable scaffolds owing to their excellent biocompatibility, and degradability. However, most protein-based hydrogels are soft brittle. In this study, a ductile and mechanically enhanced bovine serum albumin (BSA) hydrogel is fabricated by soaking the a 1-(3-dimethylaminopropyl)-3ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) induced BSA hydrogel in (NH4)2SO4 solution. An EDC/NHS coupling reaction induce protein coupling reactions that cause the BSA skeleton to resemble architectural load-bearing walls, protecting the integrity of the hydrogel and preventing collapse. The effects of the BSA and (NH4)2SO4 concentrations on the hydrogel mechanics are evaluated, and the possible strengthening mechanism is discussed. Besides, the highly kosmotropic ions greatly enhance the hydrophobic interaction within BSA gels and dehydration effect and their mechanical properties were significantly enhanced. The various mechanical properties of hydrogels can be regulated over a large window by soaking hydrogels into various ions. And most of them can be washed away, maintaining high biocompatibility of the protein. Importantly, the protein hydrogels prepared by this strategy could also be modified as strain sensors. In a word, this work demonstrates a new, universal method to provide multi-functional, biocompatible, strength enhanced and regulable mechanical pure protein hydrogel, combining the Hofmeister effect with -NH2/-COOH association groups.

Biologically Structured Water (BSW) - A Review (Part 3): Structured Water (SW) Generation, BSW Water, Bioenergetics, Consciousness and Coherence

Natural water sources become partially structured when exposed to cold temperatures, aeration, and sunlight in high mountain streams or kosmotropic ions. Drinking water devices that make structured water utilize methods such as resonance, vortex designs, and static magnets to alter H-bond configurations in liquid water. Other methods, such as the Advanced Oxidation Process (AOP) or vortexing, utilize energy or mechanical methods that are strong enough to break the covalent bonds in liquid water. After water splits into hydronium ions (H30+) and hydroxyl radicals (•OH), these molecular species rapidly reform back into SW water with stable H-bonds. Several companies offer AOP water generators for the remediation of wastewater, industrial water treatment, hydroponic, and agricultural uses. Other companies offer vortex generators for SW drinking water for households and institutions. The final section summarizes the interconnectivity and synchronization between BSW water, bioenergetics, consciousness, and quantum coherence. The continuous layer of BSW water within all cells and covering all biological membranes allows it to capture, store, resonate, amplify, and transmit a wide spectrum of EMF energy that forms the basis of bioenergetics. Application of quantum biology principles to BSW water opens promising research fields potent with solutions to enhance human health and longevity. Other SW and BSW water research areas potentially include environmental and wastewater treatment, medical treatments for age-related diseases, energy generation, and possibly even manipulation of rainfall patterns.

Salting-Out Effect Realizing High-Strength and Dendrite-Inhibiting Cellulose Hydrogel Electrolyte for Durable Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries are limited by poor Zn stripping/plating reversibility. Not only can hydrogel electrolytes address this issue, but also they are suitable for constructing flexible batteries. However, there exists a contradiction between the mechanical strength and the ionic conductivity for hydrogel electrolytes. Herein, high-concentration kosmotropic ions are introduced into the cellulose hydrogel electrolyte to take advantage of the salting-out effect. This can significantly improve both the mechanical strength and ionic conductivity. Additionally, the obtained cellulose hydrogel electrolyte (denoted as Con-CMC) has strong adhesion, a wide electrochemical stability window, and good water retaining ability. The Con-CMC is also found to accelerate the desolvation process, improve Zn deposition kinetics, promote Zn deposition along the (002) plane, and suppress parasitic reactions. Accordingly, the Zn/Zn cell with Con-CMC demonstrates dendrite-free behavior with prolonged lifespan and can endure extremely large areal capacity of 25 mAh cm-2. The Con-CMC also enables a large average Coulombic efficiency of 99.54% over 500 cycles for the Zn/Cu cell. Furthermore, the assembled pouch-type Zn/polyaniline full battery provides great rate capability, superior cyclability (even with limited Zn anode excess), a slow self-discharge rate, and outstanding affordability to external forces. Overall, this work extends our knowledge of the rational design of hydrogel electrolytes.

Influence of tail group length, amide functionality and added salt ion identity on the behaviour of betaine surfactants

HypothesisThe behaviour of surfactants in solution and at interfaces is governed by a combination of steric and electrostatic effects experienced by surfactant molecules as they interact with solvent, other species in solution, and each other. It would therefore be anticipated that highly interacting groups would significantly influence surfactant behaviour. The widely used amide functionality has polar H-bond donor/acceptor properties, and therefore its inclusion into a surfactant structure should have a profound effect on surface activity and self-assembly of that surfactant when compared to the equivalent molecule without an amide linker. Further, chaotropic or kosmotropic salt ions that affect water structuring and hydrogen bonding may provide opportunities for further tuning surfactant interactions in such cases.ExperimentsA library of betaine surfactant with tail lengths n=14−22 both with and without an amidopropyl linker were synthesised to study the effect of the amide functionality on surfactant properties. Characterisation of the molecules interfacial properties were performed using pendant drop tensiometry and their solution state formulation properties were probed using small-angle neutron scattering (SANS) and rheological measurements.FindingsPresence of an amidopropyl linker had little effect on aggregation propensity (as evidenced by critical micelle concentration) and aggregate morphology of betaine surfactants, but did increase the Krafft temperature of these surfactants. SANS analysis indicated that aggregate morphology of alkyl betaine surfactants could be influenced by the addition of sodium salts with chaotropic counterions (I− and SCN−), but they were insensitive to more kosmotropic anions (SO42−, F− and Cl−), providing unique and novel solution control methods for this (supposedly salt-insensitive) class of surfactants.

Physicochemical and sweetness behavior of kosmotropic and chaotropic ions in aqueous solutions of polyhydroxy compound

Hydrated ions have essential applications in biochemical processes. The objective of the present work is to study the behaviour of kosmotropic and chaotropic ions in aqueous solutions of polyhydroxy compounds in terms of sweetness response, volumetric and acoustic parameters such as apparent molar volume (∅v), apparent specific volume (ASV), compressibility (∅k0) etc. at different temperatures 20 °C – 45 °C and 101 kPa. The positive ∅v values of arabitol showed more kosmotropic nature for Na+ ion developing more stabilize structure of arabitol with water through strong hydrogen bonding, while the presence of K+ and Cl- form weak hydrogen bonding with water termed as chaotropic ions. The ASV values showed that arabitol remained sweet in the presence of electrolytes. The negative results of ∅k0 for arabitol in aqueous electrolytic solutions give valuable information about interactions occurring among solute, electrolytic ions, and water molecules. The structure-making/breaking behaviour has been observed by Hepler’s constant (∂2∅vo/∂T2)p.

Ion-Specific Nanoconfinement Effect in Multilayered Graphene Membranes: A Combined Nuclear Magnetic Resonance and Computational Study.

Ion adsorption within nanopores is involved in numerous applications. However, a comprehensive understanding of the fundamental relationship between in-pore ion concentration and pore size, particularly in the sub-2 nm range, is scarce. This study investigates the ion-species-dependent concentration in multilayered graphene membranes (MGMs) with tunable nanoslit sizes (0.5-1.6 nm) using nuclear magnetic resonance and computational simulations. For Na+-based electrolytes in MGMs, the concentration of anions in graphene nanoslits increases in correlation with their chaotropic properties. As the nanoslit size decreases, the concentration of chaotropic ion (BF4-) increases, whereas the concentration of kosmotropic ions (Cit3-, PO43-) and other ions (Ac-, F-) decreases or changes slightly. Notably, anions remain more concentrated than counter Na+ ions, leading to electroneutrality breakdown and unipolar anion packing in MGMs. A continuum modeling approach, integrating molecular dynamic simulation with the Poisson-Boltzmann model, elucidates these observations by considering water-mediated ion-graphene non-electrostatic interactions and charge screening from graphene walls.

Hofmeister effect-based soaking strategy for gelatin hydrogels with adjustable gelation temperature, mechanical properties, and ionic conductivity

As a natural polymer with good biocompatibility, gelatin hydrogel has been widely used in the field of biomedical science for a long time. However, the lack of suitable gelation temperature and mechanical properties often limit the clinical applicability in diverse and complex environments. Here, we proposed a strategy based on the Hofmeister effect that gelatin hydrogels were soaked in the appropriate concentration of sodium sulfate solution, and the change in molecular chain interactions mainly guided by kosmotropic ions resulted in a comprehensive adjustment of multiple properties. A series of gelatin hydrogels treated with different concentrations of the salt solution gave rise to microstructural changes, which brought a decrease in the number and size of pores, a wide range of gelation temperature from 32 °C to 46 °C, a stress enhancement of about 40 times stronger to 0.8345 MPa, a strain increase of about 7 times higher to 238.05 %, and a certain degree of electrical conductivity to be utilized for versatile applications. In this regard, for example, we prepared microneedles and obtained a remarkable compression (punctuation) strength of 0.661 N/needle, which was 55 times greater than those of untreated ones. Overall, by integrating various characterizations and suggesting the corresponding mechanism behind the phenomenon, this method provides a simpler and more convenient performance control procedure. This allowed us to easily modulate the properties of the hydrogel as per the intended purpose, revealing its vast potential applications such as smart sensors, electronic skin, and drug delivery.

Effect of Hofmeister series anions on freeze-thaw stability of emulsion stabilized with whey protein isolates

The effect of Hofmeister series anions at different concentrations on the freeze-thaw (FT) stability of emulsions stabilized with whey protein isolate (WPI) and its possible mechanism were studied. The emulsions prepared from WPI added with kosmotropic ions (Cl − and Br − ) presented good freeze-thaw stability, whereas those without NaCl were destabilized after freeze-thawing. In addition, the adsorbed protein (AP) percentage, protein load (τ), apparent viscosity, and mechanical moduli of emulsions added with Cl − and Br − were increased with the salt addition, thus facilitating the formation of elastic gel network structure in the emulsion system. WPI added with NaCl exhibited high interfacial pressure (π) and diffusion rate ( K diff ), indicating that its interfacial behavior promoted the stability of oil-water interface. During the adsorption process, the relative abundance of transferrin (TRF) and immunoglobulin (Ig) of WPI was increased, suggesting their higher interfacial affinity at the interface. After three FT cycles of the emulsion prepared from WPI added with Cl − , the proteins with low molecular weight (LMW) presented better emulsification activity. The decreased relative abundance of TRF and Ig due to the extrusion of the ice crystals would be responsible for the instability of the WPI-stabilized emulsion by freeze-thaw treatment. • WPI emulsions with Cl − and Br − addition exhibited good freeze-thaw (FT) stability. • The addition of kosmotropic ions increased the surface hydrophobicity of protein. • The surface hydrophobicity of protein with chaotropic ions was decreased. • Relative abundance of low-molecular-weight protein increased after three FT cycles. • Proteins with more quantities at the interface suggested the preferential adsorption.

A Stretchable and Healable Gelatin Hydrogel Assisted by Hofmeister Effect for All‐in‐One Flexible Supercapacitor

The all‐in‐one flexible supercapacitor holds great promise for wearable electronics due to its stable electrochemical performance under continuous strain. However, it is a challenge to achieve good mechanical strength, self‐healing performance, and high energy density for their potential applications. For this purpose, a stretchable and healable all‐in‐one supercapacitor consisting of gelatin hydrogel electrolytes and polypyrrole electrodes is constructed. The gelatin hydrogel is obtained by the hydrolysis of leather waste shavings and then physically cross‐linked by simply soaking in a sodium sulfate solution. Benefiting from the Hofmeister series, the kosmotropic sodium sulfate ions can significantly enhance the hydrophobic interactions and chain bundling, thus greatly improving the mechanical strength of gelatin hydrogel. As a result, the as‐prepared all‐in‐one supercapacitor exhibits an area‐specific capacitance of 219.0 mF cm−2, a high energy density of 19.46 μWh cm−2, and long cycling life. In particular, the all‐in‐one supercapacitor can be deformed under varied stress–strain via decross‐linking and dissociation, simultaneously delivers reliable self‐healing capability. This work presents a simple and green technology to prepare an all‐in‐one supercapacitor, which motivates the development of biomass wastes toward high‐performance electronics.

Highly Efficient and Salt-Rejecting Poly(vinyl alcohol) Hydrogels with Excellent Mechanical Strength for Solar Desalination.

Interfacial solar steam generation (ISSG)-based solar desalination has recently emerged as a promising solution to tackle the global issue of fresh water scarcity. However, the energy-intensive process of conventional vapor generation techniques limits its practical applications. Hydrogels with three-dimensional (3D) structures have been reported to alleviate this energy demand, but their applications in sustainable solar desalination are hindered by their poor mechanical stability. Herein, we propose a 3D poly(vinyl alcohol) (PVA)-based hydrogel with excellent mechanical strength for effective solar desalination. The dual polymer network hydrogel (PVA-agar) incorporated with multi-walled carbon nanotubes (MWCNTs) achieved a noticeable evaporation rate of 3.1 kg m-2 h-1 under 1 sun irradiation, owing to its broadband light absorption, intrinsic water channels, and microporous structure that help reduce the latent heat of vaporization. More importantly, the application of kosmotropic ammonium sulfate ions was found to greatly improve the mechanical strength of the hydrogels using a facile Hofmeister-assisted soaking method. Finally, the PVA-agar-MWCNT hydrogel was able to desalinate seawater efficiently (2.5 kg m-2 h-1) with self-cleaning capability of salt crystals. The salinity level of the desalinated water was also comparable to drinking clean water. The present results would pave the way for fabricating mechanically strong, hydrophilic, and highly efficient hydrogels for effective and sustainable solar desalination.

Investigation of Water Evaporation Process at Air/Water Interface using Hofmeister Ions.

Evaporation is an interfacial phenomenon in which a water molecule breaks the intermolecular hydrogen (H-) bonds and enters the vapor phase. However, a detailed demonstration of the role of interfacial water structure in the evaporation process is still lacking. Here, we purposefully perturb the H-bonding environment at the air/water interface by introducing kosmotropic (HPO4-2, SO4-2, and CO3-2) and chaotropic ions (NO3- and I-) to determine their influence on the evaporation process. Using time-resolved interferometry on aqueous salt droplets, we found that kosmotropes reduce evaporation, whereas chaotropes accelerate the evaporation process, following the Hofmeister series: HPO4-2 < SO4-2 < CO3-2 < Cl- < NO3- < I-. To extract deeper molecular-level insights into the observed Hofmeister trend in the evaporation rates, we investigated the air/water interface in the presence of ions using surface-specific sum frequency generation (SFG) vibrational spectroscopy. The SFG vibrational spectra reveal the significant impact of ions on the strength of the H-bonding environment and the orientation of free OH oscillators from ∼36.2 to 48.4° at the air/water interface, where both the effects follow the Hofmeister series. It is established that the slow evaporating water molecules experience a strong H-bonding environment with free OH oscillators tilted away from the surface normal in the presence of kosmotropes. In contrast, the fast evaporating water molecules experience a weak H-bonding environment with free OH oscillators tilted toward the surface normal in the presence of chaotropes at the air/water interface. Our experimental outcomes showcase the complex bonding environment of interfacial water molecules and their decisive role in the evaporation process.

A solvent-exchange strategy to develop stiff and tough hydrogel electrolytes for flexible and stable supercapacitor

Toughness of flexible energy storage devices and a stable energy output during dynamic deformation are two challenges to be solved in their practically application. Herein, we reported a stiff and tough poly(vinyl alcohol) (PVA) hydrogel electrolyte for flexible supercapacitor with toughness and stable energy output. A one-step solvent-exchange strategy was developed to replace the good solvent dimethyl sulfoxide (DMSO) to a poorer one water and simultaneously introduce kosmotropic ions into the PVA pre-hydrogels. This triggered the PVA chains to self-assemble and forming a homogeneous network crosslinked by the PVA crystalline domains and hydrophobic interactions. Benefiting from the excellent energy-dissipating ability of the homogeneous network, the PVA hydrogel electrolytes exhibited remarkable stiffness and toughness with tensile strength 16.54 MPa, elongation at break 1203%, and toughness 111.21 MJ m−3, which surpassed the most reported hydrogels. By utilizing polyaniline as electrodes, a flexible supercapacitor was assembled with superior areal specific capacitance of 156.50 mF cm−2 at 1.0 mA cm−2. The supercapacitor delivered high resistance to mechanical stimuli such as bending and pressure. Moreover, it could well maintain stable energy output even being dynamically deformed. The developed supercapacitor showed great potential in the wearable applications.

Artificial Intelligence Resolves Kinetic Pathways of Magnesium Binding to RNA.

Magnesium is an indispensable cofactor in countless vital processes. In order to understand its functional role, the characterization of the binding pathways to biomolecules such as RNA is crucial. Despite the importance, a molecular description is still lacking since the transition from the water-mediated outer-sphere to the direct inner-sphere coordination is on the millisecond time scale and therefore out of reach for conventional simulation techniques. To fill this gap, we use transition path sampling to resolve the binding pathways and to elucidate the role of the solvent in the binding process. The results reveal that the molecular void provoked by the leaving phosphate oxygen of the RNA is immediately filled by an entering water molecule. In addition, water molecules from the first and second hydration shell couple to the concerted exchange. To capture the intimate solute–solvent coupling, we perform a committor analysis as the basis for a machine learning algorithm that derives the optimal deep learning model from thousands of scanned architectures using hyperparameter tuning. The results reveal that the properly optimized deep network architecture recognizes the important solvent structures, extracts the relevant information, and predicts the commitment probability with high accuracy. Our results provide detailed insights into the solute–solvent coupling which is ubiquitous for kosmotropic ions and governs a large variety of biochemical reactions in aqueous solutions.

Phase stability of aqueous mixtures of bovine serum albumin with low molecular mass salts in presence of polyethylene glycol

The stability of bovine serum albumin (BSA) solutions against phase separation caused by cooling the system is studied under the combined influence of added poly(ethylene glycol) (PEG) and alkali halide salts in water as solvent. The phase stability of the system depends on the concentration of the added PEG and its molecular mass, the concentration of the low molecular mass electrolyte and its nature, as also on the pH of the solution. More specifically, the addition of NaCl to the BSA-PEG mixture promotes phase separation at pH=4.0, where BSA carries the net positive charge in aqueous solution, and it increases the stability of the solution at pH=4.6, i.e., near the isoionic point of the protein. Moreover, at pH=4.6, the cloud-point temperature decreases in the order from NaF to NaI and from LiCl to CsCl. The order of the salts at pH=4.0 is exactly reversed: LiCl and NaF show the weakest effect on the cloud-point temperature and the strongest decrease in stability is caused by RbCl and NaNO3. An attempt is made to correlate these observations with the free energies of hydration of the added salt ions and with the effect of adsorption of salt ions on the protein surface on the protein–protein interactions. Kosmotropic salt ions decrease the phase stability of BSA-PEG-salt solutions at pH<pI, while exactly the opposite is true at pH=pI.

Binary structure and dynamics of the hydrogen bonds in the hydration shells of ions.

Ion-specific effects of cations (Li+, Na+, K+, Mg2+, Ca2+) and anions (F-, Cl-) on the hydrogen bond structure and dynamics of the coordination waters in the hydration shells have been studied using molecular dynamics simulations. Our simulations indicate that the hydrogen bonds between the first and second hydration shell waters show binary structural and dynamic properties. The hydrogen bond with a first shell water as the donor (HD) is strengthened, while those with a first shell water as the acceptor (HA) are weakened. For a hydrated anion, this binary effect reverses, but is less significant. This ion-specific binary effect correlates with the size and the valence of the ion, and is more significant for the strong kosmotropic ions of high charge density.

Hofmeister Effect-Assistant Fabrication of All-Natural Protein-based Porous Materials Templated from Pickering Emulsions.

Porous materials derived from natural and biodegradable polymers have received growing interest. We demonstrate here an attractive method for the preparation of protein-based porous materials using emulsions stabilized by gliadin-chitosan hybrid particles (GCHPs) as the template, with the addition of gelatin and kosmotropic ions to improve the mechanical strength. The microstructure, mechanical properties, cytotoxicity, and fluid absorption behavior of porous materials were systematically investigated. This strategy facilitated the formation of porous materials with highly open and interconnected pore structure, which can be manipulated by altering the mass ratio of hexane or gelatin in the matrix. The Hofmeister effect resulted from kosmotropic ions greatly enhanced the Young's modulus and the compressive stress at 40% strain of porous materials from 0.56 to 6.84 MPa and 0.26 to 1.11 MPa, respectively. The developed all-natural porous materials were nontoxic to HaCaT cells; they also had excellent liquid (i.e., simulated body fluid and rabbit blood) absorption performance and advantages in resisting stress and maintaining geometry shape. The effects of different concentration amounts and type of salts in the Hofmeister series on the formation and performance of porous materials were also explored. Mechanical strength of porous materials was gradually enhanced when the (NH4)2SO4 concentration increased from 0 to 35 wt %, and the other four kosmotropic salts, including Na2S2O3, Na2CO3, NaH2PO4, and Na2SO4, also showed positive effects. This work opens a simple and feasible way to produce nontoxic and biodegradable porous materials with favorable mechanical strength and controllable pore structure. These materials have broad potential application in many fields involving biomedical and material science, such as cell culture, (bio)catalysis, and wound or bone defect healing.