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Boron clusters are applied in medicinal chemistry because of their high stability in biological environments and intrinsic ability to capture neutrons. However, their intermolecular interactions with lipid membranes, which are critical for their cellular delivery and biocompatibility, have not been comprehensively investigated. In this study, we combine different experimental methods – Langmuir monolayer isotherms at the air–water interface, calorimetry (DSC, ITC), and scattering techniques (DLS, SAXS) – with MD simulations to evaluate the impact of closo‐dodecaborate clusters on model membranes of different lipid composition. The cluster anions interact strongly with zwitterionic membranes (POPC and DPPC) via the chaotropic effect and cause pronounced expansions of lipid monolayers. The resulting lipid membranes contain up to 33 mol % and up to 52 weight % of boron cluster anions even at low aqueous cluster concentrations (1 mM). They show high (μM) affinity to the hydrophilic‐hydrophobic interface, affecting the structuring of the lipid chains, and therefore triggering a sequence of characteristic effects: (i) an expansion of the surface area per lipid, (ii) an increase in membrane fluidity, and (iii) a reduction of bilayer thickness. These results aid the design of boron cluster derivatives as auxiliaries in drug design as well as transmembrane carriers and help rationalize potential toxicity effects. [ABSTRACT FROM AUTHOR]

In living systems, protein assemblies have essential functions, serving as structural supports, transport highways for molecular cargo, and containers of genetic material. The construction of protein assemblies, which involves control over space and time, remains a significant challenge in biotechnology. Here, we show that anionic boron clusters, 3,3′‐commo‐bis[closo‐1,2‐dicarba‐3‐cobaltadodecaborane] (COSAN−), and halogenated closo‐dodecarboranes (B12X122−, X=H, Cl, or I), described as super‐chaotropic nano‐ions, induce the formation of 2D assemblies of model proteins, myoglobin, carbonic anhydrase, and trypsin inhibitor. We found that the nano‐ion concentration reversibly controls the size of the protein assemblies. Furthermore, the secondary structures of the proteins are only slightly affected by assembly formation. For myoglobin, the formation of these assemblies even prevents temperature denaturation, highlighting a preservation effect of nano‐ions. Our study reveals that inorganic boron‐based nano‐ions act as a reversible molecular glue for proteins, providing a potential starting point for the further development of controlled protein assemblies. [ABSTRACT FROM AUTHOR]

Supramolecular polymers built from stimuli‐responsive host‐guest interactions represent an attractive way of tailoring smart materials. Herein, we exploit the chaotropic effect of polyoxometalates and related host‐guest properties to design unconventional polymer systems with reversible redox and thermo‐responsive sol‐gel transition. These supramolecular networks result from the association of cyclodextrin‐based oligomers and Keggin‐type POMs acting as electro‐active crosslinking agents. The structure and the dynamics of such self‐assembly systems have been investigated using a multiscale approach involving MALDI‐TOF, viscosity measurements, cyclic voltammetry, 1H‐NMR (1D and DOSY), and Small‐Angle X‐ray Scattering. Our results reveal that the chaotropic effect corresponds to a powerful and efficient force that can be used to induce responsiveness in hybrid supramolecular oligomeric systems. [ABSTRACT FROM AUTHOR]

Nanometer‐sized anions (nano‐ions) like polyoxometalates and boron clusters exhibit so‐called superchaotropic behavior, which describes their strong binding to hydrated non‐ionic matter in water. We show here that nano‐ions, at millimolar concentrations, dramatically enhance the viscosity and induce gelation of aqueous solutions of non‐ionic cellulose ethers (CEs), a class of widely utilized polymers known for their thickening and gel‐forming ability. These phenomena arise from an interplay of attractive forces and repulsive electrostatic forces between CE‐chains upon nano‐ion binding. The attractive forces manifest themselves as aggregation of CE‐chains into a physically crosslinked polymer network (gel). In turn, the electrostatic repulsions hamper the viscosity increase and gelation. Superchaotropic nano‐ion binding emerges as a novel and general physical crosslinking motif for CE‐solutions and exceeds by far the conventional thickening effects of classical salts and ionic surfactants. [ABSTRACT FROM AUTHOR]

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Low charge density nanometric ions were recently shown to bind strongly to neutral hydrated matter in aqueous solution. This phenomenon, called the (super-)chaotropic effect, arises from the partial dehydration of both the nano-ion and the solute, leading to a significant gain in enthalpy. Here, we investigate the chaotropic effect of the polyoxometalate α-PW12O403− on the triblock copolymer P84: (EO)19(PO)43(EO)19 with (EO)19 the polyethoxylated and (PO)43 the polypropoxylated chains. The combination of phase diagrams, spectroscopic (nuclear magnetic resonance) and scattering (small angle neutron/X-ray scattering) techniques revealed that: (i) below the micellization temperature of P84, PW12O403− exclusively binds to the propylene oxide moiety of P84 unimers; and (ii) above the micellization temperature, PW12O403− mostly adsorbs on the ethylene oxide micellar corona. The preferential binding of the PW12O403− to the PPO chain over the PEO chains suggests that the binding is driven by the chaotropic effect and is reinforced by the hydrophobic effect. At higher temperatures, copolymer micellization leads to the displacement of PW12O403− from the PPO chain to the PEO chains. This study deepens our understanding of the subtle interplay between the chaotropic and hydrophobic effects in complex salt-organic matter solutions. [ABSTRACT FROM AUTHOR]

Back Cover: Superchaotropic Nano-ion Binding as a Gelation Motif in Cellulose Ether Solutions (Angew. This novel gelation phenomenon exceeds the thickening effects of typical additives like classical salts and surfactants by orders of magnitude and is due to the superchaotropicity of the nano-ions, which drives them out of the water bulk onto the polymers. Keywords: Cellulose; Chaotropic Effect; Hydrogel; Polyoxometalate; Superchaotropic EN Cellulose Chaotropic Effect Hydrogel Polyoxometalate Superchaotropic 1 1 1 01/11/23 20230116 NES 230116 B Synergy between salt and sugar b Nanometric ions like Keggin polyoxometalates are revealed to induce the cross-linking and hydrogel formation of polymeric sugars, namely non-ionic cellulose ethers, as reported by Max Hohenschutz, Walter Richtering, and co-workers in their Communication (e202210208). [Extracted from the article]

Keywords: Cellulose; Chaotropic Effect; Hydrogel; Polyoxometalate; Superchaotropic EN Cellulose Chaotropic Effect Hydrogel Polyoxometalate Superchaotropic 1 1 1 01/11/23 20230116 NES 230116 B Synergy between salt and sugar b Nanometric ions like Keggin polyoxometalates are revealed to induce the cross-linking and hydrogel formation of polymeric sugars, namely non-ionic cellulose ethers, as reported by Max Hohenschutz, Walter Richtering, and co-workers in their Communication (e202210208). This novel gelation phenomenon exceeds the thickening effects of typical additives like classical salts and surfactants by orders of magnitude and is due to the superchaotropicity of the nano-ions, which drives them out of the water bulk onto the polymers. Cellulose, Chaotropic Effect, Hydrogel, Polyoxometalate, Superchaotropic. [Extracted from the article]