The self-assembly behavior of sodium caprate (C10), a widely used intestinal permeation enhancer, was characterized under intestinally relevant conditions using small-angle neutron scattering (SANS) with contrast variation. Systems containing 100 mM C10, alone and in fasted-state (FaSSIF) and fed-state (FeSSIF) simulated intestinal fluid, together with 300 mM C10 in the presence of the therapeutic peptide octreotide, were investigated at pH 6.5 and 8.5. At pH 6.5, C10 alone formed coexisting ellipsoidal aggregates, vesicles, and large droplets. Addition of FaSSIF promoted co-assembled mixed structures, including large ellipsoidal aggregates, vesicles, and bilayer-like morphologies, while FeSSIF shifted the system further toward bilayer discs. The most pronounced structural reorganization occurred in the presence of octreotide, where C10 aggregates transformed into large bilayer discs with aggregation numbers approaching 18,000. At pH 8.5, all systems converge to small spherical micelles (radius 15-20 Å), with the notable exception of the C10-octreotide system, which forms prolate rod-like micelles. Contrast-dependent fitting showed that octreotide promotes axial micellar elongation without substantially altering radial packing, indicating amphiphilic cosurfactant-like behavior rather than peptide incorporation into the hydrophobic core. Coarse-grained molecular dynamics simulations supported this interpretation, showing rod-like aggregate formation in the presence of octreotide and cosurfactant-like behavior, with hydrophobic residues inserted into the micelle and hydrophilic Lys and Thr residues positioned at the interface. These findings demonstrate that intestinal fluid composition and peptide-excipient interactions are principal determinants of C10 aggregate architecture, providing a foundation for the rational design of caprate- and fatty-acid-based absorption enhancer systems for oral peptide delivery. Author keywords sodium caprate, small-angle neutron scattering, contrast variation, intestinal fluid, octreotide, cosurfactant, permeation enhancer.

Investigation of the properties of membrane proteins (MPs) is essential to the successful development of medicines and biotechnology. However, their study is often complicated by denaturation caused by the use of detergents during conventional extraction methods. Copolymers of styrene and maleic acid (SMA) have shown promise in extracting MPs directly from cells while reconstituting lipid membranes into nanodiscs. Despite their potential, there remains a dearth of information on the precise interactions that take place between the copolymers and lipid membranes although they are known to be sensitive to small variations in copolymer composition or structure. We have used reversible addition-fragmentation chain transfer (RAFT) polymerisation to synthesise SMA copolymers with equivalent molar mass, but with inverted block sequences and end group termini. Through a range of experiments, including dynamic light scattering and small-angle neutron scattering (SANS) on SMA aggregates and nanodisc formation studies using UV-vis spectroscopy with both model DMPC lipids and E. coli membranes, the impact of both block distribution and end group chemistry on copolymer-membrane interactions was investigated. It was found that mismatched hydrophilic and hydrophobic end groups on the styrene block and alternating block, respectively, impeded membrane disruption and subsequent solubilisation. This highlights not only how the amphiphilic balance of these blocks is important for efficient nanodisc formation, but also how end groups influence these and may be optimised towards extraction of more challenging MPs. The work contributes to a better understanding of SMA behaviour and offers insight into how these nanomaterials may be better designed and tailored for specific applications.

Co-assembly and self-sorting in multicomponent systems are typically treated as mutually exclusive outcomes. Here, we show that this distinction is incomplete. Using enantiomeric peptide nanotubes, we demonstrate that a single co-assembled structure forms only at an equimolar composition, yet remains internally self-sorted into compositionally distinct domains. Contrast-matched neutron scattering directly reveals this segregation and shows that the co-assembled structures adopt layered architectures rather than simple molecular-level mixing. These results establish that co-assembly and self-sorting can coexist within a single supramolecular object across length scales, providing a general framework for understanding and controlling multicomponent self-assembly.

The Bcl-2 family of proteins governs mitochondrial outer membrane (MOM) permeabilization, a critical step in apoptosis that is dysfunctional in many cancers. Although cellular studies have long implicated direct interactions between the pore-forming apoptotic Bax protein and its opponent, the antiapoptotic Bcl-2 protein in apoptosis regulation, the underlying basic principles behind this control remained unresolved. To provide in-depth insight, we carried out a systematic biophysical study in which we utilized neutron reflectometry (NR) and ATR-FTIR to elucidate the molecular communication between those proteins in and around the mitochondrial membrane environment. The spatial and temporal changes across model MOM surfaces were resolved during the interaction of Bax with Bcl-2. The NR-derived membrane surface Bax distributions suggested that Bcl-2 mediated Bax sequestration through both Bcl-2/Bax heterodimerization and Bax/Bax oligomerization. Kinetic analysis revealed a two-step process: rapid formation of Bcl-2/Bax heterodimers, followed by slower Bax oligomerization on these complexes. Importantly, this sequestration mechanism was also observed in the presence of cardiolipin, a lipid known to promote the formation of an apoptotic pore by Bax in the absence of Bcl-2. These findings suggest a fundamental mechanism by which cancer cells may evade apoptosis by exploiting Bcl-2’s ability to neutralize Bax through structural entrapment, even if excess Bax is present, either in response to treatment or natural death signals.

The morphology and porosity of iron oxide nanoparticles grown in deep eutectic solvents using mild conditions can be altered by addition of surfactant or water during syntheses.

The sol-gel transition of CO2-responsive polyelectrolytes is driven by electrostatic interactions between anionic groups and protonated cationic moieties, yet the critical roles of ionic stoichiometry and spatial architecture in mediating gelation behavior remain poorly understood. To address this knowledge gap, two distinct copolymer series with varying configurations and anion/CO2-responsive monomer ratios were synthesized: P(AA-co-DPM) random copolymers via free radical copolymerization of acrylamide, acrylic acid, and dimethylaminopropyl methacrylamide (DMAPMAm), while PAA-g-PDPM graft copolymers through the covalent attachment of poly(DMAPMAm) side chains to poly(AM-co-AA) backbones. CO2-induced protonation led to contrasting phase behaviors contingent on ionic balance. For P(AA-co-DPM) aqueous solution, viscosity decreased when n(DMAPMAm) <= 0.83n(NaAA), increased when n DMAPMAm >= 1.13 n(NaAA), and resulted in precipitation when n(DMAPMAm) = 0.83n(NaAA). Conversely, the PAA-g-PDPM aqueous solution exhibited continuous viscosity enhancement up to n DMAPMAm <= 0.65n(NaAA), followed by dehydration at higher cationic ratios. Notably, the graft architecture demonstrated superior gelation under CO2 exposure, forming robust hydrogels with frequency-independent modulus (0.01-0.1 rads(-1)) and minimal energy dissipation (tan delta < 0.1). In contrast, random copolymers yielded fragile networks displaying frequency-dependent moduli and elevated tan delta (>0.1). Rheology-small angle neutron scattering analysis revealed that graft copolymers underwent CO2-induced chain collapse from swollen to compact conformations, creating physical cross-links, whereas random chains maintained Gaussian statistics regardless of protonation state. These findings highlight that extended cationic side chains in graft architectures enhance intermolecular entanglement and directional electrostatic interactions, offering a strategic approach for designing CO2-responsive hydrogels with tailored mechanical properties through molecular architecture engineering.

Thermal processing is widely used in solution‐based coating techniques or to enhance solubility, yet the impact on supramolecular self‐assembly and thin film properties remains largely unexplored. Here, we demonstrate how heating and cooling cycles modulate the self‐assembly of amino acid‐appended perylene bisimides (PBIs), influencing their structural and optoelectronic properties. Using small‐angle neutron scattering (SANS), rheology, and absorption spectroscopy, we show that heating increases fibre flexibility while cooling results in spherical aggregate formation. Additionally, we demonstrate the impact of these changes on thin film performance using nanoindentation and voltammetry. When incorporated as electron transport layers (ETLs) in perovskite solar cells, heat‐cooling reduces the series resistance from 6.33 to 4.40 Ω∙cm 2 , enhancing device efficiency. Our findings highlight the importance of thermal history in supramolecular materials and emphasise the need for strict temperature control in solution‐based coating techniques to optimise optoelectronic device performance.

HYPOTHESIS:Membrane proteins serve a wide range of vital roles in the functioning of living organisms. They are responsible for many cellular functions, such as signalling, ion and molecule transport, binding and catalytic reactions. Compared to other classes of proteins, determining membrane protein structures remains a challenge, in large part due to the difficulty in establishing experimental conditions that can preserve the correct conformation and function of the protein in isolation from its native environment. Many therapeutics target membrane proteins which are accessible on the surface of cells. Here we hypothesize that the observed efficacy of antimicrobial peptides (AMPs) that interact with bacterial membranes may in part be associated with their triggering of a conformational change in the Mechansensitive Ion Channel of Large Conductance (MscL). EXPERIMENTS:We investigated the ion channel in lipid vesicles and in a planar lipid bilayer. We developed a novel method for protein-lipid planar bilayer formation, avoiding the use of detergents. By using a polymeric tether our planar membrane mimetic was not constrained by the underlying solid substrate, making it sufficiently flexible to allow for increases in bilayer curvature and changes in membrane tension. We used quartz crystal microbalance with dissipation (QCM-D), and polarised neutron reflectivity (PNR) to show the formation of MscL containing phospholipid bilayers, tethered with a high density PEG layer onto gold substrates from vesicle rupture. The MscL containing vesicles were separately characterised with small angle neutron scattering (SANS). FINDINGS:MscL was expressed into vesicles using cell free protein expression. Analysing these vesicles with small angle neutron scattering, the radius of gyration of the protein was determined to be between 26-29 Å, consistent with the crystal structure of individual MscL channels. The MscL composition of the formed bilayer was 14%v/v, close to the initial composition of the vesicles, and a protein protrusion extending ca. 46 Å into the solvent was determined by PNR. Addition of 1.6 and 3.2 μM pexiganan resulted in a decrease in the protrusion of MscL (from ∼46 to ∼38 Å). To our knowledge, these findings represent the first direct experimental evidence of a structural change in the C-terminus containing protrusion of MscL, triggered by an antimicrobial peptide.

HYPOTHESIS:Addition of cosurfactants to surfactant micelles is normally assumed to lead, via a continuous change of the packing parameter, to a transition of spherical micelles to elongated ones, then to wormlike viscoelastic micelles and finally, via a phase transition, to planar lamellae. However, this conventional structural sequence may be different, if surfactants with variable head group size and cosurfactants that favour strongly planar structures are employed. EXPERIMENTS:A phase study was done on solutions of the nonionic surfactant Tween-20 (Tw20) with increasing amounts of added cosurfactant 2-ethylhexyl glycerine (EHG). This study was supported by a detailed structural characterisation of the aqueous solutions as a function of added amount of EHG by a combination of small-angle neutron scattering (SANS) and cryo-TEM, which allows uniquely to assign the structures present. FINDINGS:We found that the initially present small Tw20 micelles become somewhat larger and more oblate with increasing EHG concentration. However, they do not form wormlike micelles, but instead these small oblate micelles arrange themselves into wormlike aggregates of individual micelles, which only show low viscosity. For higher EHG concentration, a two-phase region is found, above which still such wormlike aggregates of small micelles are still observed, which are in equilibrium with bilayer structures. Only at much higher EHG concentrations pure bilayer structures are formed. The latter effect is ascribed to the intrinsic molecular polydispersity of the surfactant head group. However, the overall assembly behaviour arises from having a surfactant that favours to have a highly curved interface, while the cosurfactant favours a rather flat structure.

N-Acyl amino acids are biodegradable anionic amphiphilic molecules made up of linear fatty acids as hydrophobic tails and amino acids as polar heads, which are promising for their applicability in different technological fields. In the light of widening their use, a deeper understanding of their interactions with biological membranes is required, especially to further assess their toxicological profile. We investigated the interaction between N-decanoyl amino acid surfactants and phospholipid bilayers as simple in vitro models for biological membranes in comparison to sodium dodecyl sulfate using neutron scattering techniques. The information from small angle neutron scattering (SANS, q range from 0.008 to 0.25 Å-1) focusing on liposome-to-surfactant interactions and neutron reflectivity (NR, Q range measured at three incident angles θ = 0.35, 0.65, and 1.5°) focusing on lipid bilayer-to-surfactant interactions was combined to provide a detailed characterization. All amino acid surfactants (C10-alanine, C10-glycine, C10-leucine, C10-methionine, C10-serine, and C10-proline) exhibited a similar behavior in terms of incorporation in liposomes and lipid removal as well as adsorption profiles in bilayers up to their critical micelle concentration (CMC). Notably, bilayer destabilization occurred for all surfactants (except for C10-serine and C10-alanine) at a concentration between CMC and 2× CMC. Such a result demonstrates the exceptional ability of C10-serine and C10-alanine to integrate into bilayers without disruption up to concentrations as high as ∼3-4× CMC. These findings support the lower cytotoxic effect of C10-serine and C10-alanine surfactants, observed in previous studies, and provide new insights on the mechanism of interaction of N-decanoyl amino acids with lipid membranes.

Thermoviscosifying polymers (TVPs), which thicken aqueous solutions upon heating, deviate from the conventional thermothinning behavior and hold promise as effective rheology modifiers under harsh conditions. However, their thickening efficiency at low concentrations remains limited by relatively low molecular weights, and the quantitative relationship between thermoviscosifying capacity and thermoassociative contributions has yet to be fully established. In this work, model TVPs were synthesized by grafting amino-terminated poly(N-isopropylacrylamide) (PNIPAM) onto high-molecular-weight partially hydrolyzed polyacrylamide, with systematic variations in backbone molecular weight (M w) and graft ratio (G r). A dual-model strategy was adopted to quantify the non-Arrhenius viscosity increase in the thermoviscosifying regime: the Cross model captured logarithmical viscosity growth, while the Gompertz function described sigmoidal viscosity amplification. By integrating molecular parameters into the Gompertz framework, scaling relationships were established between the thickening amplitude (eta max-eta ass) and M w, G r, and polymer concentration (C p), yielding eta max-eta ass similar to M w 1.75, similar to G r 1.04 and similar to C p 2.01, as exemplified by eta ( T , M w ) = eta a s s + K M w 1.75 e - e - k ( T - T c ) . The net thickening power, eta-eta ass, representing the thermoassociative contribution beyond the nonassociative baseline, scales with PNIPAM content (C PNIPAM) as eta-eta ass similar to C PNIPAM n . Analysis using the time-temperature superposition shift factor revealed distinct scaling exponents (n = 2.78 for C p vs 1.10 for G r), highlighting the stronger influence of backbone concentration over grafting density in promoting thermoassociation. These findings provide a quantitative paradigm for assessing thickening performance and establish molecular design principles for TVPs.

Photothermal effects, driven by the conversion of light into heat, offer versatile applications in fields such as photothermal therapy, energy conversion, and pollution degradation. Naphthalene diimide (NDI) molecules exhibit diverse properties with applications spanning optoelectronics, materials science, and nanomedicine. In this study, we synthesize various amino acid-functionalized naphthalene diimides, which, after irradiation with light in both gel and solution forms, produce radical anions, which enables their photothermal properties. Our findings demonstrate the influence of pH on photothermal performance. Furthermore, we demonstrate that the incorporation of polyvinyl alcohol (PVA) increases the viscosity of the solutions and reduces oxidation. To further investigate how pH affects the aggregated structures, we use small-angle neutron scattering (SANS). In addition, in situ SANS measurements were conducted to monitor the aggregation changes during irradiation to advance our understanding of NDIs' potential as photothermal materials in potential energy-related applications.

We have investigated the effect of length and chemical structure of phospholipid tails on the spontaneous formation of unilamellar liposomal vesicles in binary solute mixtures of cationic drug surfactant and zwitterionic phosphatidylcholine phospholipids. Binary drug surfactant-phospholipid mixtures with four different phospholipids with identical headgroups (two saturated phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC, 14:0) and 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, 16:0), and two unsaturated lipids 1,2dioleoyl-sn-glycero-3-phosphocholine (DOPC, 18:1) and 1,2-Dierucoyl-sn-Glycero-3-Phosphatidylcholine (DEPC, 22:1)) combined with two different tricyclic antidepressant drugs (amitriptyline hydrochloride (AMT) and doxepin hydrochloride (DXP)) have been investigated with small-angle neutron scattering (SANS) and cryotransmission electron microscopy (cryo-TEM). We observe a conspicuous impact of phospholipid tail structure on both micelle-to-vesicle transition point and vesicle size. In particular, ultrasmall unilamellar vesicles, i.e. with a diameter less than 20 nm, were observed in several samples with the two unsaturated phospholipids DOPC and DEPC, but not in any samples with the saturated phospholipids DMPC and DPPC. The smallest vesicles observed in DOPC and DEPC mixtures were smaller than 18 nm in diameter. In contrast, the smallest vesicles observed in DMPC mixtures were about 30 nm in diameter and always larger than 100 nm in DPPC mixtures. The ultrasmall vesicles showed exceptional colloidal stability. Moreover, bilayer vesicles predominated over micelles in a much wider range of concentrations for DOPC and DEPC mixtures as a result of having a smaller phospholipid mole fraction in the aggregates at the micelle-to-vesicle transition. Our results have been theoretically rationalized by combining solution thermodynamics with bending elasticity theory.

Human immunoglobulin G (IgG) exists as four subclasses IgG1-4, each of which has two Fab subunits joined by two hinges to a Fc subunit. IgG4 has the shortest hinge with 12 residues. The Fc subunit has two glycan chains, but the importance of glycosylation is not fully understood in IgG4. Here, to evaluate the stability and structure of non-glycosylated IgG4, we performed a multidisciplinary structural study of glycosylated and deglycosylated human IgG4 A33 for comparison with our similar study of human IgG1 A33. After deglycosylation, IgG4 was found to be monomeric by analytical ultracentrifugation; its sedimentation coefficient of 6.52 S was reduced by 0.27 S in reflection of its lower mass. X-ray and neutron solution scattering showed that the overall Guinier radius of gyration RG and its cross-sectional values after deglycosylation were almost unchanged. In the P(r) distance distribution curves, the two M1 and M2 peaks that monitor the two most common distances within IgG4 were unchanged following deglycosylation. Further insight from Monte Carlo simulations for glycosylated and deglycosylated IgG4 came from 111,382 and 117,135 possible structures respectively. Their comparison to the X-ray and neutron scattering curves identified several hundred best-fit models for both forms of IgG4. Principal component analyses showed that glycosylated and deglycosylated IgG4 exhibited different conformations from each other. Within the constraint of unchanged RG and M1-M2 values, the glycosylated IgG4 models showed more restricted Fc conformations compared to deglycosylated IgG4, but no other changes. Kratky plots supported this interpretation of greater disorder upon deglycosylation, also observed in IgG1. Overall, these more variable Fc conformations may demonstrate a generalisable impact of deglycosylation on Fc structures, but with no large conformational changes in IgG4 unlike those seen in IgG1.

Ionic charge transport is a ubiquitous language of communication in biological systems. As such, bioengineering is in constant need of innovative, soft, and biocompatible materials that facilitate ionic conduction. Low molecular weight gelators (LMWGs) are complex self-assembled materials that have received increasing attention in recent years. Beyond their biocompatible, self-healing, and stimuli responsive facets, LMWGs can be viewed as a "solid" electrolyte solution. In this work, we investigate 3,4-ethylenedioxythiophene (EDOT) as a capping group for a small peptide library, which we use as a system to understand the relationship between modes of assembly and charge transport in supramolecular gels. Through a combination of techniques including small-angle neutron scattering (SANS), NMR-based Van't Hoff analysis, atomic force microscopy (AFM), rheology, four-point probe, and electrochemical impedance spectroscopy (EIS), we found that modifications to the peptide sequence result in distinct assembly pathways, thermodynamic parameters, mechanical properties, and ionic conductivities. Four-point probe conductivity measurements and electrochemical impedance spectroscopy suggest that ionic conductivity is approximately doubled by programmable gel assemblies with hollow cylinder morphologies relative to gels containing solid fibers or a control electrolyte. More broadly, it is hoped this work will serve as a platform for those working on charge transport of aqueous soft materials in general.

Achieving precise control over gelator alignment and morphology is crucial for crafting tailored materials and supramolecular structures with distinct properties. We successfully aligned the self-assembled micelles formed by a functionalized dipeptide 2NapFF into long 1-D "gel noodles" by cross-linking with divalent metal chlorides. We identify the most effective cross-linker for alignment, enhancing mechanical stability, and imparting functional properties. Our study shows that Group 2 metal ions are particularly suited for creating mechanically robust yet flexible gel noodles because of their ionic and nondirectional bonding with carboxylate groups. In contrast, the covalent nature and high directional bonds of d-block metal ions with carboxylates tend to disrupt the self-assembly of 2NapFF. Furthermore, the 2NapFF-Cu noodles demonstrated selective antibacterial activity, indicating that the potent antibacterial property of the copper(II) ion is preserved within the cross-linked system. By merging insights into molecular alignment, gel extrusion processing, and integrating specific functionalities, we illustrate how the versatility of dipeptide-based gels can be utilized in creating next-generation soft materials.

Machine learning (ML) can be employed at the data-analysis stage of small-angle scattering (SAS) experiments.

The non-invasive nature and potential for sustained release make transdermal drug administration an appealing treatment option for cancer therapy. However, the strong barrier of the stratum corneum (SC) poses a challenge for the penetration of hydrophilic chemotherapy drugs such as 5-fluorouracil (5-FU). Due to its biocompatibility and capacity to increase drug solubility and permeability, especially when paired with chemical enhancers, such as oleic acid (OA), which is used in this work, choline glycinate ([Cho][Gly]) has emerged as a potential substance for transdermal drug delivery. In this work, we examined the possibility of transdermal delivery of 5-FU for the treatment of breast cancer using an ionic hydrogel formulation consisting of [Cho][Gly] with OA. Small angle neutron scattering, rheological analysis, field emission scanning electron microscopy, and dynamic light scattering analysis were used to characterize the ionic hydrogel. The non-covalent interactions present between [Cho][Gly] and OA were investigated by computational simulations and FTIR spectroscopy methods. When subjected to in vitro drug permeation using goat skin in a Franz diffusion cell, the hydrogel demonstrated sustained release of 5-FU and effective permeability in the order: [Cho][Gly]-OA gel > [Cho][Gly] > PBS (control). The hydrogel also demonstrated 92% cell viability after 48 hours for the human keratinocyte cell line (HaCaT cells) as well as the normal human cell line L-132. The breast cancer cell line MCF-7 and the cervical cancer cell line HeLa were used to study in vitro cytotoxicity that was considerably affected by the 5-FU-loaded hydrogel. These results indicate the potential of the hydrogel as a transdermal drug delivery vehicle for the treatment of breast cancer.