Interfacial Monolayer Research Articles

Drying of Soft Colloidal Films.

Thin films made of deformable micro- and nano-units, such as biological membranes, polymer interfaces, and particle-laden liquid surfaces, exhibit a complex behavior during drying, with consequences for various applications like wound healing, coating technologies, and additive manufacturing. Studying the drying dynamics and structural changes of soft colloidal films thus holds the potential to yield valuable insights to achieve improvements for applications. In this study, interfacial monolayers of core-shell (CS) microgels with varying degrees of softness are employed as model systems and to investigate their drying behavior on differently modified solid substrates (hydrophobic vs hydrophilic). By leveraging video microscopy, particle tracking, and thin film interference, this study shed light on the interplay between microgel adhesion to solid surfaces and the immersion capillary forces that arise in the thin liquid film. It is discovered that a dried replica of the interfacial microstructure can be more accurately achieved on a hydrophobic substrate relative to a hydrophilic one, particularly when employing softer colloids as opposed to harder counterparts. These observations are qualitatively supported by experiments with a thin film pressure balance which allows mimicking and controlling the drying process and by computer simulations with coarse-grained models.

Neural network-assisted model of interfacial fluids with explicit coarse-grained molecular structures.

Interfacial fluids are ubiquitous in systems ranging from biological membranes to chemical droplets and exhibit a complex behavior due to their nonlinear, multiphase, and multicomponent nature. The development of accurate coarse-grained (CG) models for such systems poses significant challenges, as these models must effectively capture the intricate many-body interactions, both inter- and intramolecular, arising from atomic-level phenomena, and account for the diverse density distributions and fluctuations at the interface. In this study, we use advanced machine learning techniques incorporating force matching and diffusion probabilistic models to construct a robust CG model of interfacial fluids. We evaluate our model through simulations in various settings, including the water-air interface, bulk decane, and dipalmitoylphosphatidylcholine monolayer membranes. Our results show that our CG model accurately reproduces the essential many-body and interfacial properties of interfacial fluids and proves effective across different CG mapping strategies. This work not only validates the utility of our model for multiscale simulations, but also lays the groundwork for future improvements in the simulation of complex interfacial systems.

Behavior of Microbubbles on Air-Aqueous Interfaces.

Animal-derived lung surfactants have saved millions of lives of preterm neonates with neonatal Respiratory Distress Syndrome (nRDS). However, a replacement for animal-derived lung surfactants has been sought for decades due to its high manufacturing cost, inaccessibility in low-income countries, and failure to show efficacy when nebulized. This study investigated the use of lipid-coated microbubbles as potential replacements for exogenous lung surfactants. Three different formulations of microbubbles (DPPC with/out PEG40-stearate and poractant alfa) were prepared, and their equilibrium and dynamic surface tensions were tested on a clean air-saline interface or a simulated air-lung fluid interface using a Langmuir-Blodgett trough. In dynamic surface measurements, microbubbles reduced the minimum surface tension compared with the equivalent composition lipid suspension: e.g., PEG-free microbubbles had a minimum surface tension of 4.3 mN/m while the corresponding lipid suspension and poractant alfa had 20.4 (p ≤ 0.0001) and 21.8 mN/m (p ≤ 0.0001), respectively. Two potential mechanisms for the reduction of surface tension were found: Fragmentation of the foams created by microbubble coalescence; and clustering of microbubbles in the aqueous subphase disrupting the interfacial phospholipid monolayer. The predominant mechanism appears to depend on the formulation and/or the environment. The use of microbubbles as a replacement for exogenous lung surfactant products thus shows promise and further work is needed to evaluate efficacy in vivo.

Graphene Oxide Covalently Functionalized with 5-Methyl-1,3,4-thiadiazol-2-amine for pH-Sensitive Ga3+ Recovery in Aqueous Solutions.

A novel graphene-based composite, 5-methyl-1,3,4-thiadiazol-2-amine (MTA) covalently functionalized graphene oxide (GO-MTA), was rationally developed and used for the selective sorption of Ga3+ from aqueous solutions, showing a higher adsorption capacity (48.20 mg g-1) toward Ga3+ than In3+ (15.41 mg g-1) and Sc3+ (~0 mg g-1). The adsorption experiment's parameters, such as the contact time, temperature, initial Ga3+ concentration, solution pH, and desorption solvent, were investigated. Under optimized conditions, the GO-MTA composite displayed the highest adsorption capacity of 55.6 mg g-1 toward Ga3+. Moreover, a possible adsorption mechanism was proposed using various characterization methods, including scanning electron microscopy (SEM) equipped with X-ray energy-dispersive spectroscopy (EDS), elemental mapping analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Ga3+ adsorption with the GO-MTA composite could be better described by the linear pseudo-second-order kinetic model (R2 = 0.962), suggesting that the rate-limiting step may be chemical sorption or chemisorption through the sharing or exchange of electrons between the adsorbent and the adsorbate. Importantly, the calculated qe value (55.066 mg g-1) is closer to the experimental result (55.60 mg g-1). The well-fitted linear Langmuir isothermal model (R2 = 0.972~0.997) confirmed that an interfacial monolayer and cooperative adsorption occur on a heterogeneous surface. The results showed that the GO-MTA composite might be a potential adsorbent for the enrichment and/or separation of Ga3+ at low or ultra-low concentrations in aqueous solutions.

Trio strategy of harmonizing electronic structure, interface, and microenvironment on amorphous indium oxide nanofiber for selective electrochemical ammonia synthesis

Suppressing parasitic hydrogen evolution reaction (HER) remains a dilemma in developing aqueous electrochemical nitrogen reduction reaction (NRR). Nevertheless, previous studies have revealed the significant challenge of relying solely on electrocatalyst design to pursue selective NRR. Herein, we present a ‘Trio’ strategy to harmonize electronic structures of electrocatalysts, properties of interfaces, and configurations of microenvironments, thereby governing the intricate proton behaviors throughout the reaction, to suppress HER while boosting NRR. As proof-of-concept demonstration, the first designed amorphous In2O3-based nanofiber electrocatalyst, with optimized electronic state by oxygen vacancy and anchoring Mo species, is in conjunction with low-surface-energy monolayer interface and molecular-crowding microenvironment. Such rational synergy creates an advantageous catalytic configuration with decelerated proton diffusion and restricted proton transfer to active sites, thus achieving NH3 yield of 59.72 μg h−1 mg−1 and a FE of 30.60 %. We expect these findings will inspire “collaborative combat” strategies and desirable systems of NRR in the future.

Advancements in Bovine Organoid Technology Using Small and Large Intestinal Monolayer Interfaces

Advancements in Bovine Organoid Technology Using Small and Large Intestinal Monolayer Interfaces

Enhanced recognition of G-quadruplex DNA oxidative damage based on DNA-mediated charge transfer

G-quadruplex (G4) DNA is present in human telomere oligonucleotide sequences. Oxidative damage to telomeric DNA accelerates telomere shortening, which is strongly associated with aging and cancer. Most of the current analyses on oxidative DNA damage are based on ds-DNA. Here, we developed a electrochemiluminescence (ECL) probe for enhanced recognition of oxidative damage in G4-DNA based on DNA-mediated charge transfer (CT), which could specifically recognize damaged sites depending on the position of 8-oxoguanine (8-oxoG). First, a uniform G4-DNA monolayer interface was fabricated; the G4-DNA mediated CT properties were examined using an iridium(III) complex [Ir(ppy)2(pip)]PF6 stacked with G4-DNA as an indicator. The results showed that G4-DNA with 8-oxoG attenuated DNA CT. The topological effects of oxidative damage at different sites of G4-DNA and their effects on DNA CT were revealed. The sensing platform was also used for the sensitive and quantitative detection of 8-oxoG in G4-DNA, with a detection limit of 28.9 fmol. Overall, these findings present a sensitive platform to study G4-DNA structural and stability changes caused by oxidative damage as well as the specific and quantitative detection of oxidation sites. The different damage sites in the G-quadruplex could provide detailed clues for understanding the function of G4-associated telomere functional enzymes.

Formation of interfacial molecular film and metal‐trapping function of azacalixarene‐containing copolymers having spherulite‐forming ability

AbstractThe interfacial molecular film behavior of a newly synthesized copolymer having spherulite‐forming ability and consisting of an azacalixarene moiety and a polyethylene glycol linker was investigated. Furthermore, the ability of the azacalixarene ring in the copolymer Langmuir monolayer to trap metals from the subphase was examined. The copolymer formed a monolayer at the air/water interface with high‐density packing. In addition, the corresponding copolymer formed a stable interfacial monolayer whose behavior did not change significantly as the temperature of the subphase changed. The monolayer morphology exhibited a dot‐like crystalline domain. When the subphase contained cadmium ions, the cyclic moiety showed the ability to trap the metal cations. In this case, the distortion angle of the cup‐shaped conformation of the cyclic moiety in the organized molecular film expanded after metal trapping.Highlights LB film of a copolymer containing azacalixarene and PEG units was prepared. The copolymer formed a dense packing in the LB film. Copolymer film formed a surface morphology containing crystalline grains. The copolymer trapped Cd ions in the azacalixarene ring from the subphase. Due to trapping of Cd ions, the distortion angle of the ring widened by 7°.

Enhancing Efficiency of Large-Area Wide-Bandgap Perovskite Solar Modules with Spontaneously Formed Self-Assembled Monolayer Interfaces.

Wide-bandgap (WBG) perovskites play a crucial role in perovskite-based tandem cells. Despite recent advances using self-assembled monolayers (SAMs) to facilitate efficiency breakthroughs, achieving precise control over the deposition of such ultrathin layers remains a significant challenge for large-scale fabrication of WBG perovskite and, consequently, for the tandem modules. To address these challenges, we propose a facile method that integrates MeO-2PACz and Me-4PACz in optimal proportions (Mixed SAMs) into the perovskite precursor solution, enabling the simultaneous codeposition of WBG perovskite and SAMs. This technique promotes the spontaneous formation of charge-selective contacts while reducing defect densities by coordinating phosphonic acid groups with the unbonded Pb2+ ions at the bottom interface. The resulting WBG perovskite solar cells (PSCs) demonstrated a power conversion efficiency of 19.31% for small-area devices (0.0585 cm2) and 17.63% for large-area modules (19.34 cm2), highlighting the potential of this codeposition strategy for fabricating high-performance, large-area WBG PSCs with enhanced reproducibility. These findings offer valuable insights for advancing WBG PSCs and the scalable fabrication of modules.

A24 AN ULCERATIVE COLITIS-ISOLATED PATHOBIONT CAN DEGRADE MUCUS PRODUCED BY UC PATIENT-DERIVED COLONOIDS

Abstract Background Inflammatory bowel disease (IBD) pathobionts are commensal microbes with pathogenic potential that may cause or exacerbate IBD symptoms. Some pathobionts (ex. Escherichia coli) reside at low levels in the lumen of a healthy gut but can rapidly grow in the inflamed colons of ulcerative colitis (UC) patients. To promote disease, these pathobionts must cross the colonic mucus barrier (comprised of MUC2) that separates the epithelium from luminal microbes. It is currently unclear how bacterial pathobionts cross the mucus barrier of UC patients. Aims Using healthy and UC patient biopsy-derived colonic organoids (colonoids) and an air liquid interface (ALI) monolayer model, we investigated how the UC-isolated E. coli pathobiont p19A crosses the mucus barrier. Methods Apical out healthy and UC patient biopsy-derived colonoids were infected with p19A to confirm this pathobiont exerts direct cytopathic effects on human colonocytes. Sequencing p19A’s genome, we found it contains two mucus degrading proteins (mucinases). Healthy human and UC colonoids, as well as mouse colonoids, were used to generate mucus-producing ALI monolayers. To detect p19A-mediated mucus degradation, concentrated p19A supernatant was incubated with ALI-derived mucus and degraded MUC2 proteins were detected by protein gel and MUC2 Western blot. MUC2 glycosylation was analyzed by protein gel and PAS staining. ALI monolayers were infected with p19A to evaluate mucus degradation and p19A localization by immunostaining. Results The UC-isolated pathobiont p19A infected and exerted cytotoxic effects on apical out healthy and UC patient colonoids. By day 14, ALI monolayers were differentiated and covered by a thick mucus layer as assessed using brightfield microscopy. Mucus removed for mucinase assays was replenished within 7 days. p19A harbours proteins capable of degrading human ALI-, but not mouse ALI-derived mucus, in vitro, suggesting the presence of host-specific mucinases. Mucus produced by UC ALI monolayers showed reduced glycosylation and increased degradation both over time and by p19A proteins. Day 21 ALI-monolayers infected with p19A for 18 hours exhibited overt mucus degradation allowing p19A to infect the underlying epithelium. Conclusions Patient-derived ALI monolayers produce a thick mucus layer that can be used to study pathobiont-mucus interactions. The UC pathobiont p19A disrupts apical out organoids and produces proteins that degrade ALI-derived mucus in vitro, with UC mucus being more susceptible to degradation than mucus from healthy controls. The results from our model suggest a potential mechanism for pathobiont-mediated mucosal barrier disruption in UC patients. Patient-derived ALI monolayer (blue/white) produces a thick mucus layer (green) that can be degraded by the pathobiont p19A (red). Funding Agencies CCC, CIHR

Enhanced Ferromagnetism in Atomically Thin Oxides Achieved by Interfacial Reconstruction

AbstractDiscoveries of ferromagnetic materials with ultrathin thickness are of great importance for both fundamental science and technological applications. Transition metal oxides (TMOs) provide promising candidates in the context of next‐generation spintronics, despite the severe decay of ferromagnetism as the thickness reduces to the nanometer regime. Here, an efficient strategy to eliminate the magnetic dead layer in atomically thin oxides is presented, by using the epitaxial interface of 3d and 5d oxide monolayers that reconciles both strong exchange interaction and large uniaxial magnetic anisotropy. Combining multiple experimental methods, a ferromagnetic transition in an ultrathin oxide heterostructure comprised of only one La0.2Sr0.8MnO3 monolayer sandwiched by SrIrO3 monolayer (total thickness of three unit‐cells) is unambiguously demonstrated. Remarkably, a largely enhanced saturation magnetization (2 µB Mn−1) and Curie temperature (80 K) are observed for the single manganite monolayer, as compared to previously reported ferromagnetic monolayer oxides. The results demonstrate a general strategy for creating robust ferromagnetism in ultrathin TMOs, potentially enabling novel oxide spin‐orbitronic devices.

Ultra-thin proton conducting carrier layers for scalable integration of atomically thin 2D materials with proton exchange polymers for next-generation PEMs.

Scalable approaches for synthesis and integration of proton selective atomically thin 2D materials with proton conducting polymers can enable next-generation proton exchange membranes (PEMs) with minimal crossover of reactants or undesired species while maintaining adequately high proton conductance for practical applications. Here, we systematically investigate facile and scalable approaches to interface monolayer graphene synthesized via scalable chemical vapor deposition (CVD) on Cu foil with the most widely used proton exchange polymer Nafion 211 (N211, ∼25 μm thick film) via (i) spin-coating a ∼700 nm thin Nafion carrier layer to transfer graphene (spin + scoop), (ii) casting a Nafion film and cold pressing (cold press), and (iii) hot pressing (hot press) while minimizing micron-scale defects to <0.3% area. Interfacing CVD graphene on Cu with N211 via cold press or hot press and subsequent removal of Cu via etching results in ∼50% lower areal proton conductance compared to membranes fabricated via the spin + scoop method. Notably, the areal proton conductance can be recovered by soaking the hot and cold press membranes in 0.1 M HCl, without significant damage to graphene. We rationalize our finding by the significantly smaller reservoir for cation uptake from Cu etching for the ∼700 nm thin carrier Nafion layer used for spin + scoop transfer compared to the ∼25 μm thick N211 film for hot and cold pressing. Finally, we demonstrate performance in H2 fuel cells with power densities of ∼0.23 W cm-2 and up to ∼41-54% reduction in H2 crossover for the N211|G|N211 sandwich membranes compared to the control N211|N211 indicating potential for our approach in enabling advanced PEMs for fuel cells, redox-flow batteries, isotope separations and beyond.

Evaluation of the interfacial elasticity of surfactant monolayer at the CO2–water interface by molecular dynamics simulation: Screening surfactants to enhance the CO2 foam stability

Foam stability is adversely affected by the drainage process in the liquid film, which has been a great challenge for CO2 foam flooding in applications. The Gibbs-Marangoni effect, which is induced by the interfacial tension (IFT) gradient, provides a resisting force to the thinning of liquid films in foams under disturbance. Surfactants with higher interfacial elasticity enable rapid recovery to the equilibrium state, thereby improving the stability of the CO2 foam film. However, there is a lack of mechanistic studies aimed at elucidating the correlation between the interfacial elasticity of surfactant monolayers and the molecular structure of surfactants. In this paper, molecular dynamics simulations were employed to investigate the impact of the headgroups and linking groups of sodium polyoxyethylene alkyl ether sulfate (AES), sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDSn), and sodium laurate (SLA) surfactants on the interfacial morphology, monolayer properties, and surfactant behaviors at the CO2–water interface under reservoir conditions. The results show that the capacity to enhance CO2 foam stability follows the order AES > SDS > SDSn > SDBS > SLA, which is in good agreement with the available experiments. AES monolayers can reach the lowest IFT (∼0.2 mN/m) and the highest interfacial elasticity (30.4 mN/m). We show that the ethylene oxide groups (EO chains) can strongly interact with water molecules via hydrogen bonding and have affinity interactions with CO2 molecules, which is beneficial to the hydrophilic-CO2-philic balance (HCB). SDS monolayers show the second-lowest IFT (3.1 mN/m) and second-highest interfacial elasticity (26.0 mN/m). The linking oxygen atom in SDS facilitates bond rotation and is favorable to film stability. The phenyl group makes SDBS molecules too rigid and has poor HCB, leading to low stability with high IFT (16.0 mN/m) and low interfacial elasticity (13.1 mN/m). SLA has the highest IFT (22.1 mN/m) and lowest interfacial elasticity (6.3 mN/m), and also presents strong aggregation behaviors at the interface owing to interactions between the carboxyl groups. The simulation method and the microscopic insights delivered here are of great significance in screening surfactants to improve CO2 foam performance in oilfields.

Suppressing Oxidation at Perovskite-NiOx Interface for Efficient and Stable Tin Perovskite Solar Cells.

Inorganic nickel oxide (NiOx) is an ideal hole transport material (HTM) for the fabrication of high-efficiency, stable, and large-area perovskite photovoltaic devices because of its low cost, stability, and ease of solution processing. However, it delivers low power conversion efficiency (PCE) in tin perovskite solar cells (TPSCs) compared to other organic HTMs. Here, the origin of hole transport barriers at the perovskite-NiOx interface is identified and a self-assembled monolayer interface modification is developed, through introducing (4-(7H-dibenzo[c,g]carbazol-7-yl)ethyl)phosphonic acid (2PADBC) into the perovskite-NiOx interface. The 2PADBC anchors undercoordinated Ni cations through phosphonic acid groups, suppressing the reaction of highly active Ni≥3+ defects with perovskites, while increasing the electron density and oxidation activation energy of Sn at the perovskite interface, reducing the interface nonradiative recombination caused by tetravalent Sn defects. The devices deliver significantly increased open-circuit voltage from 0.712 to 0.825V, boosting the PCE to 14.19% for the small-area device and 12.05% for the large-area (1 cm2) device. In addition, the 2PADBC modification enhances the operational stability of NiOx-based TPSCs, maintaining more than 93% of their initial efficiency after 1000 h.

CO2RR-to-CO Enhanced by Self-Assembled Monolayer and Ag Catalytic Interface

CO₂RR-to-CO Enhanced by Self-Assembled Monolayer and Ag Catalytic Interface

Constrained drop surfactometry for studying adsorbed pulmonary surfactant at physiologically relevant high concentrations.

Exogenous surfactant therapy has been used as a standard clinical intervention for treating premature newborns with respiratory distress syndrome. The phospholipid concentrations of exogenous surfactants used in clinical practice are consistently higher than 25 mg/mL; while it was estimated that the phospholipid concentration of endogenous surfactant is approximately in the range between 15 and 50 mg/mL. However, most in vitro biophysical simulations of pulmonary surfactants were only capable of studying surfactant concentrations up to 3 mg/mL, one order of magnitude lower than the physiologically relevant concentration. Using a new in vitro biophysical model, called constrained drop surfactometry, in conjunction with atomic force microscopy and other technological advances, we have investigated the biophysical properties, ultrastructure, and topography of the pulmonary surfactant film adsorbed from the subphase at physiologically relevant high surfactant concentrations of 10-35 mg/mL. It was found that the effect of surfactant concentration on the dynamic surface activity of the surfactant film was only important when the surface area of the surfactant film varied no more than 15%, mimicking normal tidal breathing. The adsorbed surfactant film depicts a multilayer conformation consisting of a layer-by-layer assembly of stacked bilayers with the height of the multilayers proportional to the surfactant concentration. Our experimental data suggest that the biophysical function of these multilayer structures formed after de novo adsorption is to act as a buffer zone to store surface-active materials ejected from the interfacial monolayer under extreme conditions such as deep breathing.NEW & NOTEWORTHY An in vitro biophysical model, called constrained drop surfactometry, was developed to study the biophysical properties, ultrastructure, and topography of the pulmonary surfactant film adsorbed from the subphase at physiologically relevant high surfactant concentrations of 10-35 mg/mL. These results suggest that the biophysical function of multilayers formed after de novo adsorption is to act as a buffer zone to store surface-active materials ejected from the interfacial monolayer under extreme conditions such as deep breathing.

A gut-restricted glutamate carboxypeptidase II inhibitor reduces monocytic inflammation and improves preclinical colitis.

There is an urgent need to develop therapeutics for inflammatory bowel disease (IBD) because up to 40% of patients with moderate-to-severe IBD are not adequately controlled with existing drugs. Glutamate carboxypeptidase II (GCPII) has emerged as a promising therapeutic target. This enzyme is minimally expressed in normal ileum and colon, but it is markedly up-regulated in biopsies from patients with IBD and preclinical colitis models. Here, we generated a class of GCPII inhibitors designed to be gut-restricted for oral administration, and we interrogated efficacy and mechanism using in vitro and in vivo models. The lead inhibitor, (S)-IBD3540, was potent (half maximal inhibitory concentration = 4 nanomolar), selective, gut-restricted (AUCcolon/plasma > 50 in mice with colitis), and efficacious in acute and chronic rodent colitis models. In dextran sulfate sodium-induced colitis, oral (S)-IBD3540 inhibited >75% of colon GCPII activity, dose-dependently improved gross and histologic disease, and markedly attenuated monocytic inflammation. In spontaneous colitis in interleukin-10 (IL-10) knockout mice, once-daily oral (S)-IBD3540 initiated after disease onset improved disease, normalized colon histology, and attenuated inflammation as evidenced by reduced fecal lipocalin 2 and colon pro-inflammatory cytokines/chemokines, including tumor necrosis factor-α and IL-17. Using primary human colon epithelial air-liquid interface monolayers to interrogate the mechanism, we further found that (S)-IBD3540 protected against submersion-induced oxidative stress injury by decreasing barrier permeability, normalizing tight junction protein expression, and reducing procaspase-3 activation. Together, this work demonstrated that local inhibition of dysregulated gastrointestinal GCPII using the gut-restricted, orally active, small-molecule (S)-IBD3540 is a promising approach for IBD treatment.

Unravelling the influence of surface lipids on the structure, dynamics and interactome of high-density lipoproteins

Surface lipids influence the biological activities of high-density lipoproteins (HDLs) but their species-specific effects on HDL structure, dynamics, and surface interactome has remained unclear. Building upon the five-lipid species HDL models developed and characterised in previous work, representative models of the major HDL subpopulations found in human plasma containing apolipoprotein A-I (apoA-I) have been studied using molecular dynamics simulation to describe their varying degrees of surface lipidome complexity. Specifically, two additional sets of representative HDL subpopulation particles were developed, one with sphingomyelin (SM) and the other with SM, phosphatidylethanolamine, phosphatidylinositol, and ceramide in quantities reflecting average levels characterised for HDL subpopulations derived from normolipidemic patients. These lipid species were assessed in terms of HDL size, morphology, dynamics, and overall interactome. The findings reveal that the presence of a representative SM fraction marginally enhanced HDL interfacial curvature and surface monolayer rigidity, manifesting in tighter phospholipid packing and slower surface lipid dynamics relative to SM-deficient HDL models. Furthermore, the presence of SM resulted in a reduction in the solvent exposure of core lipids and cholesterol molecules, whilst also enhancing apolipoprotein conformational flexibility and its overall twisting across the HDL surface. The hydrophobicity of apoA-I-bound lipid patches and the proportion of apoA-I hydrophobic surface area is enhanced by the overall lipidation of apoA-I irrespective of lipid composition. These findings offer new insights into how the surface lipid composition of different HDL subpopulations can significantly impact the overall interactome of HDL particles, potentially influencing subpopulation-specific biological functions like lipid scavenging and receptor interactions.

Stimuli-Responsive Langmuir Films Composed of Nanoparticles Decorated with Poly(N-isopropyl acrylamide) (PNIPAM) at the Air/Water Interface.

The nanotechnology shift from static toward stimuli-responsive systems is gaining momentum. We study adaptive and responsive Langmuir films at the air/water interface to facilitate the creation of two-dimensional (2D) complex systems. We verify the possibility of controlling the assembly of relatively large entities, i.e., nanoparticles with diameter around 90 nm, by inducing conformational changes within an about 5 nm poly(N-isopropyl acrylamide) (PNIPAM) capping layer. The system performs reversible switching between uniform and nonuniform states. The densely packed and uniform state is observed at a higher temperature, i.e., opposite to most phase transitions, where more ordered phases appear at lower temperatures. The induced nanoparticles' conformational changes result in different properties of the interfacial monolayer, including various types of aggregation. The analysis of surface pressure at different temperatures and upon temperature changes, surface potential measurements, surface rheology experiments, Brewster angle microscopy (BAM), and scanning electron microscopy (SEM) observations are accompanied by calculations to discuss the principles of the nanoparticles' self-assembly. Those findings provide guidelines for designing other adaptive 2D systems, such as programable membranes or optical interfacial devices.

Direct evidence of a charge depletion region at the interface of van der Waals monolayers and dielectric oxides: The case of superconducting FeSe/STO

Monolayers of two-dimensional (2D) van der Waals (vdW) materials grown on dielectric oxides exhibit unprecedented physical properties. For example, the superconducting transition temperature of an FeSe monolayer on ${\mathrm{SrTiO}}_{3}$ is by far higher than its bulk counterpart. However, how the charge distribution across the interface looks like and how it helps to improve these properties is hitherto unknown. Here, using momentum- and energy-resolved high-resolution electron spectroscopy, we probe the dynamic charge response of the $\mathrm{FeSe}/{\mathrm{SrTiO}}_{3}(001)$ heterostructures and, thereby, demonstrate the existence of a charge depletion layer at the interface. The presence of this depletion layer, accompanied with a considerably large charge transfer, leads to a renormalization of the ${\mathrm{SrTiO}}_{3}$ energy bands and a substantial band bending at the interface. Our discovery paves the way for designing novel 2D superconductors through interface engineering. The phenomenon is expected to occur at the interface of many vdW monolayers and dielectric oxides.