Biofilms are composed of autogenously secreted extracellular polymeric substances (EPS) and affect nearly all aspects of human activity. Biofilms with negative health and economic effects can be controlled through the integrated use of surfactants and mechanical force. However, the relationships between the surfactant molecular structures and biofilm removal pathways have not been sufficiently elucidated. Additionally, Cutibacterium acnes (C. acnes), a skin commensal bacterium with biofilm-forming capabilities that can exacerbate acne vulgaris, has been rarely investigated. In this study, we established a shear flow system and employed a multianalytical framework integrating gravimetry, spectroscopy, thermodynamics, and microscopy to investigate the removal mechanisms of C. acnes biofilms by synthetic surfactants and biosurfactant rhamnolipids (RLs). Biofilm detachment from silica substrates was observed under turbulent flow in the presence of anionic surfactants, namely, sodium dodecyl sulfate (SDS) and RLs. By contrast, biofilms remained intact under static conditions. The detachment of biofilms from hydrophobic substrates independent of surfactant presence highlights that shear force and surfactant headgroup properties are the primary drivers in overcoming the robust biofilm-silica adhesion. Mechanistically, SDS disrupted and detached the biofilm structure upon shear application, driven by its high penetrative partitioning into the biofilm consisting of the EPS matrix and bacterial cells. Conversely, RLs facilitated efficient interfacial peeling from the silica surface via their carboxylate groups without structurally disrupting the biofilm. Our findings provide valuable insights for rational screening and formulation design of cleansing agents based on the physicochemical properties of biofilms.
To address the increasing prevalence of extreme weather events, there has been a notable shift in research priorities toward the development of smart textiles capable of adaptively regulating the microclimate temperature of the human body. This study uses electrospinning technology to create multifunctional polyurethane nanofiber membranes (PUBPs) with a sandwich structure. The outer layer contains thermosensitive color-changing microcapsules (RT-BCMs) incorporated into the PU nanofiber membrane, and the middle layer contains phase-change microcapsules (RT-PCMs) incorporated into the PU nanofiber membrane. The PUBPs nanofiber membrane exhibits a reversible color change within a temperature range of 26-40 °C. At high temperatures, the membrane appears white, increasing solar reflectance to 87.4% while maintaining mid-infrared emissivity of 95.3%, thereby achieving radiative cooling. At low temperatures, the membrane appears blue, with solar reflectance reduced to 69.1% while maintaining mid-infrared emissivity of 95.1%, thereby achieving solar heating. The PUBPs nanofiber membrane is capable of acting as a temperature buffer zone, with a phase change enthalpy of up to 106.8 J/g. This property makes PUBPs nanofiber membrane effective in mitigating temperature fluctuations caused by external temperature changes. After 20 days of UV aging and 100 thermal cycles, optical property retention and phase-change performance remain essentially unchanged, showing great weather resistance ability and cycling stability. Outdoor experiments show that under low solar irradiance of 163.2 W/m2, the maximum temperature rise is 5.4 °C; under high solar irradiance of 958.2 W/m2, the maximum temperature drop reaches 8.8 °C. This PUBPs nanofiber membrane, prepared through the synergistic mechanism of thermochromic and phase-change functions, effectively achieves all-season adaptive thermal management and provides a strategy for developing smart, temperature-controlled textiles.
In this study, we investigated the adsorption and decomposition mechanisms of the organophosphorus nerve agent Sarin on reduced graphene oxide (rGO) and transition metal oxide (TMO) systems (TMO = CoO, NiO, CuO, ZnO) using density functional theory (DFT). Three key decomposition pathways of Sarin, P-F bond cleavage, P-O bond cleavage in P-OC3H7, and isopropyl elimination, were investigated in detail. For various Sarin configurations, the most stable interaction involves the phosphoryl oxygen binding to the metal atoms of TMOs. Our results reveal that the NiO-rGO system is particularly favorable for both P-F and P-OC3H7 bond cleavage, with calculated activation energies of -189.8 and -349.27 kJ mol-1, respectively. This enhanced reactivity is attributed to significant bond polarization and the presence of partially filled Ni 3d8 orbitals near the Fermi level, which facilitate both π-back-donation and σ-donation interactions with antibonding orbitals of Sarin. The isopropyl elimination pathway predominantly occurs on CoO-rGO, with an activation energy of -257.15 kJ/mol. The CuO-rGO surface promotes both P-F bond cleavage and isopropyl elimination, with activation energies of -264.07 and -217.5 kJ/mol, respectively. The ZnO-rGO system favors P-OC3H7 bond cleavage and isopropyl elimination, with activation barriers of -179.84 and -200.13 kJ/mol, respectively. The Lewis acidity of the TMOs correlates with Sarin decomposition efficiency, with NiO exhibiting the highest positive charge of +1.29 e. Partial density of states revealed a peak of the highest density, indicating an increased density of states for Ni. This work provides valuable insights into the adsorption and decomposition of Sarin, emphasizing the potential of the TMO-rGO system for the breakdown of organophosphorus nerve agents.
In this study, a magnetically controlled rough surface was prepared as a top coating to endow the coating with hydrophobicity. This hydrophobic surface coating interacted with the bottom coating to form an epoxy anticorrosive coating with both active and passive corrosion protection. The formation of the magnetically controlled rough surface is attributed to the magnetic composite (MZ-67) dispersed in the epoxy resin emulsion being subjected to the external magnetic field on the particles and the interparticle interaction force, and the particles will undergo a positional shift driven by these two forces, resulting in the formation of an irregular mountainous concave-convex structure on the surface of the coated samples (magnetically controlled rough surface). FTIR, XRD, SEM, TGA, XPS, BET, and other experimental results proved the successful synthesis of the MZ-67 magnetic material, and the results of VSM experiments proved that the MZ-67 material has magnetic properties and can form magnetically controlled surfaces in the epoxy resin. The results of water contact angle experiments (WCA) of the surface coatings of the coated samples showed that the contact angle of the coatings was increased from 87.3 to 133.2° after modulation by an external magnetic field. The surface property of the coating changed from hydrophilic to hydrophobic. The results of electrochemical alternating current impedance spectroscopy (EIS) experiments illustrated that the corrosion resistance of the coatings after magnetic field modulation was significantly improved, and the coatings still possessed a low-frequency impedance modulus of 4.34 × 108 Ω·cm2 after being immersed in a 3.5 wt % NaCl solution for 60 days.
Phthalates are the most common plasticizers on the market, produced in megaton quantities. Phthalates can be released from plastics and enter the human body, primarily through ingestion or inhalation. The phthalate used in the largest quantities is di(2-ethylhexyl) phthalate, DEHP. However, this compound is toxic: mutagenic, carcinogenic, and endocrine-disrupting. Therefore, DEHP is gradually being replaced by other phthalates, primarily diesters with longer, unbranched, or iso-branched chains. Upon entering the human body, phthalates first interact with epithelial cells, primarily their apical membrane. Our research aimed to develop models of apical membranes and to examine the effects of DEHP and its substitutes on their physical properties. In the research, the fact that the apical membrane contains raft and nonraft regions was considered, so two different membrane models were created and studied. Lipid Langmuir monolayers were used as membrane models. The effects of phthalate incorporation on the mechanical properties of these membranes, their morphology (Brewster angle microscopy), and their crystal structure (grazing incidence X-ray diffraction) were studied. Studies have shown that phthalates primarily disrupt the raft regions of the apical membrane. It was demonstrated that replacing DEHP with phthalates with long, unbranched chains is a poor option because their impact on the model membranes is more unfavorable than DEHP itself. However, using phthalates with iso-branched chains seems reasonable. These compounds have a lesser effect on the properties of the model membranes, and given their significantly lower toxicity, their use seems to be a suitable direction for the development of plasticizer chemistry.
The rock wettability is an important property governing the multiphase flow in subsurface porous media. Wettability alteration of native water-wet rocks is often linked to the destabilization of the native brine film present on the rock surface, followed by the adsorption of polar components of an organic phase. Thus, pores having intact brine films are assumed to be water-wet. In this study, we show that the calcite surface covered with intact brine film (and bulk brine) could also become oil-wet. To understand this phenomenon, calcite chips and crushed calcite powder were aged by using two different approaches. In the first approach, calcite chips and powder were first aged in brine and then separately aged in oil. In the second approach, calcite chips and powder were aged simultaneously in brine and oil. The amount of brine in the second approach was such that the calcite surface and powder were completely submerged in the brine. The aged samples were analyzed using various analytical techniques, including X-ray photoelectron spectroscopy (XPS). The effect of the brine composition on the partitioning of stearic acid and rock wettability was studied. Calcite chips become oil-wet in both the approaches, with contact angles varying from 69 ± 5° to 151 ± 6°, depending on the brine composition and the aging technique. XPS analyses confirmed the surface modification of the calcite surface with the organic acid in the second approach. Organic acid partitioning was found to be similar in all brines. However, not all calcite surfaces became oil-wet, indicating that interactions at the rock-brine interface also play important role in organic acid adsorption and calcite wettability alteration. Furthermore, oil-wet calcite surfaces prepared using both the approaches showed wettability alteration in low-salinity brines such as seawater (SW) and sulfate-rich seawater (4S-SW).
Coacervate droplets and lipid vesicles are two classes of self-assembled compartments that have been proposed as protocell models. Hybrid protocells, in which a coacervate core is surrounded by a lipid membrane, can integrate the advantages of both protocell systems while overcoming their limitations. Although hybrid protocell membranes have been produced with a variety of diacyl phospholipids related to modern biology and some single-chain amphiphiles inspired by prebiotic scenarios, little is known about how mixtures of single-chain amphiphiles impact hybrid protocell membrane formation and properties. Given the plausible diversity of amphiphiles in the prebiotic milieu, the resulting membranes would have inherently incorporated multiple lipids of different types, potentially altering the properties and viability of hybrid protocells in their environment. Here, we systematically increased the compositional heterogeneity of hybrid protocell membranes by using different prebiotically relevant single-chain amphiphiles of varying head groups and alkyl chain lengths. These membranes were assembled around model coacervate droplets generated from poly(allylamine hydrochloride) and adenosine diphosphate, and the effect of heterogeneity on membrane properties and stability was evaluated. Compared to protocells with homogeneous membranes, those with heterogeneous amphiphile membranes exhibited higher yields, smaller sizes, and greater subcompartment formation. Also, they showed increased membrane order, retained similar lateral lipid diffusion, and showed population-level variability in permeability to small anionic molecules. Notably, heterogeneous membranes showed enhanced structural stability under acidic conditions, retaining key properties like size and subcompartment heterogeneity, thereby broadening the pH range over which hybrid protocells remain intact. These findings suggest that amphiphile diversity not only would have influenced the structural properties of hybrid protocells but also created diversity within the protocell population and enhanced their robustness, thereby playing a crucial role in protocell evolution on early Earth.
The development of IL-N8 and its magnetic micelle-forming derivative MIL-N8 offers a promising advancement in nanostructured carriers for efficient hydrophobic drug delivery. The structural validation for MIL-N8 was obtained through Raman, EPR, and NMR spectroscopy, which suggested successful synthesis and molecular integrity of both IL-N8 and MIL-N8 compounds. Furthermore, the thermogravimetric analysis demonstrated that MIL-N8 exhibits better stability than its precursor. Due to the structural attributes of MIL-N8 (containing both hydrophilic and hydrophobic moieties), it readily self-assembles into uniform nanostructures, such as micelles, at the critical aggregation concentration (CAC). This was further characterized through confocal microscopy using ANS as a fluorescent probe and visualized using TEM and FESEM imaging. These nanomicellar structures enabled the efficient encapsulation of the hydrophobic anticancer drug, quercetin (QCT), with high loading and sustained release behavior adhering to the Korsmeyer-Peppas model, which suggests diffusion-controlled transport through aggregated micellar layers. Furthermore, biological evaluation using SW-480 colon cancer cells demonstrated a remarkable enhancement in the anticancer activity of QCT-encapsulated and delivered via MIL-N8, moreover, in comparison to free QCT, the QCT-MIL-N8 formulation produced substantially lower IC50 values and pronounced dose and time-dependent effects. QCT-MIL-N8 formulation demonstrated increased apoptotic features, including nuclear condensation, fragmentation, and an increase in AO/EtBr-positive cells, as well as elevated intracellular ROS levels, that further supported oxidative stress-driven cell death as the predominant mechanism. Collectively, MIL-N8 nanomicelles emerge as a highly effective, low-toxicity delivery platform that significantly improves the therapeutic potential and controlled release of QCT for anticancer applications.
Metal-organic frameworks (MOFs) constitute a rapidly expanding class of microporous materials. In recent years, numerous MOFs with tunable nanoporous architectures have been developed as promising candidates for natural gas and hydrogen storage. To enhance the hydrogen storage capacity of MOFs while reducing the overall cost, this study integrates MOFs with cost-effective materials that provide additional active sites for hydrogen adsorption. Here, we report the development of a composite consisting of graphene oxide (GO) and Ni-based MOF-74 (Ni-MOF-74), which combines the high surface area and functional groups of GO with the extensive porosity and open metal sites of the MOF. The Ni-MOF-74/GO composite was synthesized via an in situ growth method and extensively characterized by using transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis to confirm its integrated structure and porosity. Hydrogen adsorption isotherms at 77 K and up to 1 bar reveal that the Ni-MOF-74/GO composite exhibits a significantly higher H2 uptake capacity than either pristine GO or Ni-MOF-74 alone. Notably, the composite with an optimal GO loading (10 wt %) achieves the highest storage enhancement, demonstrating a synergistic effect between GO and the MOF in maximizing hydrogen adsorption. Density functional theory (DFT) and Monte Carlo simulations provided molecular-level insights, indicating that H2 molecules occupy both the microporous channels of Ni-MOF-74 and the GO surface, particularly at the Ni-MOF-74/GO interfacial regions. This hybrid framework exhibits a slightly stronger hydrogen adsorption energy (-3.34 kcal/mol) compared to Ni-MOF-74 alone (-3.25 kcal/mol), with minimal structural distortion upon H2 uptake.
The extensive application potential of nucleic acid aptamers in biosensing and therapeutic domains necessitates the development of cost-effective, time-efficient, and technically simpler synthesis protocols compared with conventional SELEX methods. In this study, an in silico-based de novo approach has been proposed to design an aptamer targeting the B subunits of Shiga-like toxin 2 (Stx2-B) protein, intended for use as a recognition element in biosensors for detecting Stx2. A single-stranded DNA library comprising 5000 sequences was generated and ranked based on their Gibbs free energy (ΔG) of the 2D structures. The top 100 sequences with the lowest ΔG values were modeled in 3D and individually docked with the Stx2 protein. Sequences exhibiting the highest docking scores were further analyzed through molecular dynamics simulations. Among the analyzed candidates, sequence A330 demonstrated the highest stability, rigidity, and compactness in complex with Stx2B, as indicated by root-mean-square deviation, root-mean-square fluctuation, radius of gyration, and hydrogen-bond analysis over 100 ns simulation trajectories. The strong binding affinity of A330 for the target (Kd = 459 ± 7 nM) was confirmed through circular dichroism and isothermal titration calorimetry analyses. This aptamer was subsequently employed as a recognition element in the fabrication of an electrochemical impedimetric aptasensor for Stx2 detection, utilizing a microscale interdigitated wave-type electrode. The developed sensor exhibited high sensitivity, a limit of detection of 4.63 pM, and a linear detection range of 10-400 pM (R2 = 0.99). The aptasensor's practical applicability was validated in milk samples, achieving a detection recovery of >93.06%. Overall, the proposed aptasensor shows strong potential for the sensitive and reliable monitoring of Shiga toxin-producing Escherichia coli contamination in real samples.
BiVO4 shows promising application prospects for photoelectrochemical (PEC) devices such as water splitting and self-powered photodetectors, but several bottlenecks still remain, including severe charge recombination effects and slow oxygen evolution reaction (OER) kinetics. We proposed a strategy to address the above issues by introducing Mo doping combined with the use of NiFeOOH as a cocatalyst. Mo doping can modulate the BiVO4 particle size and enrich the reactive surface area to enhance light absorption and the OER. Besides, Mo doping not only improves the conductivity and charge carrier concentration of the BiVO4 photoanode but also causes low Fermi energy level and large energy band bending, thereby accelerating surface charge transfer. Moreover, the NiFeOOH cocatalyst electrodeposited on Mo-doped BiVO4 can passivate the surface defect state and avoid hole accumulation. In the meantime, the increased oxygen vacancies induced by Mo doping and the presence of NiFeOOH collectively enhance the kinetics of the OER kinetics. Benefiting from the above combined effects, the synergistic integration of Mo and NiFeOOH effectively suppresses charge recombination while promoting electron extraction and hole injection. As a result, the obtained photoanode shows a photocurrent density of 2.24 mA/cm2 at 1.23 V versus RHE, approximately 2.52-fold higher than that of pristine BiVO4 photoanode. Furthermore, the as-prepared photodetector demonstrates excellent photodetection performance with high responsivity (Rph, 31.06 mA/W), superior detectivity (D*, 2.02 × 1011 Jones), and large external quantum efficiency (EQE, 7.7%) in the Na2SO4 electrolyte under 488 nm with zero bias voltage. This work contributes to the development of multifunctional strategies for enhancing the charge transport properties of PEC devices.
Large amounts of methane hydrate are trapped in natural porous media, such as marine sediments and permafrost. In this context, understanding the physical and physicochemical properties of confined methane hydrate, sometimes down to the nanoscale, is crucial for environmental and energy applications. Here, a molecular simulation strategy is employed to assess some important properties of nanoconfined methane hydrate: density, structural order parameters, thermal expansion, compressibility, and thermal conductivity. Confinement is found to affect only slightly the microscopic structure of methane hydrate close to the pore surface, with a structural ordering more pronounced than for its bulk counterpart. On the other hand, under a typical temperature and pressure range relevant to real conditions, confinement decreases the thermal expansion of methane hydrate, while it increases or decreases the isothermal compressibility depending on pressure. As for the thermal conductivity, which is determined from the anisotropic heat-flux vector using the Green-Kubo formalism, confinement increases the thermal conductivity in the tangential and normal directions with respect to the pore surface. The thermal conductivity components decomposed into acoustic and optical modes and are compared to their bulk counterpart.
The present study investigates the water-induced formation of liquid crystalline (LC) structures from a premix. The latter consisted of oleic acid (oil phase), d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS; surfactant), and Transcutol P (cosurfactant). Pseudoternary phase diagrams were constructed at three ratios of the surfactant-cosurfactant mixture (Smix) and investigated for phase transition. The compositions with 3:1 Smix ratio were comprehensively characterized along a water dilution line. Polarized light microscopy revealed the onset of birefringence with increasing water content, indicative of the evolution of LC structures. This was further verified by the shifts in scattering peaks and the emergence of higher-order Bragg peaks in SAXS experiments. The observed structures were denoted as nonlamellar liquid crystals. Amplitude and frequency sweep tests showed that the as-formed phases were viscoelastic and exhibited structural resilience under shear. Ex vivo bioadhesion experiments showed a prolonged residence of the LC formulation in the chicken ileum. The formulation was loaded with budesonide (BDS), and its efficacy was studied in a male C57BL/6 mouse model of ulcerative colitis (UC). Subsequent to rectal administration, therapeutic outcomes were compared in terms of biochemical and histopathological data. Western blotting was performed to evaluate the expression of colonic epithelial tight junction proteins (occludin and ZO-1). We found that the rectally administered formulation can alleviate the symptoms and pathological signatures of UC. The formulation exerted its effects by suppressing the oxidative stress-inflammation axis and restoring the integrity of the colonic barrier.
Photocatalytic CO2 reduction is an important approach for the resource utilization of greenhouse gases and the chemical conversion of renewable energy, and defect engineering has emerged as a well-established strategy to enhance photocatalytic efficiency. The introduction of defects into materials can precisely regulate their electronic structure and band structure, thereby optimizing their light absorption capacity, redox performance, charge transfer efficiency, and the number of active sites, which provides an effective solution to the problems encountered by traditional photocatalytic materials such as high carrier recombination rate and weak CO2 adsorption and activation capacity. This paper presents a systematic review of the latest research progress of defect engineering in the field of photocatalytic CO2 reduction, comprehensively sorting out the main types, and construction methods of defects in photocatalytic CO2 reduction, and detailing the latest research achievements and application of various defects in photocatalytic CO2 reduction reaction. Meanwhile, the technical bottlenecks and scientific problems currently faced by defect engineering in the research of photocatalytic CO2 reduction are deeply analyzed, and the future development directions of this field are prospected. This work provides references for the design of efficient and stable photocatalytic materials and also lays a foundation for promoting the development and application of defect engineering in the field of photocatalysis.
The pervasive toxicity of hexavalent chromium (Cr(VI)) to aquatic life and humans urgently demands integrated platforms capable of simultaneous detection and remediation. Herein, a bifunctional platform (CMC/PEI/MIL-53(Fe)/Nap/CP) capable of simultaneous fluorescence detection and photocatalytic removal of Cr(VI) was constructed by in situ growing MIL-53(Fe) on a carboxymethyl cellulose/polyethylenimine (CMC/PEI) matrix grafted with naphthalimide and combining it with cellulose paper (CP). In situ growth ensures the uniform dispersion of active sites, while the paper-based design enhances processability and recyclability. The protonated amino groups of PEI enrich Cr(VI) through electrostatic interactions, while MIL-53(Fe) provides photocatalytic active sites through the Fe3+/Fe2+ redox cycle. Due to the synergistic effect of adsorption and photocatalysis, the removal efficiency reached 99% within 5 h, with a reduction rate of 96%, following pseudo-first-order kinetics (k = 0.9119 h-1). Compared to other recent studies, it offers an excellent removal performance. At the same time, the enrichment effect of PEI enhanced the interaction between Cr(VI) and the naphthalimide fluorophore, achieving a detection limit of 0.34 μM and a KSV of 8.73 × 103 M-1. The good selectivity for Cr(VI) was theoretically verified through simulations by using Materials Studio software (MS). This platform provides a practical bifunctional platform for efficient fluorescence detection and removal of Cr(VI), with broad application prospects in the fields of environmental monitoring and water treatment.
The ankyrin-1 complex is a crucial multiprotein assembly that links the spectrin-based cytoskeleton to the plasma membrane, thereby preserving the cellular mechanical integrity. While recent cryo-electron microscopy studies have resolved its high-resolution structure, the dynamic behavior of its key intersubunit interfaces, critical for complex stability and membrane anchoring, remains poorly understood. To address this gap, we conducted multiscale molecular dynamics simulations of the ankyrin-1 complex embedded in an erythrocyte-mimetic lipid bilayer. Using all-atom simulations, we quantified the binding affinities of five key interfaces (AP, PB-I, AB-II, AB-III, and AR) and identified hotspot residues essential for interfacial stability. All interfaces exhibit multiple metastable substates, characterized by dynamic rearrangements of contact networks and interfacial geometry, highlighting the intrinsic structural plasticity of the complex. Coarse-grained simulations further revealed that the complex induces pronounced lipid reorganization and a distinctive "valley"-like membrane deformation, characterized by global membrane convexity coupled with localized inward indentation of the outer leaflet, thereby sculpting a membrane environment that is optimal for stable embedding. Collectively, these findings offer a comprehensive molecular view of the interface dynamics and membrane anchoring mechanism of the ankyrin-1 complex, deepening our understanding of the cytoskeleton-membrane coupling that is essential for cellular function.
The rampant abuse of antibiotics has accelerated the emergence of resistant bacteria, making infections caused by such pathogens a major challenge to effective clinical management and patient prognosis. Self-antibacterial supramolecular gels that operate via bacterial membrane disruption represent a highly promising therapeutic strategy. In this study, we designed and synthesized reactive oxygen species (ROS)-responsive low-molecular-weight gelators (LMWGs) using a bottom-up approach, based on intrinsic antibacterial synthons and an ROS-cleavable thioacetal linker. The structures of the gelators were confirmed by proton nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry (HRMS). Their gelation behavior, critical gelation concentration (CGC), and self-assembly mechanism were systematically investigated. The resulting supramolecular gel was thoroughly evaluated for its rheological properties, ROS responsiveness, ROS-scavenging capability, antibiotic-loading capacity, and controlled drug-release profile. Biocompatibility and hemocompatibility were assessed using the CCK-8 assay and hemolysis assay, respectively. The antibacterial efficacy of both blank and ciprofloxacin hydrochloride (CIP·HCl)-loaded gels against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was examined via bacterial adhesion tests and plate colony counting. Remarkably, the blank supramolecular gel exhibited potent antibacterial and bactericidal activity against both strains, with efficacy comparable to that of the CIP·HCl-loaded gel─a finding further supported by inhibition zone assays. Investigations into the antibacterial mechanism revealed significant alterations in bacterial membrane morphology and membrane potential, along with the release of intracellular DNA. Notably, owing to this membrane-disruptive action, the blank gel also demonstrated substantial efficacy against methicillin-resistant Staphylococcus aureus (MRSA). This work establishes that the rational design of LMWGs for targeted membrane disruption provides a viable and innovative platform for developing self-antibacterial supramolecular gels against drug-resistant bacterial infections.
Polyurethanes and organogels are materials with many applications spanning from industrial sectors to the preservation of Cultural Heritage. They often show scarce "green" metrics due to the use of petrochemical resources for their synthesis. Herein we report the development of new, fully sustainable castor oil polyurethane gel platforms obtained for the first time employing a green isocyanate cross-linker and oligoester additives, with potential applications in the preservation of Cultural Heritage and beyond. The presence of the oligoester additives and the increase in isocyanate feed yield faster reactivity in pre-gels, affecting the size of nuclei formed during gelation. These variations affect the gels' mechanical properties and their swelling and release of organic solvents. The organogels were loaded with two green solvents to remove an aged, yellowed varnish from an early 20th century canvas painting. Their cleaning efficacy was optimized by playing on the isocyanate cross-linker feed, oligoester additive, and solvent polarity, and tuning the mechanic and release properties of the gels, leading to varnish removal in time-effective applications. These results open a new, versatile palette of sustainable castor oil-based organogels to use in the cleaning of works of art, potentially of interest also in different sectors where bio-based polyurethanes are increasingly required.
The formation of random tiling within a two-dimensional molecular network of the asymmetric p-terphenyl-2',3,3″,5,5″-pentacarboxylic acid (TPPC) at the heptanoic acid/highly oriented pyrolytic graphite interface was investigated using scanning tunneling microscopy and density functional theory calculations. Assemblies of TPPC formed a random tiling network with molecular cavities composed of five distinct molecular cavities. Upon introduction of coronene (COR) and pyridine derivatives (Bispy and BD), the modulation of the self-assembly process was further investigated. The structure of the TPPC/COR coassembly shows obvious concentration dependence. At low concentrations, COR molecules entered the star-shaped cavities of the TPPC network preferentially. As the concentration increased, COR occupied all cavities within the TPPC network. The introduction of pyridine derivatives (Bispy and BD) with varying backbones can completely remodel the original TPPC architecture and induce a complete structural transformation to form long-range ordered TPPC/Bispy or TPPC/BD coassembly structures. This study realizes the molecular reprogramming of hydrogen-bond networks and the controllable transition from random tiling to ordered architectures, providing a robust strategy for the precise fabrication of two-dimensional supramolecular nanostructures.
We present a two-phase multirelaxation-time lattice Boltzmann framework to investigate mass transport in nanoporous membranes under transitional flow conditions. Simulations for the flow through one pore are compared with experimental data for the permeation of low molecular-weight hydrocarbons through anodic alumina membranes with a pore size of 45 nm. Knudsen numbers range between 0.2 and 1.2 for pressures between 1 and 6 bar at room temperature. The model incorporates a modified Peng-Robinson equation of state, extended cohesive and adhesive interactions, and rarefaction-sensitive relaxation times to simulate confined fluid behavior. Special attention is given to the role of adhesive strength in controlling near-wall dynamics through bounce-back and specular reflection mechanisms. To resolve near-wall density variations, a multilayer adhesive model is introduced, thereby extending the influence of wall adhesion deeper into the channel, smoothing the density gradient, and enhancing surface-dominated transport. The adsorbed layer is partially mobile and contributes to the total mass flux rate. This leads to up to a 12% increase in mass flux for light gases, while having a negligible effect on heavier hydrocarbons due to their intrinsic cohesive dominance. For isobutane, a two-phase simulation captures the nonlinear rise in mass flux due to capillary condensation, which is also observed experimentally. Simulation results for methane, ethane, and propane exhibit strong agreement with experimental permeance data, within 5% for methane and 10-15% for ethane and propane, suggesting correct treatment of rarefied gas dynamics, surface effects, and thermodynamic consistency across a range of hydrocarbon species. These findings show the model's predictive capability and highlight the critical interplay of viscous flow, Knudsen diffusion, surface adsorption, and phase change in nanoscale gas transport.