Membrane Surface Research Articles

Cellulose Surface Nanoengineering for Visualizing Food Safety.

Food safety is vital to human health, necessitating the development of nondestructive, convenient, and highly sensitive methods for detecting harmful substances. This study integrates cellulose dissolution, aligned regeneration, in situ nanoparticle synthesis, and structural reconstitution to create flexible, transparent, customizable, and nanowrinkled cellulose/Ag nanoparticle membranes (NWCM-Ag). These three-dimensional nanowrinkled structures considerably improve the spatial-electromagnetic-coupling effect of metal nanoparticles on the membrane surface, providing a 2.3 × 108 enhancement factor for the surface-enhanced Raman scattering (SERS) effect for trace detection of pesticides in foods. Notably, the distribution of pesticides in the apple peel and pulp layers is visualized through Raman imaging, confirming that the pesticides penetrate the peel layer into the pulp layer (∼30 μm depth). Thus, the risk of pesticide ingestion from fruits cannot be avoided by simple washing other than peeling. This study provides a new idea for designing nanowrinkled structures and broadening cellulose utilization in food safety.

Rapid photothermal assay for ultrasensitive point-of-care detection of tumor markers based on a filter membrane.

Anultrasensitive photothermal assay was designed for point-of-care testing (POCT) of tumor markers based on a filter membrane. Firstly, Cu2-xSe was successfully encapsulated in liposome spheres with biotin on the surface and connected to carcinoembryonic antigen (CEA) aptamer with 3'end modified biotin by streptavidin. Secondly, the CEA antibody was successfully modified on the surface of the nitrocellulose membrane through simple incubation. Finally, the assay process was completed using a disposable syringe, and the temperature was recorded using a handheld infrared temperature detector. In the range 0-50 ng mL-1, the temperature change of the nitrocellulose membrane has a strong linear relationship with CEA concentration, and the detection limit is 0.097 ng mL-1. It is worth noting that the entire testing process can be easily performed in 10 min, much shorter than traditional clinical methods. In addition, this method was successfully applied tothe quantitative determinationof CEA levels in human serum samples with a recovery of 96.2-103.3%. This rapid assay can be performed by "one suction and one push" through a disposable syringe, which is simple to operate, and the excellent sensitivity reveals the great potential of the proposed strategy in the POCT of tumor biomarkers.

Cell‐Anchored Lead‐Free Piezoelectric KNN NPs Resisting Washout for Low‐Intensity Ultrasound Driven Neuromodulation

AbstractPiezoelectric nanomaterials for wireless neuromodulation is a promising alternative to traditional electrical stimulation. However, the low‐avidity between piezoelectric nanomaterials and cellular membranes leads to low efficiency of electrical signal transmission, which requires high‐intensity thresholds of ultrasound stimulation (US). Here, lead‐free piezoelectric (K,Na)NbO3 (KNN) nanoparticles (NPs) with cholesterol coating (KNNC) are presented, in which Cholesterol can be accommodated in the membrane and make them append on the plasma membrane. Compared to non‐modified nanoparticles, cell‐anchored KNNC NPs highly resist convective washout owing to high affinity of cholesterol to biological membranes, which enables highly efficient wireless electrical stimulation to activate cell impulses under low‐intensity ultrasound. Meanwhile, after perfusion washing, the KNNC NPs distributed around the cells are washed away, while part of KNNC NPs remain on the surface of cell membrane still can induce significant Ca2+ influx under US, similar to the group without washing, indicating the KNNC NPs appended on the cell play a major role in wireless electrical stimulation. Furthermore, the highly efficient electrical transmission of KNNC enables neural differentiation of stem cells in regulating synaptic plasticity by modulating Ca2+ influx, demonstrating that KNNC NPs offer a perspective toward minimally invasive wireless neuromodulation therapies for neurological diseases.

Vibronics of multi-material nanopillared membranes and impact on the thermal conductivity.

Atomic motion in nanopillars standing on the surface of a silicon membrane generates vibrons, which are wavenumber-independent phonons that act as local resonances. These vibrons couple with the vast majority of the phonon population, including heat-carrying phonons, traveling along the base membrane causing a reduction in the in-plane lattice thermal conductivity. In this work, we examine isolated silicon and gallium nitride nanopillars and for each compare the vibrons density of states (DOS) to those of phonons in an isolated version of the silicon membrane. We show that while the conformity of the phonon-vibron DOS distribution between the two components across the full spectrum is a key factor in reducing the thermal conductivity of the assembled nanostructure, the presence of an intense vibron population at more dominant low frequencies plays a competing role. We report predictions from molecular dynamics simulations showing lower thermal conductivities for a silicon membrane with gallium-nitride nanopillars compared to a silicon membrane with silicon nanopillars.

Resolving the interactions between hydrophilic CdTe quantum dots and positively charged membranes at the nanoscale

The use of quantum dot nanoparticles (QDs) in bio-applications has gained quite some interest and requires a deep understanding of their interactions with model cell membranes. This involves assessing the extent of nanoparticle disruption of the membrane and how it depends on both nanoparticle and membrane physicochemical properties. Surface charge plays an important role in nanoparticle adsorption, which is primarily driven by electrostatic interactions; yet, once adsorbed, most reported works overlook the subsequent spatial nanoparticle insertion and location within the membrane. There is therefore a need for studies to assess the mutual role of membrane and nanoparticle charge into membrane structure and stability at the nanoscale, with a view to better design and control the functionality of these nanomaterials. In this work, we have resolved the extent of the interactions between hydrophilic, negatively charged CdTe QDs and positively charged lipid bilayers. A multiscale combination of surface-sensitive techniques enabled probing how surface charge mediates QD adsorption and membrane reorganization. Increasing membrane surface charge results into a larger adsorption of oppositely charged QDs, concomitantly inducing structural changes. Hydration of the membrane hydrophobic parts by QDs goes deeper into the inner leaflet with increasing membrane charge, resulting in supported lipid bilayers with decreased nanomechanical stability.

The role of aquaporins in osmotic cell lysis induced by Bacillus thuringiensis Cry1Ac toxin in Helicoverpa armigera

The insecticidal crystalline (Cry) and vegetative insecticidal (Vip) proteins derived from Bacillus thuringiensis (Bt) are used globally to manage insect pests, including the cotton bollworm, Helicoverpa armigera, one of the world's most damaging agricultural pests. Cry proteins bind to the ATP-binding cassette transporter C2 (ABCC2) receptor on the membrane surface of larval midgut cells, resulting in Cry toxin pores, and ultimately leading to cell swelling and/or lysis. Insect aquaporin (AQP) proteins within the membranes of larval midgut cells are proposed to allow the rapid influx of water into enterocytes following the osmotic imbalance triggered by the formation of Cry toxin pores. Here, we examined the involvement of H. armigera AQPs in Cry1Ac-induced osmotic cell swelling. We identified and characterized eight H. armigera AQPs and demonstrated that five are functional water channel proteins. Three of these (HaDrip1, HaPrip, and HaEglp1) were found to be expressed in the larval midgut. Xenopus laevis oocytes co-expressing the known Cry1Ac receptor HaABCC2 and each of the three HaAQPs displayed abnormal morphology and were lysed following exposure to Cry1Ac, suggesting a rapid influx of water was induced after Cry1Ac pore formation. In contrast, oocytes producing either HaABCC2 or HaAQP alone failed to swell or lyse after treatment with Cry1Ac, implying that both Cry1Ac pore formation and HaAQP function are needed for osmotic cell swelling. However, CRISPR/Cas9-mediated knockout of any one of the three HaAQP genes failed to cause significant changes in susceptibility to the Bt toxins Cry1Ac, Cry2Ab, or Vip3Aa. Our findings suggest that the multiple HaAQPs produced in larval midgut cells compensate for each other in allowing for the rapid influx of water in H. armigera midgut cells following Cry toxin pore formation, and that mutations affecting a single HaAQP are unlikely to confer resistance to Bt proteins.

Preparation of PVDF@TiO2 hybrid membrane and the research of the “hydration layer & rigid layer obstruction-electrostatic coalescence” anti-oil fouling mechanism

In this study, the 3-Aminopropyltriethoxysilane (APTES) was first grafted onto TiO2 nanoparticles (APTES-TiO2 nanoparticles), which were then introduced the membrane surface by reacting with anhydride on the membrane surface and Schiff base reaction with the PEI-TA. There are two types of hollow fiber hybrid membranes with varying nanoparticle distributions were constructed. The influence of hybrid mode on the ability of anti-oil fouling was researched. The results indicated that the PVDF@TiO2 hybrid membrane has a flux recovery rate of 96.68 % and a total flux decline rate of 15.52 %, indicating a good anti-emulsified oil fouling performance. By characterizing the anti-oil droplets adhesion, water-binding capacity, surface charge of membrane and concentrate system coacervate size, the coalescence ability of the hybrid membrane to the oil droplets and the spreading behavior of oil droplets on the surface were uncovered. Ultimately, the anti-fouling mechanism “hydration layer &rigid layer obstruction-electrostatic coalescence” was proposed, which can reasonably explain the weakness of the interplay between the membrane surface and oil droplets, thus slowing down the attaching and spreading of emulsified oil droplets. This study laid the foundation for developing hybrid membranes with high resistance to emulsified oil fouling ability. The proposed anti-fouling mechanism can provide new ideas for the efficient purification of oily wastewater.

Functional of thin-film composite Janus membrane with sacrificial layer for inorganic scaling control in membrane distillation

Membrane distillation technology, utilized for treating hypersaline wastewater from seawater desalination, often encounters challenges related to inorganic scaling, adversely affecting membrane performance. Herein, we introduce a innovative approach employing a sacrificial layer on the surface of Thin Film Composite (TFC) membranes to concurrently enhance inorganic scaling resistance and facilitate membrane reusability. The sacrificial layer (Fe3+-TA) consisted of tannic acid (TA) complexed with iron ions (Fe3+) and could be removed and regenerated in situ. The results demonstrated that the Fe3+-TA layer significantly improved the membrane's surface smoothness and densification, maintaining superior anti-scaling performance. The modified membrane exhibited remarkable durability, sustaining six reuse cycles with a flux recovery exceeding 97 % in gypsum scaling tests. Furthermore, the formation of new complexes during gypsum scaling tests confirmed the membrane's augmented scaling retardation capabilities. Thus, integrating of a sacrificial layer into TFC membranes presents a promising strategy for advancing membrane distillation processes in hypersaline wastewater treatment.

Rational regulation of post-electrodialysis electrochromic anion exchange membranes via TiO2@Ag synergistically strengthens visible-light photocatalytic anti-contamination activity

Membrane-contamination during electrodialysis (ED) process is still a non-negligible challenge, while irreversible consumption and unsustainability have become the main bottlenecks limiting the improvement of anion exchange membranes (AEMs) anti-contamination activity. Here, we introduce a novel approach to design AEMs by chemically assembling 4-pyndinepropanol with bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) in an electrochromic-inspired process. Subsequently, the co-mingled TiO2@Ag nanosheet with the casting-solution were sprayed onto the surface of the substrate membrane to create a micrometer-thick interfacial layer. The addition of Ag nanoparticles (NPs) enhances the active sites of TiO2, resulting in stronger local surface plasmon resonance (LSPR) effects and reducing its energy band gap limitation (From 3.11 to 2.63 eV). Post-electrodialysis electrochromic AEMs incorporating TiO2@Ag exhibit synergistic enhancement of sunlight absorption, effectively suppressing photogenerated carrier binding and promoting migration. These resultant-membranes demonstrate significantly improved bacterial inhibition properties (42.0-fold increase for E. coli) and degradation activity (7.59-fold increase for rhodamine B) compared to pure TiO2 membranes. Importantly, they maintain photocatalytic activity without compromising salt-separation performance or stability, as the spraying process utilizes the same substrate materials. This approach to rational design and regulation of anti-contamination AEMs offers new insights into the collaborative synergy of color-changing and photocatalytic materials.

Effect of surface hydroxyl group density of support membrane on water permeance of polyamide thin-film composite membrane

Polyamide-based thin-film composite (TFC) membranes are widely used in water treatment processes. Recently, the influence of support membranes on the performance of polyamide layers has garnered considerable attention. Regarding the chemical properties of the support membranes, the surface wettability and the interaction between the amine monomer used for interfacial polymerization and the membrane surface are considered to play crucial roles. In this study, we investigated the effect of the wettability of the support membrane surface and its interaction with the amine monomer on the water permeance of TFC membranes. We prepared TFC membranes on polyketone support membranes with varying surface hydroxyl group densities and aqueous solution wettabilities. While no clear correlation was observed between the support membrane's wettability and the water permeance of the TFC membrane, an increase in hydroxyl group density did result in higher water permeance. The hydroxyl groups interact with PIP, inhibiting PIP diffusion and potentially leading to the formation of a thinner polyamide layer, which enhances water permeance. Therefore, the interaction between the amine monomer and support membrane surface strongly affects the formation of the polyamide layer.

In situ polymerization of a poly(3,4-ethylenedioxythiophene):poly(sodium–styrennesulfonate) conductive layer for electro-assisted ultrafiltration and fouling mitigation

Electrification can enhance the antifouling performance of ultrafiltration membranes and improve the sustainability of membrane technologies. The design of high-performance conductive membrane materials remains one of the core technologies in electro-assisted ultrafiltration. Here, conductive PVDF/PEDOT:PSS composite membranes were prepared via in situ chemical oxidation polymerization on a PVDF surface. The PVDF/PEDOT:PSS membranes were subsequently used for electro-filtration to study the effect of the applied potential on humic acid fouling. When a voltage of 3 V was applied, the PVDF/PEDOT:PSS20 membrane was continuously polluted for 5 cycles. The results showed that after simple hydraulic cleaning, the membrane flux recovery rate reached 91 %. Compared with that of the PVDF membrane, the irreversible fouling of the PVDF/PEDOT:PSS20 membrane decreased by 65 %. The modified Poisson Boltzmann equation indicates that applying cathodic potential on the surface of PEDOT:PSS conductive layer increases the cumulative concentration of counter ions on the membrane surface and the thickness of the charged layer, thereby promoting the migration of peak forces on the membrane surface to the bulk solution, changing the fouling behaviour of HA from cake filtration to standard blocking.

Molecular insights reveal how the glycolipids in cell membrane mitigates nanomaterial's invasion

Nanomaterial-cellular membrane interaction is crucial for the cytotoxicity of such materials in theoretical investigations. However, previous research often used cellular membrane models with one or few lipid types, which deviates significantly from realistic membrane compositions. Here, employing molecular dynamics (MD) simulations, we investigate the impact of a typical nanomaterial, boron nitride (BN), on a cellular membrane model based on the realistic small intestinal epithelial cell (SIEC) membrane. This membrane contains a complex composition, including abundant glycolipids. Our MD simulations reveal that BN nanosheet can partially insert into the SIEC membrane, maintaining a stable binding conformation without causing obvious structural changes. Dynamic analyses suggest that van der Waals (vdW) interactions drive the binding process between BN and the SIEC membrane. Further simulation of the interaction between BN nanosheet and deglycosylated SIEC membrane confirms that BN nanosheet cause significant structural damage to deglycosylated SIEC membranes, completely inserting into the membrane, extracting lipids, and burying some lipid hydrophilic heads within the membrane interior. Quantitative analyses of mean squared displacements (MSD) of membranes, membrane thicknesses, area per lipid, and order parameters indicate that BN nanosheet causes more substantial damage to deglycosylated SIEC membrane than to intact SIEC membrane. This comparison suggests the molecular mechanism involved in mitigating BN invasion by SIEC membrane that the polysaccharide heads of glycolipids in the SIEC membrane form a significant steric hindrance on membrane surface, not only hindering the insertion of BN, but also resisting the lipid extraction by BN. Free energy calculations further support this conclusion. Overall, our MD simulations not only shed new light into the reduced impact of BN nanosheet on the realistic SIEC membrane but also highlight the importance of glycolipids in protecting cell membranes from nanomaterial invasion, contributing to a deeper understanding of nanomaterial-realistic cell membrane interactions.

Spray coating of 2D materials in the production of antifouling membranes for membrane distillation

Membrane surface coatings with 2D materials have been shown to exhibit antifouling properties for water-treatment applications; however, synthesis methods currently based on vacuum filtration are not easily scalable. This study describes a scalable method for coating membranes with a range of 2D materials including graphene oxide (GO), hexagonal boron nitride (hBN), molybdenum disulphide (MoS2) and tungsten disulphide (WS2). Isopropyl alcohol solutions containing each class of the 2D flakes were spray-coated onto commercial polyvinylidene fluoride (PVDF) using a pyrolyser. The nanomaterials were secured with polydopamine (PDA) as a crosslinker in a method that could easily be integrated into a scalable roll-to-roll process. Changes in morphology, surface roughness, hydrophobicity, mechanical durability and chemical composition were evaluated using scanning electron microscopy, atomic force microscopy, contact angle, tensile strength measurements and Fourier-transform infrared spectroscopy. The 2D nanomaterials-coated membranes were tested in membrane distillation (MD) experiments over 72 hours and compared to pristine PVDF and PDA/PVDF membranes. Salt rejection and MD performance stability were evaluated using feedwaters with high concentrations of humic acid (150 ppm) and paraffin oil (200 ppm) simulating simple organic wastewater from oil and gas extraction. The flux decline ratio was measured in terms of percentage permeate loss per hour (%/h), to allow for future comparisons with studies with different experimental times. The pristine PVDF membrane failed after 10 hours by pore-wetting due to fouling while the PDA/PVDF membrane had the largest flux decline ratio (0.3 %/h). The membranes coated with GO and hBN had flux decline ratios orders of magnitude lower (0.0021 ± 0.005 and 0.028 ± 0.01 %/h, respectively). All membranes had a high salt rejection (>99.9 %). The GO-coated membrane was the only membrane type that was able to treat both surfactant-containing and foulant-containing feedwaters. The improved performance is attributed to the decrease in both surface roughness and hydrophobicity, which reduces the adsorption of foulants onto the membrane surface. This work shows a facile, scalable method to overcome fouling limitations in MD.

Tourmaline triggered biofilm transformation: Boosting ultrafiltration efficiency and fouling resistance

Ultralow pressure filtration system, which integrates the dual functionalities of biofilm degradation and membrane filtration, has gained significant attention in water treatment due to its superior contaminant removal efficiency. However, it is a challenge to mitigate membrane biofouling while maintaining the high activity of biofilm. This study presents a novel ceramic-based ultrafiltration membrane functionalized with tourmaline nanoparticles to address this challenge. The incorporation of tourmaline nanoparticles enables the release of nutrient elements and the generation of an electric field, which enhances the biofilm activity on the membrane surface and simultaneously alleviates intrapore biofouling. The tourmaline-modified ceramic membrane (TCM) demonstrated a significant antifouling effect, with a substantial increase in water flux by 60%. Additionally, the TCM achieved high removal efficiencies for contaminants (48.78% in TOC, 22.28% in UV254, and 24.42% in TN) after 30 days of continuous operation. The fouling resistance by various constituents in natural water was individually analyzed using model compounds. The TCM with improved electronegativity and hydrophilicity exhibited superior resistance to irreversible fouling through increased electrostatic repulsion and reduced adhesion to foulants. Comprehensive characterizations and analyses, including interfacial interaction energies, redox reaction processes, and biofilm evolutions, demonstrated that the TCM can release nutrient elements to facilitate the development of functional microbial community within the biofilm, and generate reactive oxygen species (ROS) on the membrane surface to the degrade contaminants and mitigate membrane biofouling. The electric field generated by tourmaline nanoparticles can promote electron transfer in the Fe(III)/Fe(II) cycle, ensuring a stable and sustainable generation of ROS and bactericidal negative ions. These synergistic functions enhance contaminant removal and reduce irreversible fouling of the TCM. This study provides fundamental insights into the role of tourmaline-modified surfaces in enhancing membrane filtration performance and fouling resistance, inspiring the development of high-performance, anti-fouling membranes.

Angiopep-2 conjugated biomimetic nano-delivery system loaded with resveratrol for the treatment of methamphetamine addiction

Methamphetamine (METH) addiction can damage the central nervous system, resulting in cognitive impairment and memory deficits. Low target effects have limited the utility of anti-addiction drugs because the presence of the blood–brain barrier hinders the effective delivery of drugs to the brain. Angiopep-2 can recognize and target low-density lipoprotein receptor-associated protein 1 (LRP-1) on the surface of cerebral capillary endothelial cells, causing cross-cell phagocytosis, and thus has high blood–brain barrier transport capacity. Resveratrol (RSV) has been found to be a neuroprotective agent in many nervous system diseases. In our study, we modified Angiopep-2 on the surface of the erythrocyte membrane to obtain a modified erythrocyte membrane (Ang-RBCm) and coated RSV-loaded poly(ε-caprolactone)–poly(ethylene glycol) (PCL-PEG) nanoparticles with Ang-RBCm (Ang-RBCm@RSVNPs) to treat METH addiction. Our results showed that Ang-RBCm@RSVNPs can penetrate the blood–brain barrier and accumulate in the brain better than free RSV. Besides, mice treatetd with Ang-RBCm@RSVNPs showed less preference to METH-paired chamber and no noticeable tissue toxicity or abnormality was found in H&E staining images. Electrophysiological experiments demonstrated Ang-RBCm@RSVNPs could elevate synaptic plasticity impaired by METH. These indicated that Ang-RBCm@RSVNPs has better anti-addiction and neuroprotective effects. Therefore, Ang-RBCm@RSVNPs has great potential in the treatment of METH addiction.

Effect of Sintering Temperature on Ceramic Membrane Fabricated Using Coal Flyash and Natural Clay for Lignin Recovery

This study explores the utilization of coal fly ash combined with natural clay as a precursor for creating ceramic membranes through the uniaxial compaction method, aiming at lignin separation. These membranes were sintered at varying temperatures from 600 to 1000 °C. Thermal Gravimetric Analysis (TGA) revealed the robust thermal stability of the membranes. Fourier Transform Infrared (FTIR) analysis affirmed the presence of silica and alumina within the membranes. X-ray Diffraction (XRD) peaks indicated the crystalline structure and the presence of metal oxides originating from the fly ash and clay components. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images illustrated the porous nature and rough surface of the ceramic membranes. The average pore radius of the fabricated membrane expanded from 43.12 to 7.91 nm with increasing temperature. Concurrently, membrane flux decreased from 4.13 to 0.96 ×10-6 m3/m2 s with higher temperatures. Lower contact angles indicated the hydrophilic properties of membranes. All membranes exhibited superior corrosion resistance and negative zeta potential, owing to the significant silica content in the fly ash. Lignin separation efficiency increased from 65 % to 81 % with increasing temperatures. The optimal sintering temperature was determined to be 800 °C, achieving a lignin recovery greater than 76 % and a membrane permeability of about 7×10-9 m3/m2 s kPa. Thus, the fly ash-clay-based ultrafiltration membranes synthesized in this study offer the potential for lignin biomass recovery from biorefinery effluent.

An endothelium membrane mimetic antithrombotic coating enables safer and longer extracorporeal membrane oxygenation application

Thrombosis and plasma leakage are two of the most frequent dysfunctions of polypropylene (PP) hollow fiber membrane (PPM) used in extracorporeal membrane oxygenation (ECMO) therapy. In this study, a superhydrophilic endothelial membrane mimetic coating (SEMMC) was constructed on polydopamine-polyethyleneimine pre-coated surfaces of the PPM oxygenator and its ECMO circuit to explore safer and more sustainable ECMO strategy. The SEMMC is fabricated by multi-point anchoring of a phosphorylcholine and carboxyl side chained copolymer (PMPCC) and grafting of heparin (Hep) to form PMPCC-Hep interface, which endows the membrane superior hemocompatibility and anticoagulation performances. Furthermore, the modified PPM reduces protein adsorption amount to less than 30 ng/cm2. More significantly, the PMPCC-Hep coated ECMO system extends the anti-leakage and non-clotting oxygenation period to more than 15 h in anticoagulant-free animal extracorporeal circulation, much better than the bare and conventional Hep coated ECMO systems with severe clots and plasma leakage in 4 h and 8 h, respectively. This SEMMC strategy of grafting bioactive heparin onto bioinert zwitterionic copolymer interface has great potential in developing safer and longer anticoagulant-free ECMO systems. Statement of SignificanceA superhydrophilic endothelial membrane mimetic coating was constructed on surfaces of polypropylene hollow fiber membrane (PPM) oxygenator and its ECMO circuit by multi-point anchoring of a phosphorylcholine and carboxyl side chain copolymer (PMPCC) and grafting of heparin (Hep). The strong antifouling nature of the PMPCC-Hep coating resists the adsorption of plasma bio-molecules, resulting in enhanced hemocompatibility and anti-leakage ability. The grafted heparin on the zwitterionic PMPCC interface exhibits superior anticoagulation property. More significantly, the PMPCC-Hep coating achieves an extracorporeal circulation in a pig model for at least 15 h without any systemic anticoagulant. This endothelial membrane mimetic anticoagulation strategy shows great potential for the development of safer and longer anticoagulant-free ECMO systems.

Membrane-targeted mechanism for amphiphilic Vitamin C compounds as methicillin-resistant Staphylococcus aureus biofilm eradicating agents

Staphylococcus aureus infections and its biofilm removal is an important concern in health care management. Methicillin-resistant S. aureus is responsible for severe morbidity and mortality worldwide. The extensive use of disinfectants against biofilms has led to negative environmental impacts. Developing new and more potent biofilm eradication agents with minimal detrimental effects on human and environmental health is currently on the agenda. The alkyl esters of L-ascorbic acid (ASCn) are antioxidant amphiphiles, which show antimicrobial capacity against methicillin-sensitive and resistant S. aureus strains. ASC12 and ASC14 formulations are able to kill the persister cells of the deepest layers of the biofilm. We tested the hypothesis that the antimicrobial and antibiofilm capacity found for the ASCn emerges from a combined effect of its amphiphilic and their redox capacity. This mechanism appears related to: I) a larger diffusion capacity of the ASC12 micelles than ASC14 and ASC16 microstructures; II) the neutralization of the ASCn acid hydroxyl when the amphiphile reaches the surface of an anionic surface, followed by a rapid insertion; III) the disruption of cell membrane by alteration of membrane tension and structure and IV) ASCn accumulation in the cell membrane or biofilm extracellular matrix surfaces, reducing functional chemical groups and affecting its biological function.

Septins promote macrophage pyroptosis by regulating gasdermin D cleavage and ninjurin-1-mediated plasma membrane rupture.

The septin cytoskeleton is primarily known for roles in cell division and host defense against bacterial infection. Despite recent insights, the full breadth of roles for septins in host defense is poorly understood. In macrophages, Shigella induces pyroptosis, a pro-inflammatory form of cell death dependent upon gasdermin D (GSDMD) pores at the plasma membrane and cell surface protein ninjurin-1 (NINJ1) for membrane rupture. Here, we discover that septins promote macrophage pyroptosis induced by lipopolysaccharide (LPS)/nigericin and Shigella infection, but do not affect cytokine expression or release. We observe that septin filaments assemble at the plasma membrane, and cleavage of GSDMD is impaired in septin-depleted cells. We found that septins regulate mitochondrial dynamics and the expression of NINJ1. Using a Shigella-zebrafish infection model, we show that septin-mediated pyroptosis is an invivo mechanism of infection control. The discovery of septins as a mediator of pyroptosis may inspire innovative anti-bacterial and anti-inflammatory treatments.

Nanoscale lipid domains determine the dynamic molecular portraits of mixed DOPC/DOPS bilayers in a fluid phase: A computational insight

Lateral heterogeneity, or mosaicity, is a fundamental property inherent to cell membranes that is crucial for their functioning. While microscopic inhomogeneities (e.g. rafts) are easily detected experimentally, lipid domains with nanoscale dimensions (nanoclusters of nanodomains, NDs) resist reliable characterization by instrumental methods. In such a case, important insight can be gained via computer modeling. Here, NDs composed of lipid's head groups in the mixed zwitterionic dioleoylphosphatidylcholine (DOPC) and negatively charged dioleoylphosphatidylserine (DOPS) bilayers were studied by molecular dynamics. A new algorithm has been developed to identify NDs. Unlike most similar methods, it implicitly considers the heterogeneous distribution of lipid head atomic density and does not require subjectively chosen parameters. In DOPS-rich membranes, lipids form more compact and stable NDs due to strong interlipid interactions. In DOPC-rich systems, NDs arise due to the “packing” effect of weakly bound lipid heads. The clustering picture is related to the physical properties of the bilayer surface: DOPS-rich systems show more pronounced surface heterogeneity of hydrophilic/hydrophobic regions compared to DOPC-rich ones. The results obtained are important for the effective quantitative characterization of the “dynamic molecular portrait” of a membrane surface – its “fingerprint” characterizing dynamical distribution of its physicochemical properties.