Charged Membranes Research Articles

Ultramicroporous Tröger's Base Framework Membranes With Ionized Sub-nanochannels for Efficient Acid/Alkali Recovery.

Membrane technology holds significant potential for the recovery of acids and alkalis from industrial wastewater systems, with ion exchange membranes (IEMs) playing a crucial role in these applications. However, conventional IEMs are limited to separating only monovalent cations or anions, presenting a significant challenge in achieving concomitant H⁺/OH⁻ permselectivity for simultaneous acid and alkali recovery. To address this issue, the charged microporous polymer framework membranes are developed, featuring rigid Tröger's Base network chains constructed through a facile sol-gel process. The intrinsic ultramicropore confinement and quaternary ammonium-charged functional groups provide ultrahigh size-sieving capability and enhanced Donnan exclusion for H⁺/OH⁻ selectivity; meanwhile, the internal protoplasmic channels of the polymer frameworks serve as highways for rapid ion transfer. The resulting membrane achieves high H⁺/Fe2⁺ and OH⁻/WO₄2⁻ selectivities of 694.4 and 181.0, respectively, for concurrent acid and alkali separation in diffusion dialysis and electrodialysis processes over extended operational periods (exceeding 1600 and 600 h, respectively), while maintaining remarkable transport rates. These results outperform most literature-reported and nearly all commercially available membranes. This study validates the novel applicability of polymer framework materials with ionized angstrom-scale channels and versatile functionalities in high-performance IEMs for acid/alkali resource recovery.

Nano-viscosimetry analysis of membrane disrupting peptide magainin2 interactions with model membranes.

The rapid spread of antibiotic-resistant strains of bacteria has created an urgent need for new alternative antibiotic agents. Membrane disrupting antimicrobial peptides (AMPs): short amino acid sequences with bactericidal and fungicidal activity that kill pathogens by permeabilizing their plasma membrane may offer a solution for this global health crisis. Magainin 2 is an AMP secreted by the African clawed frog (Xenopus laevis) that is described as a toroidal pore former membrane disrupting AMP. Magainin 2 is one of the most thoroughly studied AMPs, yet its mechanism of action is still largely hypothetical: visual evidence of the pore formation is lacking, and the molecular mechanism leading to pore formation is still debated. In the present study, quartz crystal microbalance (QCM) based viscoelastic fingerprinting analysis supported by dye leakage experiments and atomic force microscopy (AFM) imaging was used to glean deeper insights into the mechanism of action. The effect of membrane charge, acyl chain unsaturation and cholesterol concentration were also investigated. The results show lipid specific disruptive mechanism of magainin 2. QCM nano-viscometry measurements revealed the presence of distinct stages in the mechanism of magainin 2 action that, with dye leakage data, confirm the existence of an initial transient pore stage that may result in peptide flip-flop between the outer and inner membrane leaflets. There is evidence of a further mechanistic stage at high peptide concentrations that is consistent with membrane collapse into a peptide-lipid mixed phase that is distinct from the transient pore formation. The results confirm some of the earliest hypotheses about magainin 2 action, while also highlighting the membrane modulating effect of this peptide.

Environmental Dissemination of SARS-CoV-2: An Analysis Employing Crassphage and Next-Generation Sequencing Protocols.

This study aimed to investigate the dissemination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in water samples obtained during the coronavirus disease 2019 pandemic period, employing cross-assembly phage (crAssphage) as a fecal contamination biomarker and next-generation sequencing protocols to characterize SARS-CoV-2 variants. Raw wastewater and surface water (stream and sea) samples were collected for over a month in Rio de Janeiro, Brazil.Ultracentrifugation and negatively charged membrane filtration were employed for viral concentration of the wastewater and surface water samples, respectively. Viruses were detected and quantified by (RT-)qPCR applying TaqMan® system protocols. SARS-CoV-2 RNA signals were detected in 92.5% (37/40) of the wastewater samples and in 31.25% (10/32) of the stream water samples, but not in seawater samples. CrAssphage was detected in 100% of the wastewater samples, 93.75% (30/32) of the stream samples, and in 2/4 of the seawater samples. CrAssphage detection and high concentrations in stream surface waters (median 8.95 log10 gc/L) revealed diffuse contamination by domestic wastewater in a region with high sanitary coverage. The correlations detected between SARS-CoV-2 data and the moving averages of clinical cases per capita over the sampling period were moderate to strong when applying a 13-day offset, regardless of normalization by crAssphage data or not. Sequencing of the receptor-binding domain of the spike protein confirmed the detection of SARS-CoV-2, but did not characterize the circulating variant. On the other hand, the whole genome sequencing protocol identified circulation of the Gamma variant, corroborating the sampling period clinical data.

Metal ion cofactors modulate integral enzyme activity by varying differential membrane curvature stress.

Metal ions are well-known cofactors of protein function and stability. In the case of the integral membrane enzyme OmpLA (outer membrane phospholipase A) the active dimer is stabilized by calcium ions. We studied the lipid hydrolysis kinetics of OmpLA in charge-neutral and charged membranes with symmetric or asymmetric transbilayer lipid distributions. In charge-neutral membranes, OmpLA was more active in symmetric bilayers due to the lower differential curvature stress between membrane leaflets. Strikingly, this behavior was completely reversed in charged bilayers. Measurements revealed intrinsic molecular shape changes in the charged lipids upon addition of calcium. This effectively reduces the differential curvature stress in charged asymmetric membranes leading to increased protein activity. This conclusion is further supported by similar effects observed upon the addition of sodium ions, which also alter the shape of the lipids, but do not specifically interact with the protein. Additional lipid-protein interactions likely contribute to this phenomenon. Our findings demonstrate that ion cofactors not only interact directly with membrane proteins but also modulate protein activity indirectly by altering the effective molecular shape of charged lipid species.

Electrophysiological dissection of the ion channel activity of the Pseudomonas aeruginosa ionophore protein toxin Tse5.

We present an in-depth electrophysiological analysis of Tse5, a pore-forming toxin (PFT) delivered by the type VI secretion system (T6SS) of Pseudomonas aeruginosa. The T6SS is a sophisticated bacterial secretion system that injects toxic effector proteins into competing bacteria or host cells, providing a competitive advantage by disabling other microbes and modulating their environment. Our findings highlight the dependency of Tse5 insertion on membrane charge and electrolyte concentration, suggesting an in vivo effect from the periplasmic space. Conductance and selectivity experiments reveal a predominant and reproducible pore architecture of Tse5, characterized by a weak cation selectivity without chemical specificity. pH titration experiments suggest a proteolipidic pore structure influenced by both protein and lipid charges, a hypothesis further supported by experiments involving engineered mutants of Tse5 with altered glycine zippers. These results significantly advance our understanding of Tse5's molecular mechanism of toxicity, paving the way for potential applications in biosensing and macromolecular delivery.

Challenges of quaternary ammonium antimicrobial agents: Mechanisms, resistance, persistence and impacts on the microecology.

Quaternary ammonium compounds (QACs) served as broad spectrum antimicrobial agents are widely applied for surface disinfection, skin and mucous disinfection, and mouthwash. The daily applications of QACs have significantly increased, especially during the COVID-19 pandemic. However, the environmental residues of QACs have demonstrated harmful impacts on the environment, leading to an increase in environmental contamination, resistant microbes and disruption of microecology. The actions of QACs were related to their cationic character, which can impact the negatively charged cell membranes, but the details are still unclear. Moreover, bacteria with lower sensitivity and resistant pathogens have been detected in clinics and environments, while QACs were also reported to induce the formation of bacterial persisters. Even worse, the resistant bacteria even showed co-resistance and cross-resistance with traditional antibiotics, decreasing therapeutic effectiveness, and disrupting the microecology homeostasis. Unfortunately, the resistance and persistence mechanisms of QACs and the effects of QACs on microecology are still not clear, which even neglected during their daily usages. Therefore, we summarized and discussed current understandings on the antimicrobial actions, resistance, persistence and impacts on the microecology to highlight the challenges in the QACs applications and discuss the possible strategies for overcoming their drawbacks.

Multifunctional role of surfactant in fabricating polyamide nanofiltration membranes for Li+/Mg2+ separation

Extracting Lithium from salt-lake brines can effectively alleviate global lithium scarcity. Separating the co-existing Mg2+ ions from Li+ ions in the brines is essential. While thin-film composite (TFC) nanofiltration (NF) membrane show potential for this separation, commercial NF membranes with negatively charged surfaces fail to meet the high rejection requirement for Mg2+ ions due to the electrostatic attractions between membranes and cations. Positively charged NF membranes fabricated by interfacial polymerization (IP) between aqueous phase polyethylenimine (PEI) and hexane phase trimesoyl chloride (TMC) have shown promise for Li+/Mg2+ separation. However, lithium extraction efficiency is greatly limited by the relatively low permeance and high lithium rejection of the membrane caused by an excessively cross-linked structure. Therefore, optimizing the pore size while maintaining the positive charge of PEI/TMC-based TFC membranes is necessary. We propose adding anionic surfactants to the aqueous PEI solution to modulate PEI/TMC-based NF membrane formation. Surfactants control PEI diffusion in IP through their interactions and improve reaction uniformity at the water-hexane interface. This results in a narrow pore size distribution of the PA network. In this study, three sulfate surfactants with varying alkyl chain lengths were used to control membrane formation. Results showed that sodium n-decyl sulfate (SDES), the shortest sulfate surfactant, improved membrane performance most effectively. The optimized membrane exhibited a crumpled surface and relatively loose pore structure with narrow pore size distribution. It demonstrated a pure water permanence of 5.65 L m−2 h−1 bar−1, high MgCl2 rejection of 92.6 %, and low LiCl rejection of 21.5 %. After filtering a Mg2+ and Li+ binary mixture solution, the Mg2+/Li+ ratio decreased significantly from 40 (feed) to 3.08 (permeate). This study provides an efficient strategy for preparing PEI/TMC-based NF membranes with favorable Li+/Mg2+ separation performance.

Molecular Design of Positively Charged 3D Covalent-Organic Framework Membranes for Li+/Mg2+ Separation.

3D covalent-organic framework (3D COF) membranes have unique features such as smaller pore sizes and more interconnected networks compared with 2D COF counterparts. However, the complicated and unmanageable fabrication hinders their rapid development. Molecular simulation, which can efficiently explore the structure-performance relationship of membranes, holds great promise in accelerating the development of 3D COF membranes. In this study, a series of 3D-COF membranes (TFPM-Pa-X) is designed with different charge densities (fully charged, partially charged, and neutral) and interpenetration numbers (2-, 3-, 4-, and 5-fold), subsequently investigate their contributions to Li+/Mg2+ separation through molecular simulation. Membrane morphology and pore size are found to strongly depend on the charged density and interpenetration number. The pore size and Cl- ion density play a crucial role in governing membrane separation performance. TFPM-Pa-X membrane with a smaller interpenetration number and a higher charge density promotes Li+/Mg2+ separation. The fully charged 2-fold interpenetrated membrane has superior performance in breaking the trade-off between the flux of Li+ (JLi +) and the selectivity of Li+ over Mg2+ (SLi + /Mg 2+). This study may facilitate the rational design of new 3D COF membranes for high-performance ion separation.

Pro-inflammatory S100A8 Protein Exhibits a Detergent-like Effect on Anionic Lipid Bilayers, as Imaged by High-Speed AFM.

Neuronal cell death induced by cell membrane damage is one of the major hallmarks of neurodegenerative diseases. Neuroinflammation precedes the loss of neurons; however, whether and how inflammation-related proteins contribute to the loss of membrane integrity remains unknown. We employed a range of biophysical tools, including high-speed atomic force microscopy, fluorescence spectroscopy, and electrochemical impedance spectroscopy, to ascertain whether the pro-inflammatory protein S100A8 induces alterations in biomimetic lipid membranes upon interaction. Our findings underscore the crucial roles played by divalent cations and membrane charge. We found that apo-S100A8 selectively interacts with anionic lipid membranes composed of phosphatidylserine (PS), causing membrane disruption through a detergent-like mechanism, primarily affecting regions where phospholipids are less tightly packed. Interestingly, the introduction of Ca2+ ions inhibited S100A8-induced membrane disruption, suggesting that the disruptive effects of S100A8 are most pronounced under conditions mimicking intracellular compartments, where calcium levels are low, and PS concentrations in the inner leaflet of the membrane are high. Overall, our results present a mechanistic basis for understanding the molecular interactions between S100A8 and the plasma membrane, emphasizing S100A8 as a potential contributor to the onset of neurodegenerative diseases.

Mathematical modelling of polyvinyl chloride embedded tin tungsto phosphate composite membrane for industrial water separation

AbstractA novel tin tungstophosphate (TTP) composite ion‐exchange membrane was made with casting a polyvinyl chloride (PVC) by co‐precipitation method. The electrochemical characterization and intermolecular interactions between the components in composite membranes are established by scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDX), X‐ray diffraction analysis (XRD) and Fourier‐transform infrared spectroscopy (FT‐IR) and thermogravimetry differential thermal analysis (TG/DTA). The membrane potential has been used to characterize the ion‐transport processes across a charged membrane and follow the order: NaCl>KCl > NaNO3 > KNO3.The fixed‐charge density is the primary determinant of transport phenomena in membranes, although additional electrochemical factors augment membrane efficiency. The electrolytes' capacity to transmit charges in a membrane in a certain sequence is influenced by the counterions. The experimental results and the theoretical prediction for membrane potential agree very well. The membrane mentioned above is excellent for separating industrial water.

Flow Cytometric Analysis for Evaluating Protein Synthesis Efficiency in Giant Unilamellar Vesicles with Charged Lipids

Quantitative investigation of the relationship between endosomal translation reactions and phospholipid membrane composition is crucial for enhancing protein translation efficiency in artificial cells. In this study, we quantitatively compared the translation reactions within liposomes containing negatively and positively charged lipids using green fluorescent protein fluorescence as an indicator to investigate whether lipid membrane charge affects translation reaction efficiency in artificial cells. Thus, translation efficiency reduced in liposomes containing both negatively and positively charged lipids. Interestingly, flow cytometry analysis revealed that the percentage of liposomes undergoing translational reactions was reduced by the charged phospholipids. This translation reaction inhibition was alleviated by adding equal amounts of negatively and positively charged lipids, indicating that phospholipid membrane charges affected translation reaction efficiency. The relationship between membrane composition and translation reaction efficiency identified in this study is significant for the constructing complex artificial cells, particularly concerning membrane composition design

Enhancement of IPMC Bending Controllability Through Immobile Negative Charges and Electrochemically Reactive Substances Within IPMC Body

A well-known soft actuator, called ionic polymer–metal composite (IPMC), is a type of electroactive polymer (EAP) that operates in bending mode. Despite its ability to exhibit large bending, its bending controllability is often poor. Therefore, identifying the key factor that allows IPMC to bend without losing its large bending capability is a natural inquiry for researchers studying IPMC for practical applications. Our study found that the sign of the immobile charge carried by the ion exchange membrane of IPMC governs its bending controllability. We also discovered that using a negatively charged ion exchange membrane, rather than a positively charged one, is highly preferable for IPMC applications. It was also found that using a doping process and an electrochemically active electrode is essential for inducing effective bending in IPMC.

Zeolite membrane with sub-nanofluidic channels for superior blue energy harvesting

Blue energy, a clean energy source derived from salinity gradients, has recently drawn increased research attention. It can be harvested using charged membranes, typically composed of amorphous materials that suffer from low power density due to their disordered structure and low charge density. Crystalline materials, with inherently ordered porous structures, offer a promising alternative for overcoming these limitations. Zeolite, a crystalline material with ordered sub-nanofluidic channels and tunable charge density, is particularly well-suited for this purpose. Here, we demonstrate that NaX zeolite functions as a high-performance membrane for blue energy generation. The NaX zeolite membrane achieves a power density of 21.27 W m⁻² under a 50-fold NaCl concentration gradient, exceeding the performance of state-of-the-art membranes under similar conditions. When tested under practical scenarios, it yields power densities of 29.1 W m⁻², 81.0 W m⁻², and 380.1 W m⁻² in the Red Sea/River, Dead Sea/River, and Qinghai Brine/River configurations, respectively. Notably, the membrane operates effectively in high alkaline conditions (~0.5 M NaOH) and selectively separates CO₃²⁻ from OH⁻ ions with a selectivity of 25. These results underscore zeolite membranes’ potential for blue energy, opening further opportunities in this field.

Low-temperature regulated interfacial polymerization of nanofiltration membrane for efficient Li+/Mg2+ separation

Selectively removing Mg2+ and enriching Li+ from salt lakes using positively charged polyamide nanofiltration (NF) membranes based on Donnan exclusion theory and size sieving effect is expected to address the issue of lithium resource scarcity. However, simultaneously achieving high selectivity and permeability remains a challenge for the currently reported membranes. In this study, we developed a novel positively charged NF membrane by the strategy of low-temperature-induced interfacial polymerization (IP). Low-temperature conditions during the IP reaction regulated the diffusion of amine monomers, resulting in changes in the morphology, chemical composition, and surface properties of the polyamide (PA) layer. Consequently, the obtained membrane features a positively charged PA layer with a relatively loose structure, owing to the low temperature slowing down both the amine monomer diffusion and the IP reaction, which finally reduces the crosslinking degree. The optimal NF membrane prepared in this study with a lower N/O ratio of 0.75 exhibited high water permeance (10.2 L m−2 h−1 bar−1) compared to the pristine membrane prepared at room temperature, high Li+/Mg2+ separation selectivity (29.9), excellent stability, and the purity of Li+ reached 60.0 %. Moreover, after two-stage filtration of the simulated brine using the prepared NF membrane, the Mg2+/Li+ mass ratio dropped significantly from the initial 40 in the initial feed solution to 0.22 in the final permeate solution, demonstrating its considerable potential for practical application in Li+ and Mg2+ separation. Since the high positive charge of the membrane also causes certain lithium rejection, future research should focus on optimizing the membrane charge for more efficient lithium extraction with high recovery.

Post-docking hydrophilic Ag-MOF-303 filled in TFC for nanofiltration of charged PhACs in water

Modifying membrane pore size and surface charge to enhance nanofiltration selectivity presents a crucial challenge in managing pollutants with varying charge properties. This study introduces Ag-MOF-303, synthesized by incorporating Ag into hydrophilic MOF-303 through molecular docking, effectively reducing the pore size to the nanofiltration scale. Subsequently, Ag-MOF-303 was deposited onto a PVDF substrate via interfacial polymerization, forming thin-film composite (TFC) polyamide membranes with enhanced selectivity and permeability. Notably, Ag-MOF-303@PVDF is positively charged, enabling the removal of differently charged pollutants from water. Structure-activity analysis confirmed the effective construction of the functional layer, where the Al3+ and Ag+ content significantly influenced the membrane’s charge properties. Cross-flow filtration experiments revealed a permeability of 14 L·m−2·h−1·bar−1 for Ag-MOF-3030.2%@PVDF, achieving rejection rates exceeding 90 % for CaCl2 and MgSO4 due to the Donnan effect. The membrane showed notable selective removal of six pharmaceutically active compounds with varying charges, maintaining a selectivity coefficient around 70, driven by the combined effects of Donnan exclusion and size sieving. Moreover, Ag-MOF-3030.2%@PVDF displayed stable pore size at 0.4 nm, achieving over 80 % flux recovery after protein and lysozyme fouling, thereby enhancing antifouling and antibacterial properties. This novel strategy of utilizing hydrophilic MOF-303, modified via molecular docking to reduce pore size for the nanofiltration of variously charged micropollutants, provides valuable insights into MOF post-modification techniques and the separation mechanisms in nanofiltration, thereby expanding the application potential of positively charged nanofiltration membranes.

Preparation of positively charged acid-resistant hollow fiber nanofiltration membrane with excellent separation performance by surface modification

There is a significant requirement for acid-resistant nanofiltration (NF) membranes with positively charged surface in order to effectively treat and recycle acidic industrial wastewater that contains heavy metal ions. Currently, acid-resistant nanofiltration membranes still exhibit low water permeance and typically display only weak positively charged or even negatively charged surface, which presents a vast challenge for the effective removal of heavy metal ions. In this work, we successfully produced a positively charged hollow fiber (HF) NF membrane with outstanding water permeability by combining interfacial polymerization and surface modification approaches. The interfacial polymerization reaction was conducted on the inner surface of an HF polysulfone substrate using polyethyleneimine as the aqueous monomer and cyanuric chloride as the organic monomer. This process results in the formation of a positively charged polyamine selective layer. Subsequently, the surface of the selective layer was modified with an aqueous solution of (3-bromopropyl) trimethylammonium bromide (BPTAB) via a Hoffman alkylation process, which increases the positive charge density and hydrophilicity of the HF NF membrane. Consequently, the BPTAB-modified HF NF membrane achieves a water permeance of 44.5 L m−2 h−1 MPa−1, which is a 130 % increase compared to the unmodified baseline HF NF membrane. Meanwhile, it exhibits excellent desalination performance, corresponding to a rejection of 97.3 %, 99.3 % and 99.1 %, for MgCl2, CoCl2 and MnCl2, respectively. Additionally, it demonstrates excellent resistance to acids, which remains a 93.3 % MgCl2 rejection after being submerged in pH = 1 HNO3 solution for 60 d.

Decoration of carbon nanotubes in the substrate or selective layer of polyvinyl alcohol/polysulfone thin-film composite membrane for nanofiltration applications

Nanofiltration (NF) membranes demonstrate considerable promise for desalinating saline water and wastewater containing mineral salts to overcome the lack of fresh water and improve drinking water quality. This research work aims to detect the influence of carbon nanotubes (CNTs) on the filtration performance of polyvinyl alcohol (PVA)/polysulfone (PSf) thin-film composite NF membranes. For this purpose, CNTs were incorporated in the PSf substrate/PVA selective layer to fabricate a thin-film composite (TFC) with nanocomposite substrate (nTFC) and a thin-film nanocomposite (TFN) membranes, respectively. To fabricate TFC membranes, PSf substrates with different concentrations (16–20 wt%) were made using the phase inversion technique. Then, the selective layer of PVA was formed on the PSf support through cross-linking with glutaraldehyde during dip-coating. The membranes’ NF performance was assessed by filtration of NaCl and Na2SO4 solutions at a relatively low pressure of 0.3 MPa. The salt rejection of all prepared membranes followed the sequence of Na2SO4 > NaCl, indicating the characteristics of negatively charged membranes. By embedment of 0.05 wt% CNT in the PSf substrate/PVA selective layer, the rejections of over 43% for NaCl and over 80% for Na2SO4 were obtained, which is higher than that of TFC-16 as a control membrane (18.1% for NaCl and 74.7% for Na2SO4). Furthermore, in the presence of CNTs, the permeance and fouling resistance of the nTFC and TFN membranes have been improved compared to the TFC-16 membrane.

A comparative study of antibiotic treatment by different charged nanofiltration membranes

Antibiotics are synthesized organic compounds for such applications as prevention of diseases. However, they have caused a series of ecotoxicological effects that can potentially be harmful to humans and living organisms. Nanofiltration (NF) can effectively remove antibiotics from many waste streams, such as pharmaceutical wastewater. NF membranes are always charged due to carboxyl and amino groups. This study aims to evaluate performance of negatively (nTFC), positively (pTFC), and dually (dTFC) charged NF membranes in treatment of several antibiotic compounds: ciprofloxacin, ofloxacin, tetracycline, amikacin, and erythromycin. The values of permeance were 26.1, 19.5, and 14.0 L/(m2·h·bar) for nTFC, dTFC, and pTFC membrane, respectively. The dTFC membrane worked well in both permeability and treatment of the antibiotics. The solution pH greatly influenced the removal efficiency of the nTFC and pTFC membranes, while it had less effect on the dTFC membranes. The results demonstrated that dTFC membrane was more efficient than nTFC and pTFC membranes. It would have great potentials in treatment of such industrial effluent as antibiotics-containing wastewater. Our findings would provide a workable approach for fabrication of NF membranes for better treatment of antibiotics and other similar ones with higher efficiencies and greater selectivity.

A Smart Polycage Membrane with Responsive Osmotic Energy Conversion Based on Synchronously Switchable Microporosity and Chargeability.

Membranes with specific pore sizes are widely used in molecular separation, ion transport, and energy conversion. However, the molecular understanding of structure-property performance in membrane science has been an urgent and long-standing problem. A promising but challenging solution lies in the fine-tuning of the membrane microstructure and properties to control membrane performance. Here, we designed an exofunctionalized triskelion cage to construct smart polycage membranes with concurrently responsive pore apertures and charge property. The synthetic polyaza cage is decorated with exoextended aldehyde groups for membrane fabrication and multiple amine sites for postmodification. The engineered polycage membranes thereby are endowed with pH-responsive porosity and chargeability, which serve as excellent candidates to explore the influence of the pore size and charge properties on membrane performance. In this regard, we successfully demonstrated the responsive osmotic energy conversion of the polycage membrane with a power density increase of over fourfold. This result indicates that the chargeability here outcompetes microporosity in energy conversion performance, which is further supported by molecular simulations. Therefore, this smart polycage membrane not only offers a feasible strategy to regulate the membrane microstructure and charge property reversibly but also balances pore size and chargeability to control the membrane performance at the molecular level.

Antimicrobial Peptides: A Promising Alternative to Conventional Antimicrobials for Combating Polymicrobial Biofilms.

Polymicrobial biofilms adhere to surfaces and enhance pathogen resistance to conventional treatments, significantly contributing to chronic infections in the respiratory tract, oral cavity, chronic wounds, and on medical devices. This review examines antimicrobial peptides (AMPs) as a promising alternative to traditional antibiotics for treating biofilm-associated infections. AMPs, which can be produced as part of the innate immune response or synthesized therapeutically, have broad-spectrum antimicrobial activity, often disrupting microbial cell membranes and causing cell death. Many specifically target negatively charged bacterial membranes, unlike host cell membranes. Research shows AMPs effectively inhibit and disrupt polymicrobial biofilms and can enhance conventional antibiotics' efficacy. Preclinical and clinical research is advancing, with animal studies and clinical trials showing promise against multidrug-resistant bacteria and fungi. Numerous patents indicate increasing interest in AMPs. However, challenges such as peptide stability, potential cytotoxicity, and high production costs must be addressed. Ongoing research focuses on optimizing AMP structures, enhancing stability, and developing cost-effective production methods. In summary, AMPs offer a novel approach to combating biofilm-associated infections, with their unique mechanisms and synergistic potential with existing antibiotics positioning them as promising candidates for future treatments.