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Membrane-based water treatment processes offer possibility to alleviate the water scarcity dilemma in energy-efficient and sustainable ways, this has been exemplified in filtration membranes assembled from two-dimensional (2D) materials for water desalination purposes. Most representatives however tend to swell or disintegrate in a hydrated state, making precise ionic or molecular sieving a tough challenge. Here we report that the chemically robust 2D carbon nitride can be activated using aluminum polycations as pillars to modulate the interlayer spacing of the conjugated framework, the noncovalent interaction concomitantly affords a well-interlinked lamellar structure, to be carefully distinguished from random stacking patterns in conventional carbon nitride membranes. The conformally packed membrane is characterized by adaptive subnanochannel and structure integrity to allow excellent swelling resistance, and breaks permeability-selectivity trade-off limit in forward osmosis due to progressively regulated transport passage, achieving high salt rejection (>99.5%) and water flux (6 L m −2  h −1 ), along with tunable permeation behavior that enables water gating in acidic and alkaline environments. These findings position carbon nitride a rising building block to functionally expand the 2D membrane library for applications in water desalination and purification scenarios. Traditional carbon nitride membranes are generally presented with random stacking behavior leading to undesired separation performance. Here, authors create lamellar membranes via polycation pillaring to afford adaptive subnanochannels, overcoming the selectivity-permeability trade-off in forward osmosis.

Diffuse intrinsic pontine glioma (DIPG) is an incurable malignant childhood brain tumor, with no active systemic therapies and a 5-year survival of less than 1%. Polyamines are small organic polycations that are essential for DNA replication, translation and cell proliferation. Ornithine decarboxylase 1 (ODC1), the rate-limiting enzyme in polyamine synthesis, is irreversibly inhibited by difluoromethylornithine (DFMO). Herein we show that polyamine synthesis is upregulated in DIPG, leading to sensitivity to DFMO. DIPG cells compensate for ODC1 inhibition by upregulation of the polyamine transporter SLC3A2. Treatment with the polyamine transporter inhibitor AMXT 1501 reduces uptake of polyamines in DIPG cells, and co-administration of AMXT 1501 and DFMO leads to potent in vitro activity, and significant extension of survival in three aggressive DIPG orthotopic animal models. Collectively, these results demonstrate the potential of dual targeting of polyamine synthesis and uptake as a therapeutic strategy for incurable DIPG. Diffuse intrinsic pontine glioma (DIPG) is an almost incurable malignant childhood brain tumor. Here, the authors show that the polyamine synthetic pathway is activated in DIPG and that the dual targeting of polyamine synthesis and uptake results in prolonged survival in animal models.

Supramolecular self-assembly of μm-to-mm sized components is essential to construct complex supramolecular systems. However, the selective assembly to form designated structures at this length scale is challenging because the short-ranged molecular recognition could hardly direct the assembly of macroscopic components. Here we demonstrate a self-sorting mechanism to automatically identify the surface chemistry of μm-to-mm components (A: polycations; B: polyanions) based on the A-B attraction and the A-A repulsion, which is realized by the additivity and the competence between long-ranged magnetic/capillary forces, respectively. Mechanistic studies of the correlation between the magnetic/capillary forces and the interactive distance have revealed the energy landscape of each assembly pattern to support the self-sorting results. By applying this mechanism, the assembly yield of ABA trimers has been increased from 30%~40% under conventional conditions to 100% with self-sorting. Moreover, we have demonstrated rapid and spontaneous self-assembly of advanced chain-like structures with alternate surface chemistry. The selective assembly of μm-to-mm sized components is challenging because of the short-ranged molecular recognition. Here, the authors demonstrate a self-sorting mechanism to automatically identify the surface chemistry via additivity and competence between long-ranged magnetic/capillary forces.

Wireless modules provide an essential platform for power-harvesting and telecommunications enabled by Internet of Things systems. However, substantial interferences in multiple energy interactions and signal transmission may arise due to fluctuations in environmental factors. Here, we report a moist-electromagnetic coupling effect enabled by ionic-electronic polymer diodes for synergistic moist energy harvesting and electromagnetic protection. The thermodynamic and kinetic mechanisms of charge carrier transport in the polymer diodes are effectively manipulated by engineering the molecular interactions within the polyanions, leveraging hydrogen bonding, metal ion coordination, and metal-organic framework modifications, alongside the controlled porous architecture of the polypyrrole polycations. The ion gradient distribution and ionic double layer induced by moist energy endow the films with rectenna effect, leading to optimized impedance matching and enhanced polarization relaxation capabilities, thereby enabling electromagnetic interference shielding. The proposed moist-electric-electromagnetic coupling mechanism demonstrates its operational feasibility through stable power output (480.19 μW·cm -2 ) and good electromagnetic capability. Our findings provide insight into the environmental adaptability of electromagnetic energy modulation, ensuring the energy and information security of the state-of-the-art self-powered smart wireless electronics. Wireless modules within self-powered Internet of Things devices are affected by external interference. Here, authors reported a moist-electromagnetic coupling effect by polymer diodes for synergistic moist energy harvesting and electromagnetic protection.

Polyethylenimine (PEI) is a gold standard polycationic transfectant. However, the highly efficient transfecting activity of PEI and many of its derivatives is accompanied by serious cytotoxic complications and safety concerns at innate immune levels, which impedes the development of therapeutic polycationic nucleic acid carriers in general and their clinical applications. In recent years, the dilemma between transfection efficacy and adverse PEI activities has been addressed from in-depth investigations of cellular processes during transfection and elucidation of molecular mechanisms of PEI-mediated toxicity and translation of these integrated events to chemical engineering of novel PEI derivatives with an improved benefit-to-risk ratio. This review addresses these perspectives and discusses molecular events pertaining to dynamic and multifaceted PEI-mediated cytotoxicity, including membrane destabilization, mitochondrial dysfunction, and perturbations of glycolytic flux and redox homeostasis as well as chemical strategies for the generation of better tolerated polycations. We further examine the effect of PEI and its derivatives on complement activation and interaction with Toll-like receptors. These perspectives are intended to lay the foundation for an improved understanding of interlinked mechanisms controlling transfection and toxicity and their translation for improved engineering of polycation-based transfectants. [Display omitted] Polycations such as polyethylenimines (PEIs) are widely used as non-viral transfectants, but they often induce cytotoxicity and may trigger immune reactions. Here we examine and discuss molecular events pertaining to dynamic and multifaceted PEI-mediated cytotoxicity and immune system modulation and their translation for improved and safer engineering of polycation-based transfectants.

Honey bee health has been an important and ongoing topic in recent years. Honey bee is also an important model organism for aging studies. Polyamines, putrescine, spermidine and spermine, are ubiquitous polycations, involved in a wide range of cellular processes such as cell growth, gene regulation, immunity, and regulation of lifespan. Spermidine, named longevity elixir, has been most analysed in the context of aging. One of the several proposed mechanisms behind spermidine actions is antioxidative activity. In present study we showed that dietary spermidine supplementation: (a) improved survival, (b) increased the average lifespan, (c) influenced the content of endogenous polyamines by increasing the level of putrescine and spermidine and decreasing the level of spermine, (d) reduced oxidative stress (MDA level), (e) increased the antioxidant capacity of the organism (FRAP), (f) increased relative gene expression of five genes involved in polyamine metabolism, and (g) upregulated vitellogenin gene in honey bees. To our knowledge, this is the first study on honey bee polyamine levels in reference to their longevity. These results provide important information on possible strategies for improving honey bee health by introducing spermidine into their diet. Here, we offer spermidine concentrations that could be considered for that purpose.

Polyelectrolyte complex coacervation underpins many critical biological processes, yet how different initial mixing protocols determine its liquid-liquid phase separation (LLPS) dynamics remains unclear. Using molecular dynamics simulations, we show that when polycations and polyanions are initially randomly mixed, coacervate domain growth exhibits transient t 1/2 scaling, driven by polymer network formation. This phase is followed by either t 1 scaling due to hydrodynamic pumping or t 1/3 scaling from droplet coarsening, depending on the initial mixing degree. Conversely, starting with spatially separated domains of polycations and polyanions-mimicking LLPS in certain marine organisms-leads to rapid coacervate formation, with early-stage growth following distinct t 2/3 scaling due to strong electrostatic attraction, followed by continued growth via polymer accumulation. Both protocols yield significantly faster dynamics than systems initialized with preformed polyion pairs, which exhibit classical t 1/3 scaling characteristic of droplet coarsening. These findings highlight the profound impact of initial conditions on LLPS dynamics in polyelectrolyte systems. Liquid-liquid phase separation is a process of interest, but the dynamics are still not fully understood. Here, the authors use molecular dynamics to consider the role of mixing protocol in polyelectrolyte complex coacervation.

Liquid embolic agents are widely used for the endovascular embolization of vascular conditions. However, embolization based on phase transition is limited by the adhesion of the microcatheter to the embolic agent, use of an organic solvent, unintentional catheter retention, and other complications. By mimicking thrombus formation, a watersoluble polymer that rapidly glues blood into a gel without triggering coagulation was developed. The polymer, which consists of cationic and aromatic residues with adjacent sequences, shows electrostatic adhesion with negatively charged blood substances in a physiological environment, while common polycations cannot. Aqueous polymer solutions are injectable through clinical microcatheters and needles. The formed blood gel neither adhered to the catheter nor blocked the port. Postoperative computed tomography imaging showed that the polymer can block the rat femoral artery in vivo and remain at the injection site without nontarget embolization. This study provides an alternative for the development of waterborne embolic agents.

Polyamines (PAs) are essential organic polycations for cell viability along the whole phylogenetic scale. In mammals, they are involved in the most important physiological processes: cell proliferation and viability, nutrition, fertility, as well as nervous and immune systems. Consequently, altered polyamine metabolism is involved in a series of pathologies. Due to their pathophysiological importance, PA metabolism has evolved to be a very robust metabolic module, interconnected with the other essential metabolic modules for gene expression and cell proliferation/differentiation. Two different PA sources exist for animals: PA coming from diet and endogenous synthesis. In the first section of this work, the molecular characteristics of PAs are presented as determinant of their roles in living organisms. In a second section, the metabolic specificities of mammalian PA metabolism are reviewed, as well as some obscure aspects on it. This second section includes information on mammalian cell/tissue-dependent PA-related gene expression and information on crosstalk with the other mammalian metabolic modules. The third section presents a synthesis of the physiological processes described as modulated by PAs in humans and/or experimental animal models, the molecular bases of these regulatory mechanisms known so far, as well as the most important gaps of information, which explain why knowledge around the specific roles of PAs in human physiology is still considered a “mysterious” subject. In spite of its robustness, PA metabolism can be altered under different exogenous and/or endogenous circumstances so leading to the loss of homeostasis and, therefore, to the promotion of a pathology. The available information will be summarized in the fourth section of this review. The different sections of this review also point out the lesser-known aspects of the topic. Finally, future prospects to advance on these still obscure gaps of knowledge on the roles on PAs on human physiopathology are discussed.

The diamine putrescine and the polyamines (PAs), spermidine (Spd) and spermine (Spm), are ubiquitously occurring polycations associated with several important cellular functions, especially antisenescence. Numerous studies have reported increased levels of PA in plant cells under conditions of abiotic and biotic stress such as drought, high salt concentrations, and pathogen attack. However, the physiological mechanism of elevated PA levels in response to abiotic and biotic stresses remains undetermined. Transgenic plants having overexpression of SAMDC complementary DNA and increased levels of putrescine (1.4-fold), Spd (2.3-fold), and Spm (1.8-fold) under unstressed conditions were compared to wild-type (WT) plants in the current study. The most abundant PA in transgenic plants was Spd. Under salt stress conditions, enhancement of endogenous PAs due to overexpression of the SAMDC gene and exogenous treatment with Spd considerably reduces the reactive oxygen species (ROS) accumulation in intra- and extracellular compartments. Conversely, as compared to the WT, PA oxidase transcription rapidly increases in the S16-S-4 transgenic strain subsequent to salt stress. Furthermore, transcription levels of ROS detoxifying enzymes are elevated in transgenic plants as compared to the WT. Our findings with OxyBlot analysis indicate that upregulated amounts of endogenous PAs in transgenic tobacco plants show antioxidative effects for protein homeostasis against stress-induced protein oxidation. These results imply that the increased PAs induce transcription of PA oxidases, which oxidize PAs, which in turn trigger signal antioxidative responses resulting to lower the ROS load. Furthermore, total proteins from leaves with exogenously supplemented Spd and Spm upregulate the chaperone activity. These effects of PAs for antioxidative properties and antiaggregation of proteins contribute towards maintaining the physiological cellular functions against abiotic stresses. It is suggested that these functions of PAs are beneficial for protein homeostasis during abiotic stresses. Taken together, these results indicate that PA molecules function as antisenescence regulators through inducing ROS detoxification, antioxidative properties, and molecular chaperone activity under stress conditions, thereby providing broad-spectrum tolerance against a variety of stresses.