Numerical simulation of the Liquid-liquid phase separation and microstructure evolution of Al-In immiscible alloys during cooling

A numerical model has been developed to describe the microstructural evolution of Al In immiscible alloys through the miscibility gap. The model considers the common action of nucleation, diffusible growth, Brownian collision and motion collision between the second phase droplets. The simulation results are dynamically visualized and show that the volume fraction, distribution and size of the second phase droplets satisfactorily agree with the experimental results. So the model can be used to predict the microstructural evolution of Al In immiscible alloys during the cooling process.

Liquid-liquid phase separation in highly undercooled Ni-Pb hypermonotectic alloys

Liquid-liquid phase separation in the undercooled Ni-20%Pb(mole fraction, the same below if not mentioned) hypermonotectic melts was investigated by the observation of the water-quenched structure and DTA analysis. The results indicate that the number of spherical cells in the water-quenched microstructure increases with dropping temperature, and the cells gather and grow up obviously. The spherical cell origins from L1 phase separated from homogeneous melt, and is the product of monotectic reaction. Both results of the water-quenched structures and DTA analysis prove that liquid phase separation still occurs in the highly undercooled Ni-Pb hypermonotectic alloy melts, and liquid phase separation in the immiscible gap can not be fully inhibited by high undercooling and rapid solidification.

Thermodynamics and kinetics of liquid-liquid phase separation in poly（acrylonitrile-co-maleic acid）/DMSO/nonsolvent system

Based on that the poly（acrylonitrile-co-maleic acid） （PANCMA）/DMSO/nonsolvent system agreed with the empirical linearized cloud point （LCP） relation, thermodynamics and kinetics of liquid-liquid phase separation behavior of this system were investigated through coagulation value and phase diagram. It was found that adding solvent to the coagulation bath decreased the coagulation power and diffusion exchange rate of solvent and nonsolvent, and the system became more stable thermodynamically. On the other hand, the system with poly（vinyl alcohol） （PVA） as additive was thermodynamically less stable than that with poly （vinylpyrrolidone） （PVP） and/or not. In addition, the polymer solution system at higher temperature became thermodynamically more stable and had a higher nonsolvent tolerance. Moreover, higher temperature heightened the diffusion exchange rate of solvent and nonsolvent and accelerated phase separation. It is indicated that phase diagram and coagulation value offered some useful and necessary thermodynamic and kinetic information to establish optimal conditions and guide practical membrane fabrication in the results.

Multistep Desolvation as a Fundamental Principle Governing Peptide Self-Assembly Through Liquid-Liquid Phase Separation

Biomolecular self-assembly based on peptides and proteins is a general phenomenon encountered in natural and synthetic systems.Liquid–liquid phase separation(LLPS)is intimately involved in biomolecular self-assembly,yet the key factors at a molecular scale activating or modulating such a process remain largely elusive.Herein,we discovered in our experiments that multistep desolvation is fundamental to the formation and evolution of peptide-rich droplets:The first step was partial desolvation of peptides to form peptide clusters,and the second step was selective desolvation of hydrophobic groups within clusters to trigger LLPS and the formation of peptiderich droplets,followed by complete desolvation of droplets,initiating the nucleation of peptide selfassembly.Manipulation of the degree of desolvation at different stages was an effective strategy to control the self-assembly pathways and polymorphisms.This study sheds light on the molecular origin of LLPS-mediated self-assembly distinct from classical one-step self-assembly and paves the way for the precise control of supramolecular self-assembly.

Bioinformatic approaches of liquid-liquid phase separation in human disease

Biomolecular aggregation within cellular environments via liquid-liquid phase separation(LLPS)spontaneously forms droplet-like structures,which play pivotal roles in diverse biological processes.These structures are closely associated with a range of diseases,including neurodegenerative disorders,cancer and infectious diseases,highlighting the significance of understanding LLPS mechanisms for elucidating disease pathogenesis,and exploring potential therapeutic interventions.In this review,we delineate recent advancements in LLPS research,emphasizing its pathological relevance,therapeutic considerations,and the pivotal role of bioinformatic tools and databases in facilitating LLPS investigations.Additionally,we undertook a comprehensive analysis of bioinformatic resources dedicated to LLPS research in order to elucidate their functionality and applicability.By providing comprehensive insights into current LLPS-related bioinformatics resources,this review highlights its implications for human health and disease.

Long-term functional maintenance of primary hepatocytes in vitro using macroporous hydrogels engineered through liquid-liquid phase separation

Preserving the functionality of hepatocytes in vitro poses a significant challenge in liver tissue engineering and bioartificial liver,as these cells rapidly lose their metabolic and functional characteristics after isolation.Inspired by the macroporous structures found in native liver tissues,here we develop synthetic hydrogel scaffolds that closely mimic the liver’s structural organization through the phase separation between polyethylene glycol(PEG)and polysaccharides.Our hydrogels exhibit interconnected macroporous structures and appropriate mechanical properties,providing an optimal microenvironment conducive to hepatocyte adhesion and the formation of sizable aggregates.Compared to two-dimensional hepatocyte cultures,enhanced functionalities of hepatocytes cultured in our macroporous hydrogels were observed for 14 days,as evidenced by quantitative reverse-transcription–polymerase chain reactions(qRT-PCR),immunofluorescence,and enzyme linked immunosorbent assay(ELISA)analyses.Protein sequencing data further confirmed the establishment of cell–cell interactions among hepatocytes when cultured in our hydrogels.Notably,these hepatocytes maintained a protein expression lineage that closely resembled freshly isolated hepatocytes,particularly in the Notch and tumor necrosis factor(TNF)signaling pathways.These results suggest that the macroporous hydrogels are attractive scaffolds for liver tissue engineering.

Regulating FUS Liquid-Liquid Phase Separation via Specific Metal Recognition

Liquid-liquid phase separation(LLPS)or biomolecular condensation that leads to formation of membraneless organelles plays a critical role in many biochemical processes.Mechanism study of regulating LLPS is therefore central to the understanding of protein aggregation and disease-relevant process.We report a fused in sarcoma protein(FUS)-derived low complexity(LC)sequence that undergoes LLPS in the presence of metal ions.The LC protein was constructed by fusing a hexhistidine-tag to the N-terminal low complexity domain(the residues 1–165 in QGSY-rich segment)of FUS.Spontaneous condensation of the intrinsic disordered protein into coacervate droplets was observed in the presence of metal ions that chelate oligohistidine moieties to form protein matrix.We demonstrate the key role of metal ion-histidine coordination in governing LLPS behaviours and the fluidity of biomolecular condensates.By taking advantage of competitive binding using chelators,we show the possibility of regulating dynamic behaviors of disease-relevant protein droplets,and developing a potential approach towards controllable biological encapsulation/release.

Self-assembly of Amphiphilic Diblock Copolymers Induced by Liquid-Liquid Phase Separation

The liquid-liquid phase separation(LLPS)widely exists in biology,synthetic chemistry,crystallization kinetics and other fields,and it is very important to realize the related functions.The research on the competition between LLPS and micellization/vesiculation has made considerable progress.However,the way to effectively control the formation paths from homogeneous state to aggregates has not been completely solved,which is vital to determine its structure and properties and even its future functions.Here we describe the phenomenon of LLPS and its effect on the dynamic process of self-assembly of amphiphilic diblock copolymers(BCPs).Starting from the establishment of phase diagram,we explore the existence conditions of LLPS state,the internal morphology and external size of large droplets,and its significant implications to the dynamic path of vesicle formation.Vesicles formed via LLPS have larger sized outer dimensions and inner cavities,and contain more solvents during certain stages.The detailed research of LLPS and its self-assembly simulation has contributed to completing its theoretical basis and practical applications in the future in various fields.

Liquid-liquid phase separation as a major mechanism of plant abiotic stress sensing and responses

Identification of environmental stress sensors is one of the most important research topics in plant abiotic stress research.Traditional strategies to identify stress sensors or early signaling components based on the cell membrane as a primary site of sensing and calcium signal as a second messenger have had only limited successes.Therefore,the current theoretical framework underlying stress sensing in plants should be reconsidered and additional mechanisms need to be introduced.Recently,accumulating evidence has emerged to suggest that liquid-liquid phase separation(LLPS)is a major mechanism for environmental stress sensing and response in plants.In this review,we briefly introduce LLPS regarding its concept,compositions,and dynamics,and then summarize recent progress of LLPS research in plants,emphasizing the contribution of LLPS to the sensing of various environmental stresses,such as dehydration,osmotic stress,and low and high temperatures.Finally,we propose strategies to identify key proteins that sense and respond to environmental stimuli on the basis of LLPS,and discuss the research directions of LLPS in plant abiotic stress responses and its potential application in enhancing stress tolerance in crops.

Phase separation and transcriptional regulation in cancer development

Liquid-liquid phase separation,a novel biochemical phenomenon,has been increasingly studied for its medical applications.It underlies the formation of membrane-less organelles and is involved in many cellular and biological processes.During transcriptional regulation,dynamic condensates are formed through interactions between transcriptional elements,such as transcription factors,coactivators,and mediators.Cancer is a disease characterized by uncontrolled cell proliferation,but the precise mechanisms underlying tumorigenesis often remain to be elucidated.Emerging evidence has linked abnormal transcriptional condensates to several diseases,especially cancer,implying that phase separation plays an important role in tumorigenesis.Condensates formed by phase separation may have an effect on gene transcription in tumors.In the present review,we focus on the correlation between phase separation and transcriptional regulation,as well as how this phenomenon contributes to cancer development.

Enhancement of vertical phase separation in sequentially deposited organic photovoltaics through the independent processing of additives

Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are investigated.The film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was applied.Grazing incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD films.Time-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive control.In addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD films.In SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied layer.This study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.

Fluorinated semi-interpenetrating polymer networks for enhancing the mechanical performance and storage stability of polymer-bonded explosives by controlling curing and phase separation rates

Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.

Physical information-enhanced graph neural network for predicting phase separation

Although phase separation is a ubiquitous phenomenon, the interactions between multiple components make it difficult to accurately model and predict. In recent years, machine learning has been widely used in physics simulations. Here,we present a physical information-enhanced graph neural network(PIENet) to simulate and predict the evolution of phase separation. The accuracy of our model in predicting particle positions is improved by 40.3% and 51.77% compared with CNN and SVM respectively. Moreover, we design an order parameter based on local density to measure the evolution of phase separation and analyze the systematic changes with different repulsion coefficients and different Schmidt numbers.The results demonstrate that our model can achieve long-term accurate predictions of order parameters without requiring complex handcrafted features. These results prove that graph neural networks can become new tools and methods for predicting the structure and properties of complex physical systems.

A Cu-Pd alloy catalyst with partial phase separation for the electrochemical CO_(2) reduction reaction

Cu catalysts can convert CO_(2) through an electrochemical reduction reaction into a variety of useful carbon-based products.However,this capability provides an obstacle to increasing the selectivity for a single product.Herein,we report a simple fabrication method for a Cu-Pd alloy catalyst for use in a membrane electrode assembly(MEA)-based CO_(2) electrolyzer for the electrochemical CO_(2) reduction reaction(ECRR)with high selectivity for CO production.When the composition of the Cu-Pd alloy catalyst was fabricated at 6:4,the selectivity for CO increased and the production of multi-carbon compounds and hydrogen is suppressed.Introducing a Cu-Pd alloy catalyst with 6:4 ratio as the cathode of the MEAbased CO_(2) electrolyzer showed a CO faradaic efficiency of 92.8%at 2.4 V_(cell).We assumed that these results contributed from the crystal planes on the surface of the Cu-Pd alloy.The phases of the Cu-Pd alloy catalyst were partially separated through annealing to fabricate a catalyst with high selectivity for CO at low voltage and C_(2)H_4 at high voltage.The results of CO-stripping testing confirmed that when Cu partially separates from the lattice of the Cu-Pd alloy,the desorption of~*CO is suppressed,suggesting that C-C coupling reaction is favored.

Liquid-liquid phase separation in biology: mechanisms,physiological functions and human diseases

Cells are compartmentalized by numerous membrane-enclosed organelles and membraneless compartments to ensure that a wide variety of cellular activities occur in a spatially and temporally controlled manner. The molecular mechanisms underlying the dynamics of membrane-bound organelles, such as their fusion and fission, vesicle-mediated trafficking and membrane contactmediated inter-organelle interactions, have been extensively characterized. However, the molecular details of the assembly and functions of membraneless compartments remain elusive. Mounting evidence has emerged recently that a large number of membraneless compartments, collectively called biomacromolecular condensates, are assembled via liquid-liquid phase separation(LLPS). Phase-separated condensates participate in various biological activities, including higher-order chromatin organization,gene expression, triage of misfolded or unwanted proteins for autophagic degradation, assembly of signaling clusters and actin-and microtubule-based cytoskeletal networks, asymmetric segregations of cell fate determinants and formation of pre-and post-synaptic density signaling assemblies. Biomacromolecular condensates can transition into different material states such as gel-like structures and solid aggregates. The material properties of condensates are crucial for fulfilment of their distinct functions, such as biochemical reaction centers, signaling hubs and supporting architectures. Cells have evolved multiple mechanisms to ensure that biomacromolecular condensates are assembled and disassembled in a tightly controlled manner. Aberrant phase separation and transition are causatively associated with a variety of human diseases such as neurodegenerative diseases and cancers. This review summarizes recent major progress in elucidating the roles of LLPS in various biological pathways and diseases.

Liquid-liquid phase separation in tumor biology

Liquid–liquid phase separation(LLPS)is a novel principle for explaining the precise spatial and temporal regulation in living cells.LLPS compartmentalizes proteins and nucleic acids into micron-scale,liquid-like,membraneless bodies with specific functions,which were recently termed biomolecular condensates.Biomolecular condensates are executors underlying the intracellular spatiotemporal coordination of various biological activities,including chromatin organization,genomic stability,DNA damage response and repair,transcription,and signal transduction.Dysregulation of these cellular processes is a key event in the initiation and/or evolution of cancer,and emerging evidence has linked the formation and regulation of LLPS to malignant transformations in tumor biology.In this review,we comprehensively summarize the detailed mechanisms of biomolecular condensate formation and biophysical function and review the recent major advances toward elucidating the multiple mechanisms involved in cancer cell pathology driven by aberrant LLPS.In addition,we discuss the therapeutic perspectives of LLPS in cancer research and the most recently developed drug candidates targeting LLPS modulation that can be used to combat tumorigenesis.

Liquid-liquid phase separation of Arabidopsis transcriptional repressor VRN1

With the support by the National Natural Science Foundation of China and the Ministry of Science and Technology and China,the research team led by Prof.Lai LuHua(来鲁华)at BNLMS,College of Chemistry and Molecular Engineering,Peking-Tsinghua Center for Life Sciences,and Center for Quantitative Biology,Peking University recently reported that Arabidopsis transcriptional repressor VRN1undergoes liquid-liquid phase separation with DNA in Angew Chem Int Ed(2019,58:4858—4862).This research uncovers the mechanism of DNA induced VRN1phase separation and provides novel insight of phase separation mediated transcriptional repression.Zhou HuaBin,agraduate student from Lai's group,is the first author of this paper.

Getting in phase: DNA damage repair mechanisms and liquid-liquid phase separation of the plant-specific histone methyltransferase MtSUVR2

Liquid-liquid phase separation(LLPS)has become a widely accepted mechanism forthedynamic compartmentalization of different cellular components into membraneless organelles or other cellular bodies.LLPS occurs when the concentration of a protein,nucleic acid,or other molecule reaches a saturation concentration and its partition into high-and low-concentration phases is energetically favorable.

Microfluidic production of liposomes through liquid-liquid phase separation in ternary droplets

Liposomes,the self-assembled phospholipid vesicles,have been extensively used in various fields such as artificial cells,drug delivery systems,biosensors and cosmetics.However,current microfluidic routes to liposomes mostly rely on water-in-oil-in-water double emulsion droplets as templates,and require complex fabrication of microfluidic devices,and tedious manipulation of multiphase fluids.Here we present a simple microfluidic approach to preparing monodisperse liposomes from oil-in-water droplets.For demonstration,we used butyl acetate-water-ethanol ternary mixtures as inner phase and an aqueous solution of surfactants as outer phase to make oil-in-water droplets,which can evolve into water-in-oil-in-water double emulsion droplets by liquid-liquid phase separation of ternary mixtures.Subsequently,the resultant water-in-oil-in-water droplets underwent a dewetting transition to form separated monodisperse liposomes and residual oil droplets,with the assistance of surfactants.The method is simple,does not require complex microfluidic devices and tedious manipulation,and provides a new platform for controllable preparation of liposomes.

Role and therapeutic potential of liquid-liquid phase separation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset neurodegenerative disease selectively affecting motor neurons, leading to pro-gressive paralysis. Although most cases are sporadic,-10% are familial. Similar proteins are found in aggregates in sporadicand familial ALS, and over the last decade, research has been focused on the underlying nature of this common pathology.Notably, TDP-43 inclusions are found in almost all ALS patients, while Fus inclusions have been reported in some familial ALSpatients. Both TDP-43 and FUS possess ‘low-complexity domains' (LCDs) and are considered as ‘intrinsically disordered proteins',which form liquid droplets in vitro due to the weak interactions caused by the LCDs. Dysfunctional ‘liquid-lquid phase separa-tion'(LLPS) emerged as a new mechanism linking AlS-related proteins to pathogenesis. Here, we review the current state ofknowledge on ALS-related gene products associated with a proteinopathy and discuss their status as lLPS proteins. n addition,we highlight the therapeutic potential of targeting LLPS for treating ALS.