综述:核小体液-液相分离中早期形核过程的分子结构

研究揭示,核小体阵列在体外具有液-液相分离(liquid⁃liquid phase separation,LLPS)的内在特性,被认为在体内引导染色质区域的结构变化。然而,对于形成的异质凝聚物在分子水平的结构研究,长期以来受到技术限制,从而阻碍了研究人员对核小体液-液相分离的深入理解。为了解决这一难题,张蒙等运用先进的冷冻电子断层扫描技术(Cryo⁃electron tomography,Cryo⁃ET)、结合单分子电子断层重构(individual⁃particle electron tomography,IPET)和基于深度学习的分割技术,确定了液-液相分离在不同阶段的凝聚物的分子组织结构。该研究揭示,核小体的液-液相分离过程涉及到两个主要步骤:首先,旋节分解形成不规则的凝聚物;然后,这些凝聚物经过一个不稳定的过渡阶段,转化为更紧凑的球状核,进一步通过聚集更多旋节材料或与其它球状凝聚物的融合,逐渐形成更大的球状聚集体。此外,连接组蛋白H1催化旋节向球状凝聚物转变的速率,比旋节分解速度快出十倍以上。因此,推测这种转变可能涉及到核小体疏水表面的暴露,进而改变了核小体之间的相互作用。这些发现为染色质从间期结构向中期结构转变提供了新的物理机制线索。

Revealing the working mechanism of a multi-functional block copolymer binder for lithium-sulfur batteries

The lithium-sulfur(Li-S)battery is one of the most promising substitutes for current energy storage systems because of its low cost,high theoretical capacity,and high energy density.However,the high solubility of intermediate products(i.e.,lithium polysulfides)and the resultant shuttle effect lead to rapidly fading capacity and a low coulombic efficiency,which hinder the practical application of Li-S batteries.In this study,block copolymers are constructed with both an ethylene oxide unit and a styrene unit and then used as binders for Li-S batteries.Electrochemical performance improvements are attributed to the synergistic effects contributed by the different units of the block copolymer.The ethylene oxide unit traps polysulfide,which bonds strongly with the intermediate lithium polysulfide,and enhances the transport of lithium ions to reach high capacity.Meanwhile,the styrene unit maintains cathode integrity by improving the mechanical properties and elasticity of the constructed block copolymer to accommodate the large volume changes.By enabling multiple functions via different units in the polymer chain,high sulfur utilization is achieved,polysulfide diffusion is confined,and the shuttle effect is suppressed during the cycle life of Li-S batteries,as revealed by operando ultraviolet-visible spectroscopy and S Kedge X-ray absorption spectroscopy.

Deciphering the Oxygen Absorption Pre-edge: A Caveat on its Application for Probing Oxygen Redox Reactions in Batteries

The pre-edges of oxygen-K X-ray absorption spectra have been ubiquitous in transition metal(TM)oxide studies in various fields,especially on the fervent topic of oxygen redox states in battery electrodes.However,critical debates remain on the use of the O-K pre-edge variations upon electrochemical cycling as evidences of oxygen redox reactions,which has been a popular practice in the battery field.This study presents an investigation of the O-K pre-edge of 55 oxides covering all 3d TMs with different elements,structures,and electrochemical states through combined experimental and theoretical analyses.It is shown unambiguously that the O-K pre-edge variation in battery cathodes is dominated by changing TM-d states.Furthermore,the pre-edge enables a unique opportunity to project the lowest unoccupied TM-d states onto one common energy window,leading to a summary map of the relative energy positions of the low-lying TM states,with higher TM oxidation states at lower energies,corresponding to higher electrochemical potentials.The results naturally clarify some unusual redox reactions,such as Cr^(3+/6+).This work provides a critical clarification on O-K pre-edge interpretation and more importantly a benchmark database of O-K pre-edge for characterizing redox reactions in batteries and other energy materials.

脂蛋白电子显微结构研究的优化负染方法

人类心血管等疾病与胆固醇含量的高低有着十分密切的关系.人体内胆固醇主要通过血液中的脂蛋白来调节和运载.因此,新一代调节胆固醇的药物设计迫切地需要揭示脂蛋白分子结构与功能之间的关系.由于脂蛋白分子的成分高度复杂、结构特征灵活、尺寸微小,传统的蛋白质结构标定技术,如X射线衍射、核磁共振谱、质谱和冷冻电子显微镜等手段都面临着巨大的困难.针对这一问题,任罡小组最近提出一种优化的电镜负染制备方法,可以观测到单个脂蛋白分子的空间结构.此方法应用的成功,使得对单个脂蛋白分子的结构研究成为可能.同时也证明该负染色技术作为一种普遍的实验手段,可以用于对蛋白质小分子的结构研究,从而将促进新一代蛋白质分子药物的研发.

使用电子断层技术对IgG1抗体逐个分子的三维重构与结构分析

抗体(antibody)又称免疫球蛋白(immunoglobulin,Ig),是人体免疫反应的重要参与者.了解抗体的结构和结构动态特征,是理解人体免疫作用机理、修复或提高免疫能力、定向设计抗体以治疗各种疾病的基础.本文以人体IgG1抗体为对象,综述了使用透射电子显微学方法研究IgG1抗体结构方向的最新进展.详细介绍了使用逐个分子的电子断层三维重构技术(individual-particle electron tomography,IPET)对抗体进行结构研究的方法,包括样品制备、图像处理和数据分析等.并描述了利用该技术,在研究抗体结合肽分子后的结构形变和通过收集不同构象来研究抗体动态结构特征方面所取得的阶段性成果.最后,对尚待解决的关键问题与该技术未来的发展方向进行了讨论与展望.

金纳米粒子修饰毛细管整体柱的制备及在多种色谱分离模式中的应用

整体柱是由单体、交联剂和致孔剂等通过自由基引发聚合反应，形成具有贯通孔及微孔结构的连续床固定相。整体柱具有良好的通透性和稳定性，并可于微管道内在线合成，特别适用于微型色谱柱或毛细管柱的制备。巯基化合物在金表面能进行白组装和交换的性质被广泛用于各种载体的修饰。

界面工程调控铁电极化增强异质结构BaTiO_(3)@TiO_(2)光催化性能

采用水解沉淀结合水热法成功合成光催化活性增强的铁电-BaTiO_(3)@光电-TiO_(2)纳米杂化光催化剂(BaTiO_(3)@TiO_(2))。与纯TiO_(2)、纯BaTiO_(3)和BaTiO_(3)/TiO_(2)机械混合物相比,采用异质结构的BaTiO_(3)@TiO_(2)降解罗丹明B(RhB)的光催化活性和循环稳定性得到提升,其光催化降解效率是纯TiO_(2)的1.7倍,纯BaTiO_(3)的7.2倍。光催化降解效率的提升与光电TiO_(2)、铁电BaTiO_(3)及两者界面结构的协同效应相关。介孔微结构的TiO_(2)因高的比表面积而具备优异的光催化活性。纳米BaTiO_(3)因铁电极化产生的内建电场及BaTiO_(3)与TiO_(2)间紧密的界面相互作用而有效地促进光生载流子的分离和传输。通过调控界面工程将促进具有优异光催化性能异质结型光催化剂的设计与开发。

Facile Microwave-Assisted Synthesis of 2D Imine-Linked Covalent Organic Frameworks for Exceptional Iodine Capture

Covalent organic frameworks(COFs)have emerged as auspicious porous adsorbents for radioiodine capture.However,their conventional solvothermal synthesis demands multiday synthetic times and anaerobic conditions,largely hampering their practical use.To tackle these challenges,we present a facile microwave-assisted synthesis of 2D imine-linked COFs,Mw-TFB-BD-X,(X=−CH_(3) and−OCH_(3))under air within just 1 h.The resultant COFs possessed higher crystallinity,better yields,and more uniform morphology than their solvothermal counterparts.Remarkably,Mw-TFB-BD-CH_(3) and Mw-TFB-BDOCH_(3) exhibited exceptional iodine adsorption capacities of 7.83 g g^(−1) and 7.05 g g^(−1),respectively,placing them among the bestperforming COF adsorbents for static iodine vapor capture.Moreover,Mw-TFB-BD-CH_(3) and Mw-TFB-BD-OCH_(3) can be reused 5 times with no apparent loss in the adsorption capacity.The exceptionally high iodine adsorption capacities and excellent reusability of COFs were mainly attributed to their uniform spherical morphology and enhanced chemical stability due to the in-built electron-donating groups,despite their low surface areas.This work establishes a benchmark for developing advanced iodine adsorbents that combine fast kinetics,high capacity,excellent reusability,and facile rapid synthesis,a set of appealing features that remain challenging to merge in COF adsorbents so far.

A stable metal-covalent-supramolecular organic framework hybrid: enrichment of catalysts for visible light-induced hydrogen production

Cubic metal-covalent-supramolecular organic framework(MCSOF-1)hybrid has been created from the reaction of two molecular components and subsequent co-assembly with cucurbit[8]uril(CB[8])in water.In the presence of CB[8],[Ru(bpy)_3]^(2+)-based acylhydrazine 1·2Cl reacted with aldehyde 2·Cl to quantitatively yield six-armed precursor 3·8Cl through the generation of MCSOF-1.MCSOF-1 combines the structural features of metal-,covalent-and supramolecular organic frameworks.Its periodicity in water and in the solid state was confirmed by synchrotron X-ray scattering and diffraction experiments.MCSOF-1could enrich discrete anionic polyoxometalates(POMs),maintain periodicity in acidic medium,and remarkably facilitate visible light-induced electron transfer from its[Ru(bpy)_3]^(2+)units to enriched POMs,leading to enhanced catalysis of the POMs for the reduction of proton to H_2in both aqueous(homogeneous)and organic(heterogeneous)media.

Synthesis of new two-dimensional titanium carbonitride Ti_(2)C_(0.5)N_(0.5)T_(x)MXene and its performance as an electrode material for sodium-ion battery

Two-dimensional(2D)layered transition metal carbides/nitrides,called MXenes,are attractive alternative electrode materials for electrochemical energy storage.Owing to their metallic electrical conductivity and low ion dif-fusion barrier,MXenes are promising anode materials for sodium-ion batteries(SIBs).Herein,we report on a new 2D carbonitride MXene,viz.,Ti_(2)C_(0.5)N_(0.5)T_(x)(T_(x) stands for surface terminations),and the only second carbonitride after Ti_(3) CNT_(x) so far.A new type of in situ HF(HCl/KF)etching condition was employed to synthesize multilayer Ti_(2)C_(0.5)N_(0.5)T_(x) powders from Ti_(2)AlC_(0.5)N_(0.5).Spontaneous intercalation of tetramethylammonium followed by sonication in water allowed for large-scale delamination of this new titanium carbonitride into 2D sheets.Multilayer Ti_(2)C_(0.5)N_(0.5)T_(x) powders showed higher specific capac-ities and larger electroactive surface area than those of Ti_(2)CT_(x) powders.Multi-layer Ti_(2)C_(0.5)N_(0.5)T_(x) powders show a specific capacity of 182 mAh g^(-1) at 20 mA g^(-1),the highest among all reported MXene electrodes as SIBs with excellent cycling stability.

Loading-free supramolecular organic framework drug delivery systems(sof-DDSs) for doxorubicin:normal plasm and multidrug resistant cancer cell-adaptive delivery and release

Four water-soluble porous supramolecular organic framework drug delivery systems（sof-DDSs） have been used to adsorb doxorubicin（DOX） in water at physiological pH of 7.4,which is driven exclusively by hydrophobicity.The resulting complexes DOX@SOFs are formed instantaneously upon dissolving the components in water.The drug-adsorbed sof-DDSs can undergo plasm circulation with important maintenance of the drug and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells.DOX is released readily in the cancer cells due to the protonation of its amino group in the acidic medium of cancer cells.In vitro and in vivo experiments reveal that the delivery of SOF-a-d remarkably improve the cytotoxicity of DOX for the MCF-7/Adr cells and tumors,leading to 13-19-fold reduction of the 1C_（50）values as compared with that of DOX.This new sof-DDSs strategy omits the indispensable loading process required by most of reported nano-scaled carriers for neutral hydrophobic chemotherapeutic agents,and thus should be highly valuable for future development of low-cost delivery systems.

A periodic metallo-supramolecular polymer from a flexible building block: self-assembly and photocatalysis for organic dye degradation

A water-soluble metallo-supramolecular polymer MSP-f-6Np,which possesses a regular pore aperture of 1.4 nm,has been assembled from a structurally flexible naphthalene-appended[Ru(bipy)3]^2+complex and cucurbit[8]uril.As the first periodic metallo-supramolecular polymer formed by a flexible building block,MSP-f-6Np exhibits a hydrodynamic diameter of 122 and 164 nm at 0.1 and 2.0 mM of the monomer concentrations.Synchrotron small angle X-ray scattering experiments confirm that MSP-f-6Np possesses porosity periodicity in both the solution and solid states.Compared with a control,the new highly ordered porous system displays enhanced photocatalytic activity for the degradation of organic dyes.

In situ-prepared homogeneous supramolecular organic framework drug delivery systems(sof-DDSs)：Overcoming cancer multidrug resistance and controlled release

Water-soluble three-dimensional porous supramolecular organic frameworks（SOFs） have been demonstrated as a new generation of homogeneous polycationic platforms for anti-cancer drug delivery.The new SOF drug delivery systems（sof-DDSs） can adsorb dianionic pemetrexed（PMX）,a clinically used chemotherapeutic agent instantaneously upon dissolving in water,which is driven by both electrostatic attraction and hydrophobicity.The in situ-prepared PMX@SOFs are highly stable and can avoid important release of the drug during plasm circulation and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells to enter the cancer cells.Acidic microenvironment of cancer cells promotes the release of the drug in cancer cells.Both in vitro and in vivo studies have revealed that sofDDSs considerably improve the treatment efficacy of PMX,leading to 6-12-fold reduction of the IC50 values,as compared with that of PMX alone.The new drug delivery strategy omits the loading process required by most of reported nanoparticle-based delivery systems and thus holds promise for future development of low-cost drug delivery systems

In Situ Loading and Delivery of Short Single- and Double-Stranded DNA by Supramolecular Organic Frameworks

Short DNA represents an important class of bioma-cromolecules that arewidely applied in gene therapy,editing,and modulation.However,the development of simple and reliable methods for their intracellular delivery remains a challenge.Herein,we describe that seven water-soluble,homogeneous supramole-cular organic frameworks(SOFs)with a well-defined pore size and high stability in water that can accom-plish in situ inclusion of single-stranded(ss)and double-stranded(ds)DNA(21,23,and 58 nt)and effective intracellular delivery(including two non-cancerous and six cancerous cell lines).

Nano-enhanced solid-state hydrogen storage:Balancing discovery and pragmatism for future energy solutions

Nanomaterials have revolutionized the battery industry by enhancing energy storage capacities and charging speeds,and their application in hydrogen(H_(2))storage likewise holds strong potential,though with distinct challenges and mechanisms.H_(2) is a crucial future zero-carbon energy vector given its high gravimetric energy density,which far exceeds that of liquid hydrocarbons.However,its low volumetric energy density in gaseous form currently requires storage under high pressure or at low temperature.This review critically examines the current and prospective landscapes of solid-state H_(2) storage technologies,with a focus on pragmatic integration of advanced materials such as metal-organic frameworks(MOFs),magnesium-based hybrids,and novel sorbents into future energy networks.These materials,enhanced by nanotechnology,could significantly improve the efficiency and capacity of H_(2) storage systems by optimizing H_(2) adsorption at the nanoscale and improving the kinetics of H_(2) uptake and release.We discuss various H_(2) storage mechanisms—physisorption,chemisorption,and the Kubas interaction—analyzing their impact on the energy efficiency and scalability of storage solutions.The review also addresses the potential of“smart MOFs”,single-atom catalyst-doped metal hydrides,MXenes and entropy-driven alloys to enhance the performance and broaden the application range of H_(2) storage systems,stressing the need for innovative materials and system integration to satisfy future energy demands.High-throughput screening,combined with machine learning algorithms,is noted as a promising approach to identify patterns and predict the behavior of novel materials under various conditions,significantly reducing the time and cost associated with experimental trials.In closing,we discuss the increasing involvement of various companies in solid-state H_(2) storage,particularly in prototype vehicles,from a techno-economic perspective.This forward-looking perspective underscores the necessity for ongoing material innovation and system optimization to meet the stringent energy demands and ambitious sustainability targets increasingly in demand.

Selective Pb^(2+) removal and electrochemical regeneration of fresh and recycled FeOOH

Heavy metal pollution is a key environmental problem.Selectively extracting heavy metals could accomplish water purification and resource recycling simultaneously.Adsorption is a promising approach with a facile process,adaptability for the broad concentration of feed water,and high selectivity.However,the adsorption method faces challenges in synthesizing highperformance sorbents and regenerating adsorbents effectively.FeOOH is an environmentally friendly sorbent with low-cost production on a large scale.Nevertheless,the selectivity behavior and regeneration of FeOOH are seldom studied.Therefore,we investigated the selectivity of FeOOH in a mixed solution of Co^(2+),Ni^(2+),and Pb^(2+)and proposed to enhance the capacity of FeOOH and regenerate it by using external charges.Without charge,the FeOOH electrode shows a Pb^(2+)uptake capacity of 20 mg/g.After applying a voltage of-0.2/+0.8 V,the uptake capacity increases to a maximum of 42 mg/g and the desorption ratio is 70%-80%.In 35 cycles,FeOOH shows a superior selectivity towards Pb^(2+)compared with Co^(2+)and Ni^(2+),with a purity of 97%±3%in the extracts.The high selectivity is attributed to the lower activation energy for Pb^(2+)sorption.The capacity retentions at the 5^(th)and the 35^(th)cycles are ca.80%and ca.50%,respectively,comparable to the chemical regeneration method.With industrially exhausted granular ferric hydroxide as the electrode material,the system exhibits a Pb^(2+)uptake capacity of 37.4 mg/g with high selectivity.Our work demonstrates the feasibility of regenerating FeOOH by charge and provides a new approach for recycling and upcycling FeOOH sorbent.

胆固醇酯转移蛋白在胆固醇酯转移中的结构与功能

人体胆固醇酯转移蛋白(CETP)会造成胆固醇酯从高密度脂蛋白(HDL)向低密度脂蛋白(LDL)或极低密度脂蛋白(VLDL)的转移,从而增加人体患心血管疾病的危险性。了解CETP在胆固醇酯转移过程中的作用和机理,是研发新的CETP抑制剂药物以预防和治疗心血管疾病的重要基础和关键步骤。本文综述了CETP结构与功能领域研究的最新进展,详细介绍了CETP与各类脂蛋白绑定结构的高分辨透射电子显微镜研究;并结合对CETP晶体结构的分析,以及生理溶液中CETP结构与动态特征、CETP与脂滴间相互作用的分子动力学模拟研究结果,阐述并讨论了CETP脂转移机理的"通道"模型;最后对尚待解决的关键问题与未来的研究方向进行了展望,以期促进CETP功能机理的研究和抑制药物的研制。

IPET:测定独个生物大分子三维空间结构的实验方法

蛋白质的动态特性和结构活性对于蛋白质功能的调控具有根本意义。传统的结构确定方法(包括X射线和电子显微镜单颗粒分析技术等)往往需要成千上万不同蛋白质分子的平均信号,因此难以确定蛋白质分子的动态结构。而电子显微断层成像技术是一种对独个生物个体结构从不同的观测角度照相、并计算来恢复该个体的三维结构密度图的方法。传统的冷冻电子断层成像重构方法采用整个大尺寸电镜图像进行重构计算,通常用来研究细菌、细胞切片等大尺寸生物个体在较低分辨率下的结构;由于分辨率的限制,不足以获得小尺寸的蛋白质分子的结构细节。最近,任罡研究小组提出一种独个生物颗粒的电子显微断层成像方法(individual-particle electron tomography,IPET)。该方法通过减小图像尺寸(直至所选区域只包含单个蛋白质分子)的策略,运用提出的FETR(focused electron tomography reconstruction)算法来提高独个大分子重构的分辨率。此方法不需要初始模型和大量分子的平均信号,同时能够容忍一定的测角误差。本文综述了IPET/FETR方法在确定独个分子结构过程中的具体步骤以及如何应用该方法来研究蛋白动态特性和结构变化特征。期望通过该综述和国内同行交流,分享最新的前沿研究,为赶超世界科技前沿的建设添砖加瓦。

Holographic planar lightwave circuit for on-chip spectroscopy

Computer-generated planar holograms are a powerful approach for designing planar lightwave circuits with unique properties.Digital planar holograms in particular can encode any optical transfer function with high customizability and is compatible with semiconductor lithography techniques and nanoimprint lithography.Here,we demonstrate that the integration of multiple holograms on a single device increases the overall spectral range of the spectrometer and offsets any performance decrement resulting from miniaturization.The validation of a high-resolution spectrometer-on-chip based on digital planar holograms shows performance comparable with that of a macrospectrometer.While maintaining the total device footprint below 2 cm2,the newly developed spectrometer achieved a spectral resolution of 0.15 nm in the red and near infrared range,over a 148 nm spectral range and 926 channels.This approach lays the groundwork for future on-chip spectroscopy and lab-on-chip sensing.

High-refractive index acrylate polymers for applications in nanoimprint lithography

The development of polymeric optical materials with a higher refractive index,transparency in the visible spectrum region and easier processability is increasingly desirable for advanced optical applications such as microlenses,image sensors,and organic light-emitting diodes.Most acrylates have a low refractive index(around 1.50)which does not meet the high perfo rmance requirements of advanced optical materials.In this research,three novel acrylates were synthesized via a facile one-step approach and used to fabricate optical transparent polymers.All of the polymers reveal good optical properties including high transparency(≥90%)in the visible spectrum region and high refractive index values(1.6363)at 550 nm.Moreover,nanostructures of these acrylate polymers with various feature sizes including nanogratings and photonic crystals were successfully fabricated using nanoimprint lithography.These results indicate that these acrylates can be used in a wide range of optical and optoelectronic devices where nanopatterned films with high refractive index and transparency are required.