Effect of pancreatic lipase on supramolecular DNA complexes in eukaryotic cellsin vivo andin situ

Effect of pancreatic lipase on supramolecular DNA complexes, nuclear matrix, and 70% ethanol-fixed cells is studied by elastoviscosimetry. It is shown that lipase induces DNA degradation not onlyin vitro but also in whole cells. Possible role of neutral lipids, in particular, DNA-bound diglycerides, in the arrangement of chromosomal DNA is discussed. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 12, pp. 635–639, December, 1997     

“Smart” Materials for Biosensing Devices: Cell-Mimicking Supramolecular Assemblies and Colorimetric Detection of Pathogenic Agents

Mimicking cell membrane and the biomolecular recognition associated with membranes represents a great technical challenge, yet it has opened doors to innovative diagnostic and therapeutic methods. Our work has focused on design and synthesis of a class of smart materials exploiting biological principals for use in biosensors: these materials are functional polymeric assemblies that mimic the cell membrane and conveniently report the presence of pathogens with a color change. Biologically active cell membrane components are incorporated into conjugated polymers with desirable optical properties and the binding of the target molecules onto the material triggers conformational and electronic shifts that are reflected in a chromatic change (a so-called biochromic shift) that is conveniently observed and recorded. Langmuir–Blodgett thin films and vesicle bilayers provide ideal configurations for precise delivery of the biological binding entity to the sensing interface, and for control of molecular orientation for effective biomolecular interaction. Polydiacetylenic membrane-mimicking materials containing cell surface receptor gangliosides and sialic acid residues, respectively were formulated into these architectures and used for colorimetric detection of bacterial toxins and influenza virus. One advantage of these biochromic conjugated polymer (BCP) sensors is that their molecular recognition and signal transduction functionalities are resident in a single functional unit, making them amenable to convenient microfabrication and use.     

A New Approach Toward Metal‐Free Self‐Healing Ionomers Based on Phosphate and Methacrylate Containing Copolymers

In order to accelerate the progress of the development of new self‐healing ionomers, a new pathway toward fully organic ionomers containing methacrylic acid and phosphate‐based functional groups, respectively, as well as butyl methacrylate as comonomer is presented in the current study. The well‐defined copolymer structures are synthesized using the reversible addition‐fragmentation chain transfer polymerization and further characterized by NMR, size exclusion chromatography as well as titration. Two different metal‐free ionomers as well as one reference K⁺ based ionomer are created and tested. The results of the detailed investigation by NMR, thermal analysis, and rheology are correlated with the scratch‐healing performance in order to identify trends and dependencies leading to preconditions for further improvements.     

基于超分子“印迹模板”理论探讨中药升降浮沉

在前期提出超分子化学对中药四性理论特殊影响的基础上,进一步分析中药升降浮沉的历史沿革、研究概况,并运用超分子"印迹模板"理论对中药"升降浮沉"理论进行解析,提出对中药"升降浮沉"的评价方法。人体与中药均是印迹模板印迹作用的聚集体,在印迹模板作用规律下,不同类型的中药成分与人体的靶点通过"锁-钥"关系以非共价键结合,中药客体超分子通过键的作用可纠正人体主体超分子在自识别、自组织、自组装、自复制过程时发生的寒热、气机失调。人体具备抵抗外界病邪侵袭的能力,有赖于其气机"升降出入"的正常;中药具有"升降浮沉"的性能并能祛除病疾,有赖于其能调整人体气机紊乱,或顺应气机、祛邪外出以增强机体免疫的能力。基于此,在分析中药"升降浮沉"药理作用的基础上,探究其物质基础,并建立中药"升降浮沉"的评价方法,通过超分子印迹模板理论对中药升降浮沉进行剖析,揭示其科学内涵,推动中药药性理论不断创新。     

Light‐Switchable Supramolecular Self‐Assembly of Soft Colloids

Self‐assembly is an efficient strategy of constructing microgel‐based intelligent materials. However, it remains a challenge to realize the reversible self‐assembly of microgels. Herein, a method to guide the self‐assembly of soft colloids with light‐stimuli is proposed, utilizing the light‐responsive host–guest interaction between an azobenzene functionalized nanogel (the guest colloid) and an α‐cyclodextrin functionalized microgel (the host colloid). The two colloids can form a stable colloid cluster when the surface of the host colloid is fully packed with the guest colloids. The colloid cluster can disassemble when irradiated with UV light and reassemble when irradiated with visible light. The reversible colloidal self‐assembly can be controlled by the interplay between the supramolecular and covalent crosslinking, and can also be adjusted by the addition of competitive host molecules. Besides the light‐sensitivity, the colloid cluster inherits the deformability and temperature‐sensitivity from its parent colloids. These features are different from the supramolecular self‐assembly of hard colloids or macroscopic gels, and manifest the as‐prepared colloid cluster potential building blocks of light‐responsive materials.     

Geometrical manipulation of complex supramolecular tessellations by hierarchical assembly of amphiphilic platinum(II) complexes

Here we report complex supramolecular tessellations achieved by the directed self-assembly of amphiphilic platinum(II) complexes. Despite the twofold symmetry, these geometrically simple molecules exhibit complicated structural hierarchy in a columnar manner. A possible key to such an order increase is the topological transition into circular trimers, which are noncovalently interlocked by metal···metal and π–π interactions, thereby allowing for cofacial stacking in a prismatic assembly. Another key to success is to use the immiscibility of the tailored hydrophobic and hydrophilic sidechains. Their phase separation leads to the formation of columnar crystalline nanostructures homogeneously oriented on the substrate, featuring an unusual geometry analogous to a rhombitrihexagonal Archimedean tiling. Furthermore, symmetry lowering of regular motifs by design results in an orthorhombic lattice obtained by the coassembly of two different platinum(II) amphiphiles. These findings illustrate the potentials of supramolecular engineering in creating complex self-assembled architectures of soft materials.

Tessellation in two dimensions (2D) is a very old topic in geometry on how one or more shapes can be periodically arranged to fill a Euclidean plane without any gaps. Tessellation principles have been extensively applied in decorative art since the early times. In natural sciences, there has been a growing attention on creating ordered structures with increasingly complex architectures inspired by semi-regular Archimedean tilings (ATs) and quasicrystalline textures on account of their intriguing physical properties (1–5) and biological functions (6). Recent advances in this regard have been achieved in various fields of supramolecular science, including the programmable self-assembly of DNA molecules (7), coordination-driven assembly (8–10), supramolecular interfacial engineering (11–13), crystallization of organic polygons (14, 15), colloidal particle superlattices (16), and other soft-matter systems (17–20). Moreover, tessellation in 2D can overcome the topological frustration to generate complex semi- or non-regular patterns by using geometrically simple motifs. As exemplified by the self-templating assembly of spherical soft microparticles (21), a vast array of 2D micropatterns encoding non-regular tilings, such as rectangular, rhomboidal, hexagonal, and herringbone superlattices were obtained by layer-by-layer strategy at a liquid–liquid interface. Tessellation principles have also been extended to the self-assembly of giant molecules in three dimensions (3D). Superlattices with high space-group symmetry (Im3¯m, Pm3¯n, and P4₂/mnm) were reported in dendrimers and dendritic polymers by Percec and coworkers (22–24). Recently, Cheng and coworkers identified the highly ordered Frank–Kasper phases obtained from giant amphiphiles containing molecular nanoparticles (25–28). Despite such advancements made in the field of soft matter, an understanding of how structural ordering in supramolecular materials is influenced by the geometric factors of its constituent molecules has so far remained elusive.In light of these developments and the desire to explore the supramolecular systems, square-planar platinum(II) (Pt^II) polypyridine complexes may serve as an ideal candidate for model studies not only because of their intriguing spectroscopic and luminescence properties (29, 30), but also because of their propensity to form supramolecular polymers or oligomers via noncovalent Pt···Pt and π–π interactions (31–39). Although rod-shaped and lamellar structures are the most commonly observed in the self-assembly of planar Pt^II complexes (34–39), 2D-ordered nanostructures, such as the hexagonally packed columns (31, 40) and honeycomb-like networks (41–43), were recently first demonstrated by us.Herein, we report a serendipitous discovery of a C_2h-symmetric Pt^II amphiphile (Fig. 1A) that can hierarchically self-assemble into a 3D-ordered nanostructure with hexagonal geometry. Interestingly, this structurally anisotropic molecule possibly undergoes topological transition and interlocks to form its circular trimer by noncovalent Pt···Pt and π–π interactions (Fig. 1B). The resultant triangular motif is architecturally stabilized and preorganized for one-dimensional (1D) prismatic assembly (Fig. 1C). Together with the phase separation of the tailored hydrophobic and hydrophilic sidechains, an unusual and unique 3D hexagonal lattice is formed (Fig. 1D), in which the Pt centers adopt a rare rhombitrihexagonal AT-like order. Finally, the nanoarchitecture develops in a hierarchical manner on the substrate due to the homogeneous nucleation (Fig. 1E).Open in a separate windowFig. 1.Hierarchical self-assembly of Pt^II amphiphile into hexagonal ordering. (A) Space-filling (CPK) model of a C_2h-symmetric Pt^II amphiphile (1). All of the hydrogen atoms and counterions are omitted for clarity. (B) CPK representations of possible models of regular triangular, tetragonal, pentagonal, and hexagonal motifs formed with Pt···Pt and π–π stacking. These motifs possess a hydrophilic core (red) with various diameters wrapped by a hydrophobic shell comprising long alkyl chains (gray). (C) CPK representation of a 1D prismatic structure consisting of circular trimers with long-range Pt···Pt and π–π stacking. (D) CPK representation of a 3D columnar lattice constructed by the prismatic assemblies adopting a rare rhombitrihexagonal AT-like order. With the assistance of the phase separation, the hydrophobic domain serves as a discrete column associated with six prismatic neighbors. (E) Schematic representation of the nanoarchitecture with homogeneous orientation.     

Supramolecular Assembly‐Assisted Synthesis of Responsive Polymeric Materials with Controlled Chain Topologies

Tremendous developments, ranging from new synthetic strategies, properties, and novel functional applications, have emerged in the field of stimuli‐responsive polymeric materials. A variety of highly efficient chemical methodologies have been exploited to synthesize stimuli‐responsive polymers, aiming to control their molecular weight, polydispersity, chemical composition, monomer sequence, and chain topologies. Of particular interest is the emerging strategy of supramolecular assembly‐assisted polymer synthesis, which possesses combined advantages such as facile accessibility, design versatility, multifunctional integration, and promising functions. In this trend article, recent advances are elaborated concerning the fabrication of stimuli‐responsive functional polymers assisted by supramolecular self‐assembly. The fabrication of three main types of responsive polymers, namely, linear polymers, non‐linear shaped polymers, and crosslinked nanostructures, aided by templates of supramolecular assemblies will be discussed.

     

A Redox‐Responsive Supramolecular Hydrogel for Controllable Dye Release

A novel and simple strategy for preparing a redox‐responsive supramolecular hydrogel coassembled from phenylalanine derivative gelator and 4,4′‐dipyridine disulfide is reported in this study. The driving force for the coassembly process is intermolecular hydrogen bonds, as confirmed by various characterization methods, such as ¹H NMR, Fourier transform infrared (FTIR) spectroscopy, and circular dichroism spectroscopy. The disulfide‐containing nanofibrous hydrogel is able to control over the release of encapsulated dyes in response to the reductive condition mimicking the intracellular environment like tumor tissues and should be a promising system for controllable drug release in the fields of nanomedicine and cancer therapy.

     

Folding of a donor-acceptor polyrotaxane by using noncovalent bonding interactions

Mechanically interlocked compounds, such as bistable catenanes and bistable rotaxanes, have been used to bring about actuation in nanoelectromechanical systems (NEMS) and molecular electronic devices (MEDs). The elaboration of the structural features of such rotaxanes into macromolecular materials might allow the utilization of molecular motion to impact their bulk properties. We report here the synthesis and characterization of polymers that contain pi electron-donating 1,5-dioxynaphthalene (DNP) units encircled by cyclobis(paraquat-p-phenylene) (CBPQT(4+)), a pi electron-accepting tetracationic cyclophane, synthesized by using the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The polyrotaxanes adopt a well defined "folded" secondary structure by virtue of the judicious design of two DNP-containing monomers with different binding affinities for CBPQT(4+). This efficient approach to the preparation of polyrotaxanes, taken alongside the initial investigations of their chemical properties, sets the stage for the preparation of a previously undescribed class of macromolecular architectures.     

One-Pot Self-Assembly of Dinuclear,Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO₄⁻, CH₃CO₂⁻, Cl⁻, NO₃⁻), sodium azide (NaN₃), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence Co^IICo^III: [Co₂^III(H₂L⁻¹)₂(AP⁻¹)(N₃)](ClO₄)₂ (1), [Co₄(H₂L⁻¹)₂(µ₃-1,1,1-N₃)₂(µ-1,1-N₃)₂Cl₂(CH₃OH)₂]·4CH₃OH (2), [Co₂^IICo₂^III(HL⁻²)₂(µ-CH₃CO₂)₂(µ₃-OH)₂](NO₃)₂·2CH₃CH₂OH (3), and [Co₂^IICo₂^III (H₂L1²⁻)₂(THMAM⁻¹)₂](NO₃)₄ (4). In 1, two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.5430(11) Å) Co-Co intermetallic separation with a coordination number of 7, a rare feature for cobalt(III). In 2, two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ₃-1,1,1-N₃ azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N₃ and two μ₃-1,1,1-N₃ azido bridges generating tetranuclear cationic [Co₄(H₂L⁻¹)₂(µ₃-1,1,1-N₃)₂(µ-1,1-N₃)₂Cl₂(CH₃OH)₂]²⁺ units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the a-axis through H-bonding. In 3, HL²⁻ holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CH₃CO₂⁻, and μ₃-OH⁻ bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ₃-OH⁻ bridges generating cationic tetranuclear [Co₂^IICo₂^III(HL⁻²)₂(µ-CH₃CO₂)₂(µ_3-OH)₂]²⁺ units with an incomplete double cubane core. In 4, H₂L1⁻² holds mixed-valent Co(II)/Co(III) ions in dinuclear units which dimerize through two ethanolic O (μ-RO⁻) in the side arms of the ligands and two ethanolic O (μ₃-RO⁻) of THMAM bridges producing centrosymmetric cationic tetranuclear [Co₂^IICo₂^III (H₂L1⁻²)₂(THMAM⁻¹)₂]⁴⁺ units which grow into 2D-sheets along the bc-axis through a network of H-bonding. Bulk magnetization measurements on 2 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.