Developing a Self‐Healing Supramolecular Nucleoside Hydrogel Based on Guanosine and Isoguanosine

Recently, supramolecular hydrogels have attracted increasing interest owing to their tunable stability and inherent biocompatibility. However, only few studies have been reported in the literature on self‐healing supramolecular nucleoside hydrogels, compared to self‐healing polymer hydrogels. In this work, we successfully developed a self‐healing supramolecular nucleoside hydrogel obtained by simply mixing equimolar amounts of guanosine (G) and isoguanosine (isoG) in the presence of K⁺. The gelation properties have been studied systematically by comparing different alkali metal ions as well as mixtures with different ratios of G and isoG. To this end, rheological and phase diagram experiments demonstrated that the co‐gel not only possessed good self‐healing properties and short recovery time (only 20 seconds) but also could be formed at very low concentrations of K⁺. Furthermore, nuclear magnetic resonance (NMR), powder X‐ray diffraction (PXRD), and circular dichroism (CD) spectroscopy suggested that possible G₂isoG₂‐quartet structures occurred in this self‐healing supramolecular nucleoside hydrogel. This co‐gel, to some extent, addressed the problem of isoguanosine gels for the applications in vivo, which showed the potential to be a new type of drug delivery system for biomedical applications in the future.     

Mixing Biomimetic Heterodimers of Nucleopeptides to Generate Biocompatible and Biostable Supramolecular Hydrogels

As a new class of biomaterials, most supramolecular hydrogels formed by small peptides require the attachment of long alkyl chains, multiple aromatic groups, or strong electrostatic interactions. Based on the fact that the most abundant protein assemblies in nature are dimeric, we select short peptide sequences from the interface of a heterodimer of proteins with known crystal structure to conjugate with nucleobases to form nucleopeptides. Being driven mainly by hydrogen bonds, the nucleopeptides self‐assemble to form nanofibers, which results in supramolecular hydrogels upon simple mixing of two distinct nucleopeptides in water. Moreover, besides being biocompatible to mammalian cells, the heterodimer of the nucleopeptides exhibit excellent proteolytic resistance against proteinase K. This work illustrates a new and rational approach to create soft biomaterials by a supramolecular hydrogelation triggered by mixing heterodimeric nucleopeptides.     

含二氢噻唑类卟啉配位聚合物自组装染料敏化太阳能电池

合成了两种不同类型(2+2型、A4型)含二氢噻唑基团的锌卟啉与Mn(Ⅱ)的配位聚合物(CPsx,x=1,2)。两种配位聚合物与锚定卟啉(ZnPA)通过金属-配体轴向配位自组装成染料敏化太阳能电池。通过电镜表征了其在TiO₂上的自组装结构。光伏性能测试表明,聚合物自组装体与单体相比具有较优的光电转换效率,特别是A4型结构(CPs2)具有较高的短路电流和转换效率。     

Fluorescence and Morphology of Self-Assembled Nucleobases and Their Diphenylalanine Hybrid Aggregates

Studies carried out in recent decades have revealed that the ability to self-assemble is a widespread property among biomolecules. Small nucleic acid moieties or very short peptides are able to generate intricate assemblies endowed with remarkable structural and spectroscopic properties. Herein, the structural/spectroscopic characterization of aggregates formed by nucleobases and peptide nucleic acid (PNA)–peptide conjugates are reported. At high concentration, all studied nucleobases form aggregates characterized by previously unreported fluorescence properties. The conjugation of these bases, as PNA derivatives, to the dipeptide Phe–Phe leads to the formation of novel hybrid assemblies, which are characterized by an amyloid-like association of the monomers. Although these compounds share the same basic cross-β motif, the nature and number of PNA units have an important impact on both the level of structural order and the intrinsic fluorescence of the self-assembled nanostructure.     

Self-Assembled Heavy Lanthanide Orthovanadate Architecture with Controlled Dimensionality and Morphology

Nearly monodisperse YVO₄ architectures with persimmon-like, cube-like and nanoparticle shapes have been synthesised on a large scale by means of a complexing-agent-assisted solution route. The shape and size of these as-prepared architectures can be tuned effectively by controlling the reaction conditions, such as reaction time, the molar ratio of complexing agent/Y³⁺ and different complexing agents. As a typical morphology, the growth process of monodisperse nanopersimmons has been examined. To extend this method, other LnVO₄ (Ln=Ce, Gd, Dy, Er) complexes with well-defined shape and dimensionality can also be achieved by adjusting different rare earth precursors. Further studies reveal that the morphology of the as-synthesised lanthanide orthovanadate is determined mainly by the interaction between rare earth ion and the complexing agent. Ultraviolet (UV) absorption and photoluminescence spectra show that the optical properties of YVO₄ nanopersimmons are relevant to their size and shape. This work sheds some light on the design of well-defined complex nanostructures, and explores the potential applications of the as-synthesised architectures.     

Tuning of Morphology by Chirality in Self-Assembled Structures of Bis(Urea) Amphiphiles in Water

We present the synthesis and self-assembly of a chiral bis(urea) amphiphile and show that chirality offers a remarkable level of control towards different morphologies. Upon self-assembly in water, the molecular-scale chiral information is translated to the mesoscopic level. Both enantiomers of the amphiphile self-assemble into chiral twisted ribbons with opposite handedness, as supported by Cryo-TEM and circular dichroism (CD) measurements. The system presents thermo-responsive aggregation behavior and combined transmittance measurements, temperature-dependent UV, CD, TEM, and micro-differential scanning calorimetry (DSC) show that a ribbon-to-vesicles transition occurs upon heating. Remarkably, chirality allows easy control of morphology as the self-assembly into distinct aggregates can be tuned by varying the enantiomeric excess of the amphiphile, giving access to flat sheets, helical ribbons, and twisted ribbons.     

Impact of the Core Chemistry of Self-Assembled Spherical Nucleic Acids on their In Vitro Fate

Nucleic acid therapeutics (NATs), such as mRNA, small interfering RNA or antisense oligonucleotides are extremely efficient tools to modulate gene expression and tackle otherwise undruggable diseases. Spherical nucleic acids (SNAs) can efficiently deliver small NATs to cells while protecting their payload from nucleases, and have improved biodistribution and muted immune activation. Self-assembled SNAs have emerged as nanostructures made from a single DNA-polymer conjugate with similar favorable properties as well as small molecule encapsulation. However, because they maintain their structure by non-covalent interactions, they might suffer from disassembly in biologically relevant conditions, especially with regard to their interaction with serum proteins. Here, we report a systematic study of the factors that govern the fate of self-assembled SNAs. Varying the core chemistry and using stimuli-responsive disulfide crosslinking, we show that extracellular stability upon binding with serum proteins is important for recognition by membrane receptors, triggering cellular uptake. At the same time, intracellular dissociation is required for efficient therapeutic release. Disulfide-crosslinked SNAs combine these two properties and result in efficient and non-toxic unaided gene silencing therapeutics. We anticipate these investigations will help the translation of promising self-assembled structures towards in vivo gene silencing applications.     

Electropolymerization of 4-Aminothiophenol Self-Assembled Monolayer on Au Electrode

Itiswellknownthatelectrochemicaloxidationofanilinedissolvedinelectrolytesolutionsisaveryusefulmethodforpreparingpolyanilinefilmsonelectrodes'.However,itisverydifficultforthismethodtoprepareauniformmonolayerpolymersincelocalnucleationandgrowthofpolyme...     

Mechanoresponsive Self-Assembled Perylene Bisimide Films

In this work, self-assembled amino-acid appended perylene bisimides (PBIs) have been studied that when processed into thin films change their resistivity in response to being bent. The PBIs assemble into structures in water and form thin films upon drying. These normally delicate thin films can be tolerant to bending, depending on the aggregates they form. Furthermore, the films then reversibly change their resistivity in response to this mechanical stimulus. This change is proportional to the degree of bending of the film giving them the potential to be used quantitatively to measure mechanical movement, such as in wearable devices.     

Resorcinarene-Encapsulated Nanoparticles: Building Blocks for Self-Assembled Nanostructures

Calix[4]resorcinarene-derived surfactants are highly effectiveat stabilizing metal nanoparticles of different sizes, creating opportunities tofabricate well-defined nanostructures with size-tunable materials properties. Theresorcinarenes have a critical role in the dispersion of nanoparticles under varioussolvent conditions and in the robustness of the protective surfactant layer.Magnetic cobalt particles stabilized by resorcinarenes self-assemble intonanostructured ``bracelets' in toluene. Resorcinarene surfactants can also promote theself-organization of gold nanoparticles as large as 170 nm into two-dimensional arrays. Thesenanostructured films possess novel optoelectronic properties such as surface-enhancedRaman scattering (SERS), and are expected to have useful applications for chemical sensing.     

Adsorption-Inhibition of Clathrate Hydrates by Self-Assembled Nanostructures

The mechanism by which safranine O (SFO), an ice growth inhibitor, halts the growth of single crystal tetrahydrofuran (THF) clathrate hydrates was explored using microfluidics coupled with cold stages and fluorescence microscopy. THF hydrates grown in SFO solutions exhibited morphology changes and were shaped as truncated octahedrons or hexagons. Fluorescence microscopy and microfluidics demonstrated that SFO binds to the surface of THF hydrates on specific crystal planes. Cryo-TEM experiments of aqueous solutions containing millimolar concentrations of SFO exhibited the formation of bilayered lamellae with an average thickness of 4.2±0.2 nm covering several μm². Altogether, these results indicate that SFO forms supramolecular lamellae in solution, which might bind to the surface of the hydrate and inhibit further growth. As an ice and hydrate inhibitor, SFO may bind to the surface of these crystals via ordered water molecules near its amine and methyl groups, similar to some antifreeze proteins.     

无环鸟苷和鸟嘌呤的高效毛细管电泳测定

对无环鸟苷和鸟嘌呤的高效毛细管电泳分离测定条件进行了 详细研究，建立了以２－氨基－５－巯基－３，４－噻二唑为内标的快速、灵敏的ＨＰＣＥ定量分析方法。     

自组装膜技术在电分析化学中的应用

本文介绍了自组装膜的类型、结构并着重评述了有机硫化物自组装膜在电分析化学方面的应用进展。     

Self-Assembled Nanofibrillar Aggregates with Amphiphilic and Lipophilic Molecules

Summary: This article gives a review on self-assembled nanofibrillar aggregates such as helical, twisted ribbon-like and tubular forms, those are produced in aqueous bilayer membrane and organogel systems. Two common features necessary for the chemical structure that yields special morphology are a chiral carbon atom and moieties feasible for intermolecular interactions although there are some exceptions. In aqueous systems, a hydrophobic effect is also an essential driving force for molecular aggregates in aqueous solution systems but almost disappear in organic media. More positive intermolecular interactions play an important role in molecular aggregation in organic media. Hydrogen bonding interaction is especially effective and many organogelators are classified into this category. Some lipophilic peptides have been investigated not only as organogelators but also with respect to their self-assembling behaviors. This latter property gives them distinct advantages compared with conventional gel systems because the gels include highly-ordered structures supramolecular functions like aqueous lipid membranes through molecular orientation. This article also introduces applicability of the organogel system.     

Histidinium-Driven Chirality Control of Self-Assembled Hybrid Molybdenum Oxyfluorides

Exploring macroscopic chiral materials with extended structures has become an important and fundamental topic in chemistry. To systematically control the chirality of novel organic–inorganic frameworks, histidinium-based cationic structure-directing agents containing specific chiral information are introduced. In this way, two chiral compounds, [(l -hisH₂)MoO₂F₄]₃ ⋅ H₂O ( L ) and [(d -hisH₂)MoO₂F₄]₃ ⋅ H₂O ( D ), and an achiral oxyfluoride, (l /d -hisH₂)MoO₂F₄ ( LD ) (his=histidine, C₆H₉N₃O₂) have been successfully self-assembled by a slow evaporation method. The structures of these compounds are composed of histidinium cations and distorted [MoO₂F₄]²⁻ octahedra. Surprisingly, the histidinium cations not only control macroscopic chirality, but also induce O/F ordering in MoO₂F₄ octahedra through hydrogen-bonding interactions. Compounds L and D crystallize in the extremely rare polar space group P1, and exhibit positive second harmonic generation (SHG) signals attributable to a net moment originating from the MoO₂F₄ groups. Solid-state circular dichroism (CD) spectra indicate that the MoO₂F₄ units templated by histidinium cations are chirally aligned through ionic interactions. Crystallization processes influenced by the chirality of the reported materials are also discussed herein.