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1.
Arikainen EO Boden N Bushby RJ Lozman OR Vinter JG Wood A 《Angewandte Chemie (International ed. in English)》2000,39(13):2333-2336
2.
Molecular self-assembly is an intrinsic property of proteins central to their biological functionality. One important industrially interesting property is the ability to control and switch on and off self-assembly using a variety of external chemical and physical triggers. Model peptides have been developed with significantly reduced chemical and structural complexity compared to biological proteins. These are ideal systems for exposing the fundamental principles that drive protein-like self-assembly, as well as for establishing in a quantitative manner their structure-function relationship. We investigate simple, short model peptides that adopt a purely β-strand conformation, align in an antiparallel manner and self-assemble in one dimension in solution into long β-sheet nanotapes and higher order aggregates with no other conformation (i.e., helices, turns or random coils) present in the aggregates. These micrometre-long nanostructures gel in solutions at concentrations as low as 0.2% v/v. Their gel-fluid transition has been previously shown to be controlled by pH, temperature, or by mixing with complementary peptides. Here we show the dramatic effect of another chemical trigger, that of physiological-like salt concentration, on the self-assembly, morphology and gelation of a series of systematically designed charged self-assembling tape-forming peptides, each 11 amino acid residues in length, in the pH range of 2-14. This study provides a detailed understanding of the self-assembly of this class of peptides in aqueous solutions of biologically relevant pH and ionic strength. This insight has led to the development of injectable self-assembling peptide lubricants as potential therapeutics for the treatment of early stage knee joint osteoarthritis. 相似文献
3.
The recently developed NMR SPDE experiment is shown to provide a new and particularly convenient technique for probing the conformational dynamics of mesogens in thermotropic liquid crystals. Measurements have been made in the nematic and smectic phases of the 4,4′-di-n-alkoxyazoxybenzenes. It is shown for the first time that the internal disorder of the alkyl end chains is intimately related to the molecular organization of these mesophases. 相似文献
4.
NMR SPDE measurements are reported for the lamellar (dispersions and multibilayer stacks) and hexagonal phases of sodium octanoate/octanol/D2O mixtures. In the lamellar Lβ and Lγ (gel) phases the octyl chains are rigid and perfectly ordered, while in the lamellar Lα and hexagonal phases they are flexible and disordered. In particular, the measurements show that in the fluid lamellar Lα phase, there is a marked discontinuity in the octyl chain flexibility at the C5-C6 segment; this behaviour is identical to that previously reported for the alkyl end-chains in smectic 4,4′-di-n-octyloxyazoxybenzene. In contrast, in the hexagonal phase, there is an effectively continuous flexibility gradient along the whole length of the octyl chain as in nematic 4,4′-di-n-octyloxyazoxybenzene. The behaviour in the lamellar phase is attributed to interference between cooperative conformational modes and localized random thermal fluctuations. 相似文献
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Neville Boden Richard J. Bushby Kevin Donovan Quanying Liu Zhibao Lu Theo Kreouzis 《Liquid crystals》2013,40(12):1739-1748
A synthesis has been developed for 2,3,7,8,12,13-hexakis[2-(2-methoxyethoxy)ethoxy]-tricycloquinazoline (TCQ6EO2M) in which the ethylenoxy side chains are introduced before elaboration of the heterocylic core. This discogen gives a hexagonal columnar phase (Colh) between 77 and 233°C. n-Doping using potassium metal is facilitated firstly by the electron poor/π-deficient nature of the core and secondly by the polyethylenoxy side chains which complex the potassium K+ counter-ions. The conductivity of the Colh phase of TCQ6EO2M doped with 10 mol % potassium (σ ∥ = 1.1 x 10-3 S m-1) is substantially higher than that previously reported for 2,3,7,8,12,13-hexa(hexylthio)tricycloquinazoline doped with 6 mol % potassium (σ ∥ = 2.9 x 10-5 S m-1). Photoconductivity studies of TCQ6EO2M using a time of flight sample configuration show transient photocurrents for both holes and electrons. From these an upper limit on the mobility for the electrons is estimated as ~10-4 cm2 V-1 s-1 at 150°C which is of the same magnitude as that for hole mobilities in other columnar discotic liquid crystals. 相似文献
8.
Dr. Selina Beatrice van der Meer Theresa Seiler Christin Buchmann Georgia Partalidou Dr. Sophia Boden Dr. Kateryna Loza Dr. Marc Heggen Dr. Jürgen Linders Dr. Oleg Prymak Prof. Dr. Cristiano L. P. Oliveira Prof. Dr. Laura Hartmann Prof. Dr. Matthias Epple 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(4):1451-1464
Ultrasmall gold nanoparticles (diameter about 2 nm) were surface-functionalized with cysteine-carrying precision macromolecules. These consisted of sequence-defined oligo(amidoamine)s (OAAs) with either two or six cysteine molecules for binding to the gold surface and either with or without a PEG chain (3400 Da). They were characterized by 1H NMR spectroscopy, 1H NMR diffusion-ordered spectroscopy (DOSY), small-angle X-ray scattering (SAXS), and high-resolution transmission electron microscopy. The number of precision macromolecules per nanoparticle was determined after fluorescent labeling by UV spectroscopy and also by quantitative 1H NMR spectroscopy. Each nanoparticle carried between 40 and 100 OAA ligands, depending on the number of cysteine units per OAA. The footprint of each ligand was about 0.074 nm2 per cysteine molecule. OAAs are well suited to stabilize ultrasmall gold nanoparticles by selective surface conjugation and can be used to selectively cover their surface. The presence of the PEG chain considerably increased the hydrodynamic diameter of both dissolved macromolecules and macromolecule-conjugated gold nanoparticles. 相似文献
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