Self-assembled Tubular Structures Research Articles

Growth of Self‐Assembling Tubular Structures of Magnesium Oxy/Hydroxide and Silicate Related With Seafloor Hydrothermal Systems Driven by Serpentinization

AbstractTubular structures self‐assemble from precipitating magnesium salts under the chemical garden chemobrionic growth process. Two experimental procedures, the dissolution of magnesium salt pellets and the injection of magnesium salt solutions into silicate solutions, were explored to reproduce in the laboratory the geochemical conditions under which similar structures may form from mineral‐rich fluids at some seafloor hydrothermal vents driven by serpentinization. X‐ray diffraction and Raman microspectroscopy applied to the materials formed indicated the presence of layers of magnesium silicate and magnesium oxide/hydroxide. Quantum mechanical calculations based on density functional theory were performed on models of hydrated magnesium silicate surfaces and related minerals to explain the Raman spectroscopy results. We examine the precipitate morphology, chemical structure, and crystal or mineral structure in our experiments and how these change with the reaction conditions. This is a fascinating example in geochemistry of a self‐organizing nonequilibrium process that creates complex structures.

Method for the Fabrication of Elastomeric Polyester Scaffolds for Tissue Engineering and Minimally Invasive Delivery.

Using the methods described herein, we have demonstrated how scaffolds can be designed for a number of applications including tissue engineering, biomedical devices and injectable tissues. Details on the methods of polymerization and physical and chemical characterization of poly(octamethylene maleate (anhydride) citrate (POMaC) are described. Two POMaC polymer recipes with different monomer ratios of maleic anhydride and citric acid were synthesized and compared. Mechanical testing was performed on scaffolds of two distinct anisotropic designs to show how scaffold design influences the apparent elasticity in the long and short axis. POMaC scaffolds of various patterns and geometries were fabricated to demonstrate: (1) scaffold function can be determined by scaffold design (e.g., inherent shape-memory or self-assembling tubular structures), and (2) the soft lithography approach to fabricating biodegradable elastomers described here can be used to suit a number of different potential applications.

Tailoring supramolecular nanotubes by bile salt based surfactant mixtures.

An approach for tailoring self-assembled tubular structures is described. By controlling the relative composition of a two-component surfactant mixture comprising the natural bile salt lithocholate and its bolamphiphilic derivative, it was possible to finely tune the nanotube cross-section of the mixed tubular aggregates that self-associated spontaneously in aqueous solution at pH 12. The diameter was found to vary up to 50% when the stoichiometric ratio of the two bile salts was changed. The tuning of supramolecular nanochannels with such remarkable precision is of significant interest for technological applications of these materials.

Optical transition induced by molecular transformation in peptide nanostructures

In this letter we present a variation in the optical properties of bio-organic peptide nanostructures, which are induced by molecular transformation. The self-assembled tubular structures are formed from short aromatic di-peptides. Upon thermal induction, the structure changes its molecular conformation, and the linear di-peptide closes into a cyclic peptide. This irreversible transition changes the molecular packing at the nanoscale, which results in reconstruction of the native quantum dot-like packing to quantum well-like packing and the generation of blue luminescence. We further show that the same cyclic peptide can exhibit different photoluminescence properties according to the formed structure.

Impregnation of Tubular Self-Assemblies into Dextran Hydrogels

Amine groups are the building units of proteins. The incorporation of amine groups into polyethylene glycol diacrylate (PEGDA) hydrogel through dextran-allyl isocyanate-ethylamine (Dex-AE) enhances sustained protein release by introducing effective interactions. To investigate such an interaction effect and to improve protein release, we impregnated self-assembled tubular structures from dextran-bromoethylamine (Dex-BH) and dextran-chloroacetic acid (Dex-CA) into Dex-AE/PEGDA hydrogel. The morphology data obtained from scanning electron microscopy (SEM) reveal that pure PEGDA hydrogel had no effect on the distribution of the self-assembled tubules; the introduction of Dex-AE brought about the dispersion of these tubules, and an increase in Dex-AE content led to more evenly distributed structures. Moreover, the implantation of the self-assembled tubules had no distinct effect on the swelling capacity of the hybrid self-assembly embedded hydrogels. The in vitro albumin release study was carried out in a pH 7.4 buffer solution; the results show that the implantation of the self-assembly into the hydrogels reduced the burst release and prolonged the protein release time. These findings demonstrate that the impregnation of tubular self-assembly into hydrogel makes the hybrid hydrogel an excellent protein delivery system.

Self‐Assembled Organic Microtubes from Amphiphilic Molecules

Getting the sizes sorted out: In recent years, there have been increasing numbers of reports about self-assembled nano- or microtubular structures because of their potential uses in a variety of technical applications, which are largely determined by the tube sizes. This Focus Review highlights microsized self-assembled organic tubular structures formed in aqueous solutions and organic solvents. In recent years, there have been increasing numbers of reports about self-assembled nano- or microtubular structures, because they have potential uses in nanofabrication, purification, medical, and encapsulation applications. A wide range of tubular structures have been constructed by the self-assembly of amphiphilic molecules in aqueous solution or organic solvents. The diameters of self-assembled tubular structures range between 10 nm and 30 mum. One of the most important factors that determine their suitability for technical applications is the size of the tubes. Therefore, analyzing and sorting tubular structures according to their size is essential. This Focus Review highlights microsized self-assembled organic tubular structures formed in aqueous solutions and organic solvents.

Formation of Self-assembled Tubular Structures by Mixing Cyclodextrin and Polymers without Solvents

Abstract Cyclodextrin has been found to form inclusion complexes with some polymers, such as poly(ethylene glycol) with high selectivity only by mixing powdered crystals of cyclodextrins and polymer samples without any solvents under ambient conditions.

Designer cyclopeptides for self-assembled tubular structures

Abstract A simple design strategy for a facile and direct entry into hydrogen-bonded peptide nanotubes is delineated with polymethylene-bridged cystine-based macrocycles. The key feature of the design is the placement of a pair of self-complementary hydrogen-bonding (NH–CO or NH–CO–NH) groups at almost opposite poles of the ring. A large variety of cyclobisamides and bisureas prepared in a single step by direct condensation of commercially available 1,ω-alkane dicarbonyl dichloride or diisocyanate with either cystine diOMe or its extended bispeptide were examined by X-ray crystallography and shown to possess an inherent property of self-assembling into hydrogen-bonded, open-ended, hollow tubular structures. The totally hydrophobic interior of the cyclobisamide tubes creates a micro environment capable of solubilizing highly lipophilic substances in water. The cyclic bisurea tubes are demonstrated to act as excellent receptors for selective binding to 1,ω-alkane dicarboxylates. The scope of the design is extended to the creation of tubular structures by stacking of rings through aromatic π-π interactions.

X-ray analysis of the self-assembling tubular structures formed by polymethacrylates with highly tapered side groups

X-ray analysis of the self-assembling tubular structures formed by polymethacrylates with highly tapered side groups