Coassembly Behavior Research Articles

In Vitro Fabrication and Physicochemical Properties of a Hybrid Fibril from Xenogeneic Collagens

A Hybrid collagen fibril (HCF) assembled from xenogeneic collagens is a special kind of collagen fibrils in vivo and plays an important role in living systems. Inspired by nature, can a HCF form in vitro? Herein, we fabricated a new HCF by neutralizing a mixture of type I bullfrog (Rana catesbeiana Shaw) skin collagen and porcine (Sus scrofa domesticus) skin collagen with a phosphate buffer, and investigated its physicochemical properties. Self-assembly kinetics and fluorescence-quenching experiments showed that a significant intermolecular interaction and co-assembly behavior occurred between bullfrog skin collagen and porcine skin collagen, thus confirming that xenogeneic collagens can self-assemble to form HCF. Differential scanning calorimetry revealed that the thermal stability of HCF was completely different from that of the syngeneic bullfrog skin and porcine skin collagen fibrils. This finding indicated that a new kind of collagen fibril was fabricated successfully. Scanning electron microscopy and transmission electron microscopy tests showed that the diameters and D-periodicity lengths of HCF were smaller than those of the syngeneic collagen fibrils, suggesting that the morphological features of HCF were distinguished from those of the syngeneic fibril samples. Moreover, viscoelasticity of a collagen gel also changed after the self-assembly of xenogeneic collagens. Meanwhile, the obtained hybrid gel still exhibited good biocompatibility and cell proliferation properties. Finding from this work provides a new idea for the improvement or regulation of collagen-based products performance.

Co-assembly behaviors and rheological properties of a salt-free catanionic tetrapeptide/surfactant system in water

The co-assembly behavior of a short tetrapeptide (I3E) and a zwitterionic surfactant (dodecyldimethylamine oxide, C14DMAO) in water have been systematically investigated. The microstructures and properties of the I3E/C14DMAO mixture were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and a HAAKE rotational rheometer. Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and circular dichroism (CD) were used to explore the formation of different microstructures. It was found that, with the increasing of C14DMAO, the co-assembly of the I3E/C14DMAO mixture changed from nanofibers to nanosheets, and then finally to wormlike micelles and spherical micelles. And the rheological properties of the mixtures also changed with the increasing of C14DMAO concentration accordingly.

ChemInform Abstract: Efficient Synthesis of Ir‐Polyoxometalate Cluster Using a Continuous Flow Apparatus and STM Investigation of Its Coassembly Behavior on HOPG Surface.

AbstractBlack needle‐like crystals of K12Na2H2 [IrCl8P2W20O72] ·37H2O are prepared in a continuous‐flow reactor from aqueous solutions of IrCl3, Na8[HPW9O34], NaH2PO4, Na2HPO4, KCl, and HCl (60 °C, 13% yield).

Tuning of Polymeric Nanoparticles by Coassembly of Thermoresponsive Polymers and a Double Hydrophilic Thermoresponsive Block Copolymer

The coassembly behavior of thermoresponsive statistical copolymers and a double hydrophilic block copolymer having a permanently hydrophilic block and a thermoresponsive block is investigated. By adjusting the hydrophilicity of the thermoresponsive statistical copolymers, hybrid nanoparticles are obtained with various ratios of the two species. Importantly, the size of these nanoparticles can be controlled in between 40 and 250 nm dependent on the TCP and the amount of statistical copolymers in the solution. Simultaneous analysis of static and dynamic light scattering data indicates that the possible structure of nanoparticles varies from hard sphere to less compact architecture and most probably depends on a difference between cloud point temperatures of individual components. This developed coassembly method provides a simple platform for the preparation of defined polymeric nanoparticles.

Efficient Synthesis of Ir-Polyoxometalate Cluster Using a Continuous Flow Apparatus and STM Investigation of Its Coassembly Behavior on HOPG Surface.

Taking advantage of a continuous-flow apparatus, the iridium(III)-containing polytungstate cluster K12Na2H2[Ir2Cl8P2W20O72]·37H2O (1) was obtained in a reasonable yield (13% based on IrCl3·H2O). Compound 1 was characterized by Fourier transform IR, UV-visible, (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and thermogravimetric analysis measurements. (31)P NMR, ESI-MS, and elemental analysis all indicated 1 was a new polytungstate cluster compared with the reported K14[(IrCl4)KP2W20O72] compound. Intriguingly, the successful isolation of 1 relied on the custom-built flow apparatus, demonstrating the uniqueness of continuous-flow chemistry to achieve crystalline materials. The catalytic properties of 1 were assessed by investigating the activity on catalyzing the electro-oxidation of ruthenium tris-2,2'-bipyridine [Ru(bpy)3](2+/3+). The voltammetric behavior suggested a coupled catalytic behavior between [Ru(bpy)3](3+/2+) and 1. Furthermore, on the highly oriented pyrolytic graphite surface, 1,3,5-tris(10-carboxydecyloxy) benzene (TCDB) was used as the two-dimensional host network to coassemble cluster 1; the surface morphology was observed by scanning tunneling microscope technique. "S"-shape of 1 was observed, indicating that the cluster could be accommodated in the cavity formed by two TCDB host molecules, leading to a TCDB/cluster binary structure.

Glucose-Responsive Hybrid Nanoassemblies in Aqueous Solutions: Ordered Phenylboronic Acid within Intermixed Poly(4-hydroxystyrene)-block-poly(ethylene oxide) Block Copolymer.

Coassembly behavior of the double hydrophilic block copolymer poly(4-hydroxystyrene)-block-poly(ethylene oxide) (PHOS-PEO) with three amphiphilic phenylboronic acids (PBA) differing in hydrophobicity, 4-dodecyloxyphenylboronic acid (C12), 4-octyloxyphenylboronic acid (C8), and 4-isobutoxyphenylboronic acid (i-Bu) was studied in alkaline aqueous solutions and in mixtures of NaOHaq/THF by spin-echo (1)H NMR spectroscopy, dynamic and electrophoretic light scattering, and SAXS. The study reveals that only the coassembly of C12 with PHOS-PEO provides spherical nanoparticles with intermixed PHOS and PEO blocks, containing densely packed C12 micelles. NMR measurements have shown that spatial proximity of PHOS-PEO and C12 leads to the formation of ester bonds between -OH of PHOS block and hydroxyl groups of -B(OH)2. Due to the presence of PBA moieties, the release of compounds with 1,2- or 1,3-dihydroxy groups loaded in the coassembled PHOS-PEO/PBA nanoparticles by covalent binding to PBA can be triggered by addition of a surplus of glucose that bind to PBA competitively. The latter feature has been confirmed by fluorescence measurements using Alizarin Red as a model compound. Nanoparticles were proved to exhibit swelling in response to glucose as detected by light scattering.

Tunable Thermoresponsiveness of Resilin via Coassembly with Rigid Biopolymers.

The ability to tune the thermoresponsiveness of recombinant resilin protein, Rec1-resilin, through a facile coassembly system was investigated in this study. The effects of change in conformation and morphology with time and the responsive behavior of Rec1-resilin in solution were studied in response to the addition of a rigid model polypeptide (poly-l-proline) or a hydrophobic rigid protein (Bombyx mori silk fibroin). It was observed that by inducing more ordered conformations and increasing the hydrophobicity the lower critical solution temperature (LCST) of the system was tuned to lower values. Time and temperature were found to be critical parameters in controlling the coassembly behavior of Rec1-resilin in both the model polypeptide and more complex protein systems. Such unique properties are useful for a wide range of applications, including drug delivery and soft tissue engineering applications.

Toward model‐driven engineering of supramolecular copolymers

ABSTRACTThe coassembly of two oligo‐(p‐phenylene vinylene) (OPV) derivatives with different sizes and opposite chirality is studied. Short R‐chiral ROPV3 molecules experience a high energetic mismatch penalty when incorporated in helices formed by long S‐chiral SOPV4 molecules. In contrast, SOPV4 easily coassembles into helices dominated by ROPV3. As a result, the coassembly behavior (i.e., mixing or phase separation of ROPV3 and SOPV4 within the assemblies) highly depends on the ratio between both molecular building blocks. By a combination of experiments and models, the assembly pathways are analyzed. Furthermore, the model allows identifying key parameters in the coassembly behavior, such as the cooperativity and the mismatch penalties. The model‐driven approach is anticipated to be generally applicable in the engineering of functional supramolecular copolymers. This article is dedicated to the 70th birthday of Jean Fréchet and we thank him for being a continuous source of inspiration for our group. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 385–391

Mesoscale Simulations of Cylindrical Nanoparticle-Driven Assembly of Diblock Copolymers in Concentrated Solutions

Dissipative particle dynamics simulations have been performed to study the coassembly behavior of short carbon nanotubes and diblock copolymers in concentrated solutions by modeling nanotubes as cylindrical nanoparticles (CNPs). With varying the hydrophobic/hydrophilic ratio of the diblock copolymers (AmBn) at fixed concentration and fixed chain length (m + n = 15), the influence of the addition of CNPs on the lyotropic mesophases including micellar, hexagonal, and lamellar phases has been examined in detail, in comparison with the reference systems involving spherical nanoparticles (SNPs). The simulations reveal that the one-dimensional nature of CNPs plays an important role in determining the final coassembly superstructures. It is interesting to find that the addition of CNPs has significantly increased the stability of the hexagonal phase of coassemblies by inducing the phase transformations of the micellar-to-hexagonal in A3B12 solutions and the lamellar-to-hexagonal in A7B8 solutions, whereas the la...

Dual redox responsive coassemblies of diselenide-containing block copolymers and polymer lipids.

A general approach is reported to fabricate a stimuli responsive system via coassembly of diselenide-containing block copolymers with polymer lipids, which integrates the stimuli-responsiveness of diselenide chemistry and the biocompatibility of polymer lipids. By using dynamic light scattering, transmission electron microscopy, and zeta potential analyzer, coassembly behavior of these two kinds of polymers and responsiveness of coassemblies have been investigated. These coassemblies can exhibit redox-responsiveness inheriting from the diselenide-containing block copolymers. In the presence of low concentration of hydrogen peroxide or glutathione, the coassemblies can be disrupted.

Demixed Micelle Morphology Control in Hydrocarbon/Fluorocarbon Cationic Surfactant Templating of Mesoporous Silica

We report a study of the coassembly behavior of mixed hydrocarbon surfactant cetyltrimethylammonium chloride (CTAC) and the fluorocarbon surfactant 1H,1H,2H,2H-perfluorodecylpyridinium chloride (HFDePC) with precipitated silica at room temperature. This pair of surfactants is known to segregate into demixed fluorocarbon-rich and hydrocarbon-rich micelles in dilute solution for a range of compositions. Synthesis parameters (including the molar composition of the surfactant mixture, the ammonia concentration, and the addition of NaCl or ethanol to the initial sols) are varied to show how the mixed or demixed micelles found in dilute aqueous solutions act as templates to form mesoporous silica. Four distinct types of pore structures are found. The first are particles with a single mesopore size and structure whose morphology is influenced by the addition of a second surfactant. Adding HFDePC to CTAC for this series of samples induces a transition from 2D hexagonal mesopores to disordered mesopores to mesh ph...

Coassembly of Graphene Oxide and Nanowires for Large-Area Nanowire Alignment

We study the coassembly behavior of graphene oxide (GO) nanosheets and Na(0.44)MnO(2) nanowires. With the addition of GO nanosheets to the nanowire aqueous suspension, we observed the concentration enrichment and orientation alignment of nanowires at the air-water interface. The aligned nanowires can be transferred to hydrophilic substrates with their orientation parallel to the liquid-substrate contact line upon evaporation of the solvent. The underlying mechanism was studied carefully. GO nanosheets can be thought as "soft" two-dimensional macromolecules. Through hydrogen bonding and ion-dipole interactions, GO nanosheets can adsorb onto the nanowire surface and alter the surface properties. As a result, the GO-adsorbed nanowires become surface active and are enriched at the air-water interface. The adsorption of GO also increases the negative surface charge density of the nanowires and thus further stabilizes the colloidal solution. When a critical concentration is reached, the alignment of nanowires occurs according to Onsager's theory. This study brings about a new application of GO in colloidal chemistry and a novel method to achieve large-area, unidirectional alignment of nanowires.