Peptide Nanotube Nematic Phase (original) (raw)
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Peptide nanotubes: molecular organisations, self-assembly mechanisms and applications
Soft Matter, 2011
Peptide nanotubes are promising bio-inspired self-assemblies with a wide range of envisioned applications. The present review addresses the recent advances in their fundamental comprehension and mechanistic aspects of their latest downstream uses. Through well-documented examples, including the Lanreotide peptide monodisperse nanotubes, the molecular organisations and interactions underlying such well-defined hierarchical nanoarchitectures are in particular examined. The kinetic and thermodynamic aspects of the corresponding self-assembly processes are also considered, especially the intriguing mechanism of nanotube wall closure. The recently unravelled Lanreotide self-assembly mechanisms have revealed, for instance, the limiting role of electrostatic repulsion in this critical step. Within the numerous applications currently explored, particular attention is given to promising inorganic deposition processes using peptide nanotubes as scaffolds. In exceptional cases, inorganic nanotubes with tunable diameters could be synthesised via peptide-based
Biophysical Journal, 2004
Lanreotide is a synthetic octapeptide used in the therapy against acromegaly. When mixed with pure water at 10% (w/w), Lanreotide (acetate salt) forms liquid crystalline and monodisperse nanotubes with a radius of 120 Å . The molecular and supramolecular organization of these structures has been determined in a previous work as relying on the lateral association of 26 b-sheet filaments made of peptide noncovalent dimers, the basic building blocks. The work presented here has been devoted to the corresponding self-association mechanisms, through the characterization of the Lanreotide structures formed in water, as a function of peptide (acetate salt) concentration (from 2% to 70% (w/w)) and temperature (from 158C to 708C). The corresponding states of water were also identified and quantified from the thermal behavior of water in the Lanreotide mixtures. At room temperature and below 3% (w/w) Lanreotide acetate in water, soluble aggregates were detected. From 3% to 20% (w/w) long individual and monodisperse nanotubes crystallized in a hexagonal lattice were evidenced. Their molecular and supramolecular organizations are identical to the ones characterized for the 10% (w/w) sample. Heating induces the dissolution of the nanotubes into soluble aggregates of the same structural characteristics as the room temperature ones. The solubilization temperature increases from 208C to 708C with the peptide concentration and reaches a plateau between 15% and 25% (w/w) in peptide. These aggregates are proposed to be the b-sheet filaments that self-associate to build the walls of the nanotubes. Above 20% (w/w) of Lanreotide acetate in water, polydisperse embedded nanotubes are formed and the hexagonal lattice is lost. These embedded nanotubes exhibit the same molecular and supramolecular organizations as the individual monodisperse nanotubes formed at lower peptide concentration. The embedded nanotubes do not melt in the range of temperature studied indicating a higher thermodynamic stability than individual nanotubes. In parallel, the thermal behaviors of water in mixtures containing 2-80% (w/w) in peptide have been studied by differential scanning calorimetry, and three different types of water were characterized: 1), bulk water melting at 08C, 2), nonfreezing water, and 3), interfacial water melting below 08C. The domains of existence and coexistence of these different water states are related to the different Lanreotide supramolecular structures. All these results were compiled into a binary Lanreotide-water phase diagram and allowed to propose a self-association mechanism of Lanreotide filaments into monodisperse individual nanotubes and embedded nanotubes.
Structural Role of Counterions Adsorbed on Self-Assembled Peptide Nanotubes
Journal of the American Chemical Society, 2012
Among noncovalent forces, electrostatic ones are the strongest and possess a rather long-range action. For these reasons, charges and counterions play a prominent role in selfassembly processes in water and therefore in many biological systems. However, the complexity of the biological media often hinders a detailed understanding of all the electrostatic-related events. In this context, we have studied the role of charges and counterions in the self-assembly of lanreotide, a cationic octapeptide. This peptide spontaneously forms monodisperse nanotubes (NTs) above a critical concentration when solubilized in pure water. Free from any screening buffer, we assessed the interactions between the different peptide oligomers and counterions in solutions, above and below the critical assembly concentration. Our results provide explanations for the selection of a dimeric building block instead of a monomeric one. Indeed, the apparent charge of the dimers is lower than that of the monomers because of strong chemisorption. This phenomenon has two consequences: (i) the dimer−dimer interaction is less repulsive than the monomer−monomer one and (ii) the lowered charge of the dimeric building block weakens the electrostatic repulsion from the positively charged NT walls. Moreover, additional counterion condensation (physisorption) occurs on the NT wall. We furthermore show that the counterions interacting with the NTs play a structural role as they tune the NTs diameter. We demonstrate by a simple model that counterions adsorption sites located on the inner face of the NT walls are responsible for this size control.
Bioinspired peptide nanotubes: deposition technology, basic physics and nanotechnology applications
Journal of Peptide Science, 2011
Synthetic peptide monomers can self-assemble into PNM such as nanotubes, nanospheres, hydrogels, etc. which represent a novel class of nanomaterials. Molecular recognition processes lead to the formation of supramolecular PNM ensembles containing crystalline building blocks. Such low-dimensional highly ordered regions create a new physical situation and provide unique physical properties based on electron-hole QC phenomena. In the case of asymmetrical crystalline structure, basic physical phenomena such as linear electro-optic, piezoelectric, and nonlinear optical effects, described by tensors of the odd rank, should be explored. Some of the PNM crystalline structures permit the existence of spontaneous electrical polarization and observation of ferroelectricity. The PNM crystalline arrangement creates highly porous nanotubes when various residues are packed into structural network with specific wettability and electrochemical properties.
Aqueous self-assembly within the homologous peptide series AnK
Langmuir : the ACS journal of surfaces and colloids, 2014
We compare the aqueous self-assembly behavior within the homologous peptide series AnK, where A is alanine, K is lysine, and n = 4, 6, 8, and 10. The aqueous peptide solubility, ϕ(s) (volume fraction), depends strongly on the number of hydrophobic alanine residues and decreases approximately as ϕ(s) ≈ 10(-n). Also the self-assembly structure depends on n. A4K is highly water-soluble and shows no relevant self-assembly. A6K, which has been extensively studied previously, forms hollow nanotubes in water. A8K and A10K self-assembly is characterized here using a combination of small- and wide-angle X-ray scattering, static and dynamic light scattering, cryo transmission electron microscopy, and circular dichroism spectroscopy. They both form similar thin rodlike aggregates with lengths on the order of 100 nm and a biaxial cross-section with dimensions of 4 nm × 8 nm. We show that different sample preparation protocols result in different lengths of the A10K rodlike aggregates. On the ba...
2011
In this study, we perform a morphological evaluation of the diverse nanostructures formed by varying concentration and amino acid sequence of a unique class of ultrasmall self-assembling peptides. We modified these peptides by replacing the aliphatic amino acid at the C-aliphatic terminus with different aromatic amino acids. We tracked the effect of introducing aromatic residues on self-assembly and morphology of resulting nanostructures. Whereas aliphatic peptides formed long, helical fibers that entangle into meshes and entrap >99.9% water, the modified peptides contrastingly formed short, straight fibers with a flat morphology. No helical fibers were observed for the modified peptides. For the aliphatic peptides at low concentrations, different supramolecular assemblies such as hollow nanospheres and membrane blebs were found. Since the ultrasmall peptides are made of simple, aliphatic amino acids, considered to have existed in the primordial soup, study of these supramolecular assemblies could be relevant to understanding chemical evolution leading to the origin of life on Earth. In particular, we propose a variety of potential applications in bioengineering and nanotechnology for the diverse self-assembled nanostructures.
Modular Design of Self-Assembling Peptide-Based Nanotubes
Journal of the American Chemical Society, 2015
An ability to design peptide-based nanotubes (PNTs) rationally with defined and mutable internal channels would advance understanding of peptide self-assembly, and present new biomaterials for nanotechnology and medicine. PNTs have been made from Fmoc dipeptides, cyclic peptides, and lock-washer helical bundles. Here we show that blunt-ended -helical barrelsi.e., pre-assembled bundles of -helices with central channels-can be used as building blocks for PNTs. This approach is general and systematic, and uses a set of de novo helical bundles as standards. One of these bundles, a hexameric -helical barrel, assembles into highly ordered PNTs, for which we have determined a structure by combining cryo-transmission electron microscopy, Xray fiber diffraction and model building. The structure reveals that the overall symmetry of the peptide module plays a critical role in ripening and ordering of the supramolecular assembly. PNTs based on pentameric, hexameric and heptameric -helical barrels sequester hydrophobic dye within their lumens.
Structural and optical properties of short peptides: nanotubes-to-nanofibers phase transformation
Journal of peptide science : an official publication of the European Peptide Society, 2014
Thermally induced phase transformation in bioorganic nanotubes, which self-assembled from two ultrashort dipeptides of different origin, aromatic diphenylalanine (FF) and aliphatic dileucine (LL), is studied. In both FF and LL nanotubes, irreversible phase transformation found at 120-180 °C is governed by linear-to-cyclic dipeptide molecular modification followed by formation of extended β-sheet structure. As a result of this process, native open-end FF and LL nanotubes are transformed into ultrathin nanofibrils. Found deep reconstructions at all levels from macroscopic (morphology) and structural space symmetry to molecular give rise to new optical properties in both aromatic FF and aliphatic LL nanofibrils and generation of blue photoluminescence (PL) emission. It is shown that observed blue PL peak is similar in these supramolecular nanofibrillar structures and is excited by the network of non-covalent hydrogen bonds that link newly thermally induced neighboring cyclic dipeptide ...