Slow release and delivery of antisense oligonucleotide drug by self-assembled peptide amphiphile nanofibers

Cataloged from PDF version of article.Antisense oligonucleotides provide a promising therapeutic approach for several disorders including cancer. Chemical stability, controlled release, and intracellular delivery are crucial factors determining their efficacy. Gels composed of nanofibrous peptide network have been previously suggested as carriers for controlled delivery of drugs to improve stability and to provide controlled release, but have not been used for oligonucleotide delivery. In this work, a self-assembled peptide nanofibrous system is formed by mixing a cationic peptide amphiphile (PA) with Bcl-2 antisense oligodeoxynucleotide (ODN), G3139, through electrostatic interactions. The self-assembly of PA-ODN gel was characterized by circular dichroism, rheology, atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM and SEM images revealed establishment of the nanofibrous PA-ODN network. Due to the electrostatic interactions between PA and ODN, ODN release can be controlled by changing PA and ODN concentrations in the PA-ODN gel. Cellular delivery of the ODN by PA-ODN nanofiber complex was observed by using fluorescently labeled ODN molecule. Cells incubated with PA-ODN complex had enhanced cellular uptake compared to cells incubated with naked ODN. Furthermore, Bcl-2 mRNA amounts were lower in MCF-7 human breast cancer cells in the presence of PA-ODN complex compared to naked ODN and mismatch ODN evidenced by quantitative RT-PCR studies. These results suggest that PA molecules can control ODN release, enhance cellular uptake and present a novel efficient approach for gene therapy studies and oligonucleotide based drug deliver

Template-Directed Synthesis of Silica Nanotubes for Explosive Detection

Cataloged from PDF version of article.Fluorescent porous organic-inorganic thin films are of interest of explosive detection because of their vapor phase fluorescence quenching property. In this work, we synthesized fluorescent silica nanotubes using a biomineralization process through self-assembled peptidic nanostructures. We designed and synthesized an amyloid-like peptide self-assembling into nanofibers to be used as a template for silica nanotube formation. The amine groups on the peptide nanofibrous system were used for nucleation of silica nanostructures. Silica nanotubes were used to prepare highly porous surfaces, and they were doped with a fluorescent dye by physical adsorption for explosive sensing. These porous surfaces exhibited fast, sensitive, and highly selective fluorescence quenching against nitro-explosive vapors. The materials developed in this work have vast potential in sensing applications due to enhanced surface area. © 2011 American Chemical Society

Self-Assembled Peptide Nanofiber Templated One-Dimensional Gold Nanostructures Exhibiting Resistive Switching

Cataloged from PDF version of article.An amyloid-like peptide molecule self-assembling into one-dimensional nanofiber structure in ethanol was designed and synthesized with functional groups that can bind to gold ions. The peptide nanofibers were used as templates for nucleation and growth of one-dimensional gold nanostructures in the presence of ascorbic acid as reducing agent. We performed multistep seed-mediated synthesis of gold nanoparticles by changing peptide/gold precursor and peptide/reducing agent ratios. Gold nanostructures with a wide range of morphologies such as smooth nanowires, noodle-like one-dimensional nanostructures, and uniform aggregates of spherical nanoparticles were synthesized by use of an environmentally friendly synthesis method. Nanoscale electrical properties of gold-peptide nanofibers were investigated using atomic force microscopy. Bias dependent current (IV) measurements on thin films of gold-peptide nanofiber hybrid revealed tunneling dominated transport and resistive switching. Gold-peptide nanofiber composite nanostructures can provide insight into electrical conduction in biomolecular/inorganic composites, highlighting their potential applications in electronics and optics. © 2012 American Chemical Society

Encapsulation of a zinc phthalocyanine derivative in self-assembled peptide nanofibers

Cataloged from PDF version of article.In this article, we demonstrate encapsulation of octakis(hexylthio) zinc phthalocyanine molecules by non-covalent supramolecular organization within self-assembled peptide nanofibers. Peptide nanofibers containing octakis(hexylthio) zinc phthalocyanine molecules were obtained via a straight-forward one-step self-assembly process under aqueous conditions. Nanofiber formation results in the encapsulation and organization of the phthalocyanine molecules, promoting ultrafast intermolecular energy transfer. The morphological, mechanical, spectroscopic and non-linear optical properties of phthalocyanine containing peptide nanofibers were characterized by TEM, SEM, oscillatory rheology, UV-Vis, fluorescence, ultrafast pump-probe and circular dichroism spectroscopy techniques. The ultrafast pump-probe experiments of octakis(hexylthio) zinc phthalocyanine molecules indicated pH controlled non-linear optical characteristics of the encapsulated molecules within self-assembled peptide nanofibers. This method can provide a versatile approach for bottom-up fabrication of supramolecular organic electronic devices. © 2012 The Royal Society of Chemistry

A deeper look at the GD1 stream::density variations and wiggles

Using deep photometric data from CFHT/Megacam, we study the morphology and density of the GD-1 stream, one of the longest and coldest stellar streams in the Milky Way. Our deep data recovers the lower main sequence of the stream with unprecedented quality, clearly separating it from Milky Way foreground and background stars. An analysis of the distance to different parts of the stream shows that GD-1 lies at a heliocentric distance between 8 and 10 kpc, with only a shallow gradient across 45 deg on the sky. Matched filter maps of the stream density show clear density variations, such as deviations from a single orbital track and tentative evidence for stream fanning. We also detect a clear under-density in the middle of the stream track at $\varphi_{1}$=-45 deg surrounded by overdense stream segments on either side. This location is a promising candidate for the elusive missing progenitor of the GD-1 stream. We conclude that the GD-1 stream has clearly been disturbed by interactions with the Milky Way disk or other sub-halos.Comment: submitted to MNRAS, comments welcom

Amyloid Inspired Self-Assembled Peptide Nanofibers

Cataloged from PDF version of article.Amyloid peptides are important components in many degenerative diseases as well as in maintaining cellular metabolism. Their unique stable structure provides new insights in developing new materials. Designing bioinspired selfassembling peptides is essential to generate new forms of hierarchical nanostructures. Here we present oppositely charged amyloid inspired peptides (AIPs), which rapidly self-assemble into nanofibers at pH 7 upon mixing in water caused by noncovalent interactions. Mechanical properties of the gels formed by selfassembled AIP nanofibers were analyzed with oscillatory rheology. AIP gels exhibited strong mechanical characteristics superior to gels formed by self-assembly of previously reported synthetic short peptides. Rheological studies of gels composed of oppositely charged mixed AIP molecules (AIP-1 + 2) revealed superior mechanical stability compared to individual peptide networks (AIP-1 and AIP-2) formed by neutralization of net charges through pH change. Adhesion and elasticity properties of AIP mixed nanofibers and charge neutralized AIP-1, AIP-2 nanofibers were analyzed by high resolution force− distance mapping using atomic force microscopy (AFM). Nanomechanical characterization of self-assembled AIP-1 + 2, AIP-1, and AIP-2 nanofibers also confirmed macroscopic rheology results, and mechanical stability of AIP mixed nanofibers was higher compared to individual AIP-1 and AIP-2 nanofibers self-assembled at acidic and basic pH, respectively. Experimental results were supported with molecular dynamics simulations by considering potential noncovalent interactions between the amino acid residues and possible aggregate forms. In addition, HUVEC cells were cultured on AIP mixed nanofibers at pH 7 and biocompatibility and collagen mimetic scaffold properties of the nanofibrous system were observed. Encapsulation of a zwitterionic dye (rhodamine B) within AIP nanofiber network was accomplished at physiological conditions to demonstrate that this network can be utilized for inclusion of soluble factors as a scaffold for cell culture studies. Copyright © 2012 American Chemical Societ

Size-controlled conformal nanofabrication of biotemplated three-dimensional TiO2 and ZnO nanonetworks

Cataloged from PDF version of article.A solvent-free fabrication of TiO2 and ZnO nanonetworks is demonstrated by using supramolecular nanotemplates with high coating conformity, uniformity, and atomic scale size control. Deposition of TiO2 and ZnO on three-dimensional nanofibrous network template is accomplished. Ultrafine control over nanotube diameter allows robust and systematic evaluation of the electrochemical properties of TiO2 and ZnO nanonetworks in terms of size-function relationship. We observe hypsochromic shift in UV absorbance maxima correlated with decrease in wall thickness of the nanotubes. Photocatalytic activities of anatase TiO2 and hexagonal wurtzite ZnO nanonetworks are found to be dependent on both the wall thickness and total surface area per unit of mass. Wall thickness has effect on photoexcitation properties of both TiO2 and ZnO due to band gap energies and total surface area per unit of mass. The present work is a successful example that concentrates on nanofabrication of intact three-dimensional semiconductor nanonetworks with controlled band gap energies

Rapid and Efficient Removal of Perfluorooctanoic Acid from Water with Fluorine-Rich Calixarene-Based Porous Polymers

On account of its nonbiodegradable nature and persistence in the environment, perfluorooctanoic acid (PFOA) accumulates in water resources and poses serious environmental issues in many parts of the world. Here, we present the development of two fluorine-rich calix[4]arene-based porous polymers, FCX4-P and FCX4-BP, and demonstrate their utility for the efficient removal of PFOA from water. These materials featured Brunauer–Emmett–Teller (BET) surface areas of up to 450 m^{2} g^{-1}, which is slightly lower than their nonfluorinated counterparts (up to 596 m^{2} g^{-1}). FCX4-P removes PFOA at environmentally relevant concentrations with a high rate constant of 3.80 g mg^{-1} h^{-1} and reached an exceptional maximum PFOA uptake capacity of 188.7 mg g^{-1}. In addition, it could be regenerated by simple methanol wash and reused without a significant decrease in performance

Discovery of a thin stellar stream in the SLAMS survey

We report the discovery of a thin stellar stream - which we name the Jet stream - crossing the constellations of Hydra and Pyxis. The discovery was made in data from the SLAMS survey, which comprises deep $g$ and $r$ imaging for a $650$ square degree region above the Galactic disc performed by the CTIO Blanco + DECam. SLAMS photometric catalogues will be made publicly available. The stream is approximately 0.18 degrees wide and 10 degrees long, though it is truncated by the survey footprint. Its colour-magnitude diagram is consistent with an old, metal-poor stellar population at a heliocentric distance of approximately 29 kpc. We corroborate this measurement by identifying a spatially coincident overdensity of likely blue horizontal branch stars at the same distance. There is no obvious candidate for a surviving stream progenitor.Comment: MNRAS accepted versio

Effects of Symmetry Breaking on the Strong and Electroweak Interactions of the Vector Nonet

Starting from a chiral invariant and quark line rule conserving Lagrangian of pseudoscalar and vector nonets we introduce first and second order symmetry breaking as well as quark line rule violating terms and fit the parameters, at tree level, to many strong and electroweak processes. A number of predictions are made. The electroweak interactions are included in a manifestly gauge invariant manner. The resulting symmetry breaking pattern is discussed in detail. Specifically, for the ``strong'' interactions, we study all the vector meson masses and V -> \phi \phi decays, including isotopic spin violations. In the electroweak sector we study the { rho^0 , omega , phi } -> e^+e^- decays, { pi^+ , K^+ , K^0 } ``charge radii'', K_{l3} ``slope factor'' and the overall e^+e^- -> pi^+ pi^- process. It is hoped that the resulting model may be useful as a reasonable description of low energy physics in the range up to about 1 GeV.Comment: 43 pages (LaTeX), 5 PostScript figures are included as uuencoded-compressed-tar file at the en