Structural and Conformational Dynamics of Self-Assembling Bioactive β‑Sheet Peptide Nanostructures Decorated with Multivalent RNA-Binding Peptides

Understanding the dynamic behavior of nanostructural systems is important during the development of controllable and tailor-made nanomaterials. This is particularly true for nanostructures that are intended for biological applications because biomolecules are usually highly dynamic and responsive to external stimuli. In this Article, we investigated the structural and conformational dynamics of self-assembling bioactive β-sheet peptide nanostructures using electron paramagnetic resonance (EPR) spectroscopy. The model peptide nanostructures are characterized by the cross-β spine of β-ribbon fibers and multiple RNA-binding bioactive peptides that constitute the shell of the nanostructures. We found first, that bioactive peptides at the shell of β-ribbon nanostructure have a mobility similar to that of an isolated monomeric peptide. Second, the periphery of the cross-β spine is more immobile than the distal part of surface-displayed bioactive peptides. Third, the rotational dynamics of short and long fibrils are similar; that is, the mobility is largely independent of the extent of aggregation. Fourth, peptides that constitute the shell are affected first by the external environment at the initial stage. The cross-β spine resists its external environment to a certain extent and abruptly disintegrates when the perturbation reaches a certain degree. Our results provide an overall picture of β-sheet peptide nanostructure dynamics, which should be useful in the development of dynamic self-assembled peptide nanostructures

Highly Transparent and Stretchable Conductors Based on a Directional Arrangement of Silver Nanowires by a Microliter-Scale Solution Process

We report an effective method for fabricating highly transparent and stretchable large-area conducting films based on a directional arrangement of silver nanowires (AgNWs) driven by a shear force in a microliter-scale solution process. The thin conducting films with parallel AgNWs or cross-junctions of AgNWs are deposited on the coating substrate by dragging a microliter drop of the coating solution trapped between two plates. The optical and electrical properties of the AgNW thin films are finely tuned by varying the simple systematic parameters in the coating process. The transparent thin films with AgNW cross-junctions exhibit the superior electrical conductivity with a sheet resistance of 10 Ω sq^–1 at a transmittance of 85% (λ = 550 nm), which is well described by the high ratio of DC to optical conductivity of 276 and percolation theory in a two-dimensional matrix model. This simple coating method enables the deposition of AgNW thin films with high optical transparency, flexibility, and stretchability directly on plastic substrates

Chemical structure and cytotoxic effect of CNT on HeLa cells.

<p>(A) The chemical structure of CNT (C₂₉H₄₂O₁₀, MW 550.64). (B) The effect of crude extract of <i>Antiaris toxicaria</i> on cell growth. (C) The effect of CNT on cell growth. (D) The effect of CNT on cell viability.</p

Anti-angiogenic effect of CNT decreased in autophagy- or apoptosis-inhibited cells.

<p>(A) Atg5 and LC3 conversion levels with 5 nM CNT treatment in normal HeLa cells or Atg5-knocked down cells. (B) Cleaved PARP levels with 10 nM CNT treatment in normal HeLa cells or Z-VAD-FMK pretreated cells. β-actin was used as an internal control. (C) Quantitative analysis of <i>in vitro</i> chemoinvasion assay with conditioned media from 5 nM CNT-treated HeLa cells or CNT-treated in Atg5-knocked down HeLa cells. (D) Quantitative analysis of <i>in vitro</i> chemoinvasion assay with conditioned media from 10 nM CNT-treated HeLa cells or with Z-VAD-FMK pretreated cells.</p

Schematic summary of CNT mediated signaling pathway related with anti-angiogenic activity.

<p>Schematic summary of CNT mediated signaling pathway related with anti-angiogenic activity.</p

Anti-angiogenic activity of CNT <i>in vitro</i> and <i>in vivo</i>.

<p>(A) Effect of CNT on HUVEC tube-forming ability. Arrows indicate broken tubes formed by VEGF-stimulated HUVECs. (B) Inhibitory activity of CNT on HUVEC invasiveness. (C) Effect of CNT on <i>in vivo</i> angiogenesis assay, CAM (NT: EtOH control, RA: Retinoic acid (1 µg/egg), and CNT (0.5 ng/egg)). Arrows indicate compound-mediated inhibition of CAM neovascularization. The inhibition ratio was calculated as the percentage of inhibited eggs relative to the total number of eggs tested.</p

CNT-induced apoptosis in HeLa cells.

<p>(A) Enhancement of sub G0/G1 cell population by CNT for 2 days, and analyzed for apoptosis by FACS. (B) Increased cleavage of PARP and caspase-3, in a dose-dependent manner after 24 h. (C) Increased cleavage of PARP and caspase-3 in a time-dependent manner with 10 nM CNT. Tubulin was used as an internal control. (D) Effect of apoptosis inhibitor on CNT-treated HeLa cells. (E) Detection of DNA fragmentation in CNT- or camptothecin-treated cells.</p

Anti-proliferative activity of CNT on HUVECs.

<p>(A) Growth inhibitory activity of CNT on HUVECs. (B) The effect of CNT on HUVEC viability as determined by the trypan blue assay. (C) The conversion of LC3-I to LC3-II and increased cleavage of PARP following treatment with 10 nM CNT over time on HUVECs. Tubulin was used as an internal control. (D) Relative ratio of LC3 conversion and cleaved PARP was calculated as the percentage of LC3-I conversion to LC3-II and PARP to cleaved PARP, respectively.</p

Effect of CNT on the mTOR/p70S6K signaling pathway.

<p>Tubulin was used as an internal control.</p

IC₅₀ values of CNT on various cell lines.

<p>IC₅₀ values of CNT on various cell lines.</p