Immunostaining of cardiomyocytes monolayers grown on fibrous rS2/12-Linker-RGDS spidroin substrate.

<p>A: Photo of fibrous substrate, scale bar 20 μm.B: α-actinin (green), connexin (red), nuclei (blue) labeling, scale bar 20 μ.m (C-F) Close-ups of segments on image B, scale bar—5 μm.</p

Pseudocardiograms of wave propagation on various types of substrates.

<p>Arrows depict starting moments of an electrical stimulation. Decreased frequency or transformation rhythm responses are marked by the asterisks. A—PCL+fibronectin pseudocardiogram for fibronectin coated PCL fibrous substrate. B—pseudocardiogram for rS1/9 fibrous substrate. C—pseudocardiogram for rS2/12-Linker-RGDS fibrous substrate. D—pseudocardiogram for rS1/9+rS2/12-Linker-RGDS fibrous substrate. The calculated critical frequencies for various substrates are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121155#pone.0121155.t001" target="_blank">Table 1</a>.</p

Fluorescent image of α-actin (green) stained with Alexa Fluor-488 Phaloidinin conjugate and nuclei (blue) stained with DAPI of cultured rat cardiomyocytes monolayers grown on fibrous rS2/12-Linker-RGDS spidroin substrate (fibers are yellow).

<p>Scale bar—50 μm.</p

Comparison of functional properties of cardiac monolayers on different substrates.

<p>Comparison of functional properties of cardiac monolayers on different substrates.</p

Verification of suitability of monolayers grown on rS2/12-Linker-RGDS spidroin fibrous substrate for excitation wave propagation.

<p>A, D: isochrone maps for point stimulation from rS2/12-Linker-RGDS fibers and fibronectin coated side, respectively. Line interval: 60 ms. Arrows show direction of wave propagation in each case. B, C—freezed frames of processed optical mapping videos represented by A,D pictures, correspondingly. E, F—time-space plots for white lines shown on pictures B, C with marked angles for velocity calculation.</p

Representation of coordinated contractile activity of cardiomyocytes monolayer grown on rS2/12-Linker-RGDS spidroin fibrous substrate.

<p>Video freeze-frame of contractile activity, scale bar 20 μm. (A-E): Graphs of intensity variation over time on corresponding outlined regions of interest.</p

SEM micrographs of recombinant spidroin and fibroin <i>Bombyx mori</i> fibrous substrates.

<p>(a) low magnification of rS1/9 spidroin substrate (frame size 257 μm × 192 μm), (b) high magnification micrograph of rS1/9 spidroin fibers (frame size 5.6 μm × 4.2 μm), (c) high magnification micrograph of rS2/12-Linker-RGDS spidroin fibers (frame size 7.7 μm × 5.8 μm), (d) high magnification micrograph of rS1/9+rS2/12-Linker-RGDS spidroin (1:1) mixture fibers (frame size 6.3 μm × 4.7 μm), (e) high magnification micrograph of fibroin <i>Bombyx mori</i> fibers (frame size 11.4 μm × 8.5 μm).</p

Quantitative analysis of an adhesion assay of fibronectin-coated common substrates and silk polymer substrates.

<p>1-fibronectin, 2- PCL coated with fibronectin (thickness 0.3 μm), 3- fibroin Bombyx mori coated with fibronectin (thickness 0.25μm), 4-fibroin Bombyx mori (thickness 0.25 μm), 5- rS1/9 (thickness 0.4 μm), 6- rS2/12 (thickness 0.4 μm), 7- rS2/12-Linker-RGDS(thickness 0.35 μm), 8- rS2/12-Linker-RGDS (thickness 0.25 μm), 9- rS1/9+rS2/12-Linker-RGDS 1:1(thickness 0.6μm)</p

Gene construction for Linker-RGDS.

<p>Gene construction for Linker-RGDS.</p

Impedance spectroscopy of single bacterial nanofilament reveals water-mediated charge transfer

<div><p>For decades respiratory chain and photosystems were the main firing field of the studies devoted to mechanisms of electron transfer in proteins. The concept of conjugated lateral electron and transverse proton transport during cellular respiration and photosynthesis, which was formulated in the beginning of 1960-s, has been confirmed by thousands of experiments. However, charge transfer in recently discovered bacterial nanofilaments produced by various electrogenic bacteria is regarded currently outside of electron and proton conjugation concept. Here we report the new study of charge transfer within nanofilaments produced by <i>Shewanella oneidensis</i> MR-1 conducted in atmosphere of different relative humidity (RH). We utilize impedance spectroscopy and DC (direct current) transport measurements to find out the peculiarities of conductivity and Raman spectroscopy to analyze the nanofilaments’ composition. Data analysis demonstrates that apparent conductivity of nanofilaments has crucial sensitivity to humidity and contains several components including one with unusual behavior which we assign to electron transport. We demonstrate that in the case of <i>Shewanella oneidensis</i> MR-1 charge transfer within these objects is strongly mediated by water. Basing on current data analysis of conductivity we conclude that the studied filaments of <i>Shewanella oneidensis</i> MR-1 are capable of hybrid (conjugated) electron and ion conductivity.</p></div