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Comelles J.,University of Strasbourg | Hortiguela V.,Biomimetic Systems | Hortiguela V.,Research Center Biomedica en Red en Bioingenieria | Martinez E.,Biomimetic Systems | And 3 more authors.
Methods in Cell Biology | Year: 2015

Cell motility is an important phenomenon in cell biology, developmental biology, and cancer. Here we report methods that we designed to identify and characterize external factors which direct cell motions by breaking locally the symmetry. We used microfabrication and microfluidics techniques to impose and combine mechanical and chemical cues to moving fibroblasts. Gradients can thereby be engineered at the cellular scale and this approach has allowed to disentangle roles of the nucleus and protrusion activity in setting cell directions. © 2015 Elsevier Inc.

PubMed | Complutense University of Madrid, University of Barcelona, Biomimetic Systems, Institute for Bioengineering of Catalonia IBEC and 4 more.
Type: | Journal: Biomaterials | Year: 2016

Genome editing on human pluripotent stem cells (hPSCs) together with the development of protocols for organ decellularization opens the door to the generation of autologous bioartificial hearts. Here we sought to generate for the first time a fluorescent reporter human embryonic stem cell (hESC) line by means of Transcription activator-like effector nucleases (TALENs) to efficiently produce cardiomyocyte-like cells (CLCs) from hPSCs and repopulate decellularized human heart ventricles for heart engineering. In our hands, targeting myosin heavy chain locus (MYH6) with mCherry fluorescent reporter by TALEN technology in hESCs did not alter major pluripotent-related features, and allowed for the definition of a robust protocol for CLCs production also from human induced pluripotent stem cells (hiPSCs) in 14 days. hPSCs-derived CLCs (hPSCs-CLCs) were next used to recellularize acellular cardiac scaffolds. Electrophysiological responses encountered when hPSCs-CLCs were cultured on ventricular decellularized extracellular matrix (vdECM) correlated with significant increases in the levels of expression of different ion channels determinant for calcium homeostasis and heart contractile function. Overall, the approach described here allows for the rapid generation of human cardiac grafts from hPSCs, in a total of 24 days, providing a suitable platform for cardiac engineering and disease modeling in the human setting.

PubMed | National University of Santiago del Estero, National University of Quilmes, University of Buenos Aires, University of Lisbon and Biomimetic Systems
Type: | Journal: Colloids and surfaces. B, Biointerfaces | Year: 2016

Cationic antimicrobial peptides (CAMPs) represent important self defense molecules in many organisms, including humans. These peptides have a broad spectrum of activities, killing or neutralizing many Gram-negative and Gram-positive bacteria. The emergence of multidrug resistant microbes has stimulated research on the development of alternative antibiotics. In the search for new antibiotics, cationic antimicrobial peptides (CAMPs) offer a viable alternative to conventional antibiotics, as they physically disrupt the bacterial membranes, leading to lysis of microbial membranes and eventually cell death. In particular, the group of linear -helical cationic peptides has attracted increasing interest from clinical as well as basic research during the last decade. In this work, we studied the biophysical and microbiological characteristics of three new designed CAMPs. We modified a previously studied CAMP sequence, in order to increase or diminish the hydrophobic face, changing the position of two lysines or replacing three leucines, respectively. These mutations modified the hydrophobic moment of the resulting peptides and allowed us to study the importance of this parameter in the membrane interactions of the peptides. The structural properties of the peptides were also correlated with their membrane-disruptive abilities, antimicrobial activities and hemolysis of human red blood cells.

Disalvo E.A.,Biomimetic Systems | Pinto O.A.,CONICET | Martini M.F.,University of Buenos Aires | Bouchet A.M.,Biomimetic Systems | And 3 more authors.
Biochimica et Biophysica Acta - Biomembranes | Year: 2015

The classical view of a cell membrane is as a hydrophobic slab in which only nonpolar solutes can dissolve and permeate. However, water-soluble non-electrolytes such as glycerol, erythritol, urea and others can permeate lipid membranes in the liquid crystalline state. Moreover, recently polar amino acid's penetration has been explained by means of molecular dynamics in which appearance of water pockets is postulated. According to Träuble (1971), water diffuses across the lipid membranes by occupying holes formed in the lipid matrix due to fluctuations of the acyl chain trans-gauche isomers. These holes, named "kinks" have the molecular dimension of CH2 vacancies. The condensation of kinks may form aqueous spaces into which molecular species of the size of low molecular weight can dissolve. This molecular view can explain permeability properties considering that water may be distributed along the hydrocarbon chains in the lipid matrix. The purpose of this review is to consolidate the mechanism anticipated by Träuble by discussing recent data in literature that directly correlates the molecular state of methylene groups of the lipids with the state of water in each of them. In addition, the structural properties of water near the lipid residues can be related with the water activity triggering kink formation by changes in the head group conformation that induces the propagation along the acyl chains and hence to the diffusion of water. © 2015 Elsevier B.V. All rights reserved.

Bao J.,Nagoya University | Yang Z.,Soochow University of China | Nakajima M.,Nagoya University | Shen Y.,University of Hong Kong | And 5 more authors.
IEEE Transactions on Robotics | Year: 2014

This paper introduces a novel catalytic mobile micro/nanorobot made only of platinum that realizes nanometer locomotion in hydrogen peroxide solution. The innovative mechanism and principle of the nanorobot are presented. A simple and effective fabrication process by focused ion beam and a stable manipulation method of the nanorobot are demonstrated. The nanorobot can steer or navigate by its finely designed geometry, and keep a stable rotational motion rather than arbitrary and uncertain movement. This paper evaluates the influence of some critical factors on the movement of the nanorobot, such as the concentration and temperature of the hydrogen peroxide solution, and the geometry of a nanorobot. The control of the nanorobot's movement can be realized based on the result of this evaluation. Compared with previous studies, this catalytic platinum nanorobot realizes bidirectional rather than unidirectional movement. The Langevin equation is used to describe the dynamic model of the platinum nanorobot. © 2013 IEEE.

Salcedo C.L.,Biomimetic Systems | Salcedo C.L.,Research Center ansferencia Of Santiago Del Estero | Frias M.A.,Biomimetic Systems | Cutro A.C.,Biomimetic Systems | And 2 more authors.
Biochimica et Biophysica Acta - Biomembranes | Year: 2014

Polyphenols are well known as antioxidant agents and by their effects on the hydration layers of lipid interphases. Among them, gallic acid and its derivatives are able to decrease the dipole potential and to act in water as a strong antioxidant. In this work we have studied both effects on lipid interphases in monolayers and bilayers of dimyristoylphosphatidylcholine. The results show that gallic acid (GA) increases the negative surface charges of large unilamellar vesicles (LUVs) and decreases the dipole potential of the lipid interphase. As a result, positively charged radical species such as ABTS+ are able to penetrate the membrane forming an association with GA. These results allow discussing the antiradical activity (ARA) of GA at the membrane phase which may be taking place in water spaces between the lipids. © 2014 Elsevier B.V.

Freedman D.S.,Boston University | Cohen H.I.,Boston University | Deligeorges S.,Biomimetic Systems | Karl C.,Intel Corporation | Hubbard A.E.,Boston University
IEEE Transactions on Biomedical Circuits and Systems | Year: 2014

An analog inner hair cell and auditory nerve circuit using a dual AGC model has been implemented using 0.35 micron mixed-signal technology. A fully-differential current-mode architecture is used and the ability to correct channel mismatch is evaluated with matched layouts as well as with digital current tuning. The Meddis test paradigm is used to examine the analog implementation's auditory processing capabilities and investigate the circuit's ability to correct DC mismatch. The correction techniques used demonstrate the analog inner hair cell and auditory nerve circuit's potential use in low-power, multiple-sensor analog biomimetic systems with highly reproducible signal processing blocks on a single massively parallel integrated circuit. © 2014 IEEE.

Disalvo E.A.,Biomimetic Systems | Disalvo E.A.,CONICET | Hollmann A.,Biomimetic Systems | Hollmann A.,CONICET | And 4 more authors.
Biochimica et Biophysica Acta - Biomembranes | Year: 2013

Surface water activity appears as a common factor when the interaction of several aqueous soluble and surface active proteins with lipid membranes of different compositions is measured by the changes in surface pressure of a lipid monolayer. The perturbation of the lipid surface caused by aqueous soluble proteins depends on the composition of the hydrocarbon phases, either modified by unsaturated bonds in the acyl chains or by inclusion of cholesterol. The cut-off (critical) surface pressure in monolayers, at which no effect of the proteins is found, is related to the composition of the head group region. The perturbation of surface pressure is produced by proteins when the area per lipid is above just 4% larger than that corresponding to the hydration shell of the phospholipid head groups found in the cut-off. This area excess gives place to regions in which the chemical potential of water changes with respect to bulk water. According to the Defay-Prigogine relation this interfacial water activity is the reason of the surface pressure increase induced by aqueous soluble proteins injected in the subphase. As predicted by solution chemistry, the increase of surface pressure is independent of the protein nature but depends on the water surface state determined by the lipid composition. © 2013 Elsevier B.V.

Yue T.,Nagoya University | Nakajima M.,Nagoya University | Takeuchi M.,Nagoya University | Hu C.,Nagoya University | And 4 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2014

Currently, research on the construction of vascular-like tubular structures is a hot area of tissue engineering, since it has potential applications in the building of artificial blood vessels. In this paper, we report a fluidic self-assembly method using cell embedded microstructures to construct vascular-like microtubes. A novel 4-layer microfluidic device was fabricated using polydimethylsiloxane (PDMS), which contains fabrication, self-assembly and extraction areas inside one channel. Cell embedded microstructures were directly fabricated using poly(ethylene glycol) diacrylate (PEGDA) in the fabrication area, namely on-chip fabrication. Self-assembly of the fabricated microstructures was performed in the assembly area which has a micro well. Assembled tubular structures (microtubes) were extracted outside the channel into culture dishes using a normally closed (NC) micro valve in the extraction area. The self-assembly mechanism was experimentally demonstrated. The performance of the NC micro valve and embedded cell concentration were both evaluated. Fibroblast (NIH/3T3) embedded vascular-like microtubes were constructed inside this reusable microfluidic device. © 2014 The Royal Society of Chemistry.

Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.45K | Year: 2010

The human auditory system out-performs all current machine-based systems for analyzing and interpreting real world acoustic environments. Central to that human performance is the method of auditory scene analysis used by listeners and the mechanisms that allow creation of auditory objects. BioMimetic Systems has implemented real-time biomimetic algorithms in embedded hardware based on the ‘what’ and ‘where’ auditory pathways which are integral components for the formation of auditory objects in the brain. These algorithms provide biologically inspired feature sets representing spike activity from the auditory periphery to various brain centers including the Superior Olive (SO) and Inferior Colliculus (IC), representing critical points in the ’what’ and ‘where’ processing streams. Under this proposal we will accomplish two basic tasks. The first is to unify the features created by these auditory models to create auditory objects as a first step in creating an auditory scene analysis system. The second is to develop models of attentional mechanisms that can be used to modulate the formation of these auditory objects that include neuronal oscillations as well as predictive and competitive mechanisms. The hardware/software system will be tested against simple speech based attention tasks and performance compared to psychophysical data. BENEFIT: The proposed system of biomimetic algorithms and hardware with intrinsic attentional mechanisms will yield significantly increased performance for detection, identification, and localization tasks for acoustic targets. These gains will come in part from the greatly improved signal to noise ratio (SNR) the attentional mechanisms can provide through segregation of component sound sources and enabling analysis on these individual components. There are numerous applications of this technology for military senors in difficult and cluttered battlespace environments, particularly for urban and mountainous terrain with strong reverberation, as well as commercial speech to text systems, cell phone systems, and for advanced robotics.

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