scholarly journals Thixotropic Hydrogels Composed of Self-Assembled Nanofibers of Double-Hydrophobic Elastin-Like Block Polypeptides

2021 ◽  
Vol 22 (8) ◽  
pp. 4104
Author(s):  
Yusuke Sugioka ◽  
Jin Nakamura ◽  
Chikara Ohtsuki ◽  
Ayae Sugawara-Narutaki
Keyword(s):  
Three Dimensional ◽  
Cell Encapsulation ◽  
Research Field ◽  
Self Healing ◽  
Structure Property ◽  
Cell Binding ◽  
Order Of Magnitude ◽  
A Cell ◽  
Reversible Gel ◽  
Binding Sequence

Physically crosslinked hydrogels with thixotropic properties attract considerable attention in the biomedical research field because their self-healing nature is useful in cell encapsulation, as injectable gels, and as bioinks for three-dimensional (3D) bioprinting. Here, we report the formation of thixotropic hydrogels containing nanofibers of double-hydrophobic elastin-like polypeptides (ELPs). The hydrogels are obtained with the double-hydrophobic ELPs at 0.5 wt%, the concentration of which is an order of magnitude lower than those for previously reported ELP hydrogels. Although the kinetics of hydrogel formation is slower for the double-hydrophobic ELP with a cell-binding sequence, the storage moduli G′ of mature hydrogels are similar regardless of the presence of a cell-binding sequence. Reversible gel–sol transitions are demonstrated in step-strain rheological measurements. The degree of recovery of the storage modulus G′ after the removal of high shear stress is improved by chemical crosslinking of nanofibers when intermolecular crosslinking is successful. This work would provide deeper insight into the structure–property relationships of the self-assembling polypeptides and a better design strategy for hydrogels with desired viscoelastic properties.

DNA Hydrogels

2006 ◽  
Vol 950 ◽  
Author(s):  
Soong Ho Um ◽  
Nokyoung Park ◽  
Dan Luo
Keyword(s):  
Drug Delivery ◽  
Three Dimensional ◽  
Cell Encapsulation ◽  
Building Blocks ◽  
Biological Degradation ◽  
Research Areas ◽  
Synthesis Properties ◽  
A Cell ◽  
Artificial Extracellular Matrix ◽  
Dna Hydrogels

ABSTRACTA hydrogel has been developed into a promising scaffold for cell encapsulation or drug delivery useful in various biorelated research areas. DNA, with its outstanding specificity and flexibility and intrinsic biocompatibility, has been utilized as a new building block in the construction of this new three dimensional material-a DNA based hydrogel. Here, we report the synthesis, properties and applications of a DNA based hydrogel system. The DNA hydrogels are entirely constructed from branched DNA building blocks such as X-shaped DNA (X-DNA), Y-shaped DNA (Y-DNA), and T-shaped DNA (T-DNA) through an enzyme-catalyzed reaction. These DNA hydrogels can be easily patterned into different sizes with millimeter or micrometer scale and different shapes including cylindrical, rectangular, cross, star, and even the “CORNELL” logo. By adjusting the initial concentrations and original shapes of the different building blocks, the external and internal morphology and chemical/physical properties of the DNA hydrogel were easily tuned: The X-DNA based hydrogel (X-DNA gel) showed both the most swelling degree and mechanical strength as well as the higher resistance to chemical and biological degradation. Inspired by these characteristics of the DNA hydrogels, we have developed them into a drug delivery system, an artificial extracellular matrix, and even a cell-free protein producing template.

scholarly journals A Tailored Biomimetic Hydrogel as Potential Bioink to Print a Cell Scaffold for Tissue Engineering Applications: Printability and Cell Viability Evaluation

2021 ◽  
Vol 11 (2) ◽  
pp. 829
Author(s):  
Shyuan-Yow Chen ◽  
Yung-Chieh Cho ◽  
Tzu-Sen Yang ◽  
Keng-Liang Ou ◽  
Wen-Chien Lan ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Cell Viability ◽  
Three Dimensional ◽  
Cell Encapsulation ◽  
Pluronic F127 ◽  
Layer By Layer ◽  
Engineering Applications ◽  
Printing Quality ◽  
A Cell ◽  
Printing Parameters

The present study established a maximum standard for printing quality and developed a preliminary ideal index to print three-dimensional (3D) construct using the Gly-Arg-Gly-Asp (GRGD) peptide modified Pluronic-F127 hydrogel (hereafter defined as 3DG bioformer (3BE)) as bioink. In addition, the biocompatibility of 3BE for 3D printing applications was carefully investigated. For biocompatibility study and ideal printing parameter, we used the formulation of 3BE in three different concentrations (3BE-1: 25%, 3BE-2: 30%, and 3BE-3: 35%). The 3BE hydrogels were printed layer by layer as a cube-like construct with all diameters of the needle head under the same feed (100 mm/s). The printing parameters were determined using combinations of 3BE-1, 3BE-2, and 3BE-3 with three different standard needle sizes (Φ 0.13 mm, Φ 0.33 mm, and Φ 0.9 mm). The printed constructs were photographed and observed using optical microscopy. The cell viability and proliferation were evaluated using Live/Dead assay and immunofluorescence staining. Results showed that a stable of printed line and construct could be generated from the 3BE-3 combinations. Cytotoxicity assay indicated that the 3BE hydrogels possessed well biocompatibility. Bioprinting results also demonstrated that significant cell proliferation in the 3BE-3 combinations was found within three days of printing. Therefore, the study discovered the potential printing parameters of 3BE as bioink to print a stable construct that may also have high biocompatibility for cell encapsulation. This finding could serve as valuable information in creating a functional scaffold for tissue engineering applications.

Detection, Averaging, and 3D Reconstruction of Biological Specimens on Hypercubes (Transputer-based) Computers

1990 ◽  
Vol 48 (1) ◽  
pp. 454-455
Author(s):  
Jose-Maria Carazo ◽  
I. Benavides ◽  
S. Marco ◽  
J.L. Carrascosa ◽  
E.L. Zapata
Keyword(s):  
3D Reconstruction ◽  
3D Structure ◽  
Three Dimensional ◽  
Software Tools ◽  
Mapping Method ◽  
Computer Architectures ◽  
Parallel Computer ◽  
Reconstruction Process ◽  
Computing Power ◽  
Order Of Magnitude

Obtaining the three-dimensional (3D) structure of negatively stained biological specimens at a resolution of, typically, 2 - 4 nm is becoming a relatively common practice in an increasing number of laboratories. A combination of new conceptual approaches, new software tools, and faster computers have made this situation possible. However, all these 3D reconstruction processes are quite computer intensive, and the middle term future is full of suggestions entailing an even greater need of computing power. Up to now all published 3D reconstructions in this field have been performed on conventional (sequential) computers, but it is a fact that new parallel computer architectures represent the potential of order-of-magnitude increases in computing power and should, therefore, be considered for their possible application in the most computing intensive tasks.We have studied both shared-memory-based computer architectures, like the BBN Butterfly, and local-memory-based architectures, mainly hypercubes implemented on transputers, where we have used the algorithmic mapping method proposed by Zapata el at. In this work we have developed the basic software tools needed to obtain a 3D reconstruction from non-crystalline specimens (“single particles”) using the so-called Random Conical Tilt Series Method. We start from a pair of images presenting the same field, first tilted (by ≃55°) and then untilted. It is then assumed that we can supply the system with the image of the particle we are looking for (ideally, a 2D average from a previous study) and with a matrix describing the geometrical relationships between the tilted and untilted fields (this step is now accomplished by interactively marking a few pairs of corresponding features in the two fields). From here on the 3D reconstruction process may be run automatically.

Scanning-tunneling spectroscopy on conjugated polymer films

2003 ◽  
Vol 771 ◽  
Author(s):  
M. Kemerink ◽  
S.F. Alvarado ◽  
P.M. Koenraad ◽  
R.A.J. Janssen ◽  
H.W.M. Salemink ◽  
...  
Keyword(s):  
Polymer Films ◽  
Conjugated Polymer ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Direct Consequence ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Band Alignment ◽  
Scanning Tunneling ◽  
Order Of Magnitude

AbstractScanning-tunneling spectroscopy experiments have been performed on conjugated polymer films and have been compared to a three-dimensional numerical model for charge injection and transport. It is found that field enhancement near the tip apex leads to significant changes in the injected current, which can amount to more than an order of magnitude, and can even change the polarity of the dominant charge carrier. As a direct consequence, the single-particle band gap and band alignment of the organic material can be directly obtained from tip height-voltage (z-V) curves, provided that the tip has a sufficiently sharp apex.

A Self‐Healing Volume Variation Three‐Dimensional Continuous Bulk Porous Bismuth for Ultrafast Sodium Storage

2021 ◽  
pp. 2011264
Author(s):  
Xiaolong Cheng ◽  
Ruiwen Shao ◽  
Dongjun Li ◽  
Hai Yang ◽  
Ying Wu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Self Healing ◽  
Volume Variation ◽  
Sodium Storage

scholarly journals Origin and Application of the Twinned Calcite Strain Gauge

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 296
Author(s):  
Richard H. Groshong
Keyword(s):  
Stress Analysis ◽  
Strain Gauge ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Constant Strain Rate ◽  
Axis Orientation ◽  
Order Of Magnitude ◽  
Rate Experiment ◽  
Strain Axis ◽  
Expected Values

This paper is a personal account of the origin and development of the twinned-calcite strain gauge, its experimental verification, and its relationship to stress analysis. The method allows the calculation of the three-dimensional deviatoric strain tensor based on five or more twin sets. A minimum of about 25 twin sets should provide a reasonably accurate result for the magnitude and orientation of the strain tensor. The opposite-signed strain axis orientation is the most accurately located. Where one strain axis is appreciably different from the other two, that axis is generally within about 10° of the correct value. Experiments confirm a magnitude accuracy of 1% strain over the range of 1–12% axial shortening and that samples with more than 40% negative expected values imply multiple or rotational deformations. If two deformations are at a high angle to one another, the strain calculated from the positive and negative expected values separately provides a good estimate of both deformations. Most stress analysis techniques do not provide useful magnitudes, although most provide a good estimate of the principal strain axis directions. Stress analysis based on the number of twin sets per grain provides a better than order-of-magnitude approximation to the differential stress magnitude in a constant strain rate experiment.

scholarly journals Small footprint optoelectrodes using ring resonators for passive light localization

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Vittorino Lanzio ◽  
Gregory Telian ◽  
Alexander Koshelev ◽  
Paolo Micheletti ◽  
Gianni Presti ◽  
...  
Keyword(s):  
State Of The Art ◽  
Three Dimensional ◽  
Network Activity ◽  
Ring Resonators ◽  
Spatiotemporal Resolution ◽  
Optical Ring Resonators ◽  
Light Localization ◽  
Order Of Magnitude ◽  
Small Footprint

AbstractThe combination of electrophysiology and optogenetics enables the exploration of how the brain operates down to a single neuron and its network activity. Neural probes are in vivo invasive devices that integrate sensors and stimulation sites to record and manipulate neuronal activity with high spatiotemporal resolution. State-of-the-art probes are limited by tradeoffs involving their lateral dimension, number of sensors, and ability to access independent stimulation sites. Here, we realize a highly scalable probe that features three-dimensional integration of small-footprint arrays of sensors and nanophotonic circuits to scale the density of sensors per cross-section by one order of magnitude with respect to state-of-the-art devices. For the first time, we overcome the spatial limit of the nanophotonic circuit by coupling only one waveguide to numerous optical ring resonators as passive nanophotonic switches. With this strategy, we achieve accurate on-demand light localization while avoiding spatially demanding bundles of waveguides and demonstrate the feasibility with a proof-of-concept device and its scalability towards high-resolution and low-damage neural optoelectrodes.

scholarly journals Mitochondria and Pharmacologic Cardiac Conditioning—At the Heart of Ischemic Injury

2021 ◽  
Vol 22 (6) ◽  
pp. 3224
Author(s):  
Christopher Lotz ◽  
Johannes Herrmann ◽  
Quirin Notz ◽  
Patrick Meybohm ◽  
Franz Kehl
Keyword(s):  
Cell Death ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition ◽  
Research Field ◽  
Calcium Handling ◽  
Control Mechanisms ◽  
Intrinsic Resistance ◽  
Atp Production ◽  
Cardiac Conditioning ◽  
A Cell

Pharmacologic cardiac conditioning increases the intrinsic resistance against ischemia and reperfusion (I/R) injury. The cardiac conditioning response is mediated via complex signaling networks. These networks have been an intriguing research field for decades, largely advancing our knowledge on cardiac signaling beyond the conditioning response. The centerpieces of this system are the mitochondria, a dynamic organelle, almost acting as a cell within the cell. Mitochondria comprise a plethora of functions at the crossroads of cell death or survival. These include the maintenance of aerobic ATP production and redox signaling, closely entwined with mitochondrial calcium handling and mitochondrial permeability transition. Moreover, mitochondria host pathways of programmed cell death impact the inflammatory response and contain their own mechanisms of fusion and fission (division). These act as quality control mechanisms in cellular ageing, release of pro-apoptotic factors and mitophagy. Furthermore, recently identified mechanisms of mitochondrial regeneration can increase the capacity for oxidative phosphorylation, decrease oxidative stress and might help to beneficially impact myocardial remodeling, as well as invigorate the heart against subsequent ischemic insults. The current review highlights different pathways and unresolved questions surrounding mitochondria in myocardial I/R injury and pharmacological cardiac conditioning.

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