scholarly journals Modeling Protein-based Hydrogels under Force

2018 ◽  
Author(s):  
Kirill Shmilovich ◽  
Ionel Popa
Keyword(s):  
Phase Transition ◽  
Mechanical Response ◽  
Network Dynamics ◽  
Protein Domains ◽  
Cross Linking ◽  
Ensemble Approach ◽  
Biomechanical Response ◽  
Protein Molecules ◽  
Scale Down ◽  
Protein Hydrogels

Hydrogels made from structured polyprotein domains combine the properties of cross-linked polymers with the unfolding phase transition. The use of protein hydrogels as an ensemble approach to study the physics of domain unfolding is limited by the lack of scaling tools and by the complexity of the system. Here we propose a model to describe the biomechanical response of protein hydrogels based on the unfolding and extension of protein domains under force. Our model takes into account the contributions on the network dynamics of the molecules inside the gels, which have random cross-linking points and random topology. This model reproduces reported macroscopic visco-elastic effects and constitutes an important step toward using rheometry on protein hydrogels to scale down to the average mechanical response of protein molecules.

scholarly journals Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

2019 ◽  
Author(s):  
Luai R. Khoury ◽  
Ionel Popa
Keyword(s):  
Protein Unfolding ◽  
Shape Change ◽  
Protein Domains ◽  
Fold Increase ◽  
Protein Mechanics ◽  
Protein Polymer ◽  
Novel Approach ◽  
Wide Range ◽  
Biomechanical Response ◽  
Protein Hydrogels

Abstract Programmable behavior combined with tailored stiffness and tunable biomechanical response are key requirements for developing successful materials. However, these properties are still an elusive goal for protein-based biomaterials. Here, we present a new method based on protein-polymer interactions, to manipulate the stiffness of protein-based hydrogels made from bovine serum albumin (BSA) by using polyelectrolytes such as poly(Ethelene)imine (PEI) and poly-L-lysine (PLL) at various concentrations. This approach confers protein-hydrogels tunable wide-range stiffness, from ~ 10 - 60 kPa when treated with PEI, without affecting the protein mechanics and nanostructure. We ascribe the increase in stiffness to the synergistic effect of the non-covalent electrostatic polymer-protein interaction, as well as the polymer-shell that stabilizes the protein domains nanomechanics. We use the 6-fold increase in stiffness induced by PEI to program BSA-hydrogels in various shapes. By utilizing the characteristic protein unfolding we can induce reversible shape-memory behavior of these composite materials using chemical denaturing solutions. We anticipate this novel approach based on protein engineering and polymer reinforcing will enable the development and investigation of new smart biomaterials and extend protein hydrogel capabilities beyond their conventional applications.

scholarly journals Mechanical Response of Carbon Nanotube Bundle to Lateral Compression

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 27 ◽  
Author(s):  
Dina U. Abdullina ◽  
Elena A. Korznikova ◽  
Volodymyr I. Dubinko ◽  
Denis V. Laptev ◽  
Alexey A. Kudreyko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Carbon Nanotube ◽  
Order Phase Transition ◽  
Mechanical Response ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Structure Evolution ◽  
Biaxial Compression ◽  
Chain Model ◽  
Bending Rigidity

Structure evolution and mechanical response of the carbon nanotube (CNT) bundle under lateral biaxial compression is investigated in plane strain conditions using the chain model. In this model, tensile and bending rigidity of CTN walls, and the van der Waals interactions between them are taken into account. Initially the bundle in cross section is a triangular lattice of circular zigzag CNTs. Under increasing strain control compression, several structure transformations are observed. Firstly, the second-order phase transition leads to the crystalline structure with doubled translational cell. Then the first-order phase transition takes place with the appearance of collapsed CNTs. Further compression results in increase of the fraction of collapsed CNTs at nearly constant compressive stress and eventually all CNTs collapse. It is found that the potential energy of the CNT bundle during deformation changes mainly due to bending of CNT walls, while the contribution from the walls tension-compression and from the van der Waals energies is considerably smaller.

Temperature-Responsive Supramolecular Hydrogels by Ternary Complex Formation with Subsequent Photo-Cross-linking to Alter Network Dynamics

2019 ◽  
Vol 20 (12) ◽  
pp. 4512-4521 ◽  
Author(s):  
Lei Zou ◽  
Bo Su ◽  
Christopher J. Addonizio ◽  
Irawan Pramudya ◽  
Matthew J. Webber
Keyword(s):  
Complex Formation ◽  
Ternary Complex ◽  
Network Dynamics ◽  
Cross Linking ◽  
Temperature Responsive ◽  
Ternary Complex Formation

scholarly journals Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Luai R. Khoury ◽  
Ionel Popa
Keyword(s):  
Protein Unfolding ◽  
Shape Change ◽  
Fold Increase ◽  
Protein Mechanics ◽  
Protein Polymer ◽  
Wide Range ◽  
Biomechanical Response ◽  
Polymer Interactions ◽  
Smart Biomaterials ◽  
Protein Hydrogels

AbstractProgrammable behavior combined with tailored stiffness and tunable biomechanical response are key requirements for developing successful materials. However, these properties are still an elusive goal for protein-based biomaterials. Here, we use protein-polymer interactions to manipulate the stiffness of protein-based hydrogels made from bovine serum albumin (BSA) by using polyelectrolytes such as polyethyleneimine (PEI) and poly-L-lysine (PLL) at various concentrations. This approach confers protein-hydrogels with tunable wide-range stiffness, from ~10–64 kPa, without affecting the protein mechanics and nanostructure. We use the 6-fold increase in stiffness induced by PEI to program BSA hydrogels in various shapes. By utilizing the characteristic protein unfolding we can induce reversible shape-memory behavior of these composite materials using chemical denaturing solutions. The approach demonstrated here, based on protein engineering and polymer reinforcing, may enable the development and investigation of smart biomaterials and extend protein hydrogel capabilities beyond their conventional applications.

scholarly journals Rat basophilic leukemia cells stiffen when they secrete.

1987 ◽  
Vol 105 (6) ◽  
pp. 2933-2943 ◽  
Author(s):  
Z Y Liu ◽  
J I Young ◽  
E L Elson
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Time Course ◽  
Mechanical Response ◽  
Cytochalasin D ◽  
Ion Concentration ◽  
Cross Linking ◽  
Ionophore A23187 ◽  
Receptor Complexes ◽  
Kinase C

RBL cells provide a useful model of the IgE and antigen-dependent stimulus-secretion coupling of mast cells and basophils. We have measured cellular deformability to investigate the participation of cytoskeletal mechanical changes. Cross-linking cell-surface IgE-receptor complexes with multivalent ligands not only triggered secretion but also caused the cells to stiffen, i.e., to become more resistant to deformation. This mechanical response required receptor cross-linking, had a time course similar to that of secretion, and was reversed by DNP-L-lysine, a competitive inhibitor of antigen binding. Hence the same stimulus seems to elicit both stiffening and secretion. Cytochalasin D, which inhibits actin filament assembly, prevented or reversed stiffening, thereby implicating the cytoskeleton in the mechanical response. Increasing intracellular calcium ion concentration with the ionophore A23187 stiffened cells and stimulated secretion. Activation of protein kinase C with a phorbol ester also stiffened cells and enhanced both the stiffening and secretion caused by the ionophore. Yet cytochalasin D enhances secretion whereas activation of protein kinase c alone is insufficient for secretion. Therefore stiffening is neither necessary nor sufficient for secretion. These results characterize a cytoskeletal mechanical response triggered by the same receptor-dependent stimulus that elicits secretion and by second messengers that are thought to mediate between the receptor signal and secretion. The function of the mechanical response, however, remains to be determined.

scholarly journals Design and Demonstration of a Microbiaxial Optomechanical Device for Multiscale Characterization of Soft Biological Tissues with Two-Photon Microscopy

2011 ◽  
Vol 17 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Joseph T. Keyes ◽  
Stacy M. Borowicz ◽  
Jacob H. Rader ◽  
Urs Utzinger ◽  
Mohamad Azhar ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Tissue Sample ◽  
Imaging Techniques ◽  
High Stress ◽  
Viscoelastic Behavior ◽  
Biological Tissues ◽  
The Body ◽  
Two Photon ◽  
Biomechanical Response ◽  
Tissue Specimens

AbstractThe biomechanical response of tissues serves as a valuable marker in the prediction of disease and in understanding the related behavior of the body under various disease and age states. Alterations in the macroscopic biomechanical response of diseased tissues are well documented; however, a thorough understanding of the microstructural events that lead to these changes is poorly understood. In this article we introduce a novel microbiaxial optomechanical device that allows two-photon imaging techniques to be coupled with macromechanical stimulation in hydrated planar tissue specimens. This allows that the mechanical response of the microstructure can be quantified and related to the macroscopic response of the same tissue sample. This occurs without the need to fix tissue in strain states that could introduce a change in the microstructural configuration. We demonstrate the passive realignment of fibrous proteins under various types of loading, which demonstrates the ability of tissue microstructure to reinforce itself in periods of high stress. In addition, the collagen and elastin response of tissue during viscoelastic behavior is reported showing interstitial fluid movement and fiber realignment potentially responsible for the temporal behavior. We also demonstrate that nonhomogeneities in fiber strain exist over biaxial regions of assumed homogeneity.

scholarly journals ELASTIC DAMPER BASED ON THE CARBON NANOTUBE BUNDLE

2020 ◽  
Vol 18 (1) ◽  
pp. 001 ◽  
Author(s):  
Leysan Kh. Rysaeva ◽  
Elena A. Korznikova ◽  
Ramil T. Murzaev ◽  
Dina U. Abdullina ◽  
Aleksey A. Kudreyko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Carbon Nanotube ◽  
Order Phase Transition ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Mechanical Response ◽  
Compressive Strain ◽  
Period Doubling ◽  
Chain Model ◽  
Nanotube Bundle

Mechanical response of the carbon nanotube bundle to uniaxial and biaxial lateral compression followed by unloading is modeled under plane strain conditions. The chain model with a reduced number of degrees of freedom is employed with high efficiency. During loading, two critical values of strain are detected. Firstly, period doubling is observed as a result of the second order phase transition, and at higher compressive strain, the first order phase transition takes place when carbon nanotubes start to collapse. The loading-unloading stress-strain curves exhibit a hysteresis loop and, upon unloading, the structure returns to its initial form with no residual strain. This behavior of the nanotube bundle can be employed for the design of an elastic damper.

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