scholarly journals Tunable Fibrin-Alginate Interpenetrating Network Hydrogels to Guide Cell Behavior

2019 ◽  
Author(s):  
Charlotte E. Vorwald ◽  
Tomas Gonzalez-Fernandez ◽  
Shreeya Joshee ◽  
Pawel Sikorski ◽  
J. Kent Leach
Keyword(s):  
Mechanical Properties ◽  
Network Formation ◽  
Mesh Size ◽  
Crosslinking Density ◽  
Biomechanical Properties ◽  
Capillary Network ◽  
Natural Polymers ◽  
Interpenetrating Network ◽  
Tunable Mechanical Properties ◽  
Fibrinogen Content

ABSTRACTHydrogels are effective platforms for use as artificial extracellular matrices, cell carriers, and to present bioactive cues. Two common natural polymers, fibrin and alginate, are broadly used to form hydrogels and have numerous advantages over synthetic materials. Fibrin is a provisional matrix containing native adhesion motifs for cell engagement, yet the interplay between mechanical properties, degradation, and gelation rate is difficult to decouple. Conversely, alginate is highly tunable yet bioinert and requires modification to present necessary adhesion ligands. To address these challenges, we developed a fibrin-alginate interpenetrating network (IPN) hydrogel to combine the desirable adhesion and stimulatory characteristics of fibrin with the tunable mechanical properties of alginate. We tested its efficacy by examining capillary network formation with entrapped co-cultures of mesenchymal stromal cells (MSCs) and endothelial cells (ECs). We manipulated thrombin concentration and alginate crosslinking density independently to modulate the fibrin structure, mesh size, degradation, and biomechanical properties of these constructs. In IPNs of lower stiffness, we observed a significant increase in total cell area (1.72×105 ± 7.9×104 μm2) and circularity (0.56 ± 0.03) compared to cells encapsulated in stiffer IPNs (3.98×104 ± 1.49×104 μm2 and 0.77 ± 0.09, respectively). Fibrinogen content did not influence capillary network formation. However, higher fibrinogen content led to greater retention of these networks confirmed via increased spreading and presence of F-actin at 7 days. This is an elegant platform to decouple cell adhesion and hydrogel bulk stiffness that will be broadly useful for cell instruction and delivery.

scholarly journals Microstructure and Mechanical Properties of Heterogeneous Ceramic-Polymer Composite Using Interpenetrating Network

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Eun-Hee Kim ◽  
Yeon-Gil Jung ◽  
Chang-Yong Jo
Keyword(s):  
Mechanical Properties ◽  
Fracture Strength ◽  
Porous Alumina ◽  
Porous Ceramic ◽  
Crosslinking Density ◽  
Porous Matrix ◽  
Interpenetrating Network ◽  
Polyurethane Acrylate ◽  
The Matrix ◽  
Distribution Of Stress

Prepolymer, which can be polymerized by a photo, has been infiltrated into a porous ceramic to improve the addition effect of polymer into the ceramic, as a function of the functionality of prepolymer. It induces the increase in the mechanical properties of the ceramic. The porous alumina (Al2O3) and the polyurethane acrylate (PUA) with a network structure by photo-polymerization were used as the matrix and infiltration materials, respectively. The porous Al2O3matrix without the polymer shows lower values in fracture strength than the composites, since the stress is transmitted more quickly via propagation of cracks from intrinsic defects in the porous matrix. However, in the case of composites, the distribution of stress between heterophases results in the improved mechanical properties. In addition, the mechanical properties of composites, such as elastic modulus and fracture strength, are enhanced with increasing the functionality of prepolymer attributed to the crosslinking density of polymer.

Biomechanical Properties of the Stifle Joint Lateral Collateral Ligament in Dogs

1992 ◽  
Vol 05 (04) ◽  
pp. 158-162 ◽  
Author(s):  
D. Blackketter ◽  
J Harari ◽  
J. Dupuis
Keyword(s):  
Mechanical Properties ◽  
Cruciate Ligament ◽  
Lateral Collateral Ligament ◽  
Biomechanical Properties ◽  
Fibular Head ◽  
Joint Stability ◽  
Collateral Ligament ◽  
Cranial Cruciate Ligament ◽  
Stifle Joint

Bone/lateral collateral ligament/bone preparations were tested and structural mechanical properties compared to properties of cranial cruciate ligament in 15 dogs. The lateral collateral ligament has sufficient stiffness to provide stifle joint stability and strength to resist acute overload following fibular head transposition.

scholarly journals 3D Printing of High Viscosity Reinforced Silicone Elastomers

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2239
Author(s):  
Nicholas Rodriguez ◽  
Samantha Ruelas ◽  
Jean-Baptiste Forien ◽  
Nikola Dudukovic ◽  
Josh DeOtte ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
New Technologies ◽  
Three Dimensional ◽  
High Viscosity ◽  
Layer By Layer ◽  
Silicone Elastomers ◽  
Uv Curable ◽  
Octet Truss ◽  
Tunable Mechanical Properties

Recent advances in additive manufacturing, specifically direct ink writing (DIW) and ink-jetting, have enabled the production of elastomeric silicone parts with deterministic control over the structure, shape, and mechanical properties. These new technologies offer rapid prototyping advantages and find applications in various fields, including biomedical devices, prosthetics, metamaterials, and soft robotics. Stereolithography (SLA) is a complementary approach with the ability to print with finer features and potentially higher throughput. However, all high-performance silicone elastomers are composites of polysiloxane networks reinforced with particulate filler, and consequently, silicone resins tend to have high viscosities (gel- or paste-like), which complicates or completely inhibits the layer-by-layer recoating process central to most SLA technologies. Herein, the design and build of a digital light projection SLA printer suitable for handling high-viscosity resins is demonstrated. Further, a series of UV-curable silicone resins with thiol-ene crosslinking and reinforced by a combination of fumed silica and MQ resins are also described. The resulting silicone elastomers are shown to have tunable mechanical properties, with 100–350% elongation and ultimate tensile strength from 1 to 2.5 MPa. Three-dimensional printed features of 0.4 mm were achieved, and complexity is demonstrated by octet-truss lattices that display negative stiffness.

scholarly journals Mechanical and Degradation Properties of Hybrid Scaffolds for Tissue Engineered Heart Valve (TEHV)

2021 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Rabia Nazir ◽  
Arne Bruyneel ◽  
Carolyn Carr ◽  
Jan Czernuszka
Keyword(s):  
Heart Valve ◽  
Crosslinking Density ◽  
Biomechanical Properties ◽  
Collagen Type I ◽  
Type I ◽  
Aortic Heart Valve ◽  
Tissue Engineered Heart Valve ◽  
Human Aortic Valve ◽  
Degradation Properties ◽  
Hybrid Scaffolds

In addition to biocompatibility, an ideal scaffold for the regeneration of valvular tissue should also replicate the natural heart valve extracellular matrix (ECM) in terms of biomechanical properties and structural stability. In our previous paper, we demonstrated the development of collagen type I and hyaluronic acid (HA)-based scaffolds with interlaced microstructure. Such hybrid scaffolds were found to be compatible with cardiosphere-derived cells (CDCs) to potentially regenerate the diseased aortic heart valve. This paper focused on the quantification of the effect of crosslinking density on the mechanical properties under dry and wet conditions as well as degradation resistance. Elastic moduli increased with increasing crosslinking densities, in the dry and wet state, for parent networks, whereas those of interlaced scaffolds were higher than either network alone. Compressive and storage moduli ranged from 35 ± 5 to 95 ± 5 kPa and 16 ± 2 kPa to 113 ± 6 kPa, respectively, in the dry state. Storage moduli, in the dry state, matched and exceeded those of human aortic valve leaflets (HAVL). Similarly, degradation resistance increased with increasing the crosslinking densities for collagen-only and HA-only scaffolds. Interlaced scaffolds showed partial degradation in the presence of either collagenase or hyaluronidase as compared to when exposed to both enzymes together. These results agree with our previous findings that interlaced scaffolds were composed of independent collagen and HA networks without crosslinking between them. Thus, collagen/HA interlaced scaffolds have the potential to fill in the niche for designing an ideal tissue engineered heart valve (TEHV).

scholarly journals Generation of Photopolymerized Microparticles Based on PEGDA Using Microfluidic Devices. Part 1. Initial Gelation Time and Mechanical Properties of the Material

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 293
Author(s):  
José M. Acosta-Cuevas ◽  
José González-García ◽  
Mario García-Ramírez ◽  
Víctor H. Pérez-Luna ◽  
Erick Omar Cisneros-López ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gelation Time ◽  
Mesh Size ◽  
Microfluidic Devices ◽  
Future Generation ◽  
Mechanical Tests ◽  
Continuous Systems ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Close Relationship

Photopolymerized microparticles are made of biocompatible hydrogels like Polyethylene Glycol Diacrylate (PEGDA) by using microfluidic devices are a good option for encapsulation, transport and retention of biological or toxic agents. Due to the different applications of these microparticles, it is important to investigate the formulation and the mechanical properties of the material of which they are made of. Therefore, in the present study, mechanical tests were carried out to determine the swelling, drying, soluble fraction, compression, cross-linking density (Mc) and mesh size (ξ) properties of different hydrogel formulations. Tests provided sufficient data to select the best formulation for the future generation of microparticles using microfluidic devices. The initial gelation times of the hydrogels formulations were estimated for their use in the photopolymerization process inside a microfluidic device. Obtained results showed a close relationship between the amount of PEGDA used in the hydrogel and its mechanical properties as well as its initial gelation time. Consequently, it is of considerable importance to know the mechanical properties of the hydrogels made in this research for their proper manipulation and application. On the other hand, the initial gelation time is crucial in photopolymerizable hydrogels and their use in continuous systems such as microfluidic devices.

scholarly journals Acute ethanol exposure disrupts VEGF receptor cell signaling in endothelial cells

2008 ◽  
Vol 295 (1) ◽  
pp. H174-H184 ◽  
Author(s):  
Katherine A. Radek ◽  
Elizabeth J. Kovacs ◽  
Richard L. Gallo ◽  
Luisa A. DiPietro
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Signaling ◽  
Network Formation ◽  
Ethanol Exposure ◽  
Capillary Network ◽  
Ethanol Metabolism ◽  
Vegf Receptor ◽  
Acute Ethanol

Physiological angiogenesis is regulated by various factors, including signaling through vascular endothelial growth factor (VEGF) receptors. We previously reported that a single dose of ethanol (1.4 g/kg), yielding a blood alcohol concentration of 100 mg/dl, significantly impairs angiogenesis in murine wounds, despite adequate levels of VEGF, suggesting direct effects of ethanol on endothelial cell signaling (40). To examine the mechanism by which ethanol influences angiogenesis in wounds, we employed two different in vitro angiogenesis assays to determine whether acute ethanol exposure (100 mg/dl) would have long-lasting effects on VEGF-induced capillary network formation. Ethanol exposure resulted in reduced VEGF-induced cord formation on collagen and reduced capillary network structure on Matrigel in vitro. In addition, ethanol exposure decreased expression of endothelial VEGF receptor-2, as well as VEGF receptor-2 phosphorylation in vitro. Inhibition of ethanol metabolism by 4-methylpyrazole partially abrogated the effect of ethanol on endothelial cell cord formation. However, mice treated with t-butanol, an alcohol not metabolized by alcohol dehydrogenase, exhibited no change in wound vascularity. These results suggest that products of ethanol metabolism are important factors in the development of ethanol-induced changes in endothelial cell responsiveness to VEGF. In vivo, ethanol exposure caused both decreased angiogenesis and increased hypoxia in wounds. Moreover, in vitro experiments demonstrated a direct effect of ethanol on the response to hypoxia in endothelial cells, as ethanol diminished nuclear hypoxia-inducible factor-1α protein levels. Together, the data establish that acute ethanol exposure significantly impairs angiogenesis and suggest that this effect is mediated by changes in endothelial cell responsiveness to both VEGF and hypoxia.

A Review of Water-Resistant Cellulose-Based Materials in Pharmaceutical and Biomedical Application

2021 ◽  
Vol 28 ◽  
Author(s):  
Bei He ◽  
Xinxin Liu ◽  
Shi Qi ◽  
Run Zheng ◽  
Minmin Chang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Biomedical Application ◽  
Drug Loading ◽  
Cellulose Fibers ◽  
Dip Coating ◽  
Wound Dressings ◽  
Attractive Alternative ◽  
Natural Polymers ◽  
Insoluble Drugs ◽  
Good Biocompatibility

Background: Cellulose, huge reserves of natural polymers, have been widely applied in pharmaceutical and biomedicine fields due to its good biocompatibility, biodegradability, non-toxicity and excellent mechanical properties. At present, water-resistant metal-based and petroleum-based materials applied in medical field exists obvious problems of poor biocompatibility and high cost. Therefore, water-resistant cellulose-based materials with good biocompatibility and low price will become an attractive alternative. This review aims to summarize the preparation of water-resistant cellulose-based materials and their potential application in pharmaceutical and biomedical in recent years. Methods: Common hydrophobic treatments of cellulose fibers or paper were overviewed. The preparation, properties and applications of water-resistant cellulose-based materials in the pharmaceutical and biomedical fields were summarized. Results: Common hydrophobic treatments of cellulose fibers or paper were divided into chemical modification (graft polymerization, crosslinking, solution casting or dip-coating), physico-chemical surface modifications (plasma treatments, surface patterning, electrostatic spraying and electrowetting) and physical processing (electrostatic spinning, SAS process and 3D EHD printing). These hydrophobically processed cellulose fibers or paper could be prepared into various water-resistant cellulose-based materials and applied in pharmaceutical excipients, drug-loaded amphiphilic micelles, drug-loaded composite fibers, hydrophobic biocomposite film/coatings and paper-based detectors. They presented excellent water resistance and biocompatibility, low cytotoxicity and high drug loading ability, and stable drug release rate, etc., which could be used for water-insoluble drugs carriers, wound dressings, and medical testing equipment. Conclusion: Currently, water-resistant cellulose-based materials were mainly applied in water-insoluble drugs delivery carriers, wound dressing and medical diagnosis and presented great application prospects. However, the contradiction between hydrophobicity and mechanical properties of these reported water-resistant cellulose-based materials limited their wider application in biomedicine such as tissue engineering. In the future, attention will be focused on the higher hydrophobicity of water-resistant cellulose-based materials with excellent mechanical properties. In addition, clinical medical research of water-resistant cellulose-based materials should be strengthened.

EFFECTS OF STOICHIOMETRY ON PROPERTIES OF DGEBF/DETDA EPOXY USING MOLECULAR DYNAMICS

2021 ◽  
Author(s):  
SAGAR PATIL ◽  
MICHAEL OLAYA ◽  
PRATHAMESH DESHPANDE ◽  
MARIANNA MAIARÙ ◽  
GREGORY ODEGARD
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Modeling ◽  
Bulk Modulus ◽  
Mass Density ◽  
Strong Dependence ◽  
Crosslinking Density ◽  
Mechanical Deformation ◽  
Epoxy System ◽  
Reactive Interface

This article details the molecular modeling of full and off-stoichiometry models of the DGEBF/DETDA epoxy system using Molecular Dynamics to predict the mechanical properties as a function of the crosslinking density. The Reactive Interface Force Field (IFF-R) is implemented in this work to simulate mechanical deformation. The “fix bond/react” command in LAMMPS is used to simulate crosslinking between epoxy monomers. The results show that the predicted mass density, volumetric shrinkage, and bulk modulus have a strong dependence on the stoichiometry of the epoxy.

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