Mechanical Properties of Collagen-Fibrin Co-Gels

2009 ◽  
Author(s):  
Victor K. Lai ◽  
Edward A. Sander ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Properties ◽  
Healing Process ◽  
Mechanical Tests ◽  
Functional Requirements ◽  
Interpenetrating Networks ◽  
Modeling Framework ◽  
Fibrin Gels ◽  
Multi Scale ◽  
Engineered Tissues ◽  
Anisotropic Mechanical Properties

Achieving desired mechanical properties is critical to meeting the functional requirements of engineered tissues. Mechanical function is inextricably linked to tissue structure. For example, replacement of fibrin with collagen during the healing process results in compositional heterogeneity which governs mechanical strength and function. Artificial tissues engineered using biopolymers such as fibrin and collagen can undergo a remodeling process that produces a compositionally and structurally complex tissue equivalent (TE) with anisotropic mechanical properties. TE functionality is assessed in part through mechanical testing, but the TE response is dependent on multi-scale interactions, which are dependent on a heterogeneously distributed microstructure, and are therefore difficult to interpret. In order to unravel the coupling between TE microstructure and macroscopic mechanical behavior, we have developed a multi-scale modeling framework for incorporating single component microstructural networks [1]. To expand our modeling framework, it is necessary to incorporate interpenetrating fibrin and collagen networks. This issue is particularly critical towards understanding the remodeling process that occurs in fibrin gels, which gradually replace fibrin with collagen networks. In this work, we have begun to investigate interpenetrating fibrin-collagen co-gels by varying the co-gel composition and subjecting the gels to uniaxial mechanical tests [2]. This study lays the experimental foundation for determining how to construct interpenetrating networks for our multiscale modeling framework, which will ultimately allows us to better assess and predict TE mechanics and produce better engineered tissues.

Collagen Network Topology is Influenced by Collagen Concentration, But Not by Co-Gelation With Fibrin

2011 ◽  
Author(s):  
Victor K. Lai ◽  
Edward A. Sander ◽  
Spencer P. Lake ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Properties ◽  
Healing Process ◽  
Biological Tissues ◽  
Wound Healing Process ◽  
Type I ◽  
Collagen Gels ◽  
Collagen Network ◽  
Modeling Framework ◽  
Collagen Concentration ◽  
Cardiovascular Tissue

Extracellular matrix (ECM) proteins (e.g. collagen, elastin) play an important role in biological tissues. In addition to conferring mechanical strength to a tissue, the ECM provides a biochemical environment essential for modulation of cellular responses such as growth and migration. Collagens are the dominant protein of the ECM, with collagen type I being most abundant. Our group and others have shown that the mechanical properties of a collagen I matrix change with collagen concentration, and when formed in the presence of a secondary fibril network such as fibrin [1]. We are interested in collagen-fibrin systems because our group uses fibrin as the starting scaffold material for cardiovascular tissue engineering, which produces interpenetrating collagen-fibrin matrices during the remodeling process as the fibrin network is degraded and replaced with cell-deposited collagen [2]. Fibrin and collagen networks are also present together around the thrombus during the wound healing process. Research has shown that ECM mechanical properties are correlated with their overall network structure characteristics such as fibril diameter [3]. Currently we have a modeling framework that generates an ECM microstructural network which can be used to predict the overall properties of a bioengineered tissue [4]. This framework allows exploration of the structure-function relation, but how the structure depends on composition remains poorly understood, especially in multi-component gels. Thus, the objective of this work was to quantify the collagen network architecture in pure collagen gels of different concentrations and in collagen-fibrin co-gels.

Structural and Mechanical Differences Between Pure Collagen and Fibrin Gels and Partially Digested Co-Gels

2011 ◽  
Author(s):  
Christina R. Frey ◽  
Victor K. Lai ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Properties ◽  
Healing Process ◽  
Tissue Growth ◽  
Wound Healing Process ◽  
Fiber Networks ◽  
Fibrin Gels ◽  
Fibrin Networks ◽  
Skin Collagen ◽  
Pure Collagen ◽  
Over Time

Natural and bio-engineered tissues are often composed of multiple fiber networks (fibrin, collagen, elastin, etc.). The microstructure and interactions between components determine the macroscopic mechanical properties of the tissues. Examples of multi-fiber networks include skin (collagen and elastin) and thrombus during the wound healing process (collagen and fibrin). In addition, tissue engineers (eg. [1]) use fibrin as a scaffold to seed cells for tissue growth; over time, networks of collagen and fibrin coexist as the fibrin is degraded and replaced with cell-synthesized collagen. Our group has previously investigated the mechanical properties of single fiber networks of fibrin and collagen, but has shown that these do not obey the law of mixtures in a collagen-fibrin co-gel [2]. The goal of this project was to understand the interactions between the collagen and fibrin networks in a collagen-fibrin co-gel.

Thermal and Mechanical Properties of Natural Rubber/Rice Starch Interpenetrating Network Hydrogel

2013 ◽  
Vol 844 ◽  
pp. 77-80
Author(s):  
Warisada Sila-On ◽  
Jatuporn Pratoomted ◽  
Utsana Puapermpoonsiri ◽  
Chaiwute Vudjung ◽  
Wiwat Pichayakorn
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Mechanical Strength ◽  
Natural Rubber Latex ◽  
Amorphous Structure ◽  
Mechanical Tests ◽  
Rice Starch ◽  
Thermal And Mechanical Properties ◽  
Interpenetrating Networks ◽  
Scanning Calorimetry

Novel hydrogels based on natural rubber latex (NRL) and rice starch (RSt) (1:2 ratio) were prepared with various amount of N,N-methylenebisacrylamide (MBA) and 2.5 phr of maleic acid to form interpenetrating networks (IPN) using free-radical polymerization technique. The thermal and mechanical properties were performed by differential scanning calorimetry and mechanical tests. From data obtained, the change in Tg of rubber and melting point of RSt indicated that polymer-polymer interaction could be formed in IPN hydrogel. The higher amount addition of MBA created more mechanical strength of IPN hydrogels caused by the higher of interlacement formation. However, their mechanical strength of such hydrogels was lower than that of NRL alone due to the formation of amorphous structure in IPN hydrogel. These IPN hydrogels also improved the swelling property which will be utilized for wound healing application.

Mechanical Properties of Collagen, Fibrin and Collagen-Fibrin Networks

2010 ◽  
Author(s):  
Victor K. Lai ◽  
Edward A. Sander ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Properties ◽  
Rational Design ◽  
Tissue Growth ◽  
Model Framework ◽  
Modeling Framework ◽  
Tissue Microstructure ◽  
Engineered Tissues ◽  
Fibrin Networks ◽  
Dynamic Cell ◽  
Engineered Tissue

The macroscopic mechanical properties of bio-engineered tissues are inextricably linked to their microstructure. Often, their microstructure is a complex arrangement of several different components (e.g. collagen, fibrin) that interact with each other to give a tissue its overall properties. These microstructural complexities are further compounded by the dynamic cell interactions with the extracellular matrix (ECM). Our group [1] uses fibrin as the starting scaffold material for cell seeding and tissue growth; over time, the underlying microstructure undergoes dynamic remodeling as the fibrin network is degraded and gradually replaced with collagen. Currently, we have a modeling framework that incorporates a single-component microstructure network to predict the mechanical properties of the engineered tissue [2]. However, this model is unable to capture the transient intermediate stages of tissue growth, during which the tissue is composed of interpenetrating collagen and fibrin networks at varying compositions. In this work, we have incorporated a second network into our model and compared these modeling results with experimental data obtained from uniaxial tests on acellular collagen-fibrin co-gels. This work represents one step in the progression of our model to capture better the relationships between tissue microstructure and macroscopic mechanical properties, with the ultimate goal of developing a comprehensive model framework for rational design of functional engineered tissues.

Effect of silver nitrate on some mechanical properties of heat polymerizing acrylic resins

2019 ◽  
Vol 14 (1) ◽  
pp. 110
Author(s):  
Assiss. Prof. Dr. Sabiha Mahdi Mahdi ◽  
Dr. Firas Abd K. Abd K.
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silver Nitrate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Hardness Tester ◽  
Acrylic Resins ◽  
The Difference

Aim: The aimed study was to evaluate the influence of silver nitrate on surfacehardness and tensile strength of acrylic resins.Materials and methods: A total of 60 specimens were made from heat polymerizingresins. Two mechanical tests were utilized (surface hardness and tensile strength)and 4 experimental groups according to the concentration of silver nitrate used.The specimens without the use of silver nitrate were considered as control. Fortensile strength, all specimens were subjected to force till fracture. For surfacehardness, the specimens were tested via a durometer hardness tester. Allspecimens data were analyzed via ANOVA and Tukey tests.Results: The addition of silver nitrate to acrylic resins reduced significantly thetensile strength. Statistically, highly significant differences were found among allgroups (P≤0.001). Also, the difference between control and experimental groupswas highly significant (P≤0.001). For surface hardness, the silver nitrate improvedthe surface hardness of acrylics. Highly significant differences were statisticallyobserved between control and 900 ppm group (P≤0.001); and among all groups(P≤0.001)with exception that no significant differences between control and150ppm; and between 150ppm and 900ppm groups(P>0.05).Conclusion: The addition of silver nitrate to acrylics reduced significantly the tensilestrength and improved slightly the surface hardness.

The Mechanical Properties of Organic Modified Epoxy Resin

2020 ◽  
Vol 43 (3) ◽  
pp. 10-14
Author(s):  
Georgel MIHU ◽  
Claudia Veronica UNGUREANU ◽  
Vasile BRIA ◽  
Marina BUNEA ◽  
Rodica CHIHAI PEȚU ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Epoxy Resin ◽  
Epoxy Matrix ◽  
Epoxy Resins ◽  
Mechanical Tests ◽  
Organic Modification ◽  
Three Point Bending ◽  
Modified Epoxy

Epoxy resins have been presenting a lot of scientific and technical interests and organic modified epoxy resins have recently receiving a great deal of attention. For obtaining the composite materials with good mechanical proprieties, a large variety of organic modification agents were used. For this study gluten and gelatin had been used as modifying agents thinking that their dispersion inside the polymer could increase the polymer biocompatibility. Equal amounts of the proteins were milled together and the obtained compound was used to form 1 to 5% weight ratios organic agents modified epoxy materials. To highlight the effect of these proteins in epoxy matrix mechanical tests as three-point bending and compression were performed.

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 Fast Preparation of High-Performance Wood Materials Assisted by Ultrasonic and Vacuum Impregnation

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 567
Author(s):  
Hong Yang ◽  
Mingyu Gao ◽  
Jinxin Wang ◽  
Hongbo Mu ◽  
Dawei Qi
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Mechanical Tests ◽  
Vacuum Impregnation ◽  
Natural Forests ◽  
Ultrasonic Pretreatment ◽  
Fast Growing ◽  
Before And After ◽  
New Material ◽  
Ft Ir

In the absence of high-quality hardwood timber resources, we have gradually turned our attention from natural forests to planted fast-growing forests. However, fast-growing tree timber in general has defects such as low wood density, loose texture, and poor mechanical properties. Therefore, improving the performance of wood through efficient and rapid technological processes and increasing the utilization of inferior wood is a good way to extend the use of wood. Densification of wood increases the strength of low-density wood and extends the range of applications for wood and wood-derived products. In this paper, the effects of ultrasonic and vacuum pretreatment on the properties of high-performance wood were explored by combining sonication, vacuum impregnation, chemical softening, and thermomechanical treatments to densify the wood; then, the changes in the chemical composition, microstructure, and mechanical properties of poplar wood before and after treatment were analyzed comparatively by FT-IR, XRD, SEM, and mechanical tests. The results showed that with ultrasonic pretreatment and vacuum impregnation, the compression ratio of high-performance wood reached its highest level and the MOR and MOE reached their maximums. With the help of this method, fast-growing softwoods can be easily prepared into dense wood materials, and it is hoped that this new material can be applied in the fields of construction, aviation, and automobile manufacturing.

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