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Articles 1 - 12 of 12

Full-Text Articles in Biomaterials

Getting To The Root Of Bacterial Hairs: What Is “S”?, Rebecca Gaddis, Samantha O'Conner, Evan Anderson, Terri Camesano, Nancy Burnham Dec 2015

Getting To The Root Of Bacterial Hairs: What Is “S”?, Rebecca Gaddis, Samantha O'Conner, Evan Anderson, Terri Camesano, Nancy Burnham

Nancy A. Burnham

An atomic force microscope (AFM) was used to measure the steric forces of lipopolysaccharides (LPS) on the biofilm-forming bacteria, Pseudomonas aeruginosa. It is well known that LPS play a vital role in biofilm formation. These forces were characterized with a modified version of the Alexander and de Gennes (AdG) model for polymers, which is a function of equilibrium brush length, L, probe radius, R, temperature, T, separation distance, D, and an indefinite density variable, s. This last parameter was originally distinguished by de Gennes as the root spacing or mesh spacing depending upon the type of polymer adhesion; however since …


3d Scaffolds In Tissue Engineering And Regenerative Medicine: Beyond Structural Templates?, Tierney Deluzio, Dawit Seifu, Kibret Mequanint Aug 2015

3d Scaffolds In Tissue Engineering And Regenerative Medicine: Beyond Structural Templates?, Tierney Deluzio, Dawit Seifu, Kibret Mequanint

Tierney GB Deluzio

The objective of this article is to systematically present the emerging understanding that 3D porous scaffolds serve not only as structural templates for tissue fabrication but also provide complex signaling cues to cells and facilitate oxygen and therapeutic agent delivery. Strategies in the field of tissue engineering and regenerative medicine often rely on 3D scaffolds to mimic the natural extracellular matrix as structural templates that support cell adhesion, migration, differentiation and proliferation, and provide guidance for neo-tissue formation. In addition to providing a temporary support for tissue fabrication, 3D scaffolds have also been used to study cell signaling that best …


3d Scaffolds In Tissue Engineering And Regenerative Medicine: Beyond Structural Templates?, Tierney Deluzio, Dawit Seifu, Kibret Mequanint Aug 2015

3d Scaffolds In Tissue Engineering And Regenerative Medicine: Beyond Structural Templates?, Tierney Deluzio, Dawit Seifu, Kibret Mequanint

Tierney GB Deluzio

The objective of this article is to systematically present the emerging understanding that 3D porous scaffolds serve not only as structural templates for tissue fabrication but also provide complex signaling cues to cells and facilitate oxygen and therapeutic agent delivery. Strategies in the field of tissue engineering and regenerative medicine often rely on 3D scaffolds to mimic the natural extracellular matrix as structural templates that support cell adhesion, migration, differentiation and proliferation, and provide guidance for neo-tissue formation. In addition to providing a temporary support for tissue fabrication, 3D scaffolds have also been used to study cell signaling that best …


Three-Dimensional Confocal Microscopy Indentation Method For Hydrogel Elasticity Measurement, Donghee Lee, Md Mahmudur Rahman, You Zhou, Sangjin Ryu Aug 2015

Three-Dimensional Confocal Microscopy Indentation Method For Hydrogel Elasticity Measurement, Donghee Lee, Md Mahmudur Rahman, You Zhou, Sangjin Ryu

Md Mahmudur Rahman

No abstract provided.


Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee Jul 2012

Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee

Debbie Chachra

Conformational changes in collagen fibrils, and indeed the triple helix, can be produced by application of mechanical stress or strain. We have demonstrated that the rate of cross-linking in glutaraldehyde and epoxide homobifunctional reagents can be modulated by uniaxial stress (strain). Two poly(glycidyl ether) epoxides were used: Denacol® EX-810 (a small bifunctional reagent), and Denacol EX-512 (a large polyfunctional reagent). To prevent any possible effect from being masked by saturation of cross-linking sites, bovine pericardium was cross-linked to such an extent that the increase in collagen denaturation temperature, Td, was one-half of the maximal rise achievable with …


Stability Of A Microvessel Subject To Structural Adaptation Of Diameter And Wall Thickness, Alisha Sarang-Sieminski, John Geddes, Ilari Shafer, Rachel Nancollas, Morgan Boes May 2012

Stability Of A Microvessel Subject To Structural Adaptation Of Diameter And Wall Thickness, Alisha Sarang-Sieminski, John Geddes, Ilari Shafer, Rachel Nancollas, Morgan Boes

John B. Geddes

Vascular adaptation—or structural changes of microvessels in response to physical and metabolic stresses—can influence physiological processes like angiogenesis and hypertension. To better understand the influence of these stresses on adaptation, Pries et al. (1998, 2001a,b, 2005) have developed a computational model for microvascular adaptation. Here, we reformulate this model in a way that is conducive to a dynamical systems analysis. Using th ese analytic methods, we determine the equilibrium geometries of a single vessel under different conditions and classify its type of stability. We demonstrate that our closed-form solution for vessel geometry exhibits the same regions of stability as the …


Engineering Strategies To Recapitulate Epithelial Morphogenesis Within Synthetic Three-Dimensional Extracellular Matrix With Tunable Mechanical Properties, Alisha Sarang-Sieminski, Yekaterina Miroshnikova, D Jorgens, L Spirio, M Auer, V Weaver Apr 2012

Engineering Strategies To Recapitulate Epithelial Morphogenesis Within Synthetic Three-Dimensional Extracellular Matrix With Tunable Mechanical Properties, Alisha Sarang-Sieminski, Yekaterina Miroshnikova, D Jorgens, L Spirio, M Auer, V Weaver

Alisha L. Sarang-Sieminski

The mechanical properties (e.g. stiffness) of the extracellular matrix (ECM) influence cell fate and tissue morphogenesis and contribute to disease progression. Nevertheless, our understanding of the mechanisms by which ECM rigidity modulates cell behavior and fate remains rudimentary. To address this issue, a number of two and three-dimensional (3D) hydrogel systems have been used to explore the effects of the mechanical properties of the ECM on cell behavior. Unfortunately, many of these systems have limited application because fiber architecture, adhesiveness and/or pore size often change in parallel when gel elasticity is varied. Here we describe the use of ECM-adsorbed, synthetic, …


Self-Assembling Short Oligopeptides And The Promotion Of Angiogenesis, Alisha Sarang-Sieminski, Daria Narmoneva, Olumuyiwa Oni, Shugang Zhang, Jonathan Gertler, Roger Kamm, Richard Lee Apr 2012

Self-Assembling Short Oligopeptides And The Promotion Of Angiogenesis, Alisha Sarang-Sieminski, Daria Narmoneva, Olumuyiwa Oni, Shugang Zhang, Jonathan Gertler, Roger Kamm, Richard Lee

Alisha L. Sarang-Sieminski

Because an adequate blood supply to and within tissues is an essential factor for successful tissue regeneration, promoting a functional microvasculature is a crucial factor for biomaterials. In this study, we demonstrate that short self-assembling peptides form scaffolds that provide an angiogenic environment promoting long-term cell survival and capillary-like network formation in three-dimensional cultures of human microvascular endothelial cells. Our data show that, in contrast to collagen type I, the peptide scaffold inhibits endothelial cell apoptosis in the absence of added angiogenic factors, accompanied by enhanced gene expression of the angiogenic factor VEGF. In addition, our results suggest that the …


Primary Sequence Of Ionic Self-Assembling Peptide Gels Affects Endothelial Cell Adhesion And Capillary Morphogenesis, Alisha Sarang-Sieminski, C. Semino, Haiyan Gong, Roger Kamm Apr 2012

Primary Sequence Of Ionic Self-Assembling Peptide Gels Affects Endothelial Cell Adhesion And Capillary Morphogenesis, Alisha Sarang-Sieminski, C. Semino, Haiyan Gong, Roger Kamm

Alisha L. Sarang-Sieminski

Appropriate choice of biomaterial supports is critical for the study of capillary morphogenesis in vitro as well as to support vascularization of engineered tissues in vivo. Self-assembling peptides are a class of synthetic, ionic, oligopeptides that spontaneously assemble into gels with an ECM-like microarchitecture when exposed to salt. In this paper, the ability of four different self-assembling peptide gels to promote endothelial cell adhesion and capillary morphogenesis is explored. Human umbilical vein endothelial cells (HUVECs) were cultured within ionic self-assembling peptide family members, RAD16-I ((RADA)4), RAD16-II ((RARADADA)2), KFE-8 ((FKFE)2), or KLD-12 ((KLDL)3). …


Biomaterial-Microvasculature Interactions, Alisha Sarang-Sieminski, Keith Gooch Apr 2012

Biomaterial-Microvasculature Interactions, Alisha Sarang-Sieminski, Keith Gooch

Alisha L. Sarang-Sieminski

The utility of implanted sensors, drug-delivery systems, immunoisolation devices, engineered cells, and engineered tissues can be limited by inadequate transport to and from the circulation. As the primary function of the microvasculature is to facilitate transport between the circulation and the surrounding tissue, interactionsbetween biomaterials and the microvasculature have been explored to understand the mechanisms controlling transport to implanted objects and ultimately improve it. This review surveys work on biomaterial-microvasculature interactions with a focus on the use of biomaterials to regulate the structure and function of the microvasculature. Several applications in which biomaterial-microvasculature interactions play a crucial role are briefly …


The Relative Magnitudes Of Endothelial Force Generation And Matrix Stiffness Modulate Capillary Morphogenesis In Vitro, Alisha Sarang-Sieminski, Robert Hebbel, Keith Gooch Apr 2012

The Relative Magnitudes Of Endothelial Force Generation And Matrix Stiffness Modulate Capillary Morphogenesis In Vitro, Alisha Sarang-Sieminski, Robert Hebbel, Keith Gooch

Alisha L. Sarang-Sieminski

When suspended in collagen gels, endothelial cells elongate and form capillary-like networks containing lumens. Human blood outgrowth endothelial cells (HBOEC) suspended in relatively rigid 3 mg/ml floating collagen gels, formed in vivo-like, thin, branched multi-cellular structures with small, thick-walled lumens, while human umbilical vein endothelial cells (HUVEC) formed fewer multi-cellular structures, had a spread appearance, and had larger lumens. HBOEC exert more traction on collagen gels than HUVEC as evidenced by greater contraction of floating gels. When the stiffness of floating gels was decreased by decreasing the collagen concentration from 3 to 1.5 mg/ml, HUVEC contracted gels more and formed …


A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas Feb 2012

A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas

Debbie Chachra

Current clinical tools for evaluating fracture risk focus only on the mineral phase of bone. However, changes in the collagen matrix may affect bone mechanical properties, increasing fracture risk while remaining undetected by conventional screening methods such as dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). The mechanical response tissue analyzer (MRTA) is a non-invasive, radiation-free potential clinical tool for evaluating fracture risk. The objectives of this study were two-fold: to investigate the ability of the MRTA to detect changes in mechanical properties of bone as a result of treatment with 1 M potassium hydroxide (KOH) and to evaluate …