Viscoelastic and Biomechanical Properties of Osteochondral Tissue Constructs Generated From Graded Polycaprolactone and Beta-Tricalcium Phosphate Composites

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Cevat Erisken ◽  
Dilhan M. Kalyon ◽  
Hongjun Wang
Keyword(s):  
Viscoelastic Material ◽  
Tricalcium Phosphate ◽  
Biomechanical Properties ◽  
Native Tissue ◽  
Tissue Constructs ◽  
Material Functions ◽  
Extracellular Matrix Components ◽  
Linear Viscoelastic ◽  
Engineered Tissue ◽  
Osteochondral Tissue

The complex micro-/nanostructure of native cartilage-to-bone insertion exhibits gradations in extracellular matrix components, leading to variations in the viscoelastic and biomechanical properties along its thickness to allow for smooth transition of loads under physiological movements. Engineering a realistic tissue for osteochondral interface would, therefore, depend on the ability to develop scaffolds with properly graded physical and chemical properties to facilitate the mimicry of the complex elegance of native tissue. In this study, polycaprolactone nanofiber scaffolds with spatially controlled concentrations of β-tricalcium phosphate nanoparticles were fabricated using twin-screw extrusion-electrospinning process and seeded with MC3T3-E1 cells to form osteochondral tissue constructs. The objective of the study was to evaluate the linear viscoelastic and compressive properties of the native bovine osteochondral tissue and the tissue constructs formed in terms of their small-amplitude oscillatory shear, unconfined compression, and stress relaxation behavior. The native tissue, engineered tissue constructs, and unseeded scaffolds exhibited linear viscoelastic behavior for strain amplitudes less than 0.1%. Both native tissue and engineered tissue constructs demonstrated qualitatively similar gel-like behavior as determined using linear viscoelastic material functions. The normal stresses in compression determined at 10% strain for the unseeded scaffold, the tissue constructs cultured for four weeks, and the native tissue were 0.87±0.08 kPa, 3.59±0.34 kPa, and 210.80±8.93 kPa, respectively. Viscoelastic and biomechanical properties of the engineered tissue constructs were observed to increase with culture time reflecting the development of a tissuelike structure. These experimental findings suggest that viscoelastic material functions of the tissue constructs can provide valuable inputs for the stages of in vitro tissue development.

scholarly journals Creating biomaterials with spatially organized functionality

2016 ◽  
Vol 241 (10) ◽  
pp. 1025-1032 ◽  
Author(s):  
Lesley W Chow ◽  
Jacob F Fischer
Keyword(s):  
Biological Function ◽  
State Of The Art ◽  
Hierarchical Organization ◽  
Tissue Constructs ◽  
Tissue Organization ◽  
Current State ◽  
Extracellular Matrix Components ◽  
Engineered Tissue ◽  
Spatial Presentation ◽  
And Function

Biomaterials for tissue engineering provide scaffolds to support cells and guide tissue regeneration. Despite significant advances in biomaterials design and fabrication techniques, engineered tissue constructs remain functionally inferior to native tissues. This is largely due to the inability to recreate the complex and dynamic hierarchical organization of the extracellular matrix components, which is intimately linked to a tissue’s biological function. This review discusses current state-of-the-art strategies to control the spatial presentation of physical and biochemical cues within a biomaterial to recapitulate native tissue organization and function.

Mechanical Characteristics of Tissue Engineered Bone-Ligament-Bone Constructs Following ACL Replacement in Sheep

2011 ◽  
Author(s):  
J. Ma ◽  
M. J. Smietana ◽  
E. M. Wojtys ◽  
L. M. Larkin ◽  
E. M. Arruda
Keyword(s):  
Mechanical Characteristics ◽  
Biomechanical Properties ◽  
Viable Option ◽  
Acl Repair ◽  
Acl Injuries ◽  
Tissue Constructs ◽  
Self Assembling ◽  
The Us ◽  
Engineered Tissue ◽  
Acl Replacement

With approximately 400,000 reported each year, anterior crucial ligament (ACL) injuries are the most common injury in the US. Unfortunately current ACL replacement strategies, which involve using either allografts from cadavers or autografts from patients’ own patellar tendons (PT) or hamstring tendons as a replacement, have several limitations including graft availability, risk of rejection, increased morbidity and, more importantly, unmatched intra-articular biomechanical properties of grafts and ACL. The objective of this study is to use self-assembling, scaffold-less bone-ligament-bone (BLB) engineered tissue constructs as grafts in a sheep ACL repair model to characterize the biomechanical behaviors of native ACL, PT, and tissue engineered ligament and subsequently present a viable option of using tissue engineered ligament graft for ACL repair.

Interconversion of Frequency Domain Complex Modulus to Time Domain Modulus and Compliance of Asphalt Concrete: Numerical Modeling and Laboratory Validation

2016 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Rafiqul A. Tarefder
Keyword(s):  
Viscoelastic Material ◽  
Asphalt Concrete ◽  
Creep Compliance ◽  
Complex Modulus ◽  
Relaxation Modulus ◽  
Modulus Function ◽  
Approximate Methods ◽  
Material Functions ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic

Viscoelastic material functions such as time domain functions, such as, relaxation modulus and creep compliance, or frequency domain function, such as, complex modulus can be used to characterize the linear viscoelastic behavior of asphalt concrete in modeling and analysis of pavement structure. Among these, the complex modulus has been adopted in the recent pavement Mechanistic-Empirical (M-E) design software AASHTOWare-ME. However, for advanced analysis of pavement, such as, use of finite element method requires that the complex modulus function to be converted into relaxation modulus or creep compliance functions. There are a number of exact or approximate methods available in the literature to convert complex modulus function to relaxation modulus or creep compliance functions. All these methods (i.e. exact or approximate methods) are applicable for any linear viscoelastic material up to a certain level of accuracy. However, the applicability and accuracy of these interconversion methods for asphalt concrete material were not studied very much in the past and thus question arises if these methods are even applicable in case of asphalt concrete, and if so, what is the precision level of the interconversion method being used. Therefore, to investigate these facts, this study undertaken an effort to validate a numerical interconversion technique by conducting representative laboratory tests. Cylindrical specimens of asphalt concrete were prepared in the laboratory for conducting complex modulus, relaxation modulus, and creep compliance tests at different test temperatures and loading rates. The time-temperature superposition principle was applied to develop broadband linear viscoelastic material functions. A numerical interconversion technique was used to convert complex modulus function to relaxation modulus and creep compliance functions, and hence, the converted relaxation modulus and creep compliance are compared to the laboratory tested relaxation modulus and creep compliance functions. The comparison showed good agreement with the laboratory test data. Toward the end, a statistical evaluation was conducted to determine if the interconverted material functions are similar to the laboratory tested material functions.

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