Cytocompatibility and Material Properties of Poly-carbonate Urethane/Carbon Nanofiber Composites for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Material Properties ◽  
Carbon Nanofiber ◽  
Scar Tissue ◽  
Tissue Response ◽  
Positive Interactions ◽  
Weight Percentage ◽  
Poly Carbonate

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

Cytocompatibility of Carbon Nanofiber Materials for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Carbon Fiber ◽  
Surface Energy ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Carbon Nanofiber ◽  
Fiber Composite ◽  
Scar Tissue ◽  
Pc 12 Cells ◽  
Low Surface Energy ◽  
Poly Carbonate

AbstractSince the cytocompatibility of carbon nanofibers with respect to neural applications remains largely uninvestigated, the objective of the present in vitro study was to determine cytocompatibility properties of formulations containing carbon nanofibers. Carbon fiber substrates were prepared from four different types of carbon fibers, two with nanoscale diameters (nanophase, or less than or equal to 100 nm) and two with conventional diameters (or greater than 200 nm). Within these two categories, both a high and a low surface energy fiber were investigated and tested. Astrocytes (glial scar tissue-forming cells) and pheochromocytoma cells (PC-12; neuronal-like cells) were seeded separately onto the substrates. Results provided the first evidence that astrocytes preferentially adhered on the carbon fiber that had the largest diameter and the lowest surface energy. PC-12 cells exhibited the most neurites on the carbon fiber with nanodimensions and low surface energy. These results may indicate that PC-12 cells prefer nanoscale carbon fibers while astrocytes prefer conventional scale fibers. A composite was formed from poly-carbonate urethane and the 60 nm carbon fiber. Composite substrates were thus formed using different weight percentages of this fiber in the polymer matrix. Increased astrocyte adherence and PC-12 neurite density corresponded to decreasing amounts of the carbon nanofibers in the poly-carbonate urethane matrices. Controlling carbon fiber diameter may be an approach for increasing implant contact with neurons and decreasing scar tissue formation.

scholarly journals Characterization of scar tissue biomechanics during adult murine flexor tendon healing

2021 ◽  
Author(s):  
Antonion Korcari ◽  
Alayna E Loiselle ◽  
Mark R Buckley
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Healing Process ◽  
Tendon Healing ◽  
Scar Tissue ◽  
Element Analysis ◽  
Material Quality ◽  
Treatment Regimens ◽  
Tangent Moduli ◽  
Experimental Findings

Tendon injuries are very common and result in significant impairments in mobility and quality of life. During healing, tendons produce a scar at the injury site, characterized by abundant and disorganized extracellular matrix and by permanent deficits in mechanical integrity compared to healthy tendon. Although a significant amount of work has been done to understand the healing process of tendons and to develop potential therapeutics for tendon regeneration, there is still a significant gap in terms of assessing the direct effects of therapeutics on the functional and material quality specifically of the scar tissue, and thus, on the overall tendon healing process. In this study, we focused on characterizing the mechanical properties of only the scar tissue in flexor digitorum longus (FDL) tendons during the proliferative and remodeling healing phases and comparing these properties with the mechanical properties of the composite healing tissue. Our method was sensitive enough to identify significant differences in structural and material properties between the scar and tendon-scar composite tissues. To account for possible inaccuracies due to the small aspect ratio of scar tissue, we also applied inverse finite element analysis (iFEA) to compute mechanical properties based on simulated tests with accurate specimen geometries and boundary conditions. We found that the scar tissue linear tangent moduli calculated from iFEA were not significantly different from those calculated experimentally at all healing timepoints, validating our experimental findings, and suggesting the assumptions in our experimental calculations were accurate. Taken together, this study first demonstrates that due to the presence of uninjured stubs, testing composite healing tendons without isolating the scar tissue overestimates the material properties of the scar itself. Second, our scar isolation method promises to enable more direct assessment of how different treatment regimens (e.g., cellular ablation, biomechanical and/or biochemical stimuli, tissue engineered scaffolds) affect scar tissue function and material quality in multiple different types of tendons.

Mechanical and Thermal Properties of Carbon-Nanofiber Infused Polyurethane Foam

2008 ◽  
Author(s):  
Md. Atiqur Bhuiyan ◽  
Mahesh V. Hosur ◽  
Yaseen Farooq ◽  
Shaik Jeelani
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Polyurethane Foam ◽  
High Speed ◽  
Carbon Nanofiber ◽  
Mechanical Analysis ◽  
Mechanical And Thermal Properties ◽  
Diphenylmethane Diisocyanate ◽  
Thermal And Mechanical Properties ◽  
Mechanical Agitator

In this study, thermal and mechanical properties of carbon nanofiber infused polyurethane foam were investigated. Low density liquid polyurethane foam composed of Diphenylmethane Diisocyanate (Part A) and Polyol (Part B) was doped with carbon nanofibers (CNF). A high-intensity ultrasonic liquid processor was used to obtain a homogeneous mixture of Diphenylmethane Diisocyanate (Part A) and carbon nanofibers (CNF). The CNF were infused into the Part A of the polyurethane foam through sonic cavitation. The modified foams containing nanoparticles were mixed with Part B (Polyol) using a high-speed mechanical agitator. The mixture was then cast into pre-heated rectangular aluminum molds to form the nano-phased foam panels. Flexure, static and high strain rate compression, and dynamic mechanical analysis (DMA) were performed on neat, 0.2 wt%, 0.4 wt% and 0.6 wt% CNF filled polyurethane foam to identify the effect of adding CNF on the thermal and mechanical properties. The highest improvement on thermal and mechanical properties was obtained with 0.2 wt% loading of CNF. Morphology of the samples was studied through X-ray diffraction.

Fabrication and Characterization of a Carbon Nanofiber Reinforced Liquid Crystalline Polymer

2006 ◽  
Author(s):  
A. Rohatgi ◽  
J. P. Thomas ◽  
W. R. Pogue ◽  
J. N. Baucom
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Carbon Nanofiber ◽  
Crystalline Polymer ◽  
Chemical Degradation ◽  
Single Wall Carbon Nanotubes ◽  
Naval Research ◽  
Fracture Surfaces

Our group at the Naval Research Laboratory is studying hierarchical arrangements of materials at multiple length scales and how such arrangements can be used to yield novel properties. We are investigating nanocomposites comprising a thermotropic liquid crystalline polymer (LCP) matrix reinforced with carbon nanofibers for potential structure + conduction multifunctional applications. The LCP matrix is known for its inherent hierarchical microstructure, and its fracture surface is typically characterized by fibrils ranging in size from nanometer to micrometer. The carbon nanofibers being compounded with the LCP matrix are vapor-grown carbon nanofibers (VGCF) and pre-processing techniques are being developed to eventually replace VGCF with single-wall carbon nanotubes (SWNT). Composites with VGCF content of 0, 1, 2, 5 and 10 wt.% were extruded using a twin-screw extruder to yield monofilaments in the range of 0.5 to 2 mm in diameter. The mechanical properties of extruded filaments were determined via quasi-static tensile tests and fracture surfaces examined under a scanning electron microscope. Porosity and hierarchical fibrillar structures were commonly observed in the fracture surfaces of tensile tested LCP and LCP-VGCF filaments. The LCP-VGCF filaments showed a maximum increase in strength and modulus of 20% and 35%, respectively, at 1-2 wt.% VGCF content. The dependence of mechanical properties on VGCF content was attributed to the interplay between the extrusion process parameters, VGCF dispersion and molecular alignment of LCP. In another set of experiments, LCP was thermo-mechanically pre-processed using a laboratory scale double-roll mixer and extruded using a Maxwell mixing extruder to yield monofilaments in the range of 0.2 to 0.7 mm. At 0.2 mm diameter, filaments of un-pre-processed and pre-processed neat LCP showed almost identical mechanical properties. At 0.7 mm diameter, however, pre-processed LCP filaments showed 10% and 30% degradation in strength and modulus, respectively, relative to un-pre-processed LCP. The lowered mechanical properties of pre-processed LCP were attributed to its chemical degradation during thermo-mechanical processing. Over the diameter range from 0.2 to 2 mm and irrespective of prior processing or extrusion method, the modulus and strength of neat LCP filaments increased with decreasing diameter. The strength and modulus dependence on filament diameter could be explained by the "skin-core" effect typically seen in liquid crystalline polymers. Future work will involve optimizing processing parameters for simultaneous enhancements in mechanical properties and electrical/thermal conductivity in LCP-VGCF/LCP-SWNT filaments.

Carbon Nanofiber Surface Roughness Increases Osteoblast Adhesion

2003 ◽  
Vol 774 ◽  
Author(s):  
Karen S. Ellison ◽  
Rachel L. Price ◽  
Karen M. Haberstroh ◽  
Thomas J. Webster
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Carbon Nanofiber ◽  
Callus Formation ◽  
Study Results ◽  
Osteoblast Adhesion ◽  
High Degree

AbstractThe present study demonstrated for the first time desirable cytocompatibility properties of carbon nanofibers pertinent for bone prosthetic applications. Specifically, osteoblast (boneforming cells), fibroblast (cells contributing to callus formation and fibrous encapsulation events that result in implant loosening), chondrocyte (cartilage-forming cells), and smooth muscle cell (for comparison purposes) adhesion were determined on carbon nanofibers in the present in vitro study. Results provided evidence that nanometer dimension carbon fibers promoted select osteoblast adhesion, in contrast to the performance of conventional carbon fibers. Moreover, adhesion of other cells was not influenced by carbon fiber dimensions. To determine properties that selectively enhanced osteoblast adhesion, similar cell adhesion assays were performed on poly-lactic-co-glycolic (PLGA) casts of carbon fiber compacts previously tested. Compared to PLGA casts of conventional carbon fibers, results provided the first evidence of enhanced select osteoblast adhesion on PLGA casts of nanophase carbon fibers. The summation of these results demonstrate that due to a high degree of nanometer surface roughness, carbon fibers and PLGA with nanometer surface dimensions may be optimal materials to selectively increase osteoblast adhesion necessary for successful orthopedic implant applications.

Small Diameter, High Surface Energy Carbon Nanofiber Formulations that Selectively Increase Osteoblast Function

2001 ◽  
Vol 711 ◽  
Author(s):  
Rachel L. Price ◽  
Kathy L. Elias ◽  
Karen M. Haberstroh ◽  
Thomas J. Webster
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Carbon Nanofibers ◽  
Alkaline Phosphatase Activity ◽  
Carbon Nanofiber ◽  
High Surface ◽  
Small Diameter ◽  
Calcium Deposition ◽  
Time Points

ABSTRACTThe objective of the present in vitro study was to investigate the potential of carbon nanofibers, which have nanometer dimensions similar to hydroxyapatite crystals in physiological bone, for orthopedic applications. Studies of alkaline phosphatase activity and calcium deposition by osteoblasts (the bone-synthesizing cells) were performed on both nanophase (less than 100 nm) and conventional (greater than 100 nm) diameter carbon nanofibers. Results provided the first evidence of a strong correlation between decreased carbon fiber diameter and both increased alkaline phosphatase activity and increased calcium deposition by osteoblasts at early time points (specifically, 7 days), but not at later time points (specifically, 14 and 21 days). Results of early calcium deposition by osteoblasts on carbon nanofibers are promising and consistent with the desired rapid formation of natural bone at the implant interface.

Decreased Macrophage Density on Carbon Nanofiber Patterns

2006 ◽  
Vol 950 ◽  
Author(s):  
Jong Youl Kim ◽  
Dongwoo Khang ◽  
Jong Eun Lee ◽  
Thomas J. Webster
Keyword(s):  
Carbon Nanofibers ◽  
Polymer Matrix ◽  
Carbon Nanofiber ◽  
In Vitro Study ◽  
Inflammatory Cells ◽  
Vitro Study ◽  
Macrophage Density ◽  
Macrophage Adhesion ◽  
First Time

ABSTRACTIn this study, we describe the selective adhesion 4 hour and proliferation 24 hour and 4 days of inflammatory cells (specifically, macrophages) on aligned carbon nanofiber/nanotube patterns on a polymer matrix. The results showed for the first time that macrophage adhesion and proliferation on aligned Carbon nanofibers (CNFs) was significantly less than on the polymer matrix. The present in vitro study thus provided evidence of the ability of CNFs to down-regulate macrophage adhesion and proliferation important to decrease harmful body reaction, which is imperative for the future consideration of CNFs for numerous implant applications.

scholarly journals A novel polycaprolactone/carbon nanofiber composite as a conductive neural guidance channel: an in vitro and in vivo study

2019 ◽  
Vol 8 (4) ◽  
pp. 239-248 ◽  
Author(s):  
Saeed Farzamfar ◽  
Majid Salehi ◽  
Seyed Mohammad Tavangar ◽  
Javad Verdi ◽  
Korosh Mansouri ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Carbon Nanofibers ◽  
Carbon Nanofiber ◽  
Peripheral Nerve Regeneration ◽  
Electrospinning Technique ◽  
Thermally Induced ◽  
Peripheral Nerve Damage ◽  
Potential Applicability

AbstractThe current study aimed to investigate the potential of carbon nanofibers to promote peripheral nerve regeneration. The carbon nanofiber-imbedded scaffolds were produced from polycaprolactone and carbon nanofibers using thermally induced phase separation method. Electrospinning technique was utilized to fabricate polycaprolactone/collagen nanofibrous sheets. The incorporation of carbon nanofibers into polycaprolactone’s matrix significantly reduced its electrical resistance from 4.3 × 109 ± 0.34 × 109 Ω to 8.7 × 104 ± 1.2 × 104 Ω. Further in vitro studies showed that polycaprolactone/carbon nanofiber scaffolds had the porosity of 82.9 ± 3.7% and degradation rate of 1.84 ± 0.37% after 30 days and 3.58 ± 0.39% after 60 days. The fabricated scaffolds were favorable for PC-12 cells attachment and proliferation. Neural guidance channels were produced from the polycaprolactone/carbon nanofiber composites using water jet cutter machine then incorporated with PCL/collagen nanofibrous sheets. The composites were implanted into severed rat sciatic nerve. After 12 weeks, the results of histopathological examinations and functional analysis proved that conductive conduit out-performed the non-conductive type and induced no toxicity or immunogenic reactions, suggesting its potential applicability to treat peripheral nerve damage in the clinic.

The Effect of Diabetes on the Viscoelastic Properties of Rat Knee Ligaments

1996 ◽  
Vol 118 (4) ◽  
pp. 557-564 ◽  
Author(s):  
J. J. Duquette ◽  
P. Grigg ◽  
A. H. Hoffman
Keyword(s):  
Mechanical Properties ◽  
Knee Joint ◽  
Experimental Model ◽  
Material Properties ◽  
Viscoelastic Properties ◽  
Tensile Testing ◽  
Diabetic Rats ◽  
Tissue Response ◽  
Collateral Ligaments ◽  
Series Of Experiments

A series of experiments was performed to determine the effect of diabetes on the viscoelastic properties of knee joint ligaments. The experimental model was collateral ligaments from spontaneously diabetic, hyperglycemic (BBZDP/Wor) rats, and various controls including nondiabetic littermates, insulin treated diabetic rats, and alloxan treated rats. Material properties were measured using a dynamic, uniaxial loading paradigm. Ligaments were subjected to load controlled, sinusoidal tensile testing, using frequencies from 0.1 to 2.0 Hz. The resulting data were used to determine the storage and loss compliances of the ligaments Storage compliance, which reflects tissue elastic properties, did not differ between groups Loss compliance, which reflects the viscous component of the tissue response, was increased in the hyperglycemic animals. Thus, hyperglycemic diabetes affects tissue mechanical properties through the viscous rather than the elastic component of the response to dynamic loading. Rats treated with alloxan to induce diabetes did not show an increase in loss compliance.

scholarly journals WPI Gel Microstructure and Mechanical Behaviour and Their Influence on the Rate of In Vitro Digestion

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1066
Author(s):  
Stephen Homer ◽  
Roderick Williams ◽  
Allison Williams ◽  
Amy Logan
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
In Vitro Digestion ◽  
Protein Isolate ◽  
In Vitro Digestibility ◽  
Gastric Digestion ◽  
Intestinal Phase ◽  
Ph Values ◽  
Oral Processing

The influence of microstructure and mechanical properties on the in vitro digestibility of 15% whey protein isolate (WPI) gels was investigated. Gels were prepared via heat set gelation at three pH values (pH 3, 5 and 7), which produced gels with distinct microstructures and mechanical properties. The gels were minced to simulate an oral/chewing phase, which led to the formation particles of various sizes and textures. The minced gels were passed through either an Infogest (pre-set pH of 3) or Glass stomach (dynamic pH) protocol. Gels were digested in the gastric phase for up to 120 min, at which point the extent of digestion was measured by the amount of filterable nitrogen passing through a sieve. The digesta from both gastric methods were passed through an in vitro simulated intestinal phase. A strong link was found between the elasticity of the initial gel and the gel particle size following simulated oral processing, which significantly (p < 0.01) affected the rate of digestion in the gastric phase. A weaker correlation was also found between the pH of the gels and the extent of gastric digestion. This work highlights the differences in the rate of gastric digestion, arising from oral processing, which can be attributed to the material properties of the substrate.

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