Design and Development of Two Test Fixtures to Test the Longitudinal and Transverse Tensile Properties of Small Diameter Tubular Polymers

Berry, C. D.

doi:10.15368/theses.2011.49

Cited by 3 publications

(5 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Longitudinal pull to failure testing A custom grip was designed for longitudinal pull-to-failure tests based on Berry et al 38 with modifications. A detailed photographic description of grip assembly is given in Supporting Information, Figure 2.…”

Section: Fiber Diameter Measurementmentioning

confidence: 99%

Fabrication and characterization of electrospun polycaprolactone and gelatin composite cuffs for tissue engineered blood vessels

et al. 2017

View full text Add to dashboard Cite

Sewing cuffs incorporated within tissue-engineered blood vessels (TEBVs) enable graft anastomosis in vivo, and secure TEBVs to bioreactors in vitro. Alternative approaches to cuff design are required to achieve cuff integration with scaffold-free TEBVs during tissue maturation. To create porous materials that promote tissue integration, we used electrospinning to fabricate cuffs from polycaprolactone (PCL), PCL blended with gelatin, and PCL coated with gelatin, and evaluated cuff mechanical properties, porosity, and cellular attachment and infiltration. Gelatin blending significantly decreased cuff ultimate tensile stress and failure strain over PCL alone, but no significant differences were observed in elastic modulus or failure load. Interestingly, gelatin incorporation by blending or coating did not produce significant differences in cellular attachment or pore size. We then created tissue tubes by fusing self-assembled smooth muscle cell rings together with electrospun cuffs on either end. After 7 days, rings and cuffs fused seamlessly, and the resulting tubes were harvested for pull-to-failure tests to measure the strength of cuff-tissue integration. Tubes with gelatin-coated PCL cuffs failed more frequently at the cuff-tissue interface compared to PCL and PCL:gelatin blended groups. This work demonstrates that electrospun cuffs integrated successfully with scaffold-free TEBVs, and that the addition of gelatin did not significantly improve cuff integration over PCL alone for this application. Electrospun cuffs may aid cannulation for dynamic culture and testing of tubular constructs during engineered tissue maturation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 817-826, 2018.

show abstract

Section: Fiber Diameter Measurementmentioning

confidence: 99%

Fabrication and characterization of electrospun polycaprolactone and gelatin composite cuffs for tissue engineered blood vessels

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Unfortunately, ePTFE was not available in the material database, however the presence of standard PTFE showed that it exhibits a lower modulus compared to PLGA. This relative difference in elastic modulus values was corroborated by material property results reported in a previous thesis, in which ePTFE and PLGA displayed values of 7.80 and 13.25 MPa respectively when full tubular scaffolds were mechanically tested 141 . The polymers that are reported to have lower Young's modulus values compared to PLGA in This preliminary materials selection phase was simply used to create a short list of potential flexible polymers for future research.…”

Section: Materials Flexibilitysupporting

confidence: 84%

“…The extreme chemical resistance of PTFE is well known, and posed a problem as the primary method of polymer preparation for electrospinning involves dissolution in a solvent. Accordingly, reports of electrospinning with PTFE are not common, and those who have done so successfully incorporated several additional mixing and sintering steps to properly use an emulsified form of PTFE, only to have produced a scaffold with altered morphologies and modulus values of 30.7±2.8 MPa, much stiffer than both the ePTFE tubing and PLGA scaffold tested previously in the BVM lab 141,162,163 .…”

Section: Polytetrafluoroethylene (Ptfe)mentioning

confidence: 99%

“…While the flexibility of electrospun polymer scaffolds may be gleaned from literature sources that state the "true" value of a particular mechanical property, tests performed in the BVM lab and in literature have presented results significantly different than those values displayed in CES, for example 141,162 . The fibrous, porous structure of an electrospun scaffold does not behave in the same manner as a solid section of the same material and bulk geometry, and any alignment or directionality in the fibers will also introduce an element of anisotropy to the scaffold.…”

Section: Characterizing Scaffold Flexibilitymentioning

confidence: 99%

See 1 more Smart Citation

Identifying and Reducing Variability, Improving Scaffold Morphology, and Investigating Alternative Materials for the Blood Vessel Mimic Lab Electrospinning Process

Dowey¹

View full text Add to dashboard Cite

The work of the Cal Poly Tissue Engineering Lab is primarily focused on the fabrication, characterization, and improvement of "Blood Vessel Mimics" (BVMs), tissue engineered constructs used to evaluate cellular response to vascular medical devices. Currently, cells are grown onto fibrous, porous tubes made using an in-house electrospinning process from PLGA, a biocompatible co-polymer. The adhesion and proliferation of cells in a BVM is reliant on the micro-scale structure of the PLGA scaffold, and as such it is of great importance for the electrospinning process to consistently produce scaffolds of similar morphologies. Additionally, it has been shown that cell proliferation increases with scaffolds of smaller fibers and pores than the current electrospinning protocol can produce. Finally, the Tissue Engineering Lab has interest in testing devices in more tortuous BVM bioreactor designs, however the use of relatively rigid PLGA scaffolds has severely limited the ability to construct more complicated vessel geometries. v protocol were identified and subsequently altered to improve consistency and usability. Specifically, this included redefining the precision with which PLGA mass was measured, repositioning electrical equipment to reduce the effect of stray electrostatic forces on the polymer solution jet, attempting to control the temperature and humidity inside the electrospinning enclosure, and improving the ease with which scaffolds are removed from their mandrels through alternative mandrel surface treatments. In addition to overall process variability, the issue of scaffold shrinkage during BVM use was investigated and two possible treatments, exposure to either ethanol or elevated temperatures, were proposed based on previous electrospinning literature results. Each was tested for their effectiveness in mitigating shrinkage through exposure to BVM setup-mimicking conditions. It was found that both treatments reduced scaffold shrinkage compared to control samples when exposed to BVM setup-mimicking conditions. Finally, 3 flexible polymers were selected and electrospun to compare against typical PLGA results and to conduct a kink radius test as a metric for measuring flexibility as it pertains to the proposed BVM lab application. It was concluded that two types of thermoplastic polyurethane (tPU) were not acceptable electrospinning materials for use in the BVM lab. Additionally, while polycaprolactone (PCL) could be successfully electrospun it could not undergo the amount bending required for more tortuous BVM bioreactor designs without kinking.Overall, the work in this thesis provided insight into multiple scaffold characterization techniques, reduced overall electrospinning variability in the fabrication and use of PLGA scaffolds, and defined processing parameters that have been shown to yield scaffolds with smaller morphological features than all prior Tissue Engineering Lab work. By creating better, more effective scaffolds, researchers in the Tissue Engineering Lab can more accurately mimic the structur...

show abstract

“…Each rod could then be pulled in opposite directions to pull the scaffold apart 97 . Future work could use a similar idea for the smaller BBB scaffold in order to prevent disruption of the mechanical properties via sample preparation.…”

Section: Tensile Testing Assessmentmentioning

confidence: 99%

Preparation and Characterization of Electrospun Poly (D,l-Lactide-Co-Glycolide) Scaffolds for Vascular Tissue Engineering and the Advancement of an in Vitro Blood Brain Barrier Model

Patel¹

View full text Add to dashboard Cite

PREPARATION AND CHARACTERIZATION OF ELECTROSPUN POLY (D,L-LACTIDE-CO-GLYCOLIDE) SCAFFOLDS FOR VASCULAR TISSUE ENGINEERING AND THE ADVANCEMENT OF AN IN VITRO BLOOD BRAIN BARRIER MODEL Deven Chandrakant PatelDeveloping an in vitro Blood Brain Barrier model that will replicate the physiological, anatomical, and functional characteristics of the native BBB has gained significant attention. Such a model would enable prediction of the penetration of CNS targeting drug candidates across the BBB, allow pre-screening and optimization strategies to be developed for new drugs and gene delivery formulations, and permit research groups to further understand how a dysfunctional BBB is involved in the pathogenesis of several neurological diseases.The Tissue Engineering laboratory at the California Polytechnic State University, San Luis Obispo is currently in the process of developing a dynamic in vitro blood brain barrier model that will implement an in-house fabricated electrospun PLGA scaffold pressure sodded with C6 glial cells and BAECs (Bovie Aortic Endothelial Cells). The aims of this thesis were to upgrade and refine the existing electrospinner system, develop a BBB scaffold electrospinning protocol, and characterize and evaluate the consistency of the scaffolds fabricated using the protocol.Ultimately, the electrospinner system was optimized in the following areas: the high voltage power supply, electrical layout and safety, as well as the syringe pump and stand. The modifications to the system will now permit new electrospinning strategies and ensure operator safety. The protocol developed for electrospinning scaffolds for the DIV-BBB system utilized 15 wt% PLGA in CHCl 3 with a 4.5 ml/hr flow rate, an applied voltage of 18,000V with a negative polarity, and a gap distance of 25.4 cm.Characterization and consistency studies revealed that scaffolds electrospun were statistically inconsistent with one another with regards to fiber diameter (P < 0.0001), porosity (P < 0.0001), and wall thickness (P < 0.0001). However, the scaffolds were mechanically consistent (P-value of 0.6134) according to the calculated Young's modulii. The average fiber diameter for the electrospun scaffolds was 2.556 µm, and had an average porosity of 70.06 µm 2 . Additionally, the wall thickness between the electrospun scaffolds ranged between 0.31 and 0.54 mm. The average Young's modulus of the electrospun scaffolds was determined to be 86.141 MPa. While the results associated with fiber diameter, porosity, and wall thickness were statistically inconsistent, it will be important to evaluate whether the variation between each scaffold will translate to a difference when conducting cellular studies after the DIV-BBB system is complete.v

show abstract

Design and Development of Two Test Fixtures to Test the Longitudinal and Transverse Tensile Properties of Small Diameter Tubular Polymers

Cited by 3 publications

References 48 publications

Fabrication and characterization of electrospun polycaprolactone and gelatin composite cuffs for tissue engineered blood vessels

Fabrication and characterization of electrospun polycaprolactone and gelatin composite cuffs for tissue engineered blood vessels

Identifying and Reducing Variability, Improving Scaffold Morphology, and Investigating Alternative Materials for the Blood Vessel Mimic Lab Electrospinning Process

Preparation and Characterization of Electrospun Poly (D,l-Lactide-Co-Glycolide) Scaffolds for Vascular Tissue Engineering and the Advancement of an in Vitro Blood Brain Barrier Model

Contact Info

Product

Resources

About