Electrospun Poly(e-caprolactone) (PCL) Nanofibrous Scaffolds for Liver Tissue Engineering

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Title: Electrospun Poly(e-caprolactone) (PCL) Nanofibrous Scaffolds for Liver Tissue Engineering
Author: Gluck, Jessica Marie
Advisors: Dr. Martin W. King, Committee Chair
Dr. Marian G. McCord, Committee Member
Dr. Behnam Pourdeyhimi, Committee Member
Abstract: Electrospinning is a process utilized to fabricate nanofibers. The latest trend in tissue engineering has been to use these nanofibrous scaffolds for in vitro studies to direct the growth of cellular development. Due to the unique nature of the liver's ability to regenerate itself, this organ has been commonly targeted for tissue engineering purposes. The two main objectives of this study were to electrospin nanofibrous scaffolds from poly(e-caprolactone) (PCL) and also to use these scaffolds for static liver tissue engineering. This two-phase study was divided as such. In order to electrospin PCL the correct solvents and process conditions had to be determined. In accordance with previous literature a solvent mix of chloroform and methanol was used in an initial ratio of 3:1 respectively. The "optimized" electrospinning process conditions were defined as those that consistently produced fibers on a nanoscale and achieved "whipping" at a consistent applied voltage. The electrospinning trials were considered optimized with a plate distance of 12cm, a capillary of ID=0.5mm, capillary exposure of 0.7cm, a flow rate of 0.25mL⁄min, and an applied voltage of 45kV. All samples were collected for a duration of 30 seconds. Upon optimization of the electrospinning process, an investigation was conducted to determine the most appropriate solvent ratio. The solutions examined were at 5% and 10% PCL concentration by weight. Within each concentration five different solvent ratios were examined, ranging from 1:1 to 5:1 chloroform:methanol. As the amount of chloroform increased in the solvent ratio, the viscosity and surface tension of the solutions also increased. A correlation between these physical features of the solutions and the fiber diameter produced existed, and it was determined the "optimal" solution for electrospinning was a 3:1 chloroform:methanol mix and 10% PCL by weight. This solution became the solution used for further electrospinning trials for collection of samples to be used in cell culture. The average fiber diameter produced was 425.83 nm + 185.89 nm. The hepatocyte culture portion of this study was designed to demonstrate the biocompatibility of the PCL nanofibrous scaffolds and to facilitate proliferation in a static cell culture. These tests were conducted in conjunction with the Transplant Lab under Dr. David Gerber's supervision at UNC-CH. The nanofibrous scaffolds when used in hepatocyte culture do not show any significant improvement from the control used. However, it was evident the presence of the PCL and nanofibers encouraged cellular growth. After viability tests, it became clear both the nanofibers and the microfibers from the nonwoven collection fabric directed the growth pattern of the cells. In some cases, cells began to show a growth in 3-D, indicating the early signs of extracellular matrix formation. Using a marker for albumin production, the electrospun scaffolds' cells showed tremendous proliferation and functionality. Overall, PCL can successfully be electrospun using a two solvent mix of 3:1 chloroform to methanol. By varying the solvent ratio and polymer concentration, it is possible to manipulate the fiber diameter and pore size. These scaffolds can be used for tissue engineering and show great promise when used with hepatocytes.
Date: 2007-07-18
Degree: MS
Discipline: Textile Technology Management
URI: http://www.lib.ncsu.edu/resolver/1840.16/2269

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