The Effect of Fiber Diameter on the Degradation Profile, Elastic Modulus, Yield Strength and Hydrophilicity of Electrospun PCL/gelatin Tissue Engineering Scaffolds

• Author / Creator

  Avci, Beste

• Tissue loss is a health problem that affects millions of people globally. The conventional methods such as the transplantation of autografts and allografts do not always result in full recovery of damaged tissues. Tissue engineering emerged as a field with the ultimate goal of obviating the need for transplantation of tissues. In tissue engineering, a construct created by combining a scaffold, cells, and growth factors is implanted to the damaged site to induce and facilitate tissue regeneration.
  Nanofibrous membranes are ideal to be used as a scaffold and to promote cellar activity because their structure resembles the structure of the native extracellular matrix (ECM). Electrospinning is the most preferred method to fabricate nanofibrous membranes.
  The selection of material determines the performance of a tissue engineering scaffold. Natural polymers such as collagen and gelatin have the binding sites, which promote the adhesion, growth, and proliferation of cells, in their structure. Therefore, their selection as a scaffolding material is favored. Electrospun collagen and gelatin membranes are soluble in water and require being crosslinked. However, crosslinking induces cytotoxicity. Alternative to natural polymers, synthetic polymers were electrospun to fabricate scaffolds. Synthetic polymers lack of binding sites but they are biocompatible and have good mechanical properties. Polycaprolactone (PCL) is a synthetic polymer, which is hydrophobic and insoluble in water. A scaffold, which is insoluble in water without being crosslinked, with improved mechanical properties and binding sites promoting cellular activity can be fabricated by electrospinning the blends of PCL and gelatin.
  The degradation profile, mechanical properties and hydrophilicity of a scaffold determine its performance. In the literature, the dependence of degradation profile on surface area of electrospun PCL/gelatin membranes has not been investigated yet. In this study, the surface area of electrospun PCL/gelatin membranes was tuned by varying the fiber diameter. PCL/gelatin solutions at three different concentrations were electrospun to fabricate PCL/gelatin membranes at three different fiber diameters. Then, each membrane was degraded in order to study the effect of fiber diameter on degradation profile and the effect of degradation profile on mechanical properties and hydrophilicity.
  PCL/gelatin solutions with 1:1 PCL to gelatin ratio at the total polymer concentrations of 6%, 10% and 14% (w/v) were electrospun and membranes at the average fiber diameters of 184 ± 51 nm, 803 ± 349 nm and 2131 ± 701 nm were obtained, respectively. It has been found that the fibrous structure of the membrane electrospun at the concentration of 6% (w/v) could not be maintained during degradation, whereas the integrity of the fibers was preserved and the average fiber diameter did not change during degradation for the membranes electrospun at the concentrations of 10% and 14% (w/v). After 1, 3, 6 and 10 days of degradation, the remaining mass% was found as approximately 76%, 61%, 55% and 55% of the initial membrane mass, respectively for all the fiber diameters. After 10 days of degradation, a significant decrease in the elastic modulus of the membranes electrospun at the total polymer concentrations of 6%, 10% and 14% (w/v) was seen from 522 ± 63 MPa, 546 ± 56 MPa and 426 ± 77 MPa to 287 ± 128 MPa, 194 ± 27 MPa and 104 ± 20 MPa, respectively. The yield strength dropped significantly from 15.4 ± 0.4 MPa and 13.8 ± 2.3 MPa to 5.6 ± 0.2 MPa and 4.7 ± 1 MPa for the membranes electrospun at total polymer concentrations of 10% and 14% (w/v), respectively, after 10 days of degradation. It was seen that the contact angle increased after 10 days of degradation for the membranes electrospun at the total polymer concentration of 10% and 14% (w/v) indicating that the membranes became more hydrophobic as they are being degraded.

• Subjects / Keywords

  • Electrospinning

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-bpye-ba71

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.