Characterization of nanofibers produced by electrospinning for biomedical applications

Identifier:  TDX:4290

Handle: https://hdl.handle.net/20.500.11797/TDX4290

Authors:  Akdemir, Reyda

Abstract:
Electrospinning is a versatile and innovative technique used to produce ultrafine fibers with mean diameter in a range from nanometers to micrometers. It involves the application of an electric field to a polymer solution or melt, resulting in the formation of continuous fibers that are collected on a grounded collector electrode. These fibers possess a high surface area-to-volume ratio and can exhibit unique properties, making them highly attractive for many and diverse applications. In this thesis, we target mostly tissue engineering applications. We propose a new method for individual fiber porosity (IFP) determination based on annealing the nanofiber to collapse the pores and on microscopy techniques (SEM and AFM). IFP experiments were done for poly(ε-caprolactone) (PCL), which is a popular polymer in tissue engineering, as well as polystyrene fibers (PS) due to their common use. SEM images were used to determine the cross-sectional area of the nanofiber before annealing. AFM and volume computation tools were used to determine the cross-sectional area of annealed fibers. We also propose a new method for tensile modulus determination where we used IFP data as well, since the porosity of nanofibers influences their mechanical properties. This allows computing the 'true' cross-section of the PCL fibers in order to exclude the area of the voids between fibers, which allows us to estimate the tensile modulus of an individual fiber. Our tensile testing results compare well with literature data for individual electrospun fibers obtained by less reliable methods. Finally, we did a 3D reconstruction of electrospun scaffolds made of poly(glycerol sebacate) (PGS) and tropoelastin (TE). 3D rendering allowed us to visualize the material distribution within the scaffold. We also made the initial attempt to simulate the mechanical properties of TE electrospun mats using the single TE fiber Young’s modulus.