Available at: https://digitalcommons.calpoly.edu/theses/3399
Date of Award
6-2026
Degree Name
MS in Biomedical Engineering
Department/Program
Biomedical Engineering
College
College of Engineering
Advisor
Kristen O'Halloran Cardinal
Advisor Department
Biomedical Engineering
Advisor College
College of Engineering
Abstract
Intracranial atherosclerotic disease (ICAD) is characterized by a buildup of fatty plaque within the walls of arteries supplying the brain, resulting in vessel narrowing, restricted blood flow, and increased risk of ischemic stroke. While various treatments exist for ICAD, most are accompanied by high recurrent stroke rates and other adverse events, highlighting the need for further investigation and models for pre-clinical testing. Tissue engineered Blood Vessel Mimics (BVMs), consisting of a polymer scaffold sodded with human vascular cells, serve as physiologically relevant in vitro models for vascular device testing. This thesis focused on the application of alternative solvents to a previously developed method for creating electrospun scaffolds with occluded internal geometries for ICAD specific BVMs.
In the first aim of this thesis, two different solvents (hexafluoroisopropanol (HFIP) and acetic acid) were assessed in their ability to produce straight, polycaprolactone (PCL) scaffolds to replace dichloromethane (DCM), the previous standard in the lab. Acetic acid was selected for further exploration due to its ease of handling in bioreactor setups and appeal as a ‘green’ solvent. In the second aim, acetic acid was applied to create occluded scaffolds using a previously developed barbell mandrel. Extensive polymer solution and electrospinning parameter optimization trials were executed to determine a functional protocol for fabricating occluded PCL scaffolds with acetic acid. A protocol validation study was then performed in which four replicate scaffolds were analyzed in terms of their fiber morphology, fiber diameter, scaffold luminal diameter, and scaffold wall thickness. Results demonstrated that acetic acid could be used to fabricate occluded scaffolds with consistent fiber morphology (average fiber diameter of 2.04 ± 0.08 µm) and target scaffold dimensions (average lesion and outer luminal diameters of 1.9 mm and 3.9 mm, respectively, with lesion and outer wall thicknesses of 0.44 mm and 0.32 mm). These findings established the feasibility of fabricating occluded scaffolds with acetic acid; however, subsequent fabrication efforts revealed issues with process reproducibility and highlighted the need for further solvent exploration and protocol optimization. In the final aim, these scaffolds were used in BVM setups to assess their preliminary performance. Results from these setups indicated early promise in the use of these scaffolds for ICAD specific BVMs with no structural deformation and relatively even cell deposition patterns across the vessel. Future work should entail further optimization of the solvent solution, electrospinning parameters, and barbell manufacturing to increase the reproducibility of the scaffolds. Overall, this work demonstrated the feasibility of using a ‘green’ solvent as an alternative to DCM for the fabrication of electrospun occluded scaffolds intended for ICAD specific BVMs.