Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Engineering Science

Program

Biomedical Engineering

Collaborative Specialization

Musculoskeletal Health Research

Supervisor

Aaron David Price

Abstract

Current efforts in the tissue engineering field are being directed towards the creation of platforms which will facilitate in instructing cells towards biologically relevant outcomes such as stem cell differentiation and disease pathophysiology. Traditional fabrication methods serve as a limiting factor for the production of such platforms as they lack feature and geometric complexity. Additive Manufacturing (AM) offers advantage over said methods by affording designers creative freedom and great control over printed constructs. Such constructs can then be used to create appropriate models for study- ing a plethora of tissues and structures. An AM methodology for Direct-Ink Write (DIW) printing of conjugated polymer-based constructs using collagen-polypyrrole (Col-PPy) is presented. Potential for Col-PPy constructs as electro-conductive and electro-active platforms is evaluated through electrical conductivity and ionic conductivity characterization, and demonstrated through bilayer performance and spectrometry evaluations. Finally, degree of polymerization and topography are reported using optical and SEM imaging.

Summary for Lay Audience

The cellular micro-environment is known to be complex, three-dimensional and intricate in its ability to instruct cells through an interplay of electrical, chemical, biochemical and/or mechanical stimulation. Each cell type of interest to tissue engineers is known to be housed in its tissue-specific niche, with unique composition and consequent proper- ties. Although researchers have successfully devised many platforms and mechanisms to achieve said stimulations in isolation or in in vitro settings, they remain challenged to reproduce these complexities in 3D cell culture settings, for extended periods of time and in a combinatory manner.

Conjugated polymer (CP) materials, such as Polypyrrole (PPy), are a branch of smart materials that are capable of emulating said unique properties of native cell micro-environments whilst retaining the tailorability of these properties familiar to tissue engineering researchers. However, to date, no platform reminiscent of the native cellular micro-environment capable of imparting combined electrochemomechanical stimulation to instruct cells towards biologically relevant outcomes has been developed. This has been largely because traditional fabrication methods for CPs serve as a limiting factor for the production of such platforms, where produced structures lack feature and geometric complexity inherent to native cell micro-environments.

Additive Manufacturing (AM) offers advantage over said methods by affording designers creative freedom and great control over printed constructs, which can then be used to create appropriate models for studying a plethora of tissues and structures. Presented in this thesis is a novel AM methodology for creating CP-based constructs. Specifically, a Direct-Ink Write (DIW) printing methodology for creating collagen-polypyrrole (Col-PPy) constructs is presented. This dissertation explores the design-ability inherent to AM processes and retention of favourable properties inherent to CP-based structures. Investigations to this end demonstrate 3D printed Col-PPy constructs to be electro-conductive, electro-active and cyto-compatible, while the degree of response from these constructs is open to modulation. Essentially, researchers armed with such a platform are now capable of modulating the morphology and geometry, electro-conductive and electro-active properties of their 3D printed constructs in 3D cell culture settings, for extended periods of time and in a combinatory manner.

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