2015 Theses Doctoral

Characterizing and controlling structural and mechanical properties of type I collagen self-assembly

Zhu, Jieling

Type I collagen matrices are used across a variety of applications in bioengineering and biophysical studies; however, a fuller understanding of the collagen self-assembly process is required to optimize control of the matrix structural and mechanical properties in these applications. The work in this thesis sought to 1) characterize collagen self-assembly using simultaneous imaging, spectroscopy, and rheological methods, 2) use collagen gels as three-dimensional microenvironments to study glioma invasion, and 3) develop a model using experimental research data to teach data analysis tools to undergraduate students. Chapter 1 provides a brief overview of collagen in the body, its applications, structural details about the collagen monomer, and descriptions of in vivo and in vitro fibrillogenesis. Advantages and disadvantages of methodologies used to study collagen self-assembly are discussed for in vitro fibrillogenesis. The materials and methods used in this thesis are described in Chapter 2. Chapters 3 and 4 describe insights into collagen self-assembly using multiple modalities. In Chapter 3, turbidity and confocal reflectance microscopy were simultaneously employed to track collagen fibrillogenesis and reconcile the information reported by the two techniques, with confocal fluorescence microscopy used to supplement information about early events in fibrillogenesis. Chapter 4 describes the novel use of simultaneous rheology and confocal microscopy to study the development of mechanical and structural properties of collagen gels. In Chapter 5, glioma migratory and invasive behaviors are observed and perturbed in the context of well-controlled in vitro two- and three-dimensional environments, including implanting multicellular tumor spheroids in collagen gels across several concentrations to test the effects of pore size on glioma invasion. This chapter serves as a preliminary investigation into how glioma behavior changes depending on environment dimensionality and lays out further studies to fully investigate the mechanisms underlying glioma invasion. Finally, Chapter 6 describes the development, evaluation, and redesign of a Microsoft Excel-based activity where data analysis from contemporary research (published in Chapter 3) was adapted into a training exercise for students taking an introductory General Chemistry Laboratory course. This activity humanized the research enterprise for the undergraduate students and can serve as a model for future collaborations between research and instructional laboratories.