Laser-based microfabrication for cell adhesion and migration
Miller, Jordan S.
West, Jennifer L.
Doctor of Philosophy
Mammalian cell adhesion and migration impact a multitude of cellular behaviors and tissue remodeling processes. Over the past several decades, investigators have methodically improved in vitro systems as mimics of the extracellular microenvironment to study these biologic phenomena. Experiments have progressed from early studies on bifunctional inorganic surfaces to those with purified adhesive proteins against an organic, non-adhesive background. Recently, subcellular geometric patterns of adhesive proteins have proven useful to restrict and direct focal contact formation, cell survival, lamellopodia extension, and the maturation of "supermature" focal contacts. The vast majority of recent studies have involved the construction of hydrophobic patches with adsorbed fibronectin as the adhesive constraint of choice. However, the extracellular matrix (ECM) in which cells operate is a complex and diverse environment where numerous signals interact with a cell simultaneously; signals that the cell must integrate and that directly impact these processes. Microfabrication methods to approximate the extracellular milieu have significant limitations in their potential to be extended to pattern multiple bioactive ligands with high precision. Current techniques require multi-step processes which lose feature fidelity at every pattern transfer step, while simultaneously increasing logistical complexity and the chance of technical missteps. We have developed a family of complementary techniques using the raster-scanning laser of a confocal microscope to address a number of current challenges in improving microfabrication. For our work with thin films of self-assembled organic monolayers, we systematically removed the multi-step processing requirements of conventional photolithographic microfabrication and characterized and verified the technical advantages of our new patterning techniques. For 3D work, we developed and demonstrated micron-scale biochemical and mechanical modifications of pre-formed photoactive hydrogels. These new microfabrication methods were then applied to direct and modulate cytoskeletal organization and cell migration. This work is broadly applicable to investigating fundamental cell-receptor, cell-substrate, and cell-cell interactions at the subcellular level, and may allow unprecedented and transformative studies of ligand arrangement and concentration effects on cell biology through the construction of multifaceted micropatterns in both two- and three-dimensions.
Cell biology; Biomedical engineering; Engineering; Materials science