UC Irvine

The ability to control cell adhesion on material surfaces is critical to the performance and compatibility of medical implants in the body. One such application that would benefit from controlled adhesion is an artificial cornea, an implant for replacing the anterior portion of the eye. For a successful implant, we need to simultaneously promote cell adhesion on the periphery of the implant to improve integration, while limiting adhesion in the central region to provide clear vision.

To address this challenge, we used nanoimprint lithography to create arrays of precisely defined nanopatterns on the scale of 100-500 nm on surfaces of polymer films. We postulated that nanoline patterns resembling the natural collagen fibers in the cornea would encourage adhesion, and that the transparent nanopillars would discourage cell adhesion on polymer films. We designed experiments to evaluate the degree of adhesion on the nanopatterned polymer surfaces, which confirmed our postulates. Using fluorescence correlation spectroscopy, we found that nanotopography influenced cell motility by inducing protein reorganization in cell adhesions. Studies under conditions of fluid flow induced shear confirmed that nanoline patterns were better than flat surfaces at encouraging cell adhesion, as significantly more cells remained on nanolines at the highest shear rate applied.

Results described in this thesis demonstrate the feasibility of using nanotopography to control the degree of cell adhesion. As for the artificial cornea, future in vitro studies with corneal keratocytes are suggested to evaluate corneal wound healing before ultimately conducing in vivo studies to evaluate the efficacy of our proposed device. This thesis shows that implementing nanotopography could lead to improved implantable medical devices and scaffolds for tissue-engineered constructs by providing greater spatial control of cell adhesion even under kinematic conditions without the need to chemically modify material surfaces.