Templating Cell Alignment and Extracellular Matrix Assembly on Spatially Modified Silicon Oxide Surfaces

Abstract

Methods were developed that enable functionalization of oxide surfaces with stripes and other patterns of cell adhesive, self-assembled monolayers of phosphonates (SAMPs) based on α,ω– bisphosphonic acids to template cell spreading, alignment, and ECM assembly. Silicon oxide served as a model surface for the photolithographic and vapor deposition methods used to generate a two-component, nanoscale interface of zirconium oxide (ZrO2, which may also contain precursor t-butoxy ligands) and a 1,4 butanediphosphonic acid SAMP. The ZrO2/SAMP interface was characterized by X ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and atomic force microscopy, which supported successful surface modification with 10-70 nm thin, spatially distinct ZrO2/SAMP stripes that were found to be stable under cell culture conditions for at least 18 days. NIH3T3 fibroblasts were used as a model cell type, and they elongated and aligned with the ZrO2/SAMP stripes with statistical significance when seeded on them after 24 hr. Longer term studies found that the NIH3T3 fibroblasts and bone marrow-derived human mesenchymal stems cells seeded on ZrO2/SAMP stripes remained in alignment with the stripes as the they proliferated to confluence. Analysis of the fibronectin ECM assembled by NIH3T3 cells found that it also aligned in the direction of the ZrO2/SAMP stripes after 5 days. The methods described in this work represent a new way to generate aligned, cell-assembled ECM. The geometric limits of ZrO2/SAMP patterns for cell alignment were examined by observing NIH3T3 growth on zigzag and letter patterns; these illustrated that broad pattern diversity can be accommodated, and new questions regarding cell spreading emerged.