Porous Silicon-Based Cell Microarrays: Optimizing Human Endothelial Cell-Material Surface Interactions and Bioactive Release

Porous silicon (pSi) substrates are a promising platform for cell expansion, since pore size and chemistry can be tuned to control cell behavior. In addition, a variety of bioactives can be loaded into the pores and subsequently released to act on cells adherent to the substrate. Here, we construct a cell microarray on a plasma polymer coated pSi substrate that enables the simultaneous culture of human endothelial cells on printed immobilized protein factors, while a second soluble growth factor is released from the same substrate. This allows three elements of candidate pSi scaffold materials-topography, surface functionalization, and controlled factor release-to be assessed simultaneously in high throughput. We show that protein conjugation within printed microarray spots is more uniform on the pSi substrate than on flat glass or silicon surfaces. Active growth factors are released from the pSi surface over a period of several days. Using an endothelial progenitor cell line, we investigate changes in cell behavior in response to the microenvironment. This platform facilitates the design of advanced functional biomaterials, including scaffolds, and carriers for regenerative medicine and cell therapy.