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. Author manuscript; available in PMC: 2011 Jul 28.
Published in final edited form as: Langmuir. 2007 Jan 23;23(8):4103–4107. doi: 10.1021/la0630559

Fig. 1. Schematic of patterning process.

Fig. 1

Two aligned photolithographic steps are used to pattern collagen I and PEG-disilane on a glass substrate. Hepatocytes seeded in serum-free medium attach preferentially to collagen-coated regions. 3T3 fibroblasts are subsequently seeded in serum-enriched medium. Serum proteins adsorb to regions of bare glass to mediate fibroblast attachment. PEG-treated regions resist protein adsorption for at least one week, thus preventing cell migration and maintaining spatial separation between the two cell types. The hydrofluoric acid etch (step 2) imprints a visible ridge in the glass substrate to facilitate visual alignment to the second mask. The edge of the collagen mask is intentionally offset to extend into PEG region (step 5), and the protruding collagen is removed by oxygen plasma (step 6), ensuring that the patterned collagen region abuts the PEG region. (Dimensions not to scale.)