Surfaces that present peptide mimics of cell adhesion molecule ligands are useful tools for a variety of applications such as immunoassays, diagnostics, and tissue engineering. We have developed surfaces for the selective presentation of biotinylated peptides and proteins by incorporating controlled amounts of a biotinylated polyethylene glycol (PEG) tether that is anchored to titanium-dioxide-coated surfaces via an adhesive tri-peptide sequence of L-3,4-dihydroxyphenylalanine (biotin-PEG3400-DOPA₃; DPB) within a PEG2000-DOPA₃ background that minimizes non-specific adsorption of serum proteins. Using optical waveguide lightmode spectroscopy, we found that the amounts of sequentially adsorbed NeutrAvidin and singly-biotinylated molecules increased proportionally with the amount of DPB in the surface. The resulting biotin-avidin-biotin linkage was stable for prolonged periods under continuous perfusion, even in the presence of excess free biotin. Hematopoietic M07e cells bound to immobilized peptide ligands for α5β1 (cyclic RGD [cRGD]) and α4β1 (cylic LDV [cLDV]) integrins in a DPB-dose-dependent manner, with near-maximal binding to cLDV for surfaces containing 1% DPB. Cell adhesion to surfaces containing both cLDV and cRGD increased in an additive manner compared to that for the individual ligands. The bioactivity of adsorbed biotinylated stem cell factor (SCF) was retained, as demonstrated by DPB-dose-dependent SCF-mediated M07e cell binding and ERK1/2 activation.

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