I have been trying for over a year now to create a PEG monolayer that adequately prevents adhesion of cell-adhesion proteins such as laminin and Poly-D-Lysine. While I get beautiful non-adhesive properties for streptavidin and other small proteins, laminin and poly-d-lysine keep non-specifically binding everywhere. Has anyone encountered this issue before?
For reference, I have tried several chemistries for monolayer formation. 1) Direct crosslinking of PEG-Silane to glass. 2) Conjugation of PEG-NH2 to an APTES monolayer using a gluteraldehyde crosslinker. 3) Conjugation of PEG-NHS to an APTES monolayer. All these methods failed to prevent non-specific laminin absorption. My precleaning method is a nanostrip (stabilized piranha) etch, followed by a 30min sonication in DI and dry under a stream of N2.
Any thoughts/suggestions would be greatly appreciated!