[mascott]

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!

[Yggdrasil]

I've encountered problems with non-specific sticking of protein to PEG-functionalized microscope slides before and one thing that I've seen helps is to "block" the slides by incubating with a high concentration of bovine serum albumen (~10mg/mL) for >1hr.  The theory here is that the BSA proteins will bind to and block any spots on the slide that your proteins of interest might bind to.