I have been having issues with non-specific protein adhesion to my PEG-monolayer that I have formed.
First things first, The surface was first cleaned using Nanostrip (stabilized piranha), and sonicated in DI for 1hr. The surface was then dried under a nitrogen stream. I then used a 2% solution of PEG-Silane (MW ~700from Gelest Inc.) in toluene, and allowed to react under nitrogen for 16 hours.
I find that the monolayer works well at resisting some protein adhesion. For example, I can prevent streptavidin from adhering to the surface. But sticker proteins, such as laminin or PDL (Poly-lysine) are non-specifically adhering to the background. I have seen very little literature on this matter of different proteins behaving differently on PEG-monolayers.
I also tried a glutaraldehyde crosslinking method of PEG-NH2 to an APTES monolayer, and a nucleophilic substitution method using PEG-NHS onto an APTES monolayer. None of these worked to prevent the adhesion either.
I cannot use a BSA blocking method, as my aim is to avoid cell adhesion, and my cell cultures are sticking to BSA passivated surfaces.
Has anyone experienced this before?