Stimuli-responsive command polymer surface for generation of protein gradients.

Mixed polyelectrolyte brushes with a composition gradient were used as a platform for fabrication of stimuli-responsive command surfaces to control the generation of concentration gradients of adsorbed protein molecules. Switching between homogeneously adsorbed protein layers and adsorbed layers with protein concentration gradients was achieved by changing the pH of protein aqueous solutions. Protein adsorption and the direction of the adsorption gradient were tuned and also turned off and on or reversed by tuning the proton concentration in the pH range 4.0-8.6.