Non-specific protein adsorption is the first process in the foreign body response. Biomaterials need to provide non-fouling surfaces to prevent adsorption of blood proteins. The molecular design of surface modifiers that prevent non-specific adsorption requires the understanding of the factors that determine protein adsorption. The hierarchy of time and length scales present in the adsorption requires a multiscale approach to treat the complexity of the process.

In the first part of this presentation we will discuss the driving forces that determine protein adsorption and how end-grafted polymers can be used to modify the ability of the proteins to reach the surface. We will discuss the differences between preventing protein adsorption thermodynamically and kinetically. In particular, we will demonstrate that polymer molecular weight plays no role for the thermodynamic control while it is very important in determining the kinetics of protein adsorption.

A different adsorption scenario is present in protein mediated cell adhesion to surfaces. In this case specific binding between the proteins and cell receptors is necessary. We have studied the specific adsorption of proteins to surface mediated by ligand-receptor binding. In particular, we will demonstrate how poly ethylene glycol (PEG) spacers can be used to optimize the binding of small proteins. We will show how mixtures of different PEG molecular weights can optimize specific binding while preventing non-specific adsorption.

Finally, we will present how to use “smart materials” for the controlled release of proteins adsorbed on polymer-modified surfaces. In one case we show how changes in pH and temperature can be used to control the structure and amount of adsorbed proteins on surfaces with grafted thermo-responsive charged polymers, such as Poly(N,N-dimethylaminoethyl methacrylate). In another case we demonstrate how electrodes modified with short oligomers of DNA and short PEG can be used for the controlled release of proteins. In particular, we will discuss how to design the variation of the applied potential on the electrode for a desired protocol of protein release.