The performance of a material intended for biomedical applications depends on its interfacial properties and reactions that occur when come in contact with biological fluids. Non-specific protein adsorption at the biomaterial interface is the first and critical event that initializes a cascade of host responses, including platelet activation, blood coagulation, and complement activation.1,2 Many approaches have been used to prevent such non-specific interactions.3−6

Coating or immobilization of surfaces with biomacromolecules such as albumin7−12 and anticoagulants like heparin13−18 have been widely studied towards this purpose. Another approach to overcome this problem is to coat the surface with synthetic hydrophilic polymers4,19 and this method has been used as a anti-fouling treatment for a number of applications including biosensors20

and drug delivery systems.21 It was demonstrated that such coatings frequently extend the life span of biomedical devices22−23 and the circulation half life of drug delivery systems.24−25

Several factors that affect the protein-repelling properties of polymer thin films on surface include the similarity of interfacial free energies of the polymer with that of water, interaction of proteinswith polymers through hydrophobic or charge interactions and environmental factors such as temperature and pH.26−28 In the case of neutral hydrophilic polymer grafted surfaces, the steric barrier due to high conformational entropy of anchored chains is one of the contributing factor towards protein repulsion.29−35 Other factors include, the structure of the polymer

on the surface (linear vs. branched), chemistry of the polymers and molecular weight of the grafted chains.