Preparation of a Surface-Grafted Protein-Selective Polymer Film by Combined Use of Controlled/living Radical Photopolymerization and Microcontact Imprinting

In this study, we describe a strategy for the formation of a molecularly imprinted polymer (MIP) capable of selective rebinding of protein-sized molecules and interfaced with a planar sensing surface. The strategy is based on the synergistic use of the surface-initiated controlled/living radical (C/LR) photopolymerization and microcontact imprinting approach aiming at design of a protein-responsive polymer for biosensing application. Bovine serum albumin (BSA), 2-(diethylamino)ethyl methacrylate, bis-acrylamide were used as a model protein, a functional monomer and a cross-linker, respectively, to prepare the BSA-MIP film. The optimal parameters of C/LR photopolymerization such as the method for photoinitiator attachment to the sensor surface, monomer:cross-linker molar ratio, polymerization time, were determined. The BSA-MIP film were studied in terms of their recognition capability and selectivity towards the target protein (BSA) through the analysis of the responses of the BSA-MIP modified SPR sensors upon interaction with BSA and interfering proteins, human serum albumin (HSA) and Fc-fragment of immunoglobulin G (Fc). It was found that BSA-MIP adsorbed BSA with the dissociation constant (KD) in the nanomolar range (68 nM) and shows more than two times higher adsorption capacity as compared to HSA and Fc, even though their molecular sizes were similar. Also, BSA-MIP could be perfectly regenerated in the alkaline solution showing nearly reversible responses (loss of 2.4%) even after the 25th regeneration cycle. The presented simple synthesis strategy could be potentially employed for the preparation of protein-MIP films on a planar sensor transducer allowing to develop sensing systems for detection of clinically relevant proteins.