Effect of Well-Defined Polymer Brush Surface on Adsorption Force of Bovine Serum Albumin

Abstract

When the materials get contact with blood, non-specific protein adsorption occurs on the surface and the protein adsorption layer induces much severe biological responses including cellular reactions. Therefore, evaluating the first protein adsorption is important for preparing the nonbiofouling surfaces. Atomic force microscopy (AFM) makes it possible to directly measure the forces generated from protein-surface interaction in aqueous media down to few piconewtons range. In this study, we evaluated the adsorption force between bovine serum albumin (BSA)-immobilized AFM cantilever and well-defined polymer brush surface with three kinds of hydrophilic monomers, which are 2-methacryloyloxyethyl phosphorylcholine (MPC), poly (ethylene glycol) methacrylate (PEGMA) and 2-hydroxyethyl methacrylate (HEMA) by surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized silicon wafer in buffer solution. We found that the protein adsorption forces depended on the both chemical structure and thickness of the polymer brush layer. In particularly, the thickness was important to reduce protein adsorption force. From these results, thick polymer brush surface is one of the candidate surfaces with nonbiofouling characteristics.

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“…Moreover, we observed clear tendency to decrease in adsorption force with an increase in the thickness in each polymer brush case. The poly(MPC) could maintain low adsorption force for protein even in the case of thinner layer [49]. From these results, polymer brush layers prepared with zwitterionic and hydrophilic monomer units have extremely weak interactions with proteins and cells.…”

“…from the BrC3DMCS-immobilized substrate using EBIB [21,43], in our case, it was 0.26 chains nm -2 on BrC10TCS-immobilized silicon wafer, respectively. While there is a little difference in the graft density of poly(MPC) brush layer by the preparation methods, all the graft densities are more than 0.1 chains nm -2 , indicating that the dense polymer brush layer are prepared on the silicon wafer [48][49][50].…”

“…After protein immobilization, the cantilever was kept in PBS at 5th FORUM ON NEW MATERIALS PART E Hz. In each force measurement, 100 approaching/retracting force-distance relationship curves were collected, and the average value was defined as the adsorption force between the protein and the surfaces [49,50].…”