Nano-scale Molecular Interaction Force Measurement for Analysis of Protein Adsorption on the Surfaces

Abstract

Protein adsorption behavior was examined from viewpoint of molecular interaction force generating on material surfaces. To achieve this, the methodology to evaluate the nano-scale molecular interaction forces on the well-defined surfaces by the force-versus-distance curve measurements using atomic force microscopy (AFM) was established. Zwitterionic, cationic, anionic, and hydrophobic polymer brush surfaces were prepared as model surfaces to analyze the interaction forces operating on the surfaces. The amount of proteins adsorbed on the polymer brush surfaces was quantified by surface plasmon resonance measurement. The molecular interaction forces operating on the polymer brush surfaces were evaluated using the AFM probes modified with functional groups. On the zwitterionic polymer brush surface, molecular interaction forces were not observed, and amount of protein adsorption was little. On the other hand, cationic, anionic, or hydrophobic polymer brush surface exhibited strong molecular interaction forces, and large amount of proteins adsorbed on these surfaces. These results indicated that the preparation of material surfaces, which avoid the molecular interactions, is significant for suppression of protein adsorption.