Study of fibrinogen adsorption on poly(ethylene glycol)-modified surfaces using a quartz crystal microbalance with dissipation and a dual polarization interferometry

Abstract

Protein adsorption behavior is a key factor that determines whether materials can be used as medical polymer materials. In this study, fibrinogen (Fib) adsorptions on three different poly(ethylene glycol) (PEG) surfaces that differed in chain length and chain density were investigated using a quartz crystal microbalance with dissipation (QCM-D) and a dual polarization interferometry (DPI) with respect to adsorbed masses, viscoelastic properties and chain conformations. On QCM-D chips, PEG chains were tight and in extended brush conformations. Meanwhile, on DPI chips, PEG₁₀₀₀ and PEG₂₀₀₀ may have the same pancake-like conformations, but PEG₅₀₀₀ had a mushroom conformation. Moreover, several bare spaces were observed on the loose pancake-like PEG₁₀₀₀- and PEG₂₀₀₀-modified DPI surfaces. Fib could fully spread on the relatively dense PEG₁₀₀₀-modified DPI surface and partly spread and tightly orient on the relatively sparse PEG₂₀₀₀-modified DPI surface. Thus, grafting density was found to have greater significance in determining Fib adsorption resistance due to its influence on Fib spreading when the chain conformations of hydrophilic molecules were loose pancake-like structures. Furthermore, brush and mushroom structured PEG₅₀₀₀ chains both had high deformation capacity, which excellently resisted protein adsorption by adjusting their conformation to decrease interaction with Fib. Therefore, the Fib adsorption resistance of PEG-modified surface depended on the grafting density of PEG layer and the deformation capacity of the PEG chain.