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, PEG 1000 and PEG 2000 may have the same pancake-like conformations, but PEG 5000 had a mushroom conformation. Moreover, several bare spaces were observed on the loose pancake-like PEG 1000 -and PEG 2000 -modified DPI surfaces. Fib could fully spread on the relatively dense PEG 1000 -modified DPI surface and partly spread and tightly orient on the relatively sparse PEG 2000 -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 PEG 5000 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.

Dual-Polarization Interferometry: A Novel Technique To Light up the Nanomolecular World

“…The tandem DPI/QCM-D has been recently applied to an interesting study about the adsorption of fibrinogen on surfaces coated with different poly(ethylene glycol) chains (Mw 1000, 2000 and 5000). 185 It was demonstrated that on QCM-D chips, polymer tight chains were in extended brush conformations, while on DPI chips, the two light chains collapsed to a pancake-like conformation but the heaviest one (5000) had a mushroom conformation. Fibrinogen completely extended on the relatively dense poly(ethylene glycol) 1000-modified DPI surface (0.10 chains/nm 2 ), but only partly on the poly(ethylene glycol) 2000-modified DPI surface (0.05chains/nm 2 ), and did not adsorb on the deformable and mushroom-shaped, poly(ethylene glycol) 5000.…”

Mechanisms of fibrinogen adsorption at the silica substrate determined by QCM-D measurements

“…Most of these disadvantages can be eliminated by applying the quartz crystal microbalance with dissipation monitoring (QCM-D) technique that enables efficient, real time studies of protein adsorption and desorption at various substrates in liquid phases under flow conditions [16,[23][24][25][26][27][28]. However, a quantitative interpretation of these results is complicated by the fact that the QCM-D signal stems from the protein molecules and the trapped water.…”

“…The amount of the latter is a complicated function of the substrate topology (roughness), protein molecule shape and conformations, monolayer coverage and molecule orientation, flow rate, viscosity of the monolayer, oscillation frequency, etc. [23][24][25]27,28]. Therefore, the deconvolution of the primary QCM signal aimed at deriving the 'dry' mass of the protein cannot be done ab initio without accepting empirical models of the monolayer structure [29].…”

Chemistry-specific surface adsorption of the barnacle settlement-inducing protein complex

“…It is, however, a model protein for molecular adhesion studies having a tendency to adsorb non-specifically to a wide range of surfaces, including the so-called non-fouling chemistries like poly(ethylene glycol) (PEG) [6][7][8][9]. The PEG surface functionality is strongly hydrophilic, both in its interior and on its surface, retaining a hydration layer of electrostatically bound water molecules at the surface interface and along the chain that makes adsorption impossible for molecules not specifically adapted to the task.…”