Kinetic and thermodynamic control of protein adsorption

Kinetic and thermodynamic control of protein adsorption

Department of Chemistry, Purdue University, West Lafayette, IN 47907

Communicated by Stuart A. Rice, University of Chicago, Chicago, IL (received for review October 22, 1999)

Abstract

Control of nonspecific protein adsorption is very important for the design of biocompatible and biomimetic materials as well as drug carriers. Grafted polymer layers can be used to prevent protein adsorption. We have studied the molecular factors that determine the equilibrium and kinetic control of protein adsorption by grafted polymer layers. We find that polymers that are not attracted to the surface are very effective for kinetic control but not very good for equilibrium reduction of protein adsorption. Polymers with attractions to the surface show exactly the opposite behavior. The implications for molecular design of biocompatible materials also are discussed in this paper.

Footnotes

↵ * To whom reprint requests should be addressed. E-mail: igal{at}purdue.edu.
↵ † Liposomes are closed spherical bilayers formed by lipid molecules with varying radii from 10 nm to micrometers.
Article published online before print: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.150236197.
Article and publication date are at www.pnas.org/cgi/doi/10.1073/pnas.150236197
↵ ‡ PEO-M, also called PEG-M for polyethylene glycol, is a chain of molecular weight M. Thus, the number of segments in the chain is given by M/45. We refer here to the commonly used experimental molecular weights. The exact number of segments used in the calculations is given in the figure legends.
↵ § The bare potential of fibrinogen with surfaces is not known and therefore it is very hard to provide a reliable estimate for the potential of mean force. The calculations presented here use the same attractive contribution between the surface and fibrinogen that was proposed in ref. 14. This interaction is only the attractive strength at contact.
↵ ¶ The potential of mean force here refers to the interaction (as a function of the distance from the surface) of a protein with the surface averaged over all of the configurations of the polymer molecules, solvent, and other proteins in the system, which is given exactly by the last term in Eq. 6.
Abbreviations:

pdf,

probability distribution function;

EO,

ethylene oxide;

PEO,

polyethylene oxide