Protein Adsorption on Surfaces with Grafted Polymers

Szleifer, Igal

doi:10.1016/s0006-3495(97)78698-3

Cited by 395 publications

(497 citation statements)

References 46 publications

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“…1). Typically, the presence of the polymers imposes a high potential barrier that the proteins need to cross to reach the surface (16)(17)(18). For these cases the amount of protein adsorbed as a function of time, pro,ads (t), can be described with an equation of the form…”

Section: Theory and Modelsmentioning

confidence: 99%

“…1). The relevant molecular organization of the modified surface contains proteins in the bulk and adsorbed in a monolayer, whereas in between them there is a depletion of proteins due to the large repulsions imposed by the grafted polymers (15,17). The free energy is obtained from a molecular approach that we have developed in which the size, shape, conformations, and charge distribution of each molecular species are explicitly accounted for (17,22,23).…”

Section: Theory and Modelsmentioning

confidence: 99%

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Controlled release of proteins from polymer-modified surfaces

Fang

Szleifer

2006

Proc. Natl. Acad. Sci. U.S.A.

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The ability to control the rate of adsorption and desorption of proteins from surfaces is studied by using a molecular theory. We show how changing the chemical structure and charge of short linear and branched grafted polymers to an electrode surface can be used to promote fast adsorption of charged proteins on a time scale of seconds and control the desorption in a time scale ranging from milliseconds to hours. The optimal controlled release is found from the interplay of electrostatic attractions at short distances from the surface and the proper electrostatic and steric repulsive barrier at distances from the surfaces larger than the proteins' size. The implications of our results to the design of controlled-release devices is discussed.protein adsorption͞desorption ͉ surface modification ͉ grafted polymers ͉ kinetic theory C ontrol of protein adsorption is of primary importance in the design of biocompatible materials, biosensors, and bioactive surfaces (1-3). Furthermore, the process of protein adsorption is of great interest from a fundamental perspective because it encompasses very large, competing energy scales, and the process typically spans many time scales ranging from microseconds to hours (4, 5). Thus, a molecular understanding of the adsorption process and its control offers a great theoretical challenge in which energy, time, and length scales can be bridged. Furthermore, the ability to quantify how surface modifiers affect the adsorption͞desorption process will help in the molecular design of materials interacting with biological f luids. The aim of the work presented here is to demonstrate that by the proper choice of polymers grafted to the surface one can take advantage of the interplay between electrostatic and steric interactions to control the time scale for adsorption and desorption. This surface modification can serve as the basis for the design of controlled-release devices (6, 7).One of the most important, and still unresolved, problems in the design of biocompatible materials is the production of surfaces that can prevent nonspecific adsorption of blood proteins in vivo (8). There have been great advances in the understanding of how surface modification in vitro can reduce or prevent protein adsorption (9). There are two main ways of doing that. The first is by chemical modification of the surface exposed to the proteins (10). The second is by grafting polymer molecules on the surface exposed to the protein solution (11). The most commonly used polymer for this purpose is polyethylene glycol (PEG) (12); however, other polymers also have shown nonfouling capabilities (13). Grafted polymer layers have been shown to affect also the desorption of proteins. Experimental observations demonstrate that charged proteins may be trapped on poylelectrolyte grafted layers (14). Further, our recent theoretical predictions have shown that model PEG polymer layers can trap proteins adsorbed on hydrophobic surfaces, whenever the film thickness is larger than the protein size (15). Thus, the longer th...

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Section: Theory and Modelsmentioning

confidence: 99%

Section: Theory and Modelsmentioning

confidence: 99%

Controlled release of proteins from polymer-modified surfaces

Fang

Szleifer

2006

Proc. Natl. Acad. Sci. U.S.A.

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“…The behavior of the grafted chains, their configuration (mushroom or brush), and the forces generated when chains bound to separate surfaces are brought into overlap all have been considered theoretically and experimentally (12,13). Because grafted polymers have been widely used to reduce protein adsorption, theoretical and experimental investigations of these effects also have been carried out (14,15). That such grafted layers are capable of greatly reducing protein adsorption at some interfaces implies that an unfavorable free energy change occurs when protein interacts with a grafted layer.…”

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confidence: 99%

Size exclusion chromatography does not require pores

Brooks

Haynes

Hritcu

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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Separation of macromolecules on the basis of their molecular weight by size exclusion chromatography has long been considered to be caused by the geometry-dependent partition of macromolecules between a continuous phase and the porous interior of a gel or cross-linked bead. The volume of a pore accessible to a solute is limited by its relative dimensions, so larger molecules will have access to a smaller volume and will remain in a bead for a shorter time than smaller solutes. Our recent alternate picture proposes that the partition coefficient can be calculated from a thermodynamic model for the free energy of mixing of the solute with the gel phase. Size-dependent exclusion caused by the unfavorable entropy of mixing associated with the partition is predicted; the magnitude of the effect is modified by enthalpic interactions between the solute and the gel phase. This concept is extended here to describe the partition of macromolecules into a layer of terminally attached polymer chains grafted onto a solid bead. Both simple mean field and self-consistent field theory calculations predict size-dependent entropic exclusion. Experimental results obtained with neutral polymer chains grafted onto solid polystyrene latex beads confirm the predictions.

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“…When macromolecules interact with mPEG-modified surfaces, they contact and compress the polymer chains resulting in a further decrease in entropy. This highly thermodynamically unfavorable state is then reduced by the rejection of molecules from the polymer contact points thereby preventing protein adsorption and increasing entropy and conformational freedom of the polymer chains [23][24][25]. At higher surface polymer densities, (Figures 2 and 3) chains are even more restricted in conformational freedom thereby increasing plasma protein rejection from the biomaterial (bead) surface.…”

Section: Discussionmentioning

confidence: 99%

Immunocamouflage of latex surfaces by grafted methoxypoly(ethylene glycol) (mPEG): Proteomic analysis of plasma protein adsorption

Wang

et al. 2012

Sci. China Life Sci.

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Protein Adsorption on Surfaces with Grafted Polymers

Cited by 395 publications

References 46 publications

Controlled release of proteins from polymer-modified surfaces

Controlled release of proteins from polymer-modified surfaces

Size exclusion chromatography does not require pores

Immunocamouflage of latex surfaces by grafted methoxypoly(ethylene glycol) (mPEG): Proteomic analysis of plasma protein adsorption

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