Topics: Polymer, Adsorption, Buffer solution Pages: 15 (2941 words) Published: February 1, 2013
L angmuir 1995,11, 2344-2347


Coating Polystyrene Particles by Adsorption of
Hydrophobically Modified Dextran
C . Fournier, M. Leonard,* I. Le Coq-Leonard, and E . Dellacherie L CPM, URA C NRS 494, ENSIC B.P. 4 51, 54001 Nancy, France
Received March 14, 1995. I n Final Form: May 22, 1995@
I n order to decrease their hydrophobicity and thus t o reduce the protein adsorption at their surface, polystyrene-divinylbenzene (PS-DVB) particles have been coated with dextran. To favor its adsorption, the polysaccharide was previously substituted with low concentrations of phenoxy groups. The amount of dextran adsorbed onto the PS-DVB surface was examined as a function of the polymer concentration, and various samples of beads, differing in surface dextran concentration, were prepared. The adsorbed polymeric layer was then chemically cross-linked and its stability was checked in the presence of sodium dodecyl sulfate. The hydrophiliccharacter of the various resulting beads was evaluated toward the adsorption ofbovine serum albumin, a stronglyhydrophobic protein. By this study, the conditionsfor coating polystyrene particles were optimized and the dextran layer was shown t o greatly reduce the nonspecific adsorption of proteins.

I. Introduction
Polymer adsorption a t solid-liquid interfaces is a widely
studied phenomenon as connected with many important
processes including colloidal stabilization, flocculation,
adhesion, or coating.
T he reduction of protein adsorption by coating hydrophobic surfaces is of significant importance for many biomedical and biotechnological applications. Particularly, there is a n increasing interest in the use of polystyrene particles for liquid chromatography of biological molecules. These materials exhibit excellent mechanical properties and a good chemical stability over

a large range of pH.IJ However, to use this packing
material for the chromatography of proteins, it is essential to make the bead surface hydrophilic-except in the
reverse-phase mode-in order to avoid irreversible interactions and protein denaturation. The use ofwater-soluble polymers in the adsorbed coating technology turns out to
be one of the most efficient methods for the hydrophilization of polystyrene-divinylbenzene (PS-DVB) particles. Thus the adsorption of polyelectrolyte onto charged
polystyrene, Le., polystyrene on which ionic groups have
been grafted, leads to highly hydrophilic ion-exchange
materiaL3 Hydrophilization of PS-DVB can also be
achieved by adsorption of nonionic polymers such as e thyl
hydroxyethyl c e l l ~ l o s e poly(ethy1ene oxide)-poly(pro,~,~ pylene oxide) copolymer^,^,^ poly(viny1
polyglycerol.1° However, it is well-known that these
polymers partially desorb when exposed to other polymers
or proteins.11J2 To overcome this problem, low concentra-

* To whom correspondence should be addressed
Abstract published in A dvance A C S Abstracts, J uly 1, 1995. ( l)Moore, J. J . P olym. Sci. 1964,Part 2, 835.
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