Biomimetic Poly(methyl methacrylate)-Based Terpolymers: Modulation of Bacterial Adhesion Effect Sandrine Berlot, ² Zoubida Aissaoui, ‡ Graciela Pavon-Djavid, ² Joel Belleney, ‡ Marcel Jozefowicz, ² Ge ´ rard He ´ lary, ² and Ve ´ ronique Migonney* ,² Laboratoire de Recherches sur les Macromole ´ cules, FRE 2314, Universite ´ Paris 13, 99 Avenue J-B Cle ´ ment, 93430, Villetaneuse, France, and Laboratoire de Chimie Macromole ´ culaire, UMR 7610, Universite ´ Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France Received June 29, 2001; Revised Manuscript Received October 30, 2001 Adherence of Staphylococcus aureus, responsible for major foreign body infections, was assessed onto functionalized poly(methyl methacrylate)-based terpolymers bearing sulfonate and carboxylate groups and onto poly(methyl methacrylate) as control. These terpolymers, have been synthesized by radical copolymer- ization of methyl methacrylate, methacrylic acid, and sodium styrene sulfonate by varying the ratio R ) [COO - ]/[COO - + SO 3 - ] from 0 to 1 and keeping ionic monomer content between 7 and 18%. Adsorption of fibronectin onto poly(methyl methacrylate) was shown to dramatically promote bacterial adherence, whereas a strong inhibition of bacteria adherence was observed onto functionalized terpolymers containing both car- boxylate and sulfonate groups. When terpolymers were predominantly functionalized by carboxylate groups, bacteria adherence was favored and reached values close to those obtained for poly(methyl methacrylate). These results have been related to the distribution of the anionic groups along the macromolecular chains, creating active sites responsible for specific interactions with fibronectin and inducing modifications of its conformation. The conformation of the adsorbed adhesive protein was then suggested to have an influence on the availability of its interaction sites to bacteria adhesins and therefore on modulation of bacteria adherence. Inhibition of Staphylococcus aureus adherence by functionalized poly(methyl methacrylate)-based terpolymers is of great interest in the field of biomedical implants and especially in the case of ophthalmic applications. Introduction Implant-associated infection is a medical problem which induces complications and may result in amputation, osteo- myelitis, or death. This is the major cause of implantation failure when antimicrobial treatment is not effective. For instance, Staphylococcus aureus (S. aureus), one of the most feared pathogens, cannot be cleared without removal of the implant. It was found that bacteria adherence to implanted material was strongly influenced by protein deposition onto the surfaces. 1,2 Indeed, every surface in contact with body fluids is rapidly coated with a monolayer of host plasma and matrix proteins. 3 The ability of S. aureus to adhere to implanted materials via adhesion proteins such as fibronectin or fibrinogen is a major factor for initiating foreign body infection. 1,4,5 Specific domains of these proteins, also called bacterial adhesins, may interact with bacterial surface proteins. 6 Therefore, a number of host matrix proteins such as fibronectin, fibrinogen, and vitronectin, which can bind S. aureus and adsorb onto the implant surfaces, are implicated in bacterial adherence to biomaterials and medical device related infection. Among these proteins, the role of fibronectin was shown to be predominant in promoting S. aureus adherence onto polymers 2,7,8 and metallic surfaces such as stainless steel, pure titanium, and titanium alloys. 9 However, the first studies devoted to prevention of prosthetic device associated infection did not take the adsorption of fibronectin into account. Immobilization of antibiotics or antimicrobial agents for permanent activity or controlled release of active molecules were suggested solu- tions. 10,11 Recently, several modifications of polymer surfaces were demonstrated to decrease protein adsorption and indirectly prevent bacterial adherence. Many authors showed that heparin-coated biomaterials reduced bacteria adherence whatever the nature of the polymer backbone. 12-15 However, the main difficulty was to graft heparin to the polymer surface while keeping the bacteriostatic properties. Another approach consisted of modifications of the hydrophilic surface properties of polymers. Indeed, low interfacial tension in biological fluids with hydrophilic coating has often been suggested to significantly decrease the adsorption of proteins. For instance, a significant reduction of bacterial adherence was observed onto poly(ethylene terephthalate) surfaces modified by poly(ethylene oxide). 16 Hydrophilic polymers such as poly(vinyl pyrrolidone) or poly(hydroxyethyl meth- acrylate) when grafted onto hydrophobic polymer surfaces have been demonstrated to reduce both protein adsorption and bacterial attachment. 17,18 * To whom correspondence should be addressed. E-mail: vmig@galilee.univ-paris13.fr. ² Laboratoire de Recherches sur les Macromole ´cules, FRE 2314, Uni- versite ´ Paris 13. ‡ Laboratoire de Chimie Macromole ´culaire, UMR 7610, Universite ´ Pierre et Marie Curie. 63 Biomacromolecules 2002, 3, 63-68 10.1021/bm015580m CCC: $22.00 © 2002 American Chemical Society Published on Web 12/01/2001