V. Migonney

Modulation of Staphylococcus aureus adhesion by biofunctional copolymers derived from polystyrene

Abstract Biomaterials-centered infections are serious complications associated with the use of implants. The infection risk of biomaterials varies between different materials and is determined by the chemical composition of materials, the host proteins and the type of bacteria. In this study we measured the initial adhesion of Staphylococcus aureus onto polystyrene derivatives containing carboxylate and sulfonate groups. Five polymers were synthesized and characterized. We studied the role of the host protein fibronectin in promoting adhesion of Staphylococcus aureus. Fibronectin adsorption was comparable on all the tested polymers (pKd=7.2±0.2) whereas bacterial adhesion was dependent on surfaces chemical compositions. Polymers substituted with sulfonate groups showed the most important inhibition of initial bacterial adhesion.

Inhibition de l’adhérence de Staphylococcus epidermidis sur des surfaces en titane par des polymères hydrosolubles bioactifs comportant des fonctions sulfonate, phosphate ou carboxylate

Implanted prostheses are sometimes subject to bacterial infections, which can threat their benefit rule on a long-term basis. Various methods are studied to fight against these infections. Among them, the grafting of bioactive polymers onto the prosthesis surface shows up as a promising way to the problem of infections. This work presents the influence of various water-soluble bioactive polymers on the inhibition of the Staphylococcus epidermidis adhesion on the titanium samples surfaces initially preadsorbed with various proteins. Whatever the studied protein is, it is shown that the bioactive polymer containing sulfonate functions generates an inhibition of the adhesion of Staphylococcus epidermidis. For a plasma preadsorption, the inhibition rate rises up to 68% when the concentration of sulfonate function is 2.5μmol/L. Titanium surfaces grafted with the bioactive polymer were also tested. We find an inhibitive activity of the adhesion close to that of the previous case. These preliminary results can point up a clinical interest in the fight against the medical devices infection, because they highlight a clear local effect of S. epidermidis adhesion inhibition. Copolymers containing other functional groups (phosphate or carboxylate) were dissolved in a bacterial suspension to monitor the influence of the composition on the adhesion inhibition. Their inhibition rates are not significantly lower than those of pNaSS homopolymers, as much as the sulfonate function proportion remains higher than 50%. Thus, the sulfonate function is the main responsible for the inhibition of the S. epidermidis adhesion.

Use of a quartz crystal resonator to study the cell adhesion process

The thickness shear mode (TSM) quartz crystal resonator has been extensively used as a sensitive sensor in various electrochemical and biological applications. This technique, based on the transverse propagation of an acoustic shear wave generated by a sinusoidal electric field through a piezoelectric quartz resonator, provides a non-destructive and powerful means of probing changes in solid-solid or solid-liquid interfaces. In this work, we propose to apply this system to characterize the inhibition properties developed by bioactive polymers towards McCoy fibroblast cells adhesion processes. Thin film of various functionalized poly(methylmethacrylate) (PMMA) based copolymers exhibiting either carboxylate and/or sulfonate functional groups and non functionalized PMMA were deposited on quartz samples as control. The effects of induced inhibition of McCoy fibroblasts cell adhesion onto thin functionalized polymeric films of various chemical compositions were analyzed. In addition. shear acoustical results were further compared to those obtained by a cell counting technique and by optical microscopy.