Photograftable Zwitterionic Coatings Prevent Staphylococcus aureus and Staphylococcus epidermidis Adhesion to PDMS Surfaces

Due to its attractive mechanical properties and biocompatibility, poly(dimethyl)siloxane (PDMS) is widely used in the fabrication of biomedical materials. On the other hand, PDMS is also prone to adsorption of both proteins and bacteria, making PDMS implants susceptible to infection. Herein, we examine the use of durably cross-linked zwitterionic coatings for PDMS surfaces to mitigate bacterial adhesion. Using a single-step photografting technique, poly(sulfobetaine methacrylate) (pSBMA) and poly(carboxybetaine methacrylate) (pCBMA) thin films were covalently attached to PDMS substrates. The abilities of these coatings to resist the adhesion of Staphylococcus aureus and Staphylococcus epidermidis were tested in vitro under both wet and droplet conditions, as well as in subcutaneous and transcutaneous implantation models using Sprague-Dawley rats. Zwitterionic thin films effectively reduced bacterial adhesion in both in vitro and in vivo conditions. This was particularly true for pCBMA-coated materials, which exhibited significant reduction in bacterial adhesion and growth with respect to S. aureus and S. epidermidis for all in vitro conditions as well as the ability to resist bacterial growth on PDMS implants. The results of this study suggest that a simple and durable photografting process can be used to produce polymer thin films capable of preventing infection of implantable medical devices.