Colloids and Surfaces B: Biointerfaces 109 (2013) 228–235 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces B: Biointerfaces jou rn al hom epage: www.elsevier.com/locate/colsurfb Physicochemical and biological evaluation of poly(ethylene glycol) methacrylate grafted onto poly(dimethyl siloxane) surfaces for prosthetic devices Sara Gonc ¸ alves a , Ana Leirós a , Theo van Kooten b , Fernando Dourado a , Lígia R. Rodrigues a,∗ a IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal b Department of Biomedical Engineering (BME), University Medical Center of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands a r t i c l e i n f o Article history: Received 24 October 2012 Received in revised form 21 March 2013 Accepted 27 March 2013 Available online xxx Keywords: Poly(dimethyl siloxane) Surface-initiated atom transfer radical polymerization Anti-adhesion Cytotoxicity a b s t r a c t Poly(dimethyl siloxane) (PDMS) was surface-polymerized with poly(ethylene glycol)methacrylate (PEGMA) by surface-initiated atom transfer radical polymerization (SI-ATRP) in aqueous media at room temperature. Modification of the PDMS surface followed a three-step procedure: (i) PDMS surface hydroxylation by UV/ozone exposure, immediately followed by (ii) covalent attachment of the initiator, 1-trichlorosilyl-2-(chloromethylphenyl)ethane, onto the hydroxylated PDMS, via chemical vapor depo- sition; finally (iii) PDMS surface-polymerization of PEGMA by ATRP. Modified PDMS was characterized by water contact angle measurement, SEM, FTIR-ATR, and XPS. Results showed that modified surfaces had a hydrophilic character, given the water contact angles around 60 ◦ ; FTIR-ATR and XPS analysis con- firmed the presence of polymerized PEGMA on the surface of PDMS and the adhesion of Staphylococcus aureus GB 2/1 and Streptococcus salivarius GB 24/9 onto the modified surfaces was inhibited 94% and 81%, respectively. Finally, the modified PDMS showed no evidence of cytotoxic effects in in vitro assays using human skin fibroblasts. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Prosthetic devices have been widely used to compensate for defects either from congenital or acquired origin (such as disease or trauma). Silicone (poly(dimethyl siloxane); PDMS) elastomers are well-known materials for the production of prosthesis. However, given their low surface-free energy (hence poor wettability), they can cause adverse reactions such as tissue irritation, abrasion and ulceration [1–5]. Additionally, PDMS surfaces are hydrophobic and highly prone to bacterial colonization. PDMS-associated implant infections often occur, mainly caused by Staphylococcus spp. and other Gram-positive bacteria [6–8]. A competition between inte- gration of the material into the surrounding tissue and adhesion of bacteria to the implant surface occurs upon implantation [9]. For a successful implant, tissue integration, which is dictated by the material biocompatibility (non-cytotoxic), should occur prior to considerable bacterial adhesion. A 6 h post-implantation period has been identified during which prevention of bacterial adhesion is critical to the long-term success of an implant [10]. Over this period, an implant is particularly susceptible to surface colonization and ∗ Corresponding author. Tel.: +351 253604401; fax: +351 253604429. E-mail address: lrmr@deb.uminho.pt (L.R. Rodrigues). any strategy that can limit bacterial adhesion is expected to have an impact in the further performance of the implant [11]. There- fore, modification of PDMS surfaces toward hydrophilic surfaces (less susceptible to bacterial adhesion) is a promising approach to reach a more generalized application of a material that is already extensively used for manufacturing implantable medical devices. The central strategy to minimize the problems associated with PDMS and thus improve its clinical performance is to modify the surface properties of the elastomers, while allowing the material to retain its bulk properties. A body of literature already exists demon- strating the applications of physical, chemical and combinations of both methods for the surface modifications of PDMS polymers (reviews [12,13] cover these topics). An anti-adhesive surface can be obtained by modification with hydrophilic polymers. Polyethyl- ene glycols (PEGs), a family of water-soluble polymers containing a common chemical structure, are widely known to resist non- specific protein adsorption and microbial adhesion, a property most likely to result from its hydrophilicity, a large excluded volume and a distinct ability to coordinate with surrounding water molecules [14,15]. In previous studies biosurfactants from probiotic bacteria were shown to inhibit the adhesion of bacterial and yeast strains on PDMS substrates [11,16,17]. This work undertakes an exploratory approach in the use of surface-initiated atom transfer radical 0927-7765/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.colsurfb.2013.03.050