Plasma initiated graft polymerization of 2-methacryloyloxyethyl phosphorylcholine on silicone elastomer surfaces to enhance bio(hemo)compatibility Shuian-Yin Lin a , Vijaya Rohini Parasuraman b , Shewaye Lakew Mekuria b , Sydney Peng b , Hsieh-Chih Tsai b, ⁎, Ging-Ho Hsiue c, ⁎ a National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu, Taiwan b Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan c Department of Chemical Engineering National Chung Hsing University, Taichung, Taiwan abstract article info Article history: Received 23 November 2016 Revised 13 February 2017 Accepted in revised form 14 February 2017 Available online 20 February 2017 Poly-2-methacryloyloxyethyl phosphorylcholine (pMPC) was grafted from the silicone elastomer (SE) surface by plasma-initiated polymerization to alter the surface properties. Argon plasma was used to activate the SE surface, and the amount of peroxide produced on the surface was determined by 1,1-diphenyl-2-picryl-hydrazyl. Suc- cessful grafting of pMPC from the SE surface was verified by attenuated total reflection-Fourier transform infrared spectroscopy and elemental analysis. The surface morphology of cells adhered to pMPC-grafted SE also differed from that of cells adhered to unmodified and Ar-plasma-treated SE surfaces due to the homogenous graft poly- merization of pMPC. Biological analyses of pMPC-grafted SE revealed that, at the polymer surface, protein adsorp- tion of bovine serum albumin was significantly reduced, and that the surface exhibited anti-coagulant activity in human whole blood and decreased platelet adhesion. In summary, the grafting of pMPC on SE significantly en- hanced the bio(hemo)-compatibility of SE. © 2017 Elsevier B.V. All rights reserved. Keywords: 2-Methacryloyloxyethyl phosphorylcholine Silicone elastomer membrane Plasma initiated grafted polymerization Protein adsorption Platelet adhesion Human blood cells assay Fibroblast cell adhesion 1. Introduction Silicone elastomer (SE) is used as a soft-tissue substitute because it is soft, stable, and bio-inert. SE is a valuable biomaterial widely used in medical applications, but its surface properties and low wettability cause serious problems in long-term implants [1–5]. Furthermore, the hemocompatibility of SE is compromised after extended implantation owing to its surface hydrophobicity [6]. Currently, several methods are used to modify the surface of silicone polymers including corona, plas- ma, and laser treatments. Of these, plasma-induced activation of con- ventionally synthesized polymer surfaces using inert gas plasmas or simple plasma UV radiation generates free radicals that enable subse- quent grafting. Plasma treatment alone can also change the polymer surface morphology, through controlled nanostructuring or chemical modification by etching, cross-linking, and/or activating the polymer substrate. Moreover, inert gas plasma treatment has played a key role in the tuning of polymer wettability [7] and has expanded the applica- tion spectrum of these polymers in biomedicine [8–9]. Current surface modification technologies are able to introduce ni- trogen and phosphorous functionalities. These functionalities are attrac- tive for biomedical applications because they are biocompatible and enable covalent immobilization of biological molecules such as polysac- charides [10], enzymes, and DNA [11]. On the other hand, the addition of an inert gas (i.e. Ar) to nitrogen-based plasma can enhance radical formation and increase the number of nitrogen and oxygen functional- ities [12]. Ar-plasma treatment of SE increases the degree of cross- linking, which reduces the mobility of the modified SE surface and min- imizes hydrophobic recovery. These functionalities can be further grafted to confer biocompatibility, anti-bacterial properties, and anti- fouling characteristics [13]. It is desirable to endow the SE with new functionalities for medical applications, including cell and tissue engi- neering and drug delivery systems [14,15]. Nevertheless, many studies have indicated that SE blood contact can lead to the formation of throm- bi, but its use in short-term blood contact is very limited. Phospholipid polymers with phosphorylcholine head groups, such as poly-2-methacryloyloxyethyl phosphorylcholine (pMPC), are anti- fouling materials suitable for biomedical use. These phospholipid poly- mers have been used for the preparation of biocompatible polymers that mimic the bio-membrane structure [16]. When used in implantable micro-devices, pMPC's are hemo-compatible and inhibit the adhesion of proteins. These zwitterionic polymers confer anti-fouling properties Surface & Coatings Technology 315 (2017) 342–349 ⁎ Corresponding author. E-mail addresses: h.c.tsai@mail.ntust.edu.tw (H.-C. Tsai), ghhsiue@mx.nthu.edu.tw (G.-H. Hsiue). http://dx.doi.org/10.1016/j.surfcoat.2017.02.039 0257-8972/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat