Applied Surface Science 258 (2012) 7202–7206 Contents lists available at SciVerse ScienceDirect Applied Surface Science jou rn al h om epa g e: www.elsevier.com/locate/apsusc Cell adhesion to cathodic arc plasma deposited CrAlSiN thin films Sun Kyu Kim a,∗ , Vuong-Hung Pham b , Chong-Hyun Kim c a School of Materials Science and Engineering, University of Ulsan, Ulsan 680-749, South Korea b Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, South Korea c Department of Food Science, Cornell University, Ithaca, NY 14853, USA a r t i c l e i n f o Article history: Received 12 March 2012 Received in revised form 5 April 2012 Accepted 5 April 2012 Available online 11 April 2012 Keywords: Cell adhesion CrAlSiN thin films Focal contact adhesion Cell proliferation Actin cytoskeleton a b s t r a c t Osteoblast cell response (cell adhesion, actin cytoskeleton and focal contact adhesion as well as cell proliferation) to CrN, CrAlSiN and Ti thin films was evaluated in vitro. Cell adhesion and actin stress fibers organization depended on the film composition significantly. Immunofluorescent staining of vinculin in osteoblast cells showed good focal contact adhesion on the CrAlSiN and Ti thin films but not on the CrN thin films. Cell proliferation was significantly greater on the CrAlSiN thin films as well as on Ti thin films than on the CrN thin films. © 2012 Elsevier B.V. All rights reserved. 1. Introduction It has been reported that almost 25% of joint replacement surgeries performed today eventually require retrieval of a failed titanium implant [1]. The average functional lifetime of joint replacement titanium implants ranges from 5 to 15 years [2]. Short implant life is a significant problem, especially for a growing num- ber of young patients, because of their active lifestyle [3]. Surgery of these failures is more difficult, expensive to perform and incon- venient to the patients than the original replacement surgery [4]. Wear is the main factor limiting the lifetime of the joint replace- ment implants and, thus, it is currently believed that minimizing wear as well as enhancing cell adhesion with minimal inflamma- tion of the implant surface should be important considerations in the implants material design [5,6]. Nitride thin film coating is one of the effective ways to improve hardness, friction coefficient and corrosion resistance of implants. Among them, CrN coatings have received wide attention. It is well known that CrN thin films have low internal stress, low friction coefficient and high toughness compared to TiN [7]. Considering the advantages of CrN thin films, it is important to improve further the mechanical properties as well as the biological response of CrN thin films. Recently, CrAlSiN thin films have been deposited suc- cessfully in our laboratory by cathodic arc plasma deposition. The hardness of SKD 11 steel tools increased significantly when coated ∗ Corresponding author. Tel.: +82 52 259 2228; fax: +82 52 259 1688. E-mail address: skim@ulsan.ac.kr (S.K. Kim). with CrAlSiN films [8]. The interaction between human osteoblast cells and CrN thin films was reported [9]. However, CrAlSiN thin films have not been evaluated for biological applications. The objec- tive of this work was to determine the cell response of CrAlSiN thin films. 2. Materials and methods 2.1. CrAlSiN, CrN and Ti thin film deposition Standard round glass coverslips (Marienfeld, Germany), 12 mm in diameter, were used as substrates. Prior to deposition, the sub- strates were cleaned with ethanol (95%) under ultrasonic vibration for 20 min. Then, they were dried in Ar gas. Finally, they were loaded into the deposition chamber. Two cathodes were used to deposit multilayered CrAlSiN thin films. The first cathode was AlSi alloy (12 at.%Si) and the second one was Cr. The arc current of the Cr cathode was 60 A and 45 A for the AlSi cathode. Deposition was done without biasing the substrate at a N 2 pressure of 4 Pa and a substrate temperature of 300 ◦ C. Single Ti and Cr cathodes were used to deposit Ti and CrN thin films, respectively. The Ti and Cr cathode arc currents were 90 A and 60 A, respectively. Deposition was done without biasing the substrate at a substrate tempera- ture of 300 ◦ C. Details of the cathodic arc plasma deposition were described elsewhere [10]. 2.1.1. Surface characterization The nano-multilayered structure of the CrAlSiN thin films was investigated by a transmission electron microscope (JEM-3000F, 0169-4332/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsusc.2012.04.036