Surface characterization of plasma deposited nano-structured fluorocarbon coatings for promoting in vitro cell growth G.S. Senesi b, * , E. D’Aloia a , R. Gristina b , P. Favia a,b , R. d’Agostino a,b a Dipartimento di Chimica, Universita ` di Bari, Via Orabona 4, I-70126 Bari, Italy b Istituto di Metodologie Inorganiche e dei Plasmi/CNR, c/o Dipartimento di Chimica, Via Orabona 4, I-70126 Bari, Italy Received 28 July 2006; accepted for publication 23 November 2006 Available online 14 December 2006 Abstract Nano-structured ‘‘teflon-like’’ coatings characterized by highly-fluorinated, random, ribbon-shaped, micrometers-long structures were deposited on polyethylenetherephtalate (PET) substrates by plasma enhanced-chemical vapour deposition (PE-CVD) using mod- ulated radiofrequency (RF, 13.56 MHz) glow discharges fed with C 2 F 4 in modulated discharge (MD) and continuous wave (CW) regimes. Surfaces obtained in this way featured identical chemical composition and different roughness in the nanometric scale. Water contact angle (WCA) measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were utilized to char- acterize the surfaces. A positive relationship was shown to exist between the WCA value and the mean nano-structure height and the area root-mean-square (RMS) roughness of coatings. The possibility of obtaining coatings of varying nano-structure height, i.e., rough- ness, in a nanometric scale represents a promising result for further use of these surfaces as substrates for experiments on cell adhesion, proliferation and growth. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Nano-structured ‘‘teflon-like’’ coatings; Plasma enhanced-chemical vapour deposition; Surface morphology; Water contact angle; Atomic force microscopy; Scanning electron microscopy 1. Introduction In recent years numerous techniques have been em- ployed to modify the surface properties that control the functions and determine the success of various surface-ac- tive materials employed in many applications. Surface modifications aim to improve surface properties that in- clude, among many others, biocompatibility, adhesion and/or bonding, protective and/or barrier performance, and catalytic properties [1,2]. Radiofrequency (RF) plasma deposition is, among various techniques, one of the most powerful and versatile tool to obtain the modification of surfaces employed in tissue engineering, medical implants and production of pharmaceuticals. In particular, the plasma enhanced-chemical vapour deposition (PE-CVD) technique allows to vary continu- ously in a very broad range the morphology and chemical composition of processed surfaces and, consequently, their physical and chemical properties, by depositing thin (10– 1000 nm) organic or inorganic coatings on the surface of substrates [1,3,4]. Fluorocarbon (CF x ) films obtained by PE-CVD have been shown to be attractive materials for application in various fields. This is due to the possibility of obtaining surfaces of tuneable wettability, adhesivity and hardness, elevated chemical inertness, and properties of biomedical interest [1]. Coatings with different surface properties can be ob- tained by PE-CVD in either the continuous wave (CW) 0039-6028/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.susc.2006.11.046 * Corresponding author. Tel.: +39 080 5929505; fax: +39 080 5929520. E-mail address: giorgio.senesi@ba.imip.cnr.it (G.S. Senesi). www.elsevier.com/locate/susc Surface Science 601 (2007) 1019–1025