DOI: 10.1002/adem.200900122 Influence of Treatment Conditions on the Chemical Oxidative Activity of H 2 SO 4 /H 2 O 2 Mixtures for Modulating the Topography of Titanium** By Fabio Variola, Alessandro Lauria, Antonio Nanci * and Federico Rosei* Implantable materials are required to have particular mechanical and physico-chemical properties to assure appro- priate functioning and durability of medical devices. [1,2] These characteristics may vary according to the intended applica- tion, however in all cases implantable materials must exhibit biocompatibility. [3] That is they must be tolerated by the human body to avoid allergic immune reactions which could eventually lead to implant failure. [4] However, the current trend in health-related research aims to confer to implantable materials additional biological properties such as the ability to promote tissue regeneration. The capacity to actively interact with the surrounding tissues, to promote improved biological responses and to guide cellular processes along predeter- mined pathways, has thus become a primary objective in the design of novel generations of biomaterials. It is now recognized that implant-host tissue interactions are regulated by specific surface properties, such as its chemical composition, energy, roughness, and topography. [5–11] The key to achieving improved bioactivity is the rational design of a material’s surface properties. Several physical and chemical methods have been adopted to modify, at different scales, the surface properties of widely used biomaterials toward an improved bioactivity. [12–14] Over the past few years, attention has focused on nanoscale surface modifications to improve biointegration, such as by creating specific nanogeometries, and on the ability to superimpose nanoscale features on microtopography (reviewed in ref. [14]). COMMUNICATION [*] Prof. F. Rosei, F. Variola INRS-EMT, Universite´du Que´bec, 1650 Boul. Lionel-Boulet Varennes, QC, J3X 1S2, Canada E-mail: rosei@emt.inrs.ca Prof. A. Nanci, F. Variola, Dr. A. Lauria Laboratory for the Study of Calcified Tissues and Biomaterials, Faculte´deMe´decine Dentaire Universite´de Montre´al, Montreal, QC, H3C 3J7, Canada E-mail: Antonio.nanci@umontreal.ca Dr. A. Lauria Department of Materials Science, University of Milano Bicocca Milano, Italy [**] Acknowledgments: We acknowledge funding from the Cana- dian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC) through a Collaborative Health Research Project grant. In addition, we thank NSERC for a Collaborative Research and Development grant with Plasmionique, Inc. (Varennes, QC, Canada). F. V. acknowledges the Canadian Bureau for International Education (CBIE) and FQRNT for graduate fellowships. A. N. acknowledges funding from the CIHR and the Canada Foundation for Innovation (CFI). F. R. is grateful to the Fonds que´be´cois de la recherche sur la nature et les technologies (FQRNT) and the CFI. F. R. also acknowledges support from the Canada Research Chairs Program for partial salary support and from NSERC (Discovery Grants). Host-tissue integration of medical implants is governed by their surface properties. The capacity to rationally design the surface physico-chemical cues of implantable materials is thus a fundamental prerequisite to confer enhanced biocompatibility. Our previous work demonstrated that different cellular processes are elicited by the nanotexture generated on titanium (cpTi) and Ti6Al4V alloy by chemical oxidation with a H 2 SO 4 /H 2 O 2 mixture. Here, we illustrate that by varying the etching parameters such as temperature, concentration, and treatment time, we can create a variety of surface features on titanium which are expected to impact its biological response. The modified submicron and nanotextured surfaces were characterized by scanning electron (SEM) and atomic force (AFM) microscopies. Contact angle measurements revealed the higher hydrophilicity of the modified surfaces compared to untreated samples and Fourier transform infrared spectroscopy (FT-IR) established that the etching generated a TiO 2 layer with a thickness in the 40–60 nm range. ADVANCED ENGINEERING MATERIALS 2009, 11, No. 12 ß 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim B227