CERAMICS INTERNATIONAL Available online at www.sciencedirect.com Ceramics International 41 (2015) 9411–9419 New evaluation of the in vitro response of silicocarnotite monophasic material S. Serena a,n , A. Caballero a , P.N. de Aza b , M.A. Sainz a a Departamento de Cerámica, Instituto de Cerámica y Vidrio, C/ Kelsen 5. Campus de Cantoblanco, 28049 Madrid Spain b Instituto de Bioingenieria, Universidad Miguel Hernández, Avda. de la Universidad s/n, 03202 Elche, Alicante Spain Received 9 January 2015; received in revised form 20 March 2015; accepted 30 March 2015 Available online 9 April 2015 Abstract In the present work the in vitro behavior in SBF of monophasic silicocarnotite material has been studied combining different techniques such as ICP-OES, FE-SEM-EDS, AFM, XRD, ATR-FTIR, and Confocal Raman microscopy. The nucleation of precipitates phases on the material surface has been observed from the first stage of the immersion test giving place to a precipitated layer with the increasing soaking time. This study put in evidence that this layer is constituted by a biphasic mixture of an amorphous Si–Ca–P–H material and carbohidroxyapatite phase. The response of silicocarnotite in SBF has been discussed on the basis of the CaO–SiO 2 –P 2 O 5 –H 2 O phase diagram. Finally, a mechanism describing the response of silicocarnotite in vitro conditions is proposed. & 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Calcium silicophosphates; Silicocarnotite; Biomaterials; AFM; Micro-Raman spectroscopy 1. Introduction The restoration of osseous and dental defects requires a material capable of integrating with its biological environment. The common characteristic of the bioactive ceramics is a time- dependent kinetic modification of the surface, which occurs on implantation. When exposed to physiologic solutions, these ceramics form a surface layer composed of an amorphous calcium phosphate, which crystallizes into a biologically active carbonated hydroxyapatite layer within few days. This phase is chemically and structurally equivalent to the mineral phase present in bone and is responsible for the interfacial bonding with the natural bone. Regarding silicon containing calcium phosphate materials, it is well know the effect of Si in the healthy bone and connective tissues. On the other hand, silicon modifies the material properties and improves the biological activity of silicon containing calcium phosphate materials so that they have been widely studied as biomaterial for osseous repair [1–9]. The interest on rich-silico phosphate biomaterial is increas- ing nowadays because of their good bioactivity response and low citotoxicity. In this context, silicocarnotite (Ca 5 (PO 4 ) 2 SiO 4 (C5SP)) is a calcium silicophosphate with carnotite structure [10], very close to hydroxyapatite, and presents a wide range of CaO, SiO 2 and P 2 O 5 solid solutions [11–13]. Some recent studies point out the good bioactive response of silicocarnotite- containig materials [14] specially in composite materials which contain silicocarnotite as mineral phase [15,16].These char- acteristics make the silicocarnotite attractive as possible con- stituent of biomaterial, however, the response mechanism of C5SP-single phase material in Simulated Body Fluid (SBF) is not yet well understood. The synthesis of silicocarnotite monophasic material was addressed by the present authors in a previous work [17] on the basis of the phase diagram of the system Ca 3 (PO 4 ) 2 –Ca 2 SiO 4 [11–13]. The synthesis by solid state reaction of pre- synthesized tricalcium phosphate and dicalcium silicate was www.elsevier.com/locate/ceramint http://dx.doi.org/10.1016/j.ceramint.2015.03.319 0272-8842/& 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author. Tel.: þ34 917355840; fax: þ 34 917355843. E-mail address: serena@icv.csic.es (S. Serena).