Processing, physico-chemical characterisation and in vitro evaluation of silicon containing β-tricalcium phosphate ceramics N. Douard a , R. Detsch b , R. Chotard-Ghodsnia a , C. Damia a , U. Deisinger c , E. Champion a, ⁎ a Université de Limoges, CNRS, ENSCI, SPCTS, UMR 6638, 123 Avenue Albert Thomas, 87060 Limoges Cedex, France b BioCer Entwicklungs-GmbH, Ludwig-Thoma-Straße 36c, 95447 Bayreuth, Germany c Friedrich-Baur-Research Institute for Biomaterials, University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany abstract article info Article history: Received 17 June 2010 Received in revised form 9 August 2010 Accepted 12 November 2010 Available online 18 November 2010 Keywords: Tricalcium phosphate Silicon Powder synthesis Sintering In vitro evaluation For bone grafting applications, the elaboration of silicon containing beta-tricalcium phosphate (β-TCP) was studied. The synthesis was performed using a wet precipitation method according to the hypothetical theoretical formula Ca 3 -x (PO 4 ) 2 -2x (SiO 4 ) x . Two silicon loaded materials (0.46 wt.% and 0.95 wt.%) were investigated and compared to a pure β-TCP. The maturation time of the synthesis required in order to obtain β-TCP decreased with the amount of silicon. Only restrictive synthesis conditions allow preparing silicon containing β-TCP with controlled composition. To obtain dense ceramics, the sintering behaviour of the powders was evaluated. The addition of silicon slowed the densification process and decreased the grain size of the dense ceramics. Rietveld refinement may indicate a partial incorporation of silicon in the β-TCP lattice. X-ray photoelectron spectroscopy and transmission electron microscopy analyses revealed that the remaining silicon formed amorphous clusters of silicon rich phase. The in vitro biological behaviour was investigated with MC3T3-E1 osteoblast-like cells. After the addition of silicon, the ceramics remained cytocompatible, highlighting the high potential of silicon containing β-TCP as optimised bone graft material. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Bone mineral is a biological calcium phosphate material which contains various ionic substitutions [1]. Therefore, calcium phosphate materials are widely used for bone replacement in surgery due to their chemical compositions close to the bone mineral. These bioceramics favour bone reconstruction, thanks to high properties of resorbability for β-tricalcium phosphate (β-TCP — Ca 3 (PO 4 ) 2 ) and good osteocon- ductivity for hydroxyapatite (HA — Ca 10 (PO 4 ) 6 (OH) 2 ) [2]. The bone remodelling process involves the coupled action of osteoblasts (bone- forming cells) and osteoclasts (bone-resorbing cells) [3] and silicon (Si) seems to play a role during this process. Indeed, Carlisle suggested that Si is implied in the first stage of mineralisation [4]. Xynos et al. stated that ionic products of bioactive glass dissolution, rich in Si element, increased the proliferation of osteoblast cells, up to 155% of the control [5]. Thus, the doping of calcium phosphates with Si would be a potential method to improve their bioactivity. The synthesis and characterisation of pure Si-substituted hydroxyapatite (Si-HA), where silicate substitutes for phosphate, was well investi- gated and conducted to the formula Ca 10 (PO 4 ) 6 - x (SiO 4 ) x (OH) 2 - x [6,7]. In vivo [8] and in vitro [9] studies revealed an enhancement of the biological behaviour of HA after the silicon doping. In order to prepare calcium phosphate bioceramics with both higher resorption rates than HA and increased bioactivity, the study of silicon doped β- tricalcium phosphate appears of interest. Ghaith et al. prepared a silica containing β-TCP material through laser irradiation of a silica sol spin coated at the surface of dense β-TCP pellets [10]. Droplets of an amorphous phase containing silica remained embedded in the β-TCP. Bandyopadhyay et al. also reported the preparation, via a solid state method, of a nontoxic β-TCP with silica as dopant [11]. Wei et al. investigated the (Si, Zn) co-doping of TCP which led to β-TCP or α-TCP or a mixture of the two phases depending on the amount of dopants [12,13]. Except these studies, mainly the doping of α-TCP with silicon has been investigated [14–16]. On this basis, the aim of the present work was to investigate the possible incorporation of silicon into the β-TCP lattice. The study is focused on the powder synthesis via a wet precipitation method and further sintering. Particular attention was given to the determination of the chemical composition of ceramics (nature and location of the chemical phases within the ceramic material). Then, the influence of silicon on the in vitro cytocompatibility of the materials was investigated using a murine pre-osteoblastic cell line. Materials Science and Engineering C 31 (2011) 531–539 ⁎ Corresponding author. Tel.: + 33 555457460; fax: + 33 555457586. E-mail address: eric.champion@unilim.fr (E. Champion). 0928-4931/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.msec.2010.11.008 Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec