In vitro bioactivity assessment and mechanical properties of novel calcium titanate/borosilicate glass composites A. Villalpando-Reyna * , D.A. Corte ´s-Herna ´ndez, A. Gorokhovsky, J.M. Almanza-Robles, J.C. Escobedo-Bocardo CINVESTAV-Unidad Saltillo, Carretera Saltillo – Monterrey km 13, CP 25900 Ramos Arizpe, Coahuila, Me ´xico Received 10 September 2010; received in revised form 21 September 2010; accepted 20 January 2011 Available online 18 February 2011 Abstract Bioactive calcium titanate/borosilicate glass composites were developed. Powder mixtures of borosilicate glass and 10, 20 or 30 wt% of potassium polytitanate particles were uniaxially pressed and sintered at 850 8C for 1 h. After heat treatment the reaction between potassium polytitanate and borosilicate glass produced composites consisting of calcium titanate particles embedded in a B-rich amorphous phase. For the in vitro bioactivity assessment sintered samples were immersed in a simulated body fluid (SBF) for 21 days under physiological conditions of pH and temperature. The compressive strength of the composites was also evaluated. A homogeneous and thick apatite layer was formed on all the materials tested. Furthermore, an appropriate compressive strength was observed (68–85 MPa). These results indicate that these composites are potential materials for bone tissue replacement and regeneration. # 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Borosilicate glasses; Potassium titanate; Calcium titanate; Apatite formation; Bioactive composites 1. Introduction Since Bioglass 1 was discovered, a great quantity of bioactive materials (glasses, glass–ceramics, ceramics and composites) has been investigated [1–3]. As it is well known, bioactive systems exhibit the ability to bond the living bone through an apatite layer formed on their surfaces when they are in contact with real or simulated body fluid. The main advantage of bioactive composites is that, as they are composed of two phases of different nature, each of the phases may provide different functional or structural properties to those of the starting materials [4]. Among such materials it is possible to note inorganic composites consisting of stainless steel fibers embedded in a Bioglass 1 matrix [1], bioactive glass ceramic toughened by zirconia particles [5], hydroxyapatite/ diopside/alumina composite [6], bioactive glass (45S5)/titania composites [7], calcium titanate/titania coating composite [8], etc. Using glass–ceramic technology, the effect of reinforcement is supported by different, preferably fiber-shaped, crystalline phases, which can be formed during the thermal treatment and partial crystallization of an original glass; whereas the same effect can be achieved with ceramic technology by sintering the compacted mixtures of powdered glass and reinforcement material. On the other hand, it is necessary to note that high mechanical strength usually is typical for non-porous bulk materials, characterized with relatively small interface and, as a result, low bioactivity properties. Whereas, good bioactive properties are characteristic for the porous glass–ceramic composites representing relatively low mechanical strength [9,10]. The goal of this research is to establish a new binary system leading to the formation of glass–ceramic composites with both high mechanical and bioactive properties. The glass composition and reinforcement were selected taking into account the following reasons: the borosilicate glasses have attractive characteristics for biomaterial applications [11,12] and the total conversion of some borosilicate glasses into calcium phosphate without silica remaining into human body has been reported [13]. Furthermore, a rapid hydroxyapatite formation mechanism has www.elsevier.com/locate/ceramint Available online at www.sciencedirect.com Ceramics International 37 (2011) 1625–1629 * Corresponding author. Tel.: +52 844 4389600x9680; fax: +52 844 4389610. E-mail addresses: dora.cortes@cinvestav.edu.mx, angelvillalpando82@gmail.com (A. Villalpando-Reyna). 0272-8842/$36.00 # 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved. doi:10.1016/j.ceramint.2011.01.034