J. Biomedical Science and Engineering, 2013, 6, 258-264 JBiSE doi:10.4236/jbise.2013.63032 Published Online March 2013 (http://www.scirp.org/journal/jbise/ ) Sol-gel bioceramic material from bentonite clay Enobong R. Essien 1 , Luqman A. Adams 2* , Rafiu O. Shaibu 2 , Aderemi Oki 3 1 Department of Chemical Sciences, Bells University of Technology, Ota, Nigeria 2 Department of Chemistry, Faculty of Science, University of Lagos, Lagos, Nigeria 3 Department of Chemistry, Prairie View A & M University, Prairie View, USA Email: * ladams@unilag.edu.ng Received 20 December 2012; revised 5 January 2013; accepted 15 January 2013 ABSTRACT Bioceramic material of the quaternary system; SiO 2 - CaO-Na 2 O-P 2 O 5 that has composition similar to Bio- glass ® 45S5 was prepared by the sol-gel method from locally obtained bentonite clay (BTC). The monolith obtained was sintered at 1000˚C for 2 h to facilitate densification and phase transformation. X-ray dif- fraction (XRD) analysis revealed the presence of so- dium calcium silicate, Na 2 Ca 2 Si 3 O 9 as major crystal phase, and another secondary orthorhombic phase, NaCaPO 4 . Fourier transform infrared (FTIR) spec- troscopic investigation confirmed the presence of Si- O-Si bonds and a crystalline phosphate in the glass network. Scanning electron microscopy (SEM) re- vealed a network of micropores and interconnected macropores. Overall, the material displays features amenable for possible utilization in tissue engineering scaffolds. Keywords: Bioceramic; Sol-Gel; Monolith; Bentonite Clay; Silica 1. INTRODUCTION The number of patients requiring and receiving bio- medical implants to correct defects and heal diseases of the skeletal system is constantly increasing [1]. Tissue engineering and regenerative medicine assist with resto- ration of damaged tissues using both functional cells and biodegradable scaffolds made from engineered biomate- rials [2,3]. Significant efforts in the last decades have been devoted to the fabrication of porous and highly in- terconnected bioceramic scaffolds based on hydroxyapa- tite (HA), tricalcium phosphate and related composite materials for application in bone tissue engineering [4-6]. In this regard, Bioglass ® 45S5 characterised with high amounts of Na 2 O and CaO, and relatively high CaO/P 2 O 5 ratio [7] has shown capacity to induce favourable intra- cellular and extracellular responses promoting rapid bone formation [8-11] through formation of a hydroxycarbon- ate apatite (HCA) layer. The major approaches to processing bioactive glass materials include; the melting and the sol-gel methods. The melting method utilizes high temperature in the range of 1300˚C - 1400˚C, while a major advantage of the sol-gel method is the much lower processing tem- perature, coupled with the ability to control the composi- tional range of the glass [6]. A major limitation of bioactive glasses, especially in the porous form is that they display low mechanical pro- perties compared to cortical and cancellous bone [12,13], thus restricting their wide range of applications. Some previous efforts [14,15] have shown that when sintered under optimal conditions, sodium containing bioglass attains nearly full densification and produces fine crystals of Na 2 Ca 2 Si 3 O 9 having high bioactivity in- dex [16] to give scaffolds with competent mechanical strength. The serious challenge to the large scale preparation of bioactive glasses and glass-ceramic materials is the high cost of the widely used alkoxide precursors such as; tet- raethyl orthosilicate (TEOS) and tetramethyl orthosili- cate (TMOS) [17-20]. Consequently, some authors like Nayak et al. [21], Wu et al. [22] and Zanotto et al. [23] have explored alternative silica sources in their pathway to large scale bioactive glasses. Clay minerals are fine grained hydrous silicates of oc- tahedral or tetrahedral layered arrangement. Their chemi- cal composition implies that they may yet serve as an economically viable non-toxic silica source for large scale synthesis of bioactive glasses. Bentonite clay; (Na,Ca)(Al,Mg) 6 (Si 4 O 10 ) 3 (OH) 6 ·nH 2 O formed from the weathering of volcanic ash is naturally occurring sedimentary clay with the 3-layered clay struc- ture. It displays one aluminium oxide sheet sandwiched by two silicon oxide sheets Figure 1 [24]. Structurally, the internal aluminium and external silicon oxide sheet share oxygen atoms, while Mg 2+ ions often substitute for Al 3+ ions resulting in net negative charge [25]. The charge in the platelet is balanced by counter ions, usually * Corresponding author. Published Online March 2013 in SciRes. http://www.scirp.org/journal/jbise