Nature and Science 2013;11(3) http://www.sciencepub.net/nature http://www.sciencepub.net/nature naturesciencej@gmail.com 26 Influence of composition on the in-vitro bioactivity of bioglass prepared by a quick alkali-mediated sol–gel method M.I. El-Gohary 1 , Khairy M. Tohamy 1 , M.M. El-Okr 2 , Ashraf F. Ali 3 , Islam E. Soliman 1* 1. Biophysics branch, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo, Egypt. 2. Physics Department, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo, Egypt. 3. Inorganic Chemistry Department, National Research Center, Tahreer St., Dokki, Cairo, Egypt. islamsoloiman@yahoo.com Abstract: Bioactive glass with composition SiO 2 , Na 2 O, CaO, P 2 O 5 with MgO additive were synthesized through a quick alkali mediated sol–gel method. MgO was substituted for SiO 2 in glass formula up to 5 wt% and in-vitro bioactivity of the samples (precipitation behavior of carbonated apatite likely bone layer) was evaluated by soaking them in simulated body fluid (SBF). The characterizations were carried out using XRD, FT-IR, TGA, and DSC. The thermal results showed that all organic and inorganic precursors were completely decomposed before 600 ° C and, hence, all glass samples were stabilized at this temperature. The results obtained showed that MgO doping to glass samples increased its degradation and the formation of apatite like bone is delayed. [El-Gohary MI, Tohamy KM, El-Okr MM, Ali AF, Soliman IE. Influence of composition on the in-vitro bioactivity of bioglass prepared by a quick alkali-mediated sol–gel method. Nat Sci 2013;11(3):26-33]. (ISSN: 1545-0740). http://www.sciencepub.net/nature . 4 Key words: bioactive glass, sol-gel, in-vitro, bioactivity 1. Introduction Ca–Si-based bioactive glasses have been studied in last decades, since Hench, (1970) first investigated bioglass. Due to their good bioactivity, such as osteoconductivity and biodegradability [1, 2] , bioactive glass was used as a bioactive material for bone repair or regeneration [3] . In addition bioactive glass is the most of bioactive materials, which could bond to hard and soft tissue [4] . When this bioactive glass was soaked into physiological solutions, silica gel layer with high surface area will be firstly formed on the material’s surface by partial glass network dissolution and surface polycondensation. It has been recognized that the silica gel layer plays an important role in the nucleation and crystal growth of hydroxycarbonate apatite (HCA) layer [5] . Sol–gel technique, as a chemical method, exhibits more interest and provides an available way to synthesize bioactive glass. When compared with the traditional melting method, sol–gel technique has the advantage of lower reaction temperature and allows one to obtain glass which owns higher purity, large surface area, better homogeneity and microporosity [6] . However, the particle size of the traditional sol –gel-derived bioactive glasses was bigger than 1 μm [7] . In addition, the time of the synthesis of bioactive glasses by traditional sol–gel process is quite long process, because of the delayed gelation and ageing time. Magnesium is one of the main trace metallic elements existing in human body and it has been shown that it plays an important role in human bone development, maintenance and repair through osteoblastic cell stimulation [8] . The aim of the present work is to prepare Mg containing-bioactive-glass by a quick alkali-mediated sol–gel method. The size of the bioactive glass particles will be controlled by using ethanol as dispersant agent to adjusting the pH value of the sol [9] . The objectives of this research work are to synthesize and characterize the different compositions (x=0, 1, 3 and 5 wt%) of MgO substituted bioactive glass powders (55-xSiO 2 –35CaO–xMgO–5Na 2 O–5P 2 O 5 ) with the presence of other modifier for better understanding changes occurred in physicochemical properties of bioglass. 2. Materials and Methods Tetraethyl orthosilicate (TEOS), calcium nitrate tetrahydrate Ca(NO) 3 ·4H 2 O, sodium nitrate NaNO 3 , magnesium nitrate hexahydrate Mg(NO 3 ) 2 .6H 2 O and triethyl phosphate (TEP) ≥ 98% were purchased from Buchs, Switzerland. Ammonia solution, 33%, and nitric acid, 68%, were purchased from Merck, USA. Both nitric acid and ammonia solutions were diluted to 2M using distilled water.