In Vitro Bioactivity of Silver-Containing Sol-Gel Glasses: FTIR Analysis

Abstract

Introduction: The sol-gel glasses (BG) have been used for various biomedical applications, such as orthopedic, dental grafting and tissue engineering. The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the BG in SiO 2 -CaO-P 2 O 5 -xAg 2 O system, where x=0,1,2 and 4wt.% Ag 2 O (BG/Ag), after soaking in a simulated body fluid (1.5 SBF) for 12 days in static conditions. Materials and Methods: BG/Ag were synthesized from tetraethyl orthosilicate (TEOS), calcium oxide (CaO), phosphoric acid (H 3 PO 4 ) and silver nitrate (AgNO 3 ) as sources. TEOS was stirred into the mixed solvent of C 2 H 5 OH and H 2 O with a very small amount of HCl in the volume ratio TEOS:C 2 H 5 OH:H 2 O:HCl=1:1:1:0.01. The mixture of calcium phosphate (CP) and appropriate amount of AgNO 3 was added to SiO 2 sol under stirring for 20h. The mixed sol obtained was gelated at 120 o C for 12h and 600 o C for 6h. Results: X-ray powder diffraction (XRD) of the synthesized samples showed that the presence of some crystalline phases is dependent on the gel composition. XRD proved the presence of CaCO 3 , wollastonite, HA and metallic Ag in accordance with gel compositions. Fourier transform infrared spectroscopy (FTIR) of the prepared BG showed the presence of basic absorption bands, corresponding to the different chemical bands and crystalline phases, in agreement with XRD results. FTIR of the examined samples, after soaking in 1.5 SBF solution for 12 days, confirmed that B-type carbonate apatite was formed preferentially on the soaked surface. Conclusions: BG in SiO 2 -CaO-P 2 O 5 -xAg 2 O system (x=0,1,2 and 4wt.% Ag 2 O) were synthesized via a polystep sol-gel method. After immersion of the studied BG in 1.5 SBF solutions for 12 days in static conditions, FTIR revealed the presence of some CO 3 2- bands, i.e. after soaking carbonate apatite (CO 3 HA) may be formed on the surface of the prepared sol-gel glasses. On the basis of FTIR results, we can assume that B-type CO 3 HA preferentially formed on the soaked samples.