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

Tanya Dimova, Lachezar Radev, Irena Michailova, Diana Zaimova

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 SiO2-CaO-P2O5-xAg2O system, where x=0,1,2 and 4wt.% Ag2O (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 (H3PO4) and silver nitrate (AgNO3) as sources. TEOS was stirred into the mixed solvent of C2H5OH and H2O with a very small amount of HCl in the volume ratio TEOS:C2H5OH:H2O:HCl=1:1:1:0.01. The mixture of calcium phosphate (CP) and appropriate amount of AgNO3 was added to SiO2 sol under stirring for 20h. The mixed sol obtained was gelated at 120oC for 12h and 600oC 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 CaCO3, 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 SiO2-CaO-P2O5-xAg2O system (x=0,1,2 and 4wt.% Ag2O) 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 CO32- bands, i.e. after soaking carbonate apatite (CO3HA) may be formed on the surface of the prepared sol-gel glasses. On the basis of FTIR results, we can assume that B-type CO3HA preferentially formed on the soaked samples.


Keywords

bioglass, sol-gel, FTIR, in-vitro bioactivity


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