Estudo da atividade bactericida de vidros boratos bioativos dopados com Ag2O

Abstract

Infections triggered by bacteria has been the most common cause of implants failure. Thereby, it is advantageous to impart antibacterial properties to bioactive glasses by means of metals incorporation as the silver to the glass structure. In this present work, the borate glasses series over compositional range in the 59.5B2O3 - 2P2O5 – 9,5CaO – 9CaF2 – (20 - xNa2O) – xAg2O system, with x = 0, 0.25, 0.50 e 0.75 mol% was synthesized, in order to investigate the silver influence on their structure and bioactive response in simulated body fluid (SBF). The glasses bioactivities were evaluated by SBF solution pH measure which the samples were soaked for 3, 7, 14 and 21 days, by X-ray diffraction technique (XRD), Raman Spectroscopy and FTIR. The antibacterial properties of the glasses were evaluated using gram-positive and gram-negative Staphylococcus aureus e Escherichia coli. The cytotoxicity of the borate glass and the silver-containing borate bioactive glass was evaluated in vitro from the response of osteoblastic cells MC3T3-E1 in media containing the dissolution products of the glass. pH measure showed an increase of the solution alkalinity. This alkalinity increases further to the dissolution of the outermost layer of the glasses and then its apatite convention. XRD, Raman and FTIR measures were realized before and after immersion in SBF. The XRD patterns revealed that the addition of the Ag2O did not cause the glasses crystallization, the diffractograms exhibited broad bands it proved their amorphous nature. In 3 days of immersion in SBF, there was crystalline peaks formation what became more intense on twenty-one day of immersion. The Raman spectra exhibited bands at 430 cm-1 and 960 cm-1 assigns as the fluorapatite and hydroxyapatite formation, respectively. All FTIR spectra exhibited a very intense band at 1042 cm-1 also attributed to apatite formation. The obtained results indicated that the Ag2O until 0.75 mol% did not affect the apatite formation on samples surface. Cytotoxic effects to the osteoblasts culture were found for the borate glass containing 0.75Ag, but not for 0.25 and 0.50 mol % Ag2O. Ag2O-doped bioactive glasses presented better antibacterial activities than on the undoped borate glass. The obtained results show that the prepared samples present great potential as biomaterials applications.