Produção e bioatividade de materiais cristalinos dopados com íons estrôncio

• Ano de defesa: 2018
• Autor(a) principal: Maciel, Panmella Pereira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Odontologia; Programa de Pós-Graduação em Odontologia; UFPB
• Palavras-chave em Português: Biomateriais; Cerâmicas; Estrôncio; Sílica; Bioactive ceramic; Powder; Crystallization; Sol-gel; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/19012

Nowadays we have clinical need to develop innovative biomaterials which provide dual functionality: regeneration of bone tissue and inhibition of pathogenic microorganisms. Glass-ceramic materials are interesting options. The aim of this study was to produce, characterize and evaluate the bio-reactivity and the antimicrobial effect of these materials doped with strontium ions using in vitro methodology. Crystalline powders (CP) of composition similar to S53P4 glass and Sr-modified were produced via sol-gel route and treated at 800 ° C. For the CP containing this ion, molar substitution of 12.5% or 25% of CaO by SrO was carried out. Three analytical groups were obtained: CP without Sr (CPSr0), CP with 12.5% Sr (CPSr12.5) and CP with 25% Sr (CPSr25). The CPs were characterized by Xray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Zeta sizer and thermogravimetric analysis (TGA / DTG). The antimicrobial effect was verified through the macrodilution and death curve tests (1, 6, 12, 24, 48 and 72 hours) (concentration ≤ 100 mg/mL) against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Streptococcus mutans and yeasts of the genus Candida: C. albicans, C. glabrata, C. krusei e C. tropicalis. Bio-reactivity was evaluated in vitro by immersion in simulated body fluid (SBF) (24, 72 and 168 hours) by means of scanning electron microscopy (SEM) and FTIR analyzis. The obtained gels partially crystallized to form a sodium-calcium silicate phase (combeite). The increasing substitution of CaO by SrO showed characteristic absorption band for SrO binding. The CPs had mean particle sizes of 1.61 ± 0.24 μm (CPSr0), 1.88 ± 0.48 μm (CPSr123.5) and 1.48 ± 0.41 μm (CPSr25). SEM images showed irregular and porous surface particles. The evaluated powders inhibited the growth of the microorganisms, demonstrating complete inhibition in the first 6h, except for S. mutans when exposed to CPSr12.5 (complete inhibition in 24h) and CPSr25 (complete inhibition in 48h) and E. faecalis when exposed to CPSr0 (complete inhibition in 24h), CPSr12.5 and CPSr25 (complete inhibition in 72h). pH values higher than 10 were obtained for the culture medium in the first 6 h, which shows a positive correlation with the inhibitory effect for the microorganisms evaluated. CPSr12.5 and CPSr25 showed higher bioactivity, with total surface coating by HA in 7 days of immersion in SBF. In addition, characteristic bands of HA in FTIR were observed for all groups. The pH increased rapidly in the first 24 h after immersion of the powders in SBF, reaching a maximum value of 8.72 ± 0.03 (CPSr0), 8.70 ± 0.02 (CPSr12.5) and 8.70 ± 0.03 (CPSr25) after 168 h. Replacement of CaO by SrO did not change the overall structure of the material. HA formation was observed, with emphasis on strontium powders. All powders showed an inhibitory effect on oral pathogens.