Low temperature synthesis of bioactive materials

Abstract

Bioactive materials possess properties that allow them to interact with natural tissues to induce reactions that favor the development and regeneration of those tissues. In this study, silica was prepared by the sol-gel method, using tetraethylorthosilicate as the precursor. The calcium and phosphor sources used here were calcium ethoxy and phosphoric acid, respectively, in ethanol solvent. The solid obtained was dried at 50 ºC. In vitro bioactivity assays were performed by soaking the materials in simulated body fluid (SBF). The samples were characterized by transmission electron microscopy (TEM), thermal analysis and photoluminescence. TEM images of the samples before contact with SBF revealed amorphous aggregates and after 12 days in SBF showed two phases, one amorphous with large quantities of Si and O, and the other a crystalline phase whose composition contained Ca and P. The electron diffraction pattern showed a planar distance of 2.86 Å, corresponding to 2θ = 32.2º. This was ascribed to hydroxyapatite. The Eu III was used as structural probe. The relative band intensity correspondent the transition 5D0 → 7F2 / 5D0 → 7F1 showed a high symmetry surrounding the Eu III ion. These materials, produced by the sol-gel route, open up new possibilities for obtaining bioactive biomaterials for medical applications.

Effect of calcium phosphate coating on polyamide substrate for biomaterial applications

“…Crystal size increased with larger contact times, and it is expected to be calcium triphosphate and silicate phosphate, such as Ca 5 (PO 4 ) 2 SiO 4 and (Ca 2 (SiO 4 )) 6 (Ca 3 (PO 4 ) 2 ) 27 and/or hydroxyapatite. This is as in our previous work, 28 in which it was observed crystalline phases that were ascribed to hydroxyapatite, using the same synthesis of the present work, but with analysis up to their xerogel.…”

Sol-gel as methodology to obtain bioactive materials

“…THERMAL ANALySIS (TG/DTA) Figure 1 depicts the TG, DTG, and DTA curves for the sample dried at 50°C, HAS, which displayed the following mass loss steps: between 26 and 128°C, ascribed to water molecules produced by hydrolysis of the precursors and the solvent (ethanol) employed during the synthesis; between 128 and 262°C, attributed to decomposition of the ethyl groups present in the precursors TEOS and TEP; from 262 to 465°C, due to residual organic product from the decomposition of the precursors; and from 445 to 604°C, assigned to the dehydroxylation of the silanol groups (Si-OH), which gives rise to the inorganic polymer (Si-O-Si) (Bandeira et al 2011). …”

“…The sol-gel process is attractive because it uses mild conditions and easily available precursors. Countless literature works have reported the use of this route to prepare calcium-based compounds with applications in biomaterials (Radev et al 2012, Wei et al 2011, Heinemann et al 2011, Jadalannagari et al 2011, Bandeira et al 2011, Chatzistavrou et al 2011, Arcos and Vallet-Regí 2010.…”

Biomaterials and Sol–Gel Process: A Methodology for the Preparation of Functional Materials

“…We aimed to obtain materials whose properties would enable their application as biomaterials. In a first work, materials containing Ca-P-Si were prepared by the sol-gel route by mixing TEOS, calcium alkoxide, and phosphoric acid [55]. The resulting materials were immersed in Simulated Body Fluid (SBF) [56], pH = 7.40, for 12 days.…”