Calcium phosphate formation on porous sol-gel-derived SiO2 and CaO-P2O5-SiO2 substratesin vitro

Abstract

Sol-gel-derived SiO2 and CaO-P2O5-SiO2 have been shown to be bioactive and bone bonding. In this study bioactive sol-gel-derived SiO2 and CaO-P2O5-SiO2 systems were tested for in in vitro bioactivity. The calcined ceramic monoliths were immersed in a simulated body fluid and analyzed to follow the hydroxyapatite formation on the ceramic surface. Apatite-forming ability was investigated in terms of structural changes by changing the composition and the preparation method. The role of Ca and P dopants in the substrate structure is complicated, and careful characterization is needed. The composition and structure together determine the in vitro bioactivity. The pore structure was analyzed using N2-adsorption/desorption isotherms. The results indicate that a great mesopore volume and a wide mesopore size distribution favor hydroxycarbonate apatite nucleation and a great surface area is not needed. The performed preparation process for silica in a basic environment provides a convenient way to prepare a mesoporous material.

Sol–gel derived aluminosilicate coatings on alumina as substrate for osteoblasts

“…This is in agreement with reports suggesting that sol-gel silica surfaces should preferably have a larger pore size than 2 nm if bioactivity is required [25,26]. However, the pores in D/Smes were clearly within the mesoporous region, without any benefits for cell functions.…”

“…Moreover, properties like osteoconductivity are explained as a consequence of porosity or the hydrophilic surface [11,24]. For sol-gel derived coatings, specific surface area (SSA) [2], pore size [25], porosity [26], and nanoscale changes in surface layer chemistry [27] can have a significant effect on the bioactive properties. For example, sol-gel derived aluminosilicates are known to yield a low isoelectric point [28], and at the physiological pH of 7.4, this likely results in a negative surface charge essential for sol-gel coatings to gain a good bone response [26,29].…”

Surface modification of titanium, titanium alloys, and related materials for biomedical applications

“…Titania gel coating can improve the bioactivity of titanium implants because titania gels can induce the formation of apatite when soaked in a simulated body fluid (SBF) [74][75][76][77]. Titanium surfaces have been shown to react with H 2 O 2 producing Ti-peroxy gels [78][79][80].…”

Nanostructured Hybrid Materials for Bone Implants Fabrication

“…These features come from the sol-gel processing that allows the production of glasses and ceramics at much lower temperatures than with conventional methods. Basically, sol-gel processing of bioactive glasses is based on the hydrolysis and polycondensation of alkoxide precursors and/or inorganic salts, in order to obtain silica-based glasses with several components such as SiO 2 -CaO-P 2 O 5 or SiO 2 -CaO systems [44][45][46][47][48][49].…”