Sol–Gel Synthesis and Characterization of a Quaternary Bioglass for Bone Regeneration and Tissue Engineering

Sol–gel synthesis using inorganic and/or organic precursors that undergo hydrolysis and condensation at room temperature is a very attractive and less energetic method for preparing bioactive glass (BG) compositions, as an alternative to the melt-quenching process. When properly conducted, sol–gel synthesis might result in amorphous structures, with all of the components intimately mixed at the atomic scale. Moreover, developing new and better performing materials for bone tissue engineering is a growing concern, as the aging of the world’s population leads to lower bone density and osteoporosis. This work describes the sol–gel synthesis of a novel quaternary silicate-based BG with the composition 60 SiO2–34 CaO–4 MgO–2 P2O5 (mol%), which was prepared using acidified distilled water as a single solvent. By controlling the kinetics of the hydrolysis and condensation steps, an amorphous glass structure could be obtained. The XRD results of samples calcined within the temperature range of 600–900 °C demonstrated that the amorphous nature was maintained until 800 °C, followed by partial crystallization at 900 °C. The specific surface area—an important factor in osteoconduction—was also evaluated over different temperatures, ranging from 160.6 ± 0.8 m2/g at 600 °C to 2.2 ± 0.1 m2/g at 900 °C, accompanied by consistent changes in average pore size and pore size distribution. The immersion of the BG particles in simulated body fluid (SBF) led to the formation of an extensive apatite layer on its surface. These overall results indicate that the proposed material is very promising for biomedical applications in bone regeneration and tissue engineering.

Preparation and Characterization of Silica-Coated Iron Oxide Nanoparticles (Fe3O4@SiO2 NPs)

In this study, this SiO2 has been coated on the surface of Fe3O4 (Fe3O4@SiO2) by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under alkaline medium at 80oC. It was found that only 500 mL TEOS is required to obtain the best coated Fe3O4 core structures which has been confirmed from its TEM micrograph. FTIR analyses revealed the formation of Si-O-Si bonds at 1084.2–1101.4 cm-1 hence confirmed that SiO2 has been successfully coated the Fe3O4 core. From the FESEM analyses, the average size of silica was ~ 50 -70 nm. EDX of the Fe3O4@SiO2 showed that silica had been effectively bonded onto the surface of Fe3O4. The VSM measurements confirmed the superparamagnetic properties of Fe3O4@SiO2 that is desirable for biomedical applications.

High Refractive Resist for UV-nanoimprint Soft Lithography Based on Titanium-containing Elemental Polymer Oligomer

This paper demonstrates a novel resist with high refractive index for UV-curing nanoimprint lithography based on o-phenoxyphenyl acrylated polytitanoxane oligomer. The oligomer is synthesized by hydrolysis and condensation of Ti-OEt...

Synthesis of silica nanoparticles to enhance the fire resistance of cement mortars

Silica nanoparticles are known to enhance the strength and durability of cementitious materials, due to their nanofilling effect and their high pozzolanic reactivity. They also have the potential to improve their thermal properties and fire resistance. However, these improvements are highly dependent on the nanoparticles’ characteristics. In this work, silica nanoparticles were prepared by sol-gel reaction and a design of experiments with four factors was used to conclude about the parameters that have more influence in the synthesis of these nanoparticles and, thus, optimize this process and the particles’ properties. Using a lower ethanol/water, higher hydrolysis and condensation time and higher volume of catalyst, the smallest particle size was obtained (118 nm). The effect of the incorporation of these silica nanoparticles into cement mortars was studied in terms of density and thermal conductivity of these mortars, after curing at room temperature. The presence of silica nanoparticles led to an increase in density and decrease of thermal conductivity. The mortars were also exposed to high temperature, which originated a significant reduction (~50%) in their thermal conductivity.