Shao-Ju Shih

The Correlation of Surfactant Concentrations on the Properties of Mesoporous Bioactive Glass

Bioactive glass (BG), a potential biomaterial, has received increasing attention since the discovery of its superior bioactivity. One of the main research objectives is to improve the bioactive property of BGs; therefore, surfactant-derived mesoporous bioactive glasses (MBGs) were developed to provide a high specific surface area for achieving higher bioactivity. In this study, various concentrations of typical triblock F127 surfactant were used to manipulate the morphology, specific surface area, and bioactivity of MBG particles. Two typical morphologies of smooth (Type I) and wrinkled (Type II) spheres were observed, and the population of Type II particles increased with an increase in the surfactant concentration. A direct correlation between specific surface area and bioactivity was observed by comparing the data obtained using the nitrogen adsorption-desorption method and in vitro bioactive tests. Furthermore, the optimal surfactant concentration corresponding to the highest bioactivity revealed that the surfactant aggregated to form Type II particles when the surface concentration was higher than the critical micelle concentration, and the high population of Type II particles may reduce the specific surface area because of the loss of bioactivity. Moreover, the formation mechanism of SP-derived MBG particles is discussed.

The Correlation of Pore Size and Bioactivity of Spray-Pyrolyzed Mesoporous Bioactive Glasses

SiO2–CaO–P2O5-based mesoporous bioactive glasses (MBGs) were synthesized by spray pyrolysis in this study. Three commonly used non-ionic tri-block copolymers (L121, P123, and F127) with various lengths of hydrophilic chains were applied as structural templates to achieve different pore sizes. A mesoporous structure was observed in each as-prepared specimen, and the results showed that the L121-treated MBG had the largest pore size. The results of bioactivity tests indicated that the growth of hydroxyapatite is related to the pore size of the materials.

Effect of Acetic Acid Concentration on Pore Structure for Mesoporous Bioactive Glass during Spray Pyrolysis

Mesoporous bioactive glass (MBG) is considered as one of the most important materials in the field of bone implants and drug carriers, owing to its superior bioactivity. In previous studies, tri-block surfactants (e.g., F127 and P123) were commonly used as pore-forming agents. However, the use of surfactants may cause serious problems such as micelle aggregation and carbon contamination and thus decrease bioactivity. Therefore, in this study, we demonstrated the synthesis of MBG using acetic acid (HAc) as a pore-forming agent to overcome the disadvantages caused by surfactants. Both untreated and HAc-treated BG powders were synthesized using spray pyrolysis and various characterizations were carried out. The results show that a mesoporous structure was successfully formed and the highest specific surface area of ~230 m2/g with improved bioactivity was reported.

Morphology Control of Eu-Doped Amorphous Gehlenite Phosphors Prepared by Spray Pyrolysis

Eu-doped amorphous gehlenite phosphors with various morphologies were synthesized using spray pyrolysis. Along with un-treated precursor, two commonly used pore-forming agents, polyethylene glycol and hydrogen peroxide, were applied to achieve porous and hollow particle structures. The phase compositions, surface morphologies, inner structures and photoluminescence properties of the resulting phosphors were examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and fluorescence spectrometry. The results showed that the morphologies of the particles were well-controlled, and a correlation between morphology and photoluminescence properties was established.