Bioactive Glasses Containing Au Nanoparticles. Effect of Calcination Temperature on Structure, Morphology, and Surface PropertiesDOI:10.1021/la100472p

Bioactive glasses containing gold nanoparticles (AuNPs) have been synthesized via the sol-gel route usingHAuCl4 x 3H2O as gold precursor. The formation process of AuNPs was studied as a function of the thermal treatment,which induces nucleation of Au particles and influences their nature, optical properties, shape, size, and distribution.The physicochemical characterization indicates that the sample treated at 600 °C presents the best characteristics to beused as a bioactive material, namely high surface area, high amount of AuNPs located at the glass surface, presence ofmicropores, and abundant surface OH groups. In the case of samples either aged at 60 °C or calcined at 150 °C, AuNPsjust begin their formation, and at this stage the gel is not completely polymerized and dried yet. A thermal treatment athigher temperatures (900 °C) causes the aggregation of AuNPs, forming “AuMPs” (i.e., Au microparticles) in adensified glass-ceramic material with low surface area, absence of pores, and low number of surface OH groups. Thesefeatures induce in the glass-ceramic materials treated at high-temperatures a lower bioactivity (evidenced by SBFreaction), as compared with that exhibited by the glass samples treated at 600 °C.