Ion-doped mesoporous bioactive glasses as antibacterial agents in tissue regeneration

1. Introduction Bioactive glasses (BGs) have been extensively studied for bone repair and, only recently, for wound healing applications. Among BGs, mesoporous bioactive glasses (MBGs), in which the texture parameters of ordered mesoporous matrices are combined with the properties of bioactive glasses, have received increasing attention as tissue-regeneration systems. Their high surface area and tunable pore dimensions give the possibility of incorporating and releasing therapeutic ions to impart antibacterial functionalities (copper [1], cerium [2], silver [3]). 2. Methods MBGs doped with three different ions (Ce3+, Cu2+, Ag+) were synthesized following two different routes: a base-catalyzed sol-gel method [4] and an aerosol-assisted, spray-drying procedure [5]. Ion-containing MBGs were characterized by FESEM coupled to EDS, XRD and N2 adsorption-desorption analysis. To study the release profiles of the therapeutic ions, nanoparticles were immersed in Tris-HCl and maintained at 37°C in an orbital shaker up to 14 days and then i on contents in the supernatants were measured by ICP-AES. The antimicrobial properties of the salts used for the nanoparticles synthesis were investigated by assessing the MIC and through viable count analysis. The antibacterial potential of the nanoparticles and their extracts were studied by viable count method using three different bacterial strains. 3. Results The prepared samples are characterized by different size-between 0.5 and 5 m for spray-dryer and around 100 nm for sol-gel particles. Their high surface area and homogeneous pore size distribution allowed for the incorporation of specific amount of ions, which were released in a sustained way throughout 14 days. Ions-doped BGs showed good antibacterial properties ascribable to the presence of ions, with a bacteria viability reduction of 100% for what concern the silver-containing nanoparticles. 4. Discussion & Conclusion In this study, novel antibacterial ion-doped mesoporous glasses were successfully obtained by two different routes.