Effects of manganese incorporation on the morphology, structure and cytotoxicity of spherical bioactive glass nanoparticles.

Bioactive glass nanoparticles (BGNPs) are of great interest in tissue engineering as they possess high dissolution rate and capability of being internalized by cells, releasing their dissolution products with therapeutic benefits intracellularly. A modified Stöber process can be applied to obtain different BGNPs compositions containing therapeutic ions while maintaining controllable particle morphology, monodispersity and reduce agglomeration. Here, BGNPs containing Mn, an ion that has been shown to influence the osteoblast proliferation and bone mineralization, were evaluated. Particles with up to 142.3 ± 10.8 nm and spherical morphology were obtained after MnO incorporation in the SiO2 - CaO system. X-ray photoelectron spectroscopy (XPS) indicated the presence of Mn2+ species and also a reduction in the number of bridging oxygen bonds due to the Ca and Mn. The Ca and Mn network modifier role on the silica network was also confirmed by magic-angle spinning 29Si solid-state nuclear magnetic resonance (MAS NMR). MTT evaluation showed no reduction in the mitochondrial metabolic activity of human mesenchymal stem cells exposed to the glass ionic products. Thus, evaluation showed that Mn could be incorporated into BGNPs by the modified Stöber method while maintaining their spherical morphology and features as a promising strategy for tissue regeneration.