Bio-Inspired Synthesis of Hollow Mesoporous Bioactive Glass Nanoparticles Using Calcium Carbonate as Solid Template

We report a surfactant free route to synthesize hollow mesoporous bioactive glass nanoparticles at ambient atmospheric condition. The synthesized particles contain hollow core as a result of mild acid mediated removal of calcium carbonate nanoparticles used as hard template. Removal of template was confirmed through FTIR and XRD while round morphology and sizes below 100 nm could be observed by TEM. In addition, N-2 adsorption and desorption analysis confirmed hollow and mesoporous nature of the bioactive glass shell. Interestingly, post removal of template, particles reported higher surface area, pore volume and pore diameter along with decrease in surface charge. Deposition of hydroxyapatite on hollow bioactive glass in Simulated Buffer Fluid (SBF) could be observed from Day 7 of immersion while well-developed hydroxyapatite depositions could be observed by Day 30. This proved bioactivity of the material while cytotoxicity analysis on Human Osteosarcoma cell line (U2OS) through MTT assay proved the biocompatible nature of the hollow bioactive glass particle.

Automated summary

We report a surfactant-free method for the synthesis of hollow mesoporous bioactive glass nanoparticles at ambient atmospheric conditions. The hollow core is achieved by gently removing calcium carbonate nanoparticles used as a template. The removal of the template is confirmed by FTIR and XRD analysis, and the spherical morphology and sub-100 nm size of the particles are observed by TEM. Furthermore, N2 adsorption and desorption analysis confirm the hollow and mesoporous nature of the bioactive glass shell. Interestingly, the post-template removal particles show increased surface area, pore volume, and pore diameter, along with a decrease in surface charge. The deposition of hydroxyapatite on the hollow bioactive glass in Simulated Buffer Fluid (SBF) is observed from Day 7 of immersion, with well-developed hydroxyapatite depositions observed by Day 30. This demonstrates the bioactivity of the material, and cytotoxicity analysis on the Human Osteosarcoma cell line (U2OS) through MTT assay confirms the biocompatible nature of the hollow bioactive glass particles.