Abstract
Hierarchically porous bioactive glass particles (BGPs) were synthesized by a facile sol–gel process using pollen grains as the templates. The synthesized pollen-templated bioactive glass particles (PBGPs) exhibited dual macro–nano porous structure. The macro pores (∼1μm) were inherited from the template of pollen grains while the nano pores (∼9.5nm) were induced by the intrinsic mechanism of the sol–gel process. PBGPs possessed a high specific surface area (111.4m2/g) and pore volume (0.35cm3/g). Hydroxyapatite (HA) formation on PBGPs was detected within 3 days after immersion in simulated body fluid (SBF). Due to their larger specific surface area and pore volume, PBGPs could be loaded with more tetracycline hydrochloride (TCH) than non-templated BGPs and conventional melt-derived 45S5 BGPs. In addition, PBGPs exhibited a low initial burst release (within 10% of the loaded amount) within 18h and a sustained release with a two-stage release pattern for up to 6 days in phosphate buffered saline (PBS). The antibacterial assay confirmed that the TCH-loaded PBGPs could release TCH within 5 days, and the released TCH could reach the minimum inhibitory concentration (MIC) against Escherichia coli. MTT assay indicated that PBGPs showed non-cytotoxic effects toward human hepatocellular carcinoma (Hep G2) cells after co-culture for up to 72h in vitro. These results showed that the biocompatible hierarchically macro–nano porous PBGPs are potential for bone regeneration and local drug delivery applications.
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