Abstract
The cellular response of murine primary macrophages to monodisperse strontium containing bioactive glass nanoparticles (SrBGNPs), with diameters of 90 ± 10 nm and a composition (mol%) of 88.8 SiO2–1.8CaO-9.4SrO (9.4% Sr-BGNPs) was investigated for the first time. Macrophage response is critical as applications of bioactive nanoparticles will involve the nanoparticles circulating in the blood stream and macrophages will be the first cells to encounter the particles, as part of inflammatory response mechanisms. Macrophage viability and total DNA measurements were not decreased by particle concentrations of up to 250 μg/mL. The Sr-BGNPs were actively internalised by the macrophages via formation of endosome/lysosome-like vesicles bordered by a membrane inside the cells. The Sr-BGNPs degraded inside the cells, with the Ca and Sr maintained inside the silica network. When RAW264.7 cells were incubated with Sr-BGNPs, the cells were polarised towards the pro-regenerative M2 population rather than the pro-inflammatory M1 population. Sr-BGNPs are potential biocompatible vehicles for therapeutic cation delivery for applications in bone regeneration.
•Monodisperse bioactive glass nanoparticles (Sr-BGNPs), diameters of 90 ± 10 nm, containing strontium, did not cause toxicity in macrophages.•Sr-BGNPs were actively internalised by macrophages via formation of endosome/lysosome-like vesicles bordered by a membrane inside the cells.•TEM enabled visualisation of Sr-BGNPs inside macrophages and EDX showed Ca and Sr were maintained inside Sr-BGNPs during degradation.•Internalisation was via mixed mechanisms but was within vesicles and not the cytoplasm, which is beneficial for therapeutic strategies.•RAW264.7 cells exposed to Sr-BGNPs were poloarised towards the pro-regenerative M2 population rather than the pro-inflammatory M1 population.