In vitro toxicity evaluation of Ti4+-stabilized γ-Bi2O3 sillenites

•Bi12TiO20 microparticles with γ-Bi2O3 structure show low cytotoxicity.•NO release/ROS production is directly/inversely proportional to γ-BTO concentration.•NO release is more prominent for fibroblasts and neurons compared to hepatocytes.•Intracellular ROS production is greater in the case of hepatocytes.•Cell proliferation appears after longer treatment times (48 and 72 h).

We report results regarding the in vitro toxicology of γ-Bi2O3 represented by its isomorphous phase Bi12TiO20 (γ-BTO). The γ-BTO microparticles were synthesized by two methods: coprecipitation from a bismuth nitrate-tetrabutyl titanate solution and solid state reaction of Bi2O3 and TiO2 oxides. The structural and morphological characteristics of the obtained materials were determined using X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission (TEM) and scanning (SEM) electron microscopy. The elemental composition was investigated using energy dispersive spectrometry (EDS). The cytotoxicity and oxidative/nitrosative stress (intracellular reactive oxygen species (ROS) and nitric oxide (NO) release) induced by the studied microparticles in HepG2, SH-SY5Y and 3T3-L1 cell cultures were determined using the MTT, DCF-DA (2′,7′-dichlorfluorescein-diacetate) and Griess methods respectively. Depending on the cell type and γ-BTO concentration, results showed only weak cytotoxic effects after 24 h of γ-BTO exposure and cell proliferation effects for longer treatment times. Only reduced NO release increases (corresponding to high γ-BTO concentrations) were detected in case of SH-SY5Y and 3T3-L1 cells. The intracellular ROS production (higher for HepG2 cells) appeared inversely proportional to the γ-BTO concentration.The obtained results indicated a promising in vitro biocompatibility of γ-BTO and encourage further studies regarding its potential for biomedical applications.