Interface interaction between high-siliceous/calcareous mineral granules and model cell membranes dominated by electrostatic force.

High-siliceous/calcareous mineral granules may cause cytotoxicity by attaching to cell membranes. In this research, giant (GUVs) and small unilamellar vesicles (SUVs) were used as model membranes for studying the interaction between high-siliceous/calcareous mineral granules (micro calcite, micro quartz, nano calcium carbonate, and nano silica) and artificial membranes. Confocal laser scanning microscopy (CLSM) and fluorescence labeling experiments suggest that nano calcium carbonate (nano CaCO) and nano silica (nano SiO) induce gelation by disrupting the oppositely charged membranes, indicating the important role of electrostatic forces. Thereby, the mineral granule size affects the electrostatic interactions and thus leading to the damage of the membranes. FTIR spectra and molecular dynamics reveal that mineral granules mainly interact with -PO, -OH, and -C-N(CH) groups in phospholipids. The electrostatic force between nano minerals and phospholipids is greater in the case SiO when compared to CaCO. Moreover, nano SiO forms the strongest hydrogen bond with the -PO group as confirmed by FTIR. Thus, nano SiO causes the greatest damage to membranes. This research provides a deeper understanding of the mechanism regarding the interaction between inhalable mineral granules and cell membranes.