Synthesis of calcium carbonate nanoparticles in erythrocytes enables efficient removal of extracellular lead ions

The “cyborg cells”, living cells with built-in nanoscaffolds, which could integrate the biological function of the cells with the functionality of nanomaterials, have been rarely explored. Here we report a method to construct “cyborg erythrocytes” through the in situ reaction of exogenous calcium and carbonate ions to generate calcium carbonate nanodots inside erythrocytes. The intracellular calcium carbonate nanodots combined with proteins are hidden under the membrane of erythrocytes, which can restrict migration and unexpected accumulation of nanodots in the body, improving the biosecurity of the nanodots. Most importantly, the calcium carbonate nanodots not only do not bring adverse effects on the nature of erythrocytes, but also endow erythrocytes with new properties. The in vitro and in vivo results show that the “cyborg erythrocytes” can remove 80% of lead ions in a blood poisoning model and reduce the lead level in the kidney and liver of mice through a precipitation transformation mechanism. Precipitation of inorganic materials on cell surfaces is well established but intracellular nanoparticle synthesis is less common. Here the crystallisation of calcium carbonate from exogenous ions within red blood cells is shown to selectively sequester Pb(II) from blood and to reduce accumulation of Pb(II) in mouse kidney and liver tissue.