Multifunctionality of Silicified Nanoshells at Cell Interfaces of Oryza sativa

Abstract

The mimic and design of artificial nanoshell materials on individual cells have been explored in microbial and mammalian cells, and these synthetic interfacial materials can confer new and unique properties on living cells to resist various environmental stresses. However, no attempts have been made toward chemical nanoencapsulation of higher plant cells. Here, we cultivated rice (Oryza sativa) single cells whose cell walls were silicified identically by mimicking diatom biomineralization. Results show that the silica nanoshell at the cell interface is effective at adsorbing cadmium (Cd2+) ions by in situ noninvasive microtest technology to quantitatively measure Cd2+ ion fluxes, rapidly sequestering and immobilizing Cd ions in the silicified cell walls with adsorption fluxes 6- to 10-times greater than those of the unsilicified cell walls. This, therefore, confers increased Cd tolerance by inhibiting Cd ion uptake into cells. In addition, using in situ atomic force microscopy to probe cell mechanical properties, the cell walls are remarkably strong by virtue of the material properties of the silica nanoshells that physically protects the cells against mechanical challenges. Chemically silicified cells may have acquired a multifunctionality of co-optimized mechanical protection and heavy metal detoxification by organic–inorganic composite materials of the silicified cell walls.