Mechanistic study of the adsorption and penetration of modified SiO₂ nanoparticles on cellular membrane

SiO₂ nanoparticles (NPs) are ubiquitous in the atmosphere and have been proved to be harmful to human by bioaccumulation. The bioaccumulation of SiO₂ NPs begins with their partitioning into membrane phospholipids. However, the uptake of SiO₂ particle onto lipid bilayers has been not completely understood. In this study, the uptake process of different modified SiO₂ particles (with adsorbed trace gas molecules, including formic acid (FA), methyl vinyl ketone (MVK), and methacrolein (MAC)) into DPPC bilayers were investigated by molecular dynamics (MD) simulations. Results suggest that after the SiO₂ particle absorbed on the surface of bilayers, it spun by itself to form the most stable adsorption configurations. MAC and MVK molecule tend to be absorbed into DPPC bilayer while FA molecule was more likely located at the surface region of bilayer from the viewpoint of thermodynamics. Besides, it was also found apart from the commonly accepted "Trojan-horse" effect, SiO₂ NPs may increase biohazard via modulating the concentration of pollutants. This work is beneficial for understanding the toxicity and bioaccumulation of FA, MVK, MAC, and SiO₂ NPs at molecular level.