Numerical Investigations of Translocation Characteristics of Paired Nonspherical Silica Nanoparticles across Pulmonary Surfactant Monolayer.

To understand and prevent the toxic effects of lunar dust on astronauts' health in future manned lunar exploration missions, the translocation characteristics of paired nonspherical silica nanoparticles (P-NS-SiNPs) across a pulmonary surfactant (PS) monolayer are studied using a coarse-grained molecular dynamics method considering both ellipsoidal and cubic SiNPs with/without bugles. The key findings are as follows: (1) Compared with an individual SiNP, the translocation times for 4 and 6 nm ellipsoidal P-SiNPs decrease by 25-50% and 7.7-30.7% respectively, while those for 4 and 6 nm cubic P-SiNPs increase by 428.6% and 44.4% respectively, due to cooperative effects. (2) As initial minimum distance increases, the crossing times for ellipsoidal P-SiNPs first decrease and then increase, while embedding times for cubic P-SiNPs first increase and then decrease, due to different local curvature. (3) In the combinations of ellipsoidal-coupled cubic P-SiNPs, the translocation times for the 4 nm combination decrease by 25% and 14.3% respectively, while those for the 6 nm combination increase by 30.8% and 88.9%, respectively. (4) As the number of bulges on P-SiNPs increases, the average crossing times for 4 and 6 nm ellipsoidal-type P-SiNPs increase by 40%, 20%, as well as 14.3% and 219.1% respectively, while the embedding times for 4 nm cubic-type P-SiNPs decrease by 60.8% and 68.9% respectively, and those for 6 nm cubic-type P-SiNPs increase by 80.8% and 46.2%, respectively. In conclusion, due to the differences in contact area and local curvature, the translocation characteristics of ellipsoidal and cubic P-SiNPs exhibit two opposite trends under varying situations.