Understanding the factors determining the translocation of nanoparticles (NPs) across membranes is the key to designing versatile NPs for applications in nanotechnology and biomedicine. NP functionalization, for example coating with polymers or ligands, can directly change the NP-membrane interaction and open a way to control the NP cytotoxicity and translocation. Now, reporting in Nanotechnology, researchers at the Institute of Chemistry of the Chinese Academy of Sciences in China have revealed the important role of grafted polymers on the NP surface in its translocation through a fluidic membrane channel.
The translocation of a nanoparticle grafted with polymers through a fluidic membrane channel. Left: Snapshot of the simulation system. The (20, 20) type carbon nanotube (CNT) combined with two graphite sheets (cyan) solved in a periodic water box represents a nanometre water channel, and a polymer-functionalized nanoparticle (NP) is driven through it by an external electric field. |
As carbon nanotubes (CNTs) are excellent water transporters, the researchers use all-atom molecular dynamics simulations to study the translocation of charged NPs through a fluidic CNT. A series of simulations are conducted for NPs with different polymer length, polymer number, charge amount and charge position. With the increase in polymer length, the NP flux decreases as a whole due to the increase in NP size. The –NP translocation fails at the smallest polymer length because of the strong binding of Na+.
Surprisingly, the NP flux exhibits a maximum with the increase of polymer number or charge amount, which is co-determined by the NP net charge and size. Owing to the NP-membrane adsorption and NP-ion binding, the NP flux decreases with the decrease of charge position.
These results reveal the important role of grafted polymers in the NP translocation and may have implications in the design of highly efficient NP delivery. As in recent experiments, single NP translocation and detection has been achieved technically, so the researchers hope that their results can guide experimental researchers in the near future. (Nanotechnology)
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