Polystyrene-modified carbon nanotubes: Promising carriers in targeted drug delivery

To design drug-delivery agents for therapeutic and diagnostic applications, understanding the mechanisms by which covalently functionalized carbon nanotubes penetrate and interact with cell membranes is of great importance. Here, we report all-atom molecular dynamics results from polystyrene and carboxyl-terminated polystyrene-modified carbon nano -tubes and show their translocation behavior across a model lipid bilayer together with their potential to deliver a molecule of the drug ibuprofen into the cell. Our results indicate that functionalized carbon nanotubes are internalized by the membrane in hundreds of nanoseconds and that drug loading increases the internalization speed further. Both loaded and unloaded tubes cross the closest leaflet of the bilayer by nonendocytic pathways, and for the times studied, the drug molecule remains trapped inside the pristine tube while remaining attached at the end of polystyrene-modified tube. On the other hand, carboxyl-terminated polystyrene functionalization allows the drug to be completely released into the lower leaflet of the bilayer without imposing dam-age to the membrane. This study shows that polystyrene functionalization is a promising alternative and facilitates drug delivery as a benchmark case.

Automated summary

This study investigates the translocation behavior of polystyrene and carboxyl-terminated polystyrene-modified carbon nanotubes across cell membranes, as well as the potential delivery of the drug molecule ibuprofen. The results suggest that functionalized carbon nanotubes can be internalized by the membrane and that drug loading enhances their penetration speed.