Molecular-dynamics studies of competitive replacement in peptide-nanotube assembly for control of drug release.

We report molecular-dynamics simulation of carbon-nanotube-based drug delivery and release systems. We show that a peptide encapsulated inside or attached to the outer surface of a carbon nanotube can be released by another nanotube through a competitive replacement process. Energy analysis reveals that the van der Waals interaction plays the key role in this process, and the potential well between two nanotubes drives the competitive replacement. We further show that competitive replacement is a basic principle which may be generally explored for drug release. For example, one type of peptide can be used to replace/release another type of peptide, depending on the difference in their affinity for the nanotube. The effects of the peptide sequence and the nanotube size on the drug release process are also studied in this paper.