Release of an Encapsulated Peptide from Carbon Nanotubes Driven by Electric Fields: A Molecular Dynamics Study.

Targeted drug delivery into cells has been of tremendous scientific interest, and carbon nanotubes (CNTs) can be deemed as a promising material for the loading and unloading of drugs. One of the major challenges is the release of drugs from CNTs, which have a great potential well to trap molecules. By performing molecular dynamics simulations, this work attempts to study the releasing process of encapsulated protein/peptide molecules from CNTs in the presence of uniform electric fields. Zadaxin serves as a model for protein/peptide drugs. External electric fields can assist the peptide in overcoming the potential well during its release. It is found that successful release of the peptide depends on the pore width, the pore length, and the net charges on the peptide. The peptide is less likely to be released either from CNTs with a smaller pore diameter due to a deeper potential well of the tubes or from CNTs with a longer pore length due to a broader and deeper potential well. Peptides with more net charges are ideal for the releasing process driven by electric fields. This work can provide insights into the design of an optimal tube size for effective release of a given protein/peptide.