title: Adsorption mechanism of an antimicrobial peptide on carbonaceous surfaces: A molecular dynamics study.
abstract: Peptides are versatile molecules with applications spanning from biotechnology to nanomedicine. They exhibit a good capability to unbundle carbon nanotubes (CNT) by improving their solubility in water. Furthermore, they are a powerful drug delivery system since they can easily be uptaken by living cells, and their high surface-to-volume ratio facilitates the adsorption of molecules of different natures. Therefore, understanding the interaction mechanism between peptides and CNT is important for designing novel therapeutical agents. In this paper, the mechanisms of the adsorption of antimicrobial peptide Cecropin A-Magainin 2 (CA-MA) on a graphene nanosheet (GNS) and on an ultra-short single-walled CNT are characterized using molecular dynamics simulations. The results show that the peptide coats both GNS and CNT surfaces through preferential contacts with aromatic side chains. The peptide packs compactly on the carbon surfaces where the polar and functionalizable Lys side chains protrude into the bulk solvent. It is shown that the adsorption is strongly correlated to the loss of the peptide helical structure. In the case of the CNT, the outer surface is significantly more accessible for adsorption. Nevertheless when the outer surface is already covered by other peptides, a spontaneous diffusion, via the amidated C-terminus into the interior of the CNT, was observed within 150 ns of simulation time. We found that this spontaneous insertion into the CNT interior can be controlled by the polarity of the entrance rim. For the positively charged CA-MA peptide studied, hydrogenated and fluorinated rims, respectively, hinder and promote the insertion.
authors.affiliation: School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom.
authors.forename: Danilo
authors.identifier: 0000000284953815
authors.initials: D
authors.lastname: Roccatano
authors.affiliation: School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Edita
authors.initials: E
authors.lastname: Sarukhanyan
authors.affiliation: Polymat and Department of Organic Chemistry I, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018 San Sebastian, Spain.
authors.forename: Ronen
authors.initials: R
authors.lastname: Zangi
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D016503:Drug Delivery Systems; D006108:Graphite / Q000737:chemistry*; D054806:Magainins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D054806:Magainins; D037742:Nanotubes, Carbon; D014867:Water; D006108:Graphite; C031161:cecropin A