Dynamics of Antimicrobial Peptide Encapsulation in Carbon Nanotubes: The Role of Hydroxylation

Introduction: Carbon nanotubes (CNTs) have been widely employed as biomolecule carriers, but there is a need for further functionalization to broaden their therapeutic application in aqueous environments. A few reports have unraveled biomolecule-CNT interactions as a measure of response of the nanocarrier to drug-encapsulation dynamics. Methods: Herein, the dynamics of encapsulation of the antimicrobial peptide HA-FD-13 (accession code 2L24) into CNTs and hydroxylated CNTs (HCNTs) is discussed. Results: The van der Waals (vdW) interaction energy of CNT-peptide and HCNT-peptide complexes decreased, reaching -110.6 and -176.8 kcal.Mol(-1), respectively, once encapsulation of the peptide inside the CNTs had been completed within 15 ns. The free energy of the two systems decreased to -43.91 and -69.2 kcal.Mol(-1) in the same order. Discussion: The peptide was encased in the HCNTs comparatively more rapidly, due to the presence of both electrostatic and vdW interactions between the peptide and HCNTs. However, the peptide remained encapsulated throughout the vdW interaction in both systems. The negative values of the free energy of the two systems showed that the encapsulation process had occurred spontaneously. Of note, the lower free energy in the HCNT system suggested more stable peptide encapsulation.

Automated summary

This study discusses the encapsulation dynamics of an antimicrobial peptide in CNTs and HCNTs. The results show that the van der Waals interaction energy and free energy of the peptide complexes with CNTs and HCNTs are negative, indicating spontaneous encapsulation. HCNTs exhibit a more stable encapsulation, possibly due to the presence of electrostatic and van der Waals interactions.