# Peptide–Carbon Nanotube Hybrids under Confinement: Structure and Stability from Atomistic Simulations

## TL;DR

This paper studies how peptides interact with carbon nanotubes in a confined space, revealing how they can form stable structures useful for bioelectronics.

## Contribution

The study reveals how electrostatic and dispersion forces govern peptide organization and stability in nanoscale confinement.

## Key findings

- Peptide-solvent interactions dominate over peptide-peptide aggregation in confined environments.
- Peptides adopt α-helical conformations compatible with the cylindrical geometry of carbon nanotubes.
- Hydrophobic alanine residues attract to CNT surfaces, while aspartic acid residues form hydrogen bonds with water.

## Abstract

The interaction between peptides and carbon nanotubes
(CNTs) represents
a promising route for developing biofunctional nanomaterials that
couple structural flexibility to superior electronic performance.
In this work, we investigate the structural and energetic behavior
of A6D peptides confined inside a single-walled CNT using
classical molecular dynamics simulations. The system consists of a
2 nm-radius CNT containing 35 A6D peptides and an equivalent
number of counterions, fully solvated in water. Analyses of hydrogen-bond
dynamics, Coulombic and van der Waals energies, and Ramachandran distributions
reveal that peptide–solvent interactions dominate peptide–peptide
aggregation, maintaining high flexibility within the confined environment.
The alanine residues exhibit strong hydrophobic attraction to the
CNT surface, while aspartic acid residues form extensive hydrogen
bonds with water, resulting in a balanced solvation–stabilization
regime. The confined peptides preferentially adopt α-helical
conformations compatible with the cylindrical geometry of the nanotube,
suggesting the potential formation of an internal peptide-membrane-like
structure. These findings provide molecular-level insights into how
electrostatic (peptide–peptide) and dispersion forces (peptide–peptide
and peptide–CNT) govern organization and stability under nanoscale
confinement. The results highlight the potential of peptide-coated
CNTs as building blocks for bioelectronic interfaces, selective molecular
transport systems, and controlled-release nanocarriers, bridging biomolecular
self-assembly with advanced carbon nanotechnology.