Understanding Protein Adsorption on Carbon Nanotube Inner and Outer Surfaces by Molecular Dynamics Simulations

Area of Science:

• Nanobiotechnology
• Computational Biophysics
• Materials Science

Background:

• Proteins interact with carbon nanotubes (CNTs) via van der Waals forces, crucial for nanobiotechnology.
• Understanding differences in protein adsorption on inner versus outer CNT surfaces is limited.

Purpose of the Study:

• Investigate protein interaction mechanisms with inner and outer CNT surfaces.
• Analyze the impact of CNT curvature and protein orientation on adsorption.
• Determine protein conformational changes and binding energies.

Main Methods:

• Classical all-atom molecular dynamics simulations with explicit solvents.
• Poisson-Boltzmann surface area (MM-PBSA) for binding free energies.
• Steered molecular dynamics simulations with Jarzynski equality.

Main Results:

• Inner surface adsorption depends on CNT curvature and protein orientation, causing varied conformational changes.
• Outer surface adsorption is dominated by orientation, with greater structural loss when aromatic residues face the CNT.
• Protein desorption is configuration-dependent, influenced by binding modes.

Conclusions:

• Confined space within CNTs significantly influences protein adsorption.
• CNT curvature is a critical factor in modulating protein structure, particularly beta-sheet stability.
• Distinct interaction mechanisms exist for inner and outer CNT surfaces.