DNA Assembly Templated by Chiral Nanotube Lattices: From Helix to Rings

Area of Science:

• Materials Science
• Nanotechnology
• Biomolecular Engineering

Background:

• DNA-based materials typically utilize Watson-Crick base pairing and stacking for controlled assembly.
• Single-stranded DNA (ssDNA) adsorbs onto carbon nanotubes (CNTs) forming sequence- and chirality-dependent helices.
• Direct structural evidence for nanotube lattice templating in ssDNA assembly has been limited.

Purpose of the Study:

• To investigate the influence of carbon nanotube (CNT) chirality on single-stranded DNA (ssDNA) assembly.
• To provide direct structural evidence for a nanotube lattice-templating mechanism in ssDNA-CNT interactions.
• To explore novel DNA assembly strategies beyond traditional base pairing.

Main Methods:

• Cryo-electron microscopy was employed to compare ssDNA assembly on enantiomeric (6,5) CNTs.
• The specific ssDNA sequence TTA TAT TAT ATT (ss65) was used for assembly studies.
• Structural analysis focused on the resulting ssDNA topologies and their relationship to CNT handedness.

Main Results:

• On left-handed (+) (6,5) CNTs, ss65 formed stacked, ring-like wraps with a 15.3 Å axial repeat and micrometer-scale coherence.
• On right-handed (-) (6,5) CNTs, ss65 adopted a conventional 1-start helical wrap with a pitch of approximately 16.4 Å.
• CNT lattice handedness demonstrably biases ssDNA into distinct topological structures (rings vs. helices).

Conclusions:

• The handedness of the chiral carbon nanotube lattice dictates the specific topology of ssDNA assembly.
• This finding suggests a new strategy for DNA assembly based on recognizing the CNT lattice structure.
• This approach complements traditional DNA assembly methods relying on base pairing and stacking.