Chaperone-Assisted Host-Guest Interactions Revealed by Single-Molecule Force Spectroscopy.

Area of Science:

• Supramolecular chemistry
• Biomaterials science
• Single-molecule biophysics

Background:

• Cucurbit[7]uril (CB7) exhibits high binding affinities in aqueous environments, making it promising for analytical and biomedical uses.
• Mechanical stability of CB7 host-guest complexes is largely uncharacterized due to limitations in measurement platforms.
• Existing conjugation pairs like streptavidin-biotin are widely used but lack the unique properties of CB7.

Purpose of the Study:

• To develop a novel platform for characterizing the mechanical stability of CB7 host-guest complexes.
• To investigate the influence of guest charge on the mechanical properties of CB7 complexes.
• To uncover new mechanisms for assembling stable supramolecular structures using CB7.

Main Methods:

• Assembly of a DNA template with a flexible linker to tether CB7 host and adamantane guest.
• Single-molecule force spectroscopy using optical tweezers for mechanical measurements.
• Comparison of mechanical stability between neutral and positively charged adamantane guests.

Main Results:

• The DNA template enabled efficient single-molecule characterization of CB7-adamantane complexes.
• Positively charged adamantane guests exhibited greater mechanical stability (49 pN) than neutral guests (44 pN).
• A hexyl group adjacent to adamantane acted as a chaperone, facilitating adamantane-CB7 complex formation.

Conclusions:

• The study reveals the mechanical properties of CB7 host-guest interactions, highlighting the role of guest charge.
• A novel chaperone-assisted mechanism for supramolecular assembly was discovered, enhancing efficiency and stability.
• These findings offer new strategies for developing advanced supramolecular materials for biomedical and sensing applications.