Chirality-assisted ring-like aggregation of aβ(1-40) at liquid-solid interfaces: a stereoselective two-step assembly...

Area of Science:

• Surface Chemistry
• Biophysics
• Nanotechnology

Background:

• Molecular chirality plays a crucial role in biological systems.
• Amyloid proteins, such as Aβ(1-40), are implicated in various diseases.
• Controlling protein aggregation at interfaces is vital for understanding biological processes and developing new materials.

Purpose of the Study:

• To investigate the influence of chiral surfaces on the assembly of amyloid Aβ(1-40).
• To observe and characterize the nanoscale secondary structure of Aβ(1-40) aggregates in situ.
• To elucidate the mechanisms underlying chiral recognition and guided protein assembly.

Main Methods:

• Modification of gold substrates with N-isobutyryl-L-cysteine (L-NIBC) and its enantiomer D-NIBC.
• Atomic force microscopy (AFM) for high-resolution imaging of protein aggregates.
• Tip-enhanced Raman scattering (TERS) for nanoscale secondary structure analysis of Aβ(1-40) assembly.

Main Results:

• Low concentrations of Aβ(1-40) formed ring-like aggregates on L-NIBC modified surfaces.
• D-NIBC modified surfaces resulted in rod-like aggregation of Aβ(1-40).
• AFM-TERS directly visualized nanoscale secondary structures and guided alignment of β-hairpins in Aβ(1-40) assemblies.

Conclusions:

• Chiral surfaces can effectively control the morphology and alignment of amyloid Aβ(1-40) aggregates.
• A two-step process involving electrostatic interactions and stereoselective recognition dictates the assembly.
• Proposed interaction sites (R5, K16, H14) on Aβ(1-40) offer insights into chiral recognition mechanisms at liquid-solid interfaces.