Backbone-Constrained Peptides: Temperature and Secondary Structure Affect Solid-State Electron Transport.

Area of Science:

• Biomolecular electronics
• Peptide self-assembly
• Charge transport mechanisms

Background:

• Charge migration in peptides is vital for biomolecular devices and sensors.
• Both electron transfer (ET) in solution and electron transport (ETp) in solid-state are influenced by peptide structure.
• Understanding these charge migration pathways is fundamental for advancing molecular electronics.

Purpose of the Study:

• To investigate electron transport (ETp) in Aib-containing helical peptide analogues.
• To explore the role of helical structure and electron-rich side chains in ETp.
• To correlate solid-state conductance with solution-phase electron transfer (ET) rates.

Main Methods:

• Fabrication and characterization of Au/peptide/Au junctions using four helical peptide analogues.
• Measurement of ETp across peptide monolayers at temperatures ranging from 80 to 340 K.
• Utilized molecular dynamics (MD) simulations to complement experimental findings.

Main Results:

• Both peptide helical structure and electron-rich side chains enhance ETp.
• Increasing temperature leads to decreased conductance due to loss of helical structure, altered monolayer tilt, and increased thermal fluctuations.
• Room temperature conductance correlates with previously reported ET rates, highlighting backbone rigidity and side-chain interactions.

Conclusions:

• Peptide helical structure and side-chain functionalization are critical for modulating electronic transport.
• Temperature-dependent changes in peptide conformation and arrangement significantly impact conductance.
• Findings offer novel strategies for controlling charge transport in solid-state peptide-based electronic systems.