Efficient Electron Hopping Transport through Azurin-Based Junctions

Area of Science:

• Biophysics
• Quantum Chemistry
• Molecular Electronics

Background:

• Electron transport in biological molecules is crucial for understanding biological processes.
• Azurin, a blue-copper protein, serves as a model system for studying electron transfer.
• Interpreting experimental current-voltage (IV) curves in protein junctions is challenging due to system complexity.

Purpose of the Study:

• To theoretically investigate electron transport mechanisms through azurin protein junctions.
• To compare single-site hopping transport with fully coherent transport.
• To analyze factors influencing current asymmetry and temperature dependence in these junctions.

Main Methods:

• Utilized fully quantum calculations to model electron transport.
• Simulated transport through azurin junctions with varying structural details and orbital alignments.
• Investigated the impact of hopping site number and tip position on current.

Main Results:

• Single-site hopping can result in higher or lower currents than coherent transport, depending on junction structure and orbital alignment.
• The asymmetry of IV curves is sensitive to the tip's position within the junction.
• Hopping currents increase with a greater number of hopping sites.
• The hopping mechanism can exhibit low temperature dependence under specific conditions.

Conclusions:

• Theoretical findings provide a deeper understanding of electron transport mechanisms in azurin junctions.
• The study offers guidance for interpreting complex experimental IV curves.
• Quantum calculations reveal the significant role of hopping transport in protein-based molecular electronics.