Exploring the electronic and mechanical properties of protein using conducting atomic force microscopy

Area of Science:

• Biophysics
• Molecular Electronics
• Protein Engineering

Background:

• Interfacing electronic devices with biomolecules requires understanding junction effects on signal transmission.
• Blue copper metalloproteins like azurin are key for electron transfer studies.

Purpose of the Study:

• To investigate the electron transfer characteristics of azurin.
• To analyze how compressional force affects azurin's current-voltage (I-V) behavior.
• To explore the relationship between protein mechanics and electron tunneling.

Main Methods:

• Conducting atomic force microscopy (C-AFM) to measure I-V behavior under varying force.
• Modified Simmons formula to analyze tunneling characteristics.
• Molecular dynamics simulations to model protein deformation and atomic density changes.

Main Results:

• Azurin's I-V behavior was modulated by applied compressional force.
• Tunneling barrier height decreased with increasing force, correlating with protein deformation.
• Atom packing density increased linearly with force at low compression, retaining secondary structure.
• Results align with an atom packing density model for protein electron tunneling.

Conclusions:

• Compressional force significantly impacts electron tunneling through azurin.
• The atom packing density model effectively explains force-dependent modulation of the tunneling barrier.
• Findings support the use of biomolecules in molecular electronics and advanced biosensing applications.