Energetics of surface confined ferritin during iron loading

Area of Science:

• Biophysics
• Nanotechnology
• Materials Science

Background:

• Ferritin self-assembly on surfaces is crucial for nanotechnology.
• Understanding iron loading dynamics within surface-bound ferritin is key to controlling ferritin-based nanomaterials.

Purpose of the Study:

• To quantitatively characterize the energetics of inter-ferritin interactions during iron loading on solid surfaces.
• To elucidate the forces governing ferritin-protein surface transformations upon iron uptake.

Main Methods:

• Adsorption of recombinant human ferritin H-chain onto microcantilever beams to form thin films.
• Real-time nanomechanical tracking of inter-ferritin forces during Fe(II) incubation and iron loading.

Main Results:

• Observed increasing attractive in-plane inter-ferritin interactions during iron loading.
• Quantified maximum surface work of 6.0±1.5mJ/m², equivalent to ~40kbT per ferritin.
• Identified attractive electrostatic forces from nascent iron cores as a significant contributor to surface work, alongside steric, bridging, and depletion forces.

Conclusions:

• Iron loading induces significant changes in surface energy and inter-ferritin forces.
• Nascent iron cores within ferritin shells generate attractive electrostatic forces that influence surface interactions.
• Findings provide fundamental insights for the rational design and application of ferritin-based nanotechnology.