Magneto-optics of Ferritin

Area of Science:

• Physics
• Biophysics
• Materials Science

Background:

• Ferritin, a protein shell, is typically considered optically isotropic due to its spherical geometry.
• Macromolecules like ferritin are not expected to exhibit magnetic anisotropy.
• However, experimental observations suggest otherwise in solution.

Purpose of the Study:

• To investigate the magneto-optical properties of ferritin in solution.
• To understand the origin of induced magnetic birefringence and light scattering changes in ferritin.
• To quantify the linear and nonlinear magneto-optical polarizabilities of ferritin.

Main Methods:

• Rayleigh light scattering measurements.
• Nonlinear light scattering measurements in DC magnetic fields.
• Cotton-Mouton effect measurements.

Main Results:

• Ferritin exhibits induced magnetic birefringence and changes in scattered light intensity in a magnetic field.
• The observed phenomena are attributed to the deformation of linear optical polarizability by the magnetic field.
• Quantified values for anisotropy of linear and nonlinear magneto-optical polarizability, and optical polarizability were determined.

Conclusions:

• Magnetic fields induce significant magneto-optical effects in ferritin solutions.
• The deformation of optical polarizability is the primary mechanism behind these effects.
• This research provides key parameters for understanding ferritin's behavior in magnetic fields.