Nanometer-resolved radio-frequency absorption and heating in biomembrane hydration layers

Area of Science:

• Biophysics
• Computational Biology
• Materials Science

Background:

• Radio-frequency (RF) electromagnetic fields are absorbed by biological matter, causing dielectric heating.
• Understanding RF-biomolecule interactions requires high-resolution dielectric absorption and heating descriptions.
• Existing effective medium approaches lack the necessary nanometer resolution.

Purpose of the Study:

• To develop a multiscale theoretical framework for quantifying RF absorption and heating in biomembranes at nanometer resolution.
• To investigate the influence of RF radiation on macromolecular structures and biological function.
• To provide a basis for refined physiological risk assessment of RF fields.

Main Methods:

• Atomistic simulations of RF absorption spectra for a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer.
• Calculation of electric field distribution in planar and spherical cell models.
• Prediction of nanometer-resolved temperature profiles under steady RF radiation.

Main Results:

• The 2 nm lipid hydration layer strongly absorbs RF energy across a wide frequency range (10 MHz–100 GHz).
• RF absorption strength is highly dependent on the incident wave's direction, necessitating tensorial dielectric spectral functions.
• Spherical cell models show enhanced RF absorption at the equator, inducing temperature gradients within cells.

Conclusions:

• RF fields can induce significant temperature gradients within cells at the nanoscale, even with small overall temperature increases.
• This study provides atomistically resolved predictions of thermal RF effects.
• Findings have implications for physiological risk assessment and potential technological applications in nanodevice temperature control.