Theoretical Investigation on Terahertz Wave Radiation From Ion Transport in the Calcium Membrane Channel

In this paper, a mathematical physics model is set up to study the terahertz (THz) wave radiation as Ca²⁺ transports in the calcium membrane channel. By means of the proposed model, the energy distribution in the three dimensional membrane channel, and the trajectories of ions under THz irradiation are analyzed. It is observed that the Ca²⁺ transmembrane transport time is in the scale of picosecond, corresponding the spectrum concentrated in the THz range. Meanwhile, both the ion number in the membrane channel and the temperature have significant effects on the spectrum. In the multi-ion channel, the frequency change of the radiation spectrum of the multi-ion system is slight compared to the single-ion channel, but the total radiation energy increases obviously. In addition, the increase of temperature will accelerate the thermal motion of ions and lead to the radiation spectrum shifting towards high frequencies. Brownian dynamics (BD) simulations are carried out to demonstrate greatly enhanced permeation of the calcium channel in reaction to an external THz wave, i.e., the amplitude and frequency of which increase, the ion transport rate across the channel increases significantly. These discoveries are expected to provide a theoretical basis for the future treatment of THz waves in the neurological field.