Effect of terahertz radiation on cells and cellular structures

Abstract

The paper presents the results of modern research on the effects of electromagnetic terahertz radiation in the frequency range 0.5-100 THz at different levels of power density and exposure time on the viability of normal and cancer cells. As an accompanying tool for monitoring the effect of radiation on biological cells and tissues, spectroscopic research methods in the terahertz frequency range are described, and attention is focused on the possibility of using the spectra of interstitial water as a marker of pathological processes. The problem of the safety of terahertz radiation for the human body from the point of view of its effect on the structures and systems of biological cells is also considered.

Keywords: Biological effects; Cancer cells; Electromagnetic radiation; Living cell; Terahertz radiation.

Fig. 1

Identified various cellular targets for existing and future promising studies in the THz range, adapted from [32]

Fig. 2

THz images of living and dead bacteria. a Comparison of terahertz images of live and dead Staphylococcus aureus cells [75]. b Statistical analysis of the average transmittances of the 2 groups after repeated measurements (n = 15). Data are presented as mean ± standard deviation. For statistical comparison of two groups, an independent t-test was used (P < 0.05)

Fig. 3

Spectral dependences of the a absorption coefficient and b refractive index of the bovine muscle tissue treated with 99.9% glycerol. The time corresponds to the cumulative time of holding the sample with glycerol. c Spectrum of the reflected signal from a total internal reflection prism in air (1) and for bovine muscle tissue (2, 3) under the influence of propylene glycol for 3 min (3) and 90 min (2). The signal from the tissue gradually increases with time, indicating a loss of water in the prism-sample interface and an increase in the propylene glycol content in the tissue [77]

Fig. 4

Simulation model and dielectric constant of nervous tissue. a Terahertz wave transport and thermal effect model in the nervous tissue, including neurons, terahertz sources, cerebrospinal fluid and PML layers. b A three-dimensional neuronal model consisting of a nucleus, cell membrane (CM) and cytoplasm. The red area is the location of the sampling point (M1–M4). c The real and imaginary parts of the relative permittivity of the CM (3–3 THz). d The real and imaginary parts of the relative permittivity of the intracellular physiologic fluid (IPF). A perfectly matched layer (PML) is an artificial absorbing layer for wave equations, commonly used to truncate computational regions in numerical methods to simulate problems with open boundaries, especially in the FDTD and FE methods. The key property of a PML that distinguishes it from an ordinary absorbing material is that it is designed so that waves incident upon [60]

Fig. 5

Specific frequency THz photons resonate voltage-gated potassium (Kv) channels and decrease the action potential (AP) firing rate in cortical neurons through molecular dynamics simulation. a Absorbance spectra of voltage-gated potassium/sodium ion channels and the bulk water. b The dynamic attributes of the low-threshold Kv1.2 filter structure in pre- and post-exposure to HFTS. Purple balls represent the K⁺, blue balls represent the Cl⁻. c The alterations in potassium/sodium ion conductance consequent to the influence of HFTS [95]

Fig. 6

a Difference between the two modes of potassium ion transport. b Lifetime (Life) of the hydrogen bond formed by water molecules and hydroxyl oxygen atoms on the side chain 374 Threonine [97]

Fig. 7

Illustration of cell system under the stimulation of terahertz unipolar picosecond pulse train [92]

Fig. 8

Review of the penetration of K⁺, Na⁺, and Ca²⁺ ions through the cell membrane when exposed to THz radiation, THM is the terahertz modulation, adapted from [51, 98, 99]

Fig. 9

Effect of THz radiation on actin filaments [23]. G-actin solution (0.8 μM) was polymerized by adding F-actin buffer with 20 min irradiation with THz radiation (0.46 THz) and without irradiation (control): a Images of actin filaments; b Comparison of actin filament morphology; c Comparison of the number of actin filaments. More than 100 actin filaments were counted in each experiment, *p < 0.05; d Pyrene-actin filaments were formed for 1 h, and then fluorescence was measured each time with or without THz irradiation. The relative fluorescence of pyrene at 0 min was determined to be 1.0. Data shown is the average of three independent measurements, **p < 0.01 [27]

Fig. 10

Effects of THz irradiation on HeLa cell morphology [64]: a Schematics of the experimental setup (THz waves were generated by a gyrotron FIR-UF on frequency of 0.46 THz with pulse duration of 10 ms and a repetition rate of 1 Hz. The THz irradiating beam passed vertically from the bottom of the dish via an aperture of 4 mm in the heating stage has a power density of 600 mW/cm². Also, CW IMPATT-diode (TeraSense Group Inc) with a frequency of 0.28 THz providing a power density of 125 mW/cm² on the output of horn antenna was used). b Microscopy images of cells at 0, 30, and 60 min of irradiation on frequency of 0.46 THz. c Schematics of mitotic progression. d Percentage of cells arrested at cytokinesis. More than 184 cells were measured in each experiment

Fig. 11

Study of predicting the mutational status of IDH glioma based on THz spectral data using the THz-TDS technique [73]

Fig. 12

a THz spectra for different IDH mutation states. b Parameters characterizing the features of IDH mutation. Red and blue colors represent groups of mutants. Alpha = absorption coefficient, ns = refractive index, kappa = extinction coefficient, e_real = dielectric constant, e_imag = dielectric loss factor, and tan_e = dielectric loss tangent (p < 0.05, “***” = 0.001, “**” = 0.01, “*” = 0.05) [73]

Fig. 13

THz images of breast cancer in three mice in the frequency range 108–143 GHz. a The projection area of the cancer tumor is about 0.480 mm². b The projection area of the cancer tumor is about 0.853 mm². c The tumor volume in a mouse is about 0.704 mm³ [72]

Fig. 14

Scheme of the inhibitory effect of THM on cancer cells. THM at a specific wavelength (3.6 µm) significantly inhibited the migration and glycolysis of cancer cells [4]