Advances in the biological effects of terahertz wave radiation

MEMS-actuated terahertz metamaterials driven by phase-transition materials

The non-ionizing and penetrative characteristics of terahertz (THz) radiation have recently led to its adoption across a variety of applications. To effectively utilize THz radiation, modulators with precise control are imperative. While most recent THz modulators manipulate the amplitude, frequency, or phase of incident THz radiation, considerably less progress has been made toward THz polarization modulation. Conventional methods for polarization control suffer from high driving voltages, restricted modulation depth, and narrow band capabilities, which hinder device performance and broader applications. Consequently, an ideal THz modulator that offers high modulation depth along with ease of processing and operation is required. In this paper, we propose and realize a THz metamaterial comprised of microelectromechanical systems (MEMS) actuated by the phase-transition material vanadium dioxide (VO2). Simulation and experimental results of the three-dimensional metamaterials show that by leveraging the unique phase-transition attributes of VO2, our THz polarization modulator offers notable advancements over existing designs, including broad operation spectrum, high modulation depth, ease of fabrication, ease of operation condition, and continuous modulation capabilities. These enhanced features make the system a viable candidate for a range of THz applications, including telecommunications, imaging, and radar systems.

Terahertz Irradiation Improves Cognitive Impairments and Attenuates Alzheimer's Neuropathology in the APPSWE/PS1DE9 Mouse: A Novel Therapeutic Intervention for Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the deposition of amyloid-β (Aβ), neurofibrillary tangles, neuroinflammation, and neurodegeneration in the brain. In recent years, considering the unsatisfied benefits of pharmacological therapies, non-pharmacological therapy has become a research hotspot for AD intervention. Terahertz (THz) waves with a range between microwave and infrared regions in the electromagnetic spectrum and high permeability to a wide range of materials have great potential in the bioengineering field. However, its biological impacts on the central nervous system, under either physiological or pathological conditions, are poorly investigated. In this study, we first measured the 0.14 THz waves penetration across the skull of a C57BL/6 mouse and found the percentage of THz penetration to be ~70%, guaranteeing that THz waves can reach the relevant brain regions. We then exposed the APPSWE/PS1DE9 mouse model of AD to repeated low-frequency THz waves on the head. We demonstrated that THz waves treatment significantly improved the cognitive impairment and alleviated AD neuropathology including Aβ deposition and tau hyperphosphorylation in the AD mice. Moreover, THz waves treatment effectively attenuated mitochondrial impairment, neuroinflammation, and neuronal loss in the AD mouse brain. Our findings reveal previously unappreciated beneficial effects of THz waves treatment in AD and suggest that THz waves may have the potential to be used as a novel therapeutic intervention for this devastating disease.

The biological effects of terahertz wave radiation-induced injury on neural stem cells

Terahertz (THz) is an electromagnetic wave with a radiation wavelength range of 30-3000 μm and a frequency of 0.1-10 THz. With the development of new THz sources and devices, THz has been widely applied in various fields. However, there are few studies on biological effects of THz irradiation on the human neural stem cells (hNSCs) and mouse neural stem cells (mNSCs), which need to be further studied. We studied the biological effects of THz radiation on hNSCs and mNSCs. The effects of THz irradiation time and average output power on the proliferation, apoptosis, and DNA damage of NSCs were analyzed by flow cytometry and immunofluorescence. The results showed that the proliferation and apoptosis of NSCs were dose-dependently affected by THz irradiation time and average output power. The proliferation of hNSCs was more vulnerable to damage and apoptosis was more serious under the same terahertz irradiation conditions compared to those of mNSCs.

Inhibition of Cancer Cell Migration and Glycolysis by Terahertz Wave Modulation via Altered Chromatin Accessibility

Metastasis and metabolic disorders contribute to most cancer deaths and are potential drug targets in cancer treatment. However, corresponding drugs inevitably induce myeloid suppression and gastrointestinal toxicity. Here, we report a nonpharmaceutical and noninvasive electromagnetic intervention technique that exhibited long-term inhibition of cancer cells. Firstly, we revealed that optical radiation at the specific wavelength of 3.6 μm (i.e., 83 THz) significantly increased binding affinity between DNA and histone via molecular dynamics simulations, providing a theoretical possibility for THz modulation- (THM-) based cancer cell intervention. Subsequent cell functional assays demonstrated that low-power 3.6 μm THz wave could successfully inhibit cancer cell migration by 50% and reduce glycolysis by 60%. Then, mRNA sequencing and assays for transposase-accessible chromatin using sequencing (ATAC-seq) indicated that low-power THM at 3.6 μm suppressed the genes associated with glycolysis and migration by reducing the chromatin accessibility of certain gene loci. Furthermore, THM at 3.6 μm on HCT-116 cancer cells reduced the liver metastasis by 60% in a metastatic xenograft mouse model by splenic injection, successfully validated the inhibition of cancer cell migration by THM in vivo. Together, this work provides a new paradigm for electromagnetic irradiation-induced epigenetic changes and represents a theoretical basis for possible innovative therapeutic applications of THM as the future of cancer treatments.

Efficient sub-pixel convolutional neural network for terahertz image super-resolution

Terahertz waves are electromagnetic waves located at 0.1-10 THz, and terahertz imaging technology can be applied to security inspection, biomedicine, non-destructive testing of materials, and other fields. At present, terahertz images have unclear data and rough edges. Therefore, improving the resolution of terahertz images is one of the current hot research topics. This paper proposes an efficient terahertz image super-resolution model, which is used to extract low-resolution (LR) image features and learn the mapping of LR images to high-resolution (HR) images, and then introduce an attention mechanism to let the network pay attention to more information features. Finally, we use sub-pixel convolution to learn a set of scaling filters to upgrade the final LR feature map to an HR output, which not only reduces the model complexity, but also improves the quality of the terahertz image. The resolution reaches 31.67 db on the peak signal-to-noise ratio (PSNR) index and 0.86 on the structural similarity (SSIM) index. Experiments show that the efficient sub-pixel convolutional neural network used in this article achieves better accuracy and visual improvement compared with other terahertz image super-resolution algorithms.

Terahertz spectral properties of glucose and two disaccharides in solid and liquid states

The vibrational and rotational frequencies of most biological macromolecules fall within the terahertz (THz) band; therefore, the THz wave has a strong ability to distinguish substances. Saccharides are important organic substances and the main source of life-sustaining activities. In this study, the spectral characteristics of D-glucose, α-lactose hydrate, and β-maltose hydrate were measured in the solid state through THz time-domain spectroscopy in the frequency range of 0.1–2.5 THz. The crystal configurations of these three saccharides were then simulated using solid-state density functional theory, and the experimental results were found to be in good agreement with the simulation results. Furthermore, the spectral characteristics of the three saccharides in solutions were measured. Each saccharide was found to have unique spectral characteristics, and a correlation existed between the THz absorption spectra of the same substance in the solid state and aqueous solution.

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Solid D-glucose, α-lactose hydrate, and β-maltose hydrate have unique absorption peaks

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The simulated results of the three saccharides are consistent with the experimental ones

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The THz spectra of the three saccharides in solid and aqueous solutions are correlated

Advances of terahertz technology in neuroscience: Current status and a future perspective

Terahertz (THz) waves are ranged between microwave and infrared region in the electromagnetic spectrum. THz technology has been demonstrated promising potential for biomedical applications. Exploration of biological effects of THz waves has emerged as a critical new area in life sciences. It is critical to uncover the effects of THz waves on complex biological systems in order to lay out the framework for THz technology development and future applications. Specifically, THz radiation has been shown to affect the nervous system, including the structure of nerve cell membranes, genes expressions, and cytokines level. In this review, we primarily discuss the biological impacts and mechanisms of THz waves on the nervous system at the organisms, cellular, and molecular levels. The future application perspectives of THz technologies in neuroscience are also highlighted and proposed.

Terahertz exposure enhances neuronal synaptic transmission and oligodendrocyte differentiation in vitro

Terahertz (THz) frequency occupies a large portion of the electromagnetic spectrum that is between the infrared and microwave regions. Recent advances in THz application have stimulated interests regarding the biological effects within this frequency range. In the current study, we report that irradiation with a single-frequency THz laser on mice cortical neuron cultures increases excitatory synaptic transmission and neuronal firing activities. Microarray assay reveals gene expression dynamics after THz exposure, which is consistent with morphology and electrophysiology results. Besides, certain schedule of THz irradiation inhibits the proliferation of oligodendrocyte precursor cells (OPCs) and promotes OPC differentiation. Of note, the myelination process is enhanced after THz exposure. In summary, our observations suggest that THz irradiation can modulate the functions of different neuronal cells, with different sensitivity to THz. These results provide important understanding of the mechanisms that govern THz interactions with nervous systems and suggest THz wave as a new strategy for neuromodulation.

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THz irradiation increases excitatory synaptic transmission and neuronal firing

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Microarray assay reveals neuronal gene expression dynamics after THz exposure

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THz irradiation promotes the maturation of oligodendrocytes

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The myelination process in neuron is enhanced after THz exposure

Terahertz pulses induce segment renewal via cell proliferation and differentiation overriding the endogenous regeneration program of the earthworm Eisenia andrei

Terahertz (THz) irradiation of excised Eisenia andrei earthworms is shown to cause overriding of the genetically determined, endogenously mediated segment renewing capacity of the model animal. Single-cycle THz pulses of 5 µJ energy, 0.30 THz mean frequency, 293 kV/cm peak electric field, and 1 kHz repetition rate stimulated the cell proliferation (indicated by the high number of mitotic cells) and both histogenesis and organogenesis, producing a significantly higher number of regenerated segments. The most conspicuous alteration in THz-treated animals was the more intense development of the new central nervous system and blood vessels. These results clearly demonstrate that THz pulses are capable to efficiently trigger biological processes and suggest potential applications in medicine.

PC 12 Pheochromocytoma Cell Response to Super High Frequency Terahertz Radiation from Synchrotron Source

High frequency (HF) electromagnetic fields (EMFs) have been widely used in many wireless communication devices, yet within the terahertz (THz) range, their effects on biological systems are poorly understood. In this study, electromagnetic radiation in the range of 0.3–19.5 × 10¹² Hz, generated using a synchrotron light source, was used to investigate the response of PC 12 neuron-like pheochromocytoma cells to THz irradiation. The PC 12 cells remained viable and physiologically healthy, as confirmed by a panel of biological assays; however, exposure to THz radiation for 10 min at 25.2 ± 0.4 °C was sufficient to induce a temporary increase in their cell membrane permeability. High-resolution transmission electron microscopy (TEM) confirmed cell membrane permeabilization via visualisation of the translocation of silica nanospheres (d = 23.5 ± 0.2 nm) and their clusters (d = 63 nm) into the PC 12 cells. Analysis of scanning electron microscopy (SEM) micrographs revealed the formation of atypically large (up to 1 µm) blebs on the surface of PC 12 cells when exposed to THz radiation. Long-term analysis showed no substantial differences in metabolic activity between the PC 12 cells exposed to THz radiation and untreated cells; however, a higher population of the THz-treated PC 12 cells responded to the nerve growth factor (NGF) by extending longer neurites (up to 0–20 µm) compared to the untreated PC12 cells (up to 20 µm). These findings present implications for the development of nanoparticle-mediated drug delivery and gene therapy strategies since THz irradiation can promote nanoparticle uptake by cells without causing apoptosis, necrosis or physiological damage, as well as provide a deeper fundamental insight into the biological effects of environmental exposure of cells to electromagnetic radiation of super high frequencies.

[The complex correction of the pathophysiological disorders in the patients presenting with orthopedic and traumatological problems with the application of the electromagnetic waves of the terahertz range at the radiation frequencies of nitric oxide]

Experimental and clinical studies have shown that a skeletal trauma causes a whole complex of pathophysiological disorders, both local and systemic. The main factors determining the severity of the trauma, as well as the nature of the course of the post-traumatic period, are the degree of hypoxia (acidosis), hypercoagulation and immune disorders. To influence these pathophysiological disorders in the patients presenting the with skeletal traumas, various approaches have been proposed, including the use of antihypoxants and antioxidants, the methods and means for the stimulation and support of the immune system, medications to regulate hemostasis. According to the literature publications, terahertz-frequency therapy is presently regarded as a promising method the minimally invasive interference in the metabolic processes proceeding in the tissues of the musculoskeletal system. The analysis of the literature data and clinical observations indicate that electromagnetic waves of the terahertz range are efficient in the treatment of many chronic diseases when applied both as monotherapy and in combination with other physical methods and medications strengthening and consolidating the therapeutic effect of the latter. The electromagnetic waves of the terahertz range are currently used in medicine as a biophysical factor for the correction of the microcirculatory disorders. It has been shown that the use of these waves for the combined restorative treatment of the patients suffering fractures of the limb bones not only improves the dynamics of fracture consolidation symptoms but also contributes to the prevention of posttraumatic complications (thrombosis, ossification of soft tissues). However, the experience with the application of the electromagnetic waves of the terahertz range waves in clinical traumatology and orthopedics is rather modest. The analysis of the results of fundamental research and experience with the application of electromagnetic waves in the terahertz range has shown that the systemic effects produced by the waves of this range promote the correction of such pathophysiological disorders as hypoxia, hypercoagulation, and impaired immunity. Given that these disorders develop during the post-traumatic period in the patients presenting with severe multiple and combined traumas, it can be assumed that the use of electromagnetic waves of the terahertz range for the the combined treatment of these patients provides a very promising tool for the stimulation of the reparative processes especially bearing in mind that the first results described in the literature, look quite optimistic. The investigation into the mechanisms regulating the regenerative capacity of connective tissue, the creation of the scientifically-sound foundations for its management with the help of the modern electronics devices is a promising task for the developers of the new biomedical technologies.

Graphene-based plastic absorber for total sub-terahertz radiation shielding

Increasing the requirements on telecommunications systems such as the need for higher data rates and connectivity via the Internet of things results in continuously increasing amounts of electromagnetic radiation in ever-higher telecommunications bands (up to terahertz). This can generate unwanted electromagnetic radiation that can affect the operation of electronic devices and human health. Here, we demonstrate that nonconductive and lightweight, graphene-based composites can shield more than 99.99% of the electromagnetic energy in the sub-THz range mainly via absorption. This contrasts with state-of-the-art electromagnetic radiation shielding materials that simply redirect the energy of the radiation from a protected area via conduction-based reflection mechanisms. This shifts the problem of electromagnetic pollution from one place to another. We have demonstrated that the proposed composites can be fabricated by industrial compatible methods and are characterized by specific shielding efficiency values that exceed 30 dB cm3 g-1, which is more than those for typical metals used today. Therefore these materials might help to solve the problem of electromagnetic environmental pollution.

The interaction between electromagnetic fields at megahertz, gigahertz and terahertz frequencies with cells, tissues and organisms: risks and potential

Since regular radio broadcasts started in the 1920s, the exposure to human-made electromagnetic fields has steadily increased. These days we are not only exposed to radio waves but also other frequencies from a variety of sources, mainly from communication and security devices. Considering that nearly all biological systems interact with electromagnetic fields, understanding the affects is essential for safety and technological progress. This paper systematically reviews the role and effects of static and pulsed radio frequencies (100-109 Hz), millimetre waves (MMWs) or gigahertz (109-1011 Hz), and terahertz (1011-1013 Hz) on various biomolecules, cells and tissues. Electromagnetic fields have been shown to affect the activity in cell membranes (sodium versus potassium ion conductivities) and non-selective channels, transmembrane potentials and even the cell cycle. Particular attention is given to millimetre and terahertz radiation due to their increasing utilization and, hence, increasing human exposure. MMWs are known to alter active transport across cell membranes, and it has been reported that terahertz radiation may interfere with DNA and cause genomic instabilities. These and other phenomena are discussed along with the discrepancies and controversies from published studies.

Investigation of terahertz radiation influence on rat glial cells

We studied an influence of continuous terahertz (THz) radiation (0.12 - 0.18 THz, average power density of 3.2 mW/cm²) on a rat glial cell line. A dose-dependent cytotoxic effect of THz radiation is demonstrated. After 1 minute of THz radiation exposure a relative number of apoptotic cells increased in 1.5 times, after 3 minutes it doubled. This result confirms the concept of biological hazard of intense THz radiation. Diagnostic applications of THz radiation can be restricted by the radiation power density and exposure time.