Research progress in the effects of terahertz waves on biomacromolecules

Progress of the Impact of Terahertz Radiation on Ion Channel Kinetics in Neuronal Cells

In neurons and myocytes, selective ion channels in the plasma membrane play a pivotal role in transducing chemical or sensory stimuli into electrical signals, underpinning neural and cardiac functionality. Recent advancements in biomedical research have increasingly spotlighted the interaction between ion channels and electromagnetic fields, especially terahertz (THz) radiation. This review synthesizes current findings on the impact of THz radiation, known for its deep penetration and non-ionizing properties, on ion channel kinetics and membrane fluid dynamics. It is organized into three parts: the biophysical effects of THz exposure on cells, the specific modulation of ion channels by THz radiation, and the potential pathophysiological consequences of THz exposure. Understanding the biophysical mechanisms underlying these effects could lead to new therapeutic strategies for diseases.

Prediction and Control in DNA Nanotechnology

DNA nanotechnology is a rapidly developing field that uses DNA as a building material for nanoscale structures. Key to the field's development has been the ability to accurately describe the behavior of DNA nanostructures using simulations and other modeling techniques. In this Review, we present various aspects of prediction and control in DNA nanotechnology, including the various scales of molecular simulation, statistical mechanics, kinetic modeling, continuum mechanics, and other prediction methods. We also address the current uses of artificial intelligence and machine learning in DNA nanotechnology. We discuss how experiments and modeling are synergistically combined to provide control over device behavior, allowing scientists to design molecular structures and dynamic devices with confidence that they will function as intended. Finally, we identify processes and scenarios where DNA nanotechnology lacks sufficient prediction ability and suggest possible solutions to these weak areas.

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.

Highly nonlinear optic nucleic acid thin-solid film to generate short pulse laser

Using aqueous precursors, we report successfully fabricating thin-solid films of two nucleic acids, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). We investigated the potential of these films deposited on a fiber optic platform as all-fiber integrated saturable absorbers (SAs) for ultrafast nonlinear optics. RNA-SA performances were comparable to those of DNA-SA in terms of its nonlinear transmission, modulation depth, and saturation intensity. Upon insertion of these devices into an Erbium-doped fiber ring-laser cavity, both RNA and DNA SAs enabled efficient passive Q-switching operation. RNA-SA application further facilitated robust mode-locking and generated a transform-limited soliton pulse, exhibiting a pulse duration of 633 femtoseconds. A detailed analysis of these pulsed laser characteristics compared RNA and DNA fiber optic SAs with other nonlinear optic materials. The findings of this research establish the feasibility of utilizing RNA as a saturable absorber in ultrafast laser systems with an equal or higher potential as DNA, which presents novel possibilities for the nonlinear photonic applications of nucleic acid thin solid films.

Sub-THz acoustic excitation of protein motion

The application of terahertz radiation has been shown to affect both protein structure and cellular function. As the key to such structural changes lies in the dynamic response of a protein, we focus on the susceptibility of the protein's internal dynamics to mechanical stress induced by acoustic pressure waves. We use the open-boundary molecular dynamics method, which allows us to simulate the protein exposed to acoustic waves. By analyzing the dynamic fluctuations of the protein subunits, we demonstrate that the protein is highly susceptible to acoustic waves with frequencies corresponding to those of the internal protein vibrations. This is confirmed by changes in the compactness of the protein structure. As the amplitude of the pressure wave increases, even larger deviations from average positions and larger changes in protein compactness are observed. Furthermore, performing the mode-projection analysis, we show that the breathing-like character of collective modes is enhanced at frequencies corresponding to those used to excite the protein.

THz-PCR Based on Resonant Coupling between Middle Infrared and DNA Carbonyl Vibrations

The carbonyl groups of deoxyribonucleotide can resonantly couple with 53 THz middle infrared, which can highly transmit water without ionization-based damage to DNA molecules. Herein, we predict that vibrational coupling with THz irradiation could lower down the hybridization landscape of nucleic acids and thus affect DNA replication. Using polymerase chain reaction (PCR) as a measure, we found that THz shining can reduce the denature temperature of DNA duplexes by about 3 °C, which allows one to conduct PCR at lower temperature, facilitating long-time amplification reaction without losing enzymatic fidelity, i.e., normal PCR should be carried out at denaturing temperature ∼4 °C higher than the melting temperature (T_m), but THz-PCR only requires temperature ∼1 °C higher than T_m due to the nonthermal effect of THz shining. Moreover, the melting time can also be shortened to 1/5 due to the enhanced vibration coupling with 53 THz irradiation. We proposed THz-PCR as an innovated DNA amplification technique with ultrahigh specificity and sensitivity and also successfully demonstrated its advantages in forensic detections.

Terahertz spectra of proteinuria and non-proteinuria

In clinical practice, proteinuria detection is of great significance in the diagnosis of kidney diseases. Dipstick analysis is used in most outpatient settings to semi-quantitatively measure the urine protein concentration. However, this method has limitations for protein detection, and alkaline urine or hematuria will cause false positive results. Recently, terahertz time-domain spectroscopy (THz-TDS) with strong hydrogen bonding sensitivity has been proven to be able to distinguish different types of biological solutions, which means that protein molecules in urine may have different THz spectral characteristics. In this study, we performed a preliminary clinical study investigating the terahertz spectra of 20 fresh urine samples (non-proteinuria and proteinuria). The results showed that the concentration of urine protein was positively correlated with the absorption of THz spectra at 0.5-1.2 THz. At 1.0 THz, the pH values (6, 7, 8, and 9) had no significant effect on the THz absorption spectra of urine proteins. The terahertz absorption of proteins with a high molecular weight (albumin) was greater than that of proteins with a low molecular weight (β2-microglobulin) at the same concentration. Overall, THz-TDS spectroscopy for the qualitative detection of proteinuria is not affected by pH and has the potential to discriminate between albumin and β2-microglobulin in urine.

The laws and effects of terahertz wave interactions with neurons

Introduction: Terahertz waves lie within the energy range of hydrogen bonding and van der Waals forces. They can couple directly with proteins to excite non-linear resonance effects in proteins, and thus affect the structure of neurons. However, it remains unclear which terahertz radiation protocols modulate the structure of neurons. Furthermore, guidelines and methods for selecting terahertz radiation parameters are lacking. Methods: In this study, the propagation and thermal effects of 0.3-3 THz wave interactions with neurons were modelled, and the field strength and temperature variations were used as evaluation criteria. On this basis, we experimentally investigated the effects of cumulative radiation from terahertz waves on neuron structure. Results: The results show that the frequency and power of terahertz waves are the main factors influencing field strength and temperature in neurons, and that there is a positive correlation between them. Appropriate reductions in radiation power can mitigate the rise in temperature in the neurons, and can also be used in the form of pulsed waves, limiting the duration of a single radiation to the millisecond level. Short bursts of cumulative radiation can also be used. Broadband trace terahertz (0.1-2 THz, maximum radiated power 100 μW) with short duration cumulative radiation (3 min/day, 3 days) does not cause neuronal death. This radiation protocol can also promote the growth of neuronal cytosomes and protrusions. Discussion: This paper provides guidelines and methods for terahertz radiation parameter selection in the study of terahertz neurobiological effects. Additionally, it verifies that the short-duration cumulative radiation can modulate the structure of neurons.

Specific Features of the Proteomic Response of Thermophilic Bacterium Geobacillus icigianus to Terahertz Irradiation

Studying the effects of terahertz (THz) radiation on the proteome of temperature-sensitive organisms is limited by a number of significant technical difficulties, one of which is maintaining an optimal temperature range to avoid thermal shock as much as possible. In the case of extremophilic species with an increased temperature tolerance, it is easier to isolate the effects of THz radiation directly. We studied the proteomic response to terahertz radiation of the thermophilic Geobacillus icigianus, persisting under wide temperature fluctuations with a 60 °C optimum. The experiments were performed with a terahertz free-electron laser (FEL) from the Siberian Center for Synchrotron and Terahertz Radiation, designed and employed by the Institute of Nuclear Physics of the SB of the RAS. A G. icigianus culture in LB medium was THz-irradiated for 15 min with 0.23 W/cm² and 130 μm, using a specially designed cuvette. The life cycle of this bacterium proceeds under conditions of wide temperature and osmotic fluctuations, which makes its enzyme systems stress-resistant. The expression of several proteins was shown to change immediately after fifteen minutes of irradiation and after ten minutes of incubation at the end of exposure. The metabolic systems of electron transport, regulation of transcription and translation, cell growth and chemotaxis, synthesis of peptidoglycan, riboflavin, NADH, FAD and pyridoxal phosphate cofactors, Krebs cycle, ATP synthesis, chaperone and protease activity, and DNA repair, including methylated DNA, take part in the fast response to THz radiation. When the response developed after incubation, the systems of the cell's anti-stress defense, chemotaxis, and, partially, cell growth were restored, but the respiration and energy metabolism, biosynthesis of riboflavin, cofactors, peptidoglycan, and translation system components remained affected and the amino acid metabolism system was involved.

Quantitative protein sensing with germanium THz-antennas manufactured using CMOS processes

The development of a CMOS manufactured THz sensing platform could enable the integration of state-of-the-art sensing principles with the mixed signal electronics ecosystem in small footprint, low-cost devices. To this aim, in this work we demonstrate a label-free protein sensing platform using highly doped germanium plasmonic antennas realized on Si and SOI substrates and operating in the THz range of the electromagnetic spectrum. The antenna response to different concentrations of BSA shows in both cases a linear response with saturation above 20 mg/mL. Ge antennas on SOI substrates feature a two-fold sensitivity as compared to conventional Si substrates, reaching a value of 6 GHz/(mg/mL), which is four-fold what reported using metal-based metamaterials. We believe that this result could pave the way to a low-cost lab-on-a-chip biosensing platform.

Clinical and experimental study of a terahertz time-domain system for the determination of the pathological margins of laryngeal carcinoma

Objective

Laryngeal cancer is a common malignancy in otorhinolaryngological head and neck surgery, accounting for approximately one-third of all head and neck malignancies. Terahertz time-domain spectroscopy (THz-TDS) has recently been found to be useful for the detection of tumors. This study was conducted to investigate the application of THz-TDS in the diagnosis of pathological resection margins of laryngeal cancer.

Methods

Fresh laryngeal cancer tissues from 10 patients with laryngeal cancer were extracted, and after simultaneous HE staining and terahertz imaging, the tumor area, paracancerous area, and normal tissue area of each laryngeal cancer tissue sample were located under a microscope according to the pathological results of HE staining.

Results

The shape contours of the tumor region revealed by terahertz imaging maps and HE staining were similar. In the terahertz spectrum in the frequency range of 0.5–1.9 THz, both the absorption coefficient and refractive index values followed the order tumor > para cancer > normal tissue, with statistically significant differences (P < 0.01). When the terahertz frequency was 1.5 THz, the absorption coefficient of terahertz light waves by laryngeal cancer tissue and the percentage of nuclei showed an extremely high positive correlation (P < 0.01, r = 0.971). In the frequency ranges of 0.5–1.2 THz and 1.6–1.9 THz, the absorption coefficients of the highly differentiated group were higher than those of the moderately differentiated group. In the frequency range of 1.2–1.6 THz, the results were reversed, with statistically significant differences (P < 0.05). In the frequency range of 0.5–1.9 THz, the highly differentiated group had a higher refractive index than the moderately differentiated group, with a statistically significant difference (P < 0.05).

Conclusions

THz-TDS can be used to determine the pathological margins of laryngeal cancer based on the absorption coefficient and refractive index, and the magnitudes of the absorption coefficient and refractive index are related to the percentage of nuclei. The degree of differentiation of laryngeal cancer tissue can be assessed by THz-TDS. The study shows that the terahertz time-domain system is promising for applications in the diagnosis of laryngeal cancer, especially for the more accurate identification of intraoperative margins.

Terahertz Vibrational Fingerprints Detection of Molecules with Particularly Designed Graphene Biosensors

In this research, an arc I-shaped graphene sensing structure with multi-resonance characteristics is proposed for the simultaneous detection of vibrational fingerprints with spectral separation in the terahertz range. The resonant frequencies of the sensor can be dynamically tuned by changing the gate voltage applied to the graphene arrays. The two vibrational fingerprints of lactose molecules (0.53 THz and 1.37 THz) in the transmission spectrum can be enhanced simultaneously by strictly optimizing the geometrical parameters of the sensor. More importantly, these two resonant frequencies can be tuned precisely to coincide with the two standard resonances of the lactose molecule. The physical mechanism of the sensor is revealed by inspection of the electric field intensity distribution, and the advantage of the sensor, which is its ability to operate at a wide range of incident angles, has been demonstrated. The sensing performance of the structure as a refractive index sensor has also been studied. Finally, a double arc I-shaped graphene sensor is further designed to overcome the polarization sensitivity, which demonstrates excellent molecular detection performance under different polarization conditions. This study may serve as a reference for designing graphene biosensors for molecular detection.

Highly Sensitive Terahertz Dielectric Sensor for Liquid Crystal

This paper presents the design and process of two highly sensitive sensors working in the terahertz band. The sensors comprise the quartz substrate, medium, reflection plate, and metal resonant layer with a symmetrical single-slot patch array. The devices help study the electrically induced permittivity of two liquid crystals in different frequency bands and at different voltages, and the experimental data verify that both liquid crystals have a large birefringence. Based on experimental results, the sensitivity of the fabricated sensor is 47.03 GHz/RIU in the frequency range 90–140 GHz. Similarly, the other fabricated sensor has a sensitivity of 112.47 GHz/RIU in the frequency range 325–500 GHz. The results show that both sensors have superior sensing properties and potential applications in biological and chemical liquid sensing.

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.

External bias dependent dynamic terahertz propagation through BiFeO3film

Interactions of terahertz radiations with matter can lead to the realization of functional devices related to sensing, high-speed communications, non-destructive testing, spectroscopy, etc In spite of the versatile applications that THz can offer, progress in this field is still suffering due to the dearth of suitable responsive materials. In this context, we have experimentally investigated emerging multiferroic BiFeO3 film (∼200 nm) employing terahertz time-domain spectroscopy (THz-TDS) under vertically applied (THz propagation in the same direction) electric fields. Our experiments reveal dynamic modulation of THz amplitude (up to about 7% within 0.2-1 THz frequency range) because of the variation in electric field from 0 to 600 kV cm^-1. Further, we have captured signatures of the hysteretic nature of polarization switching in BiFeO₃film through non-contact THz-TDS technique, similar trends are observed in switching spectroscopy piezoresponse force microscope measurements. We postulate the modulation of THz transmissions to the alignment/switching of ferroelectric polarization domains (under applied electric fields) leading to the reduced THz scattering losses (hence, reduced refractive index) experienced in the BiFeO₃film. This work indicates ample opportunities in integrating nanoscale multiferroic material systems with THz photonics in order to incorporate dynamic functionalities to realize futuristic THz devices.

Antibodies Processed Using High Dilution Technology Distantly Change Structural Properties of IFNγ Aqueous Solution

Terahertz spectroscopy allows for the analysis of vibrations corresponding to the large-scale structural movements and collective dynamics of hydrogen-bonded water molecules. Previously, differences had been detected in the emission spectra of interferon-gamma (IFNγ) solutions surrounded by extremely diluted solutions of either IFNγ or antibodies to IFNγ without direct contact compared to a control. Here we aimed to analyse the structural properties of water in a sample of an aqueous solution of IFNγ via terahertz time-domain spectroscopy (THz-TDS). Tubes with the IFNγ solution were immersed in fluidised lactose saturated with test samples (dilutions of antibodies to IFNγ or control) and incubated at 37 °C for 1, 1.5-2, 2.5-3, or 3.5-4 h. Fluidised lactose was chosen since it is an excipient in the manufacture of drugs based on diluted antibodies to IFNγ. After incubation, spectra were recorded within a wavenumber range of 10 to 110 cm-1 with a resolution of 4 cm-1. Lactose saturated with dilutions of antibodies to IFNγ (incubated for more than 2.5 h) changed the structural properties of an IFNγ aqueous solution without direct contact compared to the control. Terahertz spectra revealed stronger intermolecular hydrogen bonds and an increase in the relaxation time of free and weakly bound water molecules. The methodology developed on the basis of THz-TDS could potentially be applied to quality control of pharmaceuticals based on extremely diluted antibodies.