Effects of electromagnetic waves on pathogenic viruses and relevant mechanisms: a review

Selected microwave irradiation effectively inactivates airborne avian influenza A(H5N1) virus

The highly pathogenic avian influenza A(H5N1) virus threatens animal and human health globally. Innovative strategies are crucial for mitigating risks associated with airborne transmission and preventing outbreaks. In this study, we sought to investigate the efficacy of microwave inactivation against aerosolized A(H5N1) virus by identifying the optimal frequency band for a 10-min exposure and evaluating the impact of varying exposure times on virus inactivation. A(H5N1) was aerosolized and exposed to various microwave frequencies ranging from 8 to 16 GHz for a duration of 10 min. Viral titers were quantified using TCID50, and inactivation was assessed by comparing irradiated samples to controls. The 11-13 GHz band yielded the highest inactivation, with an average 89% mean reduction in A(H5N1) titer, particularly within the 11-12 GHz range, which exhibited peak efficacy. Based on the overall results, the optimal frequency band (8-12 GHz) was further tested with exposure durations of 1, 3, and 5 min. Inactivation was time-dependent, with a 5-minute exposure resulting in a 94% mean reduction, compared to 58% and 48% for 3- and 1-minute exposures, respectively. We conclude that optimized microwave emitters in high-risk environments like poultry farms and veterinary clinics could offer a novel, non-chemical approach to mitigating avian influenza spread and outbreaks.

Inactivation of β-coronavirus MHV-A59 by 2.8 GHz microwave

From the severe acute respiratory syndrome coronavirus in 2003 to the severe acute respiratory syndrome coronavirus 2 in 2019, coronavirus has seriously threatened human health. Electromagnetic waves not only own high penetration and low pollution but also can physically resonate with the virus. Several studies have demonstrated that electromagnetic waves can inactivate viruses efficiently. However, there is still a lack of systemic studies to analyze the potential factors closely associated with the effectiveness of inactivation, such as pH, temperature, and so on. In this study, we evaluated the inactivation ability of a 2.8 GHz microwave (MW) on MHV-A59, a substitute virus for coronavirus. Moreover, the influences of environmental pH and temperature on inactivation abilities were also discussed. The results showed that the viral morphology was destroyed, and the infectivity of MHV-A59 was significantly decreased after exposure to a 2.8 GHz MW at a density of 100 mW/cm2. Furthermore, alteration of pH 8 could produce synergistic effects with MW on virus inactivation. And, it was also proved that MWs could inactivate viruses better at room temperature than that under lower environmental temperatures. These results suggested that electromagnetic wave has great promise to become an effective tool to eliminate coronavirus.

Inactivation efficacy and mechanism of 9.375 GHz electromagnetic wave on coronavirus

Epidemics caused by pathogenic viruses are a severe threat to public health worldwide. Electromagnetic waves are a type of noncontact and nonionizing radiation technology that has emerged as an effective tool for inactivating bacterial pathogens. In this study, we used a 9.375 GHz electromagnetic wave to study the inactivation effect and mechanism of electromagnetic waves on MHV-A59, a substitute virus for pathogenic human coronavirus, and to evaluate the inactivation efficiency on different surface materials. We showed that 9.375 GHz electromagnetic waves inactivate MHV-A59 by destroying viral particles, envelopes, or genomes. We also found that 9.375 GHz electromagnetic waves can decrease the infectivity of viruses on the surface of inanimate materials such as plastic, glass, cloth, and wood. In conclusion, our results suggested that the 9.375 GHz electromagnetic wave is a promising disinfection technique for preventing the spread and infection of pathogenic viruses.

Breathing Clean Air: Navigating Indoor Air Purification Techniques and Finding the Ideal Solution

The prevalence of airborne pathogens in indoor environments presents significant health risks due to prolonged human occupancy. This review addresses diverse air purification systems to combat airborne pathogens and the factors influencing their efficacy. Indoor aerosols, including bioaerosols, harbor biological contaminants from respiratory emissions, highlighting the need for efficient air disinfection strategies. The COVID-19 pandemic has emphasized the dangers of airborne transmission, highlighting the importance of comprehending how pathogens spread indoors. Various pathogens, from viruses like SARS-CoV-2 to bacteria like Mycobacterium (My) tuberculosis, exploit unique respiratory microenvironments for transmission, necessitating targeted air purification solutions. Air disinfection methods encompass strategies to reduce aerosol concentration and inactivate viable bioaerosols. Techniques like ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), filters, and unipolar ion emission are explored for their specific roles in mitigating airborne pathogens. This review examines air purification systems, detailing their operational principles, advantages, and limitations. Moreover, it elucidates key factors influencing system performance. In conclusion, this review aims to provide practical knowledge to professionals involved in indoor air quality management, enabling informed decisions for deploying efficient air purification strategies to safeguard public health in indoor environments.

Giant vesicles form in physiological saline and encapsulate pDNA by the modified electroformation method

Giant vesicles (GVs) are used to study the structures and functions of cells and cell membranes. Electroformation is the most commonly used method for GV preparation. However, the electroformation of GVs is hindered in highly concentrated ionic solutions, limiting their application as cell models for research under physiological conditions. In this study, giant multilayer vesicles were successfully generated in physiological saline using a modified electroformation device by adding an insulating layer between the two electrode plates. The influence of the electric frequency and strength on the electroformation of GVs in physiological saline was explored, and a possible mechanism for this improvement was assessed. It has been shown that an insulating layer between the two electrodes can improve the electroformation of GVs in physiological saline by increasing the electrical impedance, which is weakened by the saline solution, thereby restoring the reduced effective electric field strength. Furthermore, macromolecular plasmid DNA (pDNA) was successfully encapsulated in the electroformed GVs of the modified device. This modified electroformation method may be useful for generating eukaryotic cell models under physiological conditions.

SARS-CoV-2 Inactivation in Aerosol by Means of Radiated Microwaves

Coronaviruses are a family of viruses that cause disease in mammals and birds. In humans, coronaviruses cause infections on the respiratory tract that can be fatal. These viruses can cause both mild illnesses such as the common cold and lethal illnesses such as SARS, MERS, and COVID-19. Air transmission represents the principal mode by which people become infected by SARS-CoV-2. To reduce the risks of air transmission of this powerful pathogen, we devised a method of inactivation based on the propagation of electromagnetic waves in the area to be sanitized. We optimized the conditions in a controlled laboratory environment mimicking a natural airborne virus transmission and consistently achieved a 90% (tenfold) reduction of infectivity after a short treatment using a Radio Frequency (RF) wave emission with a power level that is safe for people according to most regulatory agencies, including those in Europe, USA, and Japan. To the best of our knowledge, this is the first time that SARS-CoV-2 has been shown to be inactivated through RF wave emission under conditions compatible with the presence of human beings and animals. Additional in-depth studies are warranted to extend the results to other viruses and to explore the potential implementation of this technology in different environmental conditions.

Electromagnetic deactivation spectroscopy of human coronavirus 229E

An investigation of the deactivation of pathogens using electromagnetic waves in the microwave region of the spectrum is achieved using custom-built waveguide structures. The waveguides feature sub-wavelength gratings to allow the integration of an air cooling system without disturbing the internal propagating fields. The waveguides are tapered to accommodate an experimental sample internally with sufficient surrounding airflow. The proposed methodology allows for precise control over power densities due to the well-defined fundamental mode excited in each waveguide, in addition to temperature control of the sample due to microwave exposure over time. Human coronavirus (HCoV-229E) is investigated over the 0-40 GHz range, where a peak 3-log viral reduction is observed in the 15.0-19.5 GHz sub-band. We conclude HCoV-229E has an intrinsic resonance in this range, where nonthermal structure damage is optimal through the structure-resonant energy transfer effect.