Ionic Silver and Electrical Treatment for Susceptibility and Disinfection of Escherichia coli Biofilm-Contaminated Titanium Surface

In this work, surface disinfection and biofilm susceptibility were investigated by applying ionic silver of 0.4–1.6 µg/mL and cathodic voltage-controlled electrical treatment of 1.8 V and a current of 30 mA to Escherichia coli (E. coli) ATCC 25922 biofilm-contaminated titanium substrates. Herein, it is evident that the treatment exhibited the potential use to enhance the susceptibility of bacterial biofilms for surface disinfection. In vitro studies have demonstrated that the ionic silver treatment of 60 min significantly increased the logarithmic reduction (LR) of bacterial populations on disinfectant-treated substrates and the electrical treatment enhanced the silver susceptibility of E. coli biofilms. The LR values after the ionic silver treatments and the electric-enhanced silver treatments were in the ranges of 1.94–2.25 and 2.10–2.73, respectively. The treatment was also associated with morphological changes in silver-treated E. coli cells and biofilm-contaminated titanium surfaces. Nevertheless, the treatments showed no cytotoxic effects on the L929 mouse skin fibroblast cell line and only a slight decrease in pH was observed during the electrical polarization of titanium substrate.

The effectiveness of commercial household ultraviolet C germicidal devices in Thailand

Ultraviolet C (UVC), or ultraviolet germicidal irradiation (UVGI), is known for its effective air, water, and surface disinfectant properties. With the rise of global awareness about public sanitation and personal hygiene due to the emergence of the current coronavirus disease 2019 pandemic, several applications of UVC were introduced to the commercial market. The present experimental study aimed to evaluate the effectiveness of commercial household UVC germicidal devices for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivation. Ten UVC devices were included in the study comprising of 7 low-pressure mercury lamps (LPMLs) and 3 UVC- light-emitting diodes (LEDs). Considering applications, 3 were handheld UVGI surface disinfection equipment, 4 were UVGI disinfection chambers, and 3 were movable UVGI air and surface purifiers. To determine SARS-CoV-2 inactivation performance, UVC irradiance (mW/cm2) was measured 3 times repeatedly at distance and duration corresponding to manufacturers’ usage instructions. The required UVC dosage could not be achieved by either of UVC-LED devices (1 handheld UVGI surface disinfection equipment and 2 UVGI disinfection chambers). Five of seven LPMLs can sufficiently emit UVC irradiance for SARS-CoV-2-inactivation. A lack of standardization in the distance and cycle duration for each UVC application was observed. Standard usage guidelines for UVC devices are required to improve the effectiveness of UVC irradiance for SARS-CoV-2 inactivation as well as to minimize the potential side effects of UVC.

Mechanisms for destabilisation of RNA viruses at air-water and liquid-liquid interfaces

Understanding the interactions between viruses and surfaces or interfaces is important, as they provide the principles underpinning the cleaning and disinfection of contaminated surfaces. Yet, the physics of such interactions is currently poorly understood. For instance, there are longstanding experimental observations suggesting that the presence of air-water interfaces can generically inactivate and kill viruses, yet the mechanism underlying this phenomenon remains unknown. Here we use theory and simulations to show that electrostatics may provide one such mechanism, and that this is very general. Thus, we predict that the electrostatic free energy of an RNA virus should increase by several thousands of kBT as the virion breaches an air-water interface. We also show that the fate of a virus approaching a generic liquid-liquid interface depends strongly on the detailed balance between interfacial and electrostatic forces, which can be tuned, for instance, by choosing different media to contact a virus-laden respiratory droplet. Tunability arises because both the electrostatic and interfacial forces scale similarly with viral size. We propose that these results can be used to design effective strategies for surface disinfection.

Flow-Through Portable Antivirus UV-C Optical Enclosures to be Used with Protective Masks

UV-C light is an important disinfection tool against airborne viruses, while also being harmful if the light reaches the human skin. Body-attached reflective flow-through optical enclosures can be used for isolating the UV-C light from the user as well as elevating the irradiance level. In this study, we explain why air-sterilizing light enclosures are more effective than the expectations by introducing a dose multiplication factor of 4. As a result of omnidirectional illumination, air sterilization becomes more effective than surface disinfection if similar irradiance levels are measured from the enclosure wall. The methodology is explained by the design of a portable enclosure device primarily targeting the COVID-19 virus, and disinfection effectiveness better than 99.5% is demonstrated by biological tests.

Application of uv radiators for disinfection of air and surfaces in premises

Objective: We compared the antimicrobial efficacy of different types of UV radiators. Materials and methods: In the work, we used the ultraviolet radiators of various types and manufacturers recommended for disinfection of air and surfaces of the premises. The effectiveness of surface disinfection from the test microorganisms Staphylococcus aureus and Pseudomonas aeruginosa was established by the Regulations “Methods for testing disinfectants to assess their safety and effectiveness". We determined a total number of aerobic microorganisms and molds according to the State Pharmacopoeia of Ukraine 2.0, p. 2.6.12. Results: The efficacy of the use of ultraviolet radiation for disinfection of the surfaces with the most resistant representatives of gram-negative and gram-positive microorganisms using a portable "Individual ultraviolet irradiator ALED UVC-1W" for 1 min. was established. The disinfection effect was 4.02 lg for S. aureus and 4.08 lg for P. aeruginosa. The effective action of the bactericidal ultraviolet radiation with the use of open-type radiators (with louvers) "UV-BLAZE" was demonstrated. A decrease of the total number of microorganisms, including molds in the air, by a factor of 36 (room № 1) and 136 (room № 2) was noted. Disinfection of the surfaces in the premises for the similar indicators was 98.6% and 99.5%, respectively. A decrease in the level of microbiological air pollution in the premises, when using LED radiation with the open-type ALED T5NXXX UVC-5W-01 luminaires for a long period of time (8 hours), was noted. The disinfection efficacy was 77% for bacteria and 83.3% for fungi.

The use of cold plasma technology in the surface disinfection system

The work is devoted to the presentation of the system analysis results of hierarchical processes of the viral pandemic and development, based on the use of cold plasma, of technical means to counteract viral threats. The main place is occupied by the description of the application of cold plasma technologies for the purpose of viral disinfection and countering the spread of viruses in various environments. The results of practical field experiments are presented