Light-base technology to neutralize viral infections

Over the past two years, during the coronavirus (COVID-19) pandemic, science has been on the hotspot as it became the route to save lives, to avoid individual sickness, to decrease the level of population infection, and to create new solutions to easy the viremia. Light (specially UV radiation, but also visible light) is known to affect virus infection and light-induced technologies are increasingly important in the disinfection of surfaces, oral/nasal cavities and biological fluids, as well as in effectively treating microbial and viral infections. As a contribution to our society we have prepared this special issue in the Journal of Photochemistry and Photobiology focusing on the current knowledge of the use of light to neutralize viral infections. Helena Carvalho (Lisbon, PORTUGAL) discussed the importance of two related factors - latitude and solar ultraviolet radiation as determining the spread of pandemic SARS-CoV-2 outbreaks across the globe, highlighting the possible role of UV-induced immunosuppression on the virus spread. Fábio Sellera and co-authors (São Paulo, Brazil) critically evaluated the scientific literature concerning the ultraviolet germicidal irradiation using UV-C (UVC), concluding that there is sufficient evidence to support the use of UVC-based technologies against SARS-CoV-2. Karina Bispo-dos-Santos and co-workers (several cities in Brazil) compared the effectivity of Ultraviolet germicidal irradiation to decontaminate SARS-CoV-2 in makeup powder and lipstick with that of transparent plastic surfaces, concluding that cosmetics can be effectively decontaminate but with a UVC dose ten times higher than that of necessary to decontaminate transparent surfaces. Maria O.P. Alvarenga and co-workers (Recife, Brazil) worked on a systematic review considering whether UV-C technology enhances disinfection on surfaces dental and medical practices. The evidence points out the effectiveness of UV-C technology in reducing manual cleaning failures, enhancing the logarithmic reduction of surface pathogen colonies. Mário Clerici and co-workers (Milan, Italy) analyzed the virucidal effect of discrete wavelengths: UVC (278 nm), UV-B (308 nm), UV-A (366 nm) and violet (405 nm) on SARS-CoV-2 and observed that the violet light is 100 times less efficient than UV-C light to cause a 2-log viral inactivation, suggesting that blue light can also be used to neutralize SARS-CoV-2. Chukuka S. Enwemeka (San Diego, USA) critically compared far UV and pulsed blue light (PBL) in photo-eradication of microorganisms, suggesting their comparative benefits to disinfect surface and the oronasal cavity of infected patients. By analyzing virus effectivity and intracellular expression of viral proteins they confirmed the inactivating effect of visible-light LED irradiation, Riccardo De Santis and co-workers (Rome, Italy) with colleagues from Sweden and Germany evaluated the rapid inactivation of SARS-CoV-2 with wide-spectrum visible-LED irradiation. Indeed, as Rafael T. Aroso and coworkers (Coimbra, Portugal) concluded, the use of photodynamic inactivation to neutralize influenza and SARS-CoV-2 viruses as a potential alternative for the control of respiratory tract infections.