ABSTRACT
There is an urgent need to mineralize organic pollutants such as antibiotics and other toxic organic materials discharged by various pharmaceutical and chemical industries into freshwater. These organic pollutants affect the aquatic ecosystem and human health due to bioaccumulation in the food chains and food webs. Heterogeneous photocatalysis is an advanced oxidation-based green technique by which these pharmaceutics can be degraded in the wastewater by using nontoxic and eco-friendly catalysts in the presence of light-emitting diodes (LEDs) as a source of irradiation. The main aim of the chapter is to disseminate information regarding the degradation of antibiotics and other pharmaceutics by green, non-toxic, and effective catalysts via economically viable techniques. Antibiotics are oxidized by hydroxyl radicals and superoxides generated during the irradiation of light on the surface of the catalyst. In this chapter, the authors discuss the most commonly prescribed antibiotics in the COVID-19 pandemic and how these antibiotics become environmental contaminants. They have also proposed the mechanism of degradation of these antibiotics in the presence of LED irradiation to attain a green and sustainable environment. © 2023 Nova Science Publishers, Inc. All rights reserved.
ABSTRACT
Legionella pneumophila (L. pneumophila) is the causative agent of Legionnaires’ disease and Pontiac fever, collectively known as legionellosis. L. pneumophila infection occurs through inhalation of contaminated aerosols from water systems in workplaces and institutions. The development of disinfectants that can eliminate L. pneumophila in such water systems without evacuating people is needed to prevent the spread of L. pneumophila. Photocatalysts are attractive disinfectants that do not harm human health. In particular, the TiO2 photocatalyst kills L. pneumophila under various conditions, but its mode of action is unknown. Here, we confirmed the high performance of TiO2 photocatalyst containing PtO2 via the degradation of methylene blue (half-value period: 19.2 min) and bactericidal activity against Escherichia coli (half-value period: 15.1 min) in water. Using transmission electron microscopy, we demonstrate that the disinfection of L. pneumophila (half-value period: 6.7 min) by TiO2 photocatalyst in water is accompanied by remarkable cellular membrane and internal damage to L. pneumophila. Assays with limulus amebocyte lysate and silver staining showed the release of endotoxin from L. pneumophila due to membrane damage and photocatalytic degradation of this endotoxin. This is the first study to demonstrate the disinfection mechanisms of TiO2 photocatalyst, namely, via morphological changes and membrane damage of L. pneumophila. Our results suggest that TiO2 photocatalyst might be effective in controlling the spread of L. pneumophila.
ABSTRACT
Difficulty in controlling SARS-CoV-2 transmission made the ability to inactivate viruses in aerosols and fomites to be an important and attractive risk reduction measure. Evidence that light frequencies have the ability to inhibit microorganisms has already been reported by many studies which, however, focused on ultraviolet (UV) wavelengths, which are known to induce potential injury in humans. In the present study, the effect on suspensions of SARS-CoV-2 of a Light Emitting Diode (LED) device capable of radiating frequencies in the non-hazardous visible light spectrum (VIS) was investigated. In order to evaluate the efficiency of viral inactivation, plaque assay and western blot of viral proteins were performed. The observed results showed a significant reduction in infectious particles that had been exposed to the LED irradiation of visible light. Furthermore, the analysis of the intracellular expression of viral proteins confirmed the inactivating effect of this irradiation technology. This in vitro study revealed for the first time the inactivation of SARS-CoV-2 through LED irradiation with multiple wavelengths of the visible spectrum. However additional and more in-depth studies can aim to demonstrate the data obtained during these experiments in different matrices, in mutable environmental conditions and on other respiratory viruses such as the influenza virus. The type of LED technology can decisively contribute on reducing virus transmission through the continuous sanitation of common environments without risks for humans and animals.