Rutile-TiO2/PtO2 Glass Coatings Disinfects Aquatic Legionella pneumophila via Morphology Change and Endotoxin Degradation under LED Irradiation

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.

Space disinfection using TiO2 photocatalyst reduces the incidence of febrile neutropenia in cancer patients

“…In contrast, a decreasing trend in the number of microorganisms was observed with the LED-TiO 2 device operating (photocatalysis) (P = 0.09). Furthermore, spatial disinfection using photocatalyst has a detoxifying effect on endotoxins of gram-negative bacteria such as Escherichia coli and Legionella sp [34,35]. In addition, maintenance of the LED-TiO 2 device is simple, requiring only lter cleaning with water, and is economically superior.…”

TiO2-Photocatalyst-Induced Degradation of Dog and Cat Allergens under Wet and Dry Conditions Causes a Loss in Their Allergenicity

“…It is well known that photocatalysts decompose organic matter and inactivate microorganisms and viruses [ 19 , 20 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. Photocatalysts can also inactivate viruses in the air [ 19 ].…”

“…Hydrogen production via this photocatalytic oxidation–reduction reaction is attracting a great deal of attention in the production of clean energy [ 24 ]. Additionally, ROS produced by photocatalysts kill microorganisms, such as Escherichia coli , Bacillus cereus , Enterobacter spp., Porphyromonas gingivalis , Salmonella spp., Vibrio parahaemolyticus , and Legionella pneumophila [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], and inactivate viruses such as influenza, hepatitis C, vesicular stomatitis, enterovirus, herpes, Zika, human coronavirus, bovine coronavirus, human norovirus, murine norovirus, severe acute respiratory syndrome (SARS)-associated coronavirus, bacteriophage, and SARS-CoV2 [ 19 , 20 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. In particular, our previous study showed that a TiO 2 photocatalyst, which is the most common photocatalyst, inactivates SARS-CoV-2 in aerosols [ 19 ], suggesting that it is effective for inactivating organic matter suspended in the air.…”

“…In particular, our previous study showed that a TiO 2 photocatalyst, which is the most common photocatalyst, inactivates SARS-CoV-2 in aerosols [ 19 ], suggesting that it is effective for inactivating organic matter suspended in the air. In addition, photocatalysts can degrade viral proteins and endotoxins, which are the lipopolysaccharides on the outer membrane of Gram-negative bacteria [ 19 , 36 ]. These results suggest that photocatalysts can degrade high-molecular-weight organic matter, such as animal allergens.…”

Purification of living environments using photocatalysts: Inactivation of microorganisms and decomposition of allergens

“…Viral inactivation is known to degrade viral particles, proteins, and nucleic acids [ 34 , 48 , 53 , 60 , 86 , 87 ]. Sterilization is primarily caused by damage to the bacterial cell membranes [ 1 , 12 , 25 , 46 , 91 ]. Although detailed research is limited, allergens can be degraded [ 47 , 64 , 73 , 74 , 85 ].…”