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The inactivation effect of photocatalytic titanium apatie filter on SARS virus
Abstract
Photocatalytic titanium apatite filter (PTAF) is a new material that has been reported to have an ability to absorb and inactivate bacteria. The inactivation effect of PTAF on serious acute respiratory syndrome coronary virus (SARS-CoV) was tested. The results showed that PTAF filter inactivated/ decomposed SARS CoV up to 99.99% after 6 h interaction under the condition of non-UV irradiation. However, under the condition of UV irradiation, PTAF and HAF both were able to inactivate/decompose SARS CoV completely. The study has provided the first evidences that PTAF could inactivate SARS-CoV virus, suggesting that the PTAF material will be applied for the prevention of SARS-CoV as well as other viruses.
... Inactivates enveloped viruses upto 99.99％ [6,142,159,171,193,195,[198][199][200][201][202][203][204][205][206]214,[217][218][219][220]237,238] Other Processes practised [70] and will further intensify when rainfall events occur. ...
... TiO 2 is a potential photocatalyst semiconductor material due to its strong oxidizing power [201], prolonged stability high reactivity and faster disinfection kinetics. Illumination of UV light at a wavelength (< 385 nm), TiO 2 generates an electron-hole on the surface pair by photon energy and generated hydroxyl radicals (*OH), and the electrons present in the conduction band produced superoxide ions (O 2 − ).*OH radicals are highly reactive species upon contacting the virus surface and enable inactivation rapidly [171,198,[202][203][204][205][206][207]. The generated oxidative species penetrate into the lipid layer of the virus which leads to inhibition or lysis [208]. ...
... Photocatalytic oxidation using undoped TiO 2 and platinized sulfated TiO 2 (Pt/TiO 2 ) yielded 90% inactivation within 30 min using UV-irradiation on TiO2 and 90% to 99.8% with Pt/TiO 2 over the viral and bacterial aerosols of influenza A (H3N2) virus, vaccinia virus, Mycobacterium smegmatis and Bacillus thuringiensis [214]. Photocatalytic titanium apatite filter (PTAF) absorbs and inactivates SARS-CoV-1 up to 99.99％ within 6 h interaction under non-UV irradiation [203]. Photoelectrocatalytical (PEC) reactors perform the photocatalytic reactions enhancing the viral inactivation significantly (> 90%) by applying a negative potential lead to damage of the virus due to the manifested electrostatic attraction between negatively charged viral capsid and catalyst surface [208,215]. ...
The unprecedented global spread of the severe acute respiratory syndrome caused by SARS-CoV-2 is depicting the distressing pandemic consequence on human health, the economy as well as ecosystem services. So far novel coronavirus (CoV) outbreaks were associated with SARS-CoV-2 (2019), middle east respiratory syndrome coronavirus (MERS-CoV, 2012), and SARS-CoV-1 (2003) events. CoV relates to the enveloped family of Betacoronavirus (βCoV) with positive-sense single-stranded RNA (+ssRNA). Knowing well the persistence, transmission, and spread of SARS-CoV-2 through proximity, the fecal-oral route is now emerging as a major environmental concern to community transmission. The replication and persistence of CoV in the gastrointestinal (GI) tract and shedding through stools is indicating a potential transmission route to the environment settings. In spite of the evidence, based on fewer reports on SARS-CoV-2 occurrence and persistence in wastewater/sewage/water, the transmission of the infective virus to the community is yet to be established. In this realm, this communication attempted to review the possible influx route of the enteric enveloped viral transmission in the environmental settings with reference to its occurrence, persistence, detection, and inactivation based on the published literature so far. The possibilities of airborne transmission through enteric virus-laden aerosols, environmental factors that may influence the viral transmission, and disinfection methods (convention and emerging) as well as the inactivation mechanism with reference to the enveloped virus were reviewed. The need for wastewater epidemiology studies for surveillance as well as for early warning signal was elaborated. This communication will provide a basis to understand the SARS-CoV-2 as well as other viruses in the context of the environmental engineering perspective to design effective strategies to counter the enteric virus transmission and also serves as a working paper for researchers, policymakers and regulators.
... The photocatalytic reaction of titanium dioxide (TiO 2 ) is useful for disinfecting surfaces, air, and water. Indeed, the photocatalytic reaction of TiO 2 kills microorganisms, such as bacteria and fungi, and inactivates influenza virus, hepatitis C virus, vesicular stomatitis virus, enterovirus, herpes virus, Zika virus, human coronavirus, bovine coronavirus, human norovirus, murine norovirus, SARS coronavirus, and bacteriophage [16][17][18][19][20][21][22][23]. Furthermore, it has previously been reported that phage B1 present in aerosols are effectively inactivated by the photocatalytic reaction of TiO 2 [24]. ...
... Indeed, the present study is the first to report that TiO 2 photocatalytic reaction for 20 min inactivated 99.9% SARS-CoV-2 in aerosols. Furthermore, our results provide evidence that TiO 2 photocatalytic reaction for 120 min inactivates 99.9% SARS-CoV-2 in liquid, consistent with recent reports showing that TiO 2 photocatalytic reaction kills microorganisms, such as bacteria and fungi, and inactivates SARS-CoV-2, influenza virus, norovirus, SARS coronavirus, and bacteriophage [16][17][18]21,22,29,34]. Thus, it is possible that TiO 2 effectively inactivates many kinds of viruses. ...
SARS-CoV-2 is the causative agent of COVID-19, which is a global pandemic. SARS-CoV-2 is transmitted rapidly via contaminated surfaces and aerosols, emphasizing the importance of environmental disinfection to block the spread of virus. Ultraviolet C radiation and chemical compounds are effective for SARS-CoV-2 disinfection, but can only be applied in the absence of humans due to their toxicities. Therefore, development of disinfectants that can be applied in working spaces without evacuating people is needed. Here we showed that TiO2-mediated photocatalytic reaction inactivates SARS-CoV-2 in a time-dependent manner and decreases its infectivity by 99.9% after 20 min and 120 min of treatment in aerosol and liquid, respectively. The mechanistic effects of TiO2 photocatalyst on SARS-CoV-2 virion included decreased total observed virion count, increased virion size, and reduced particle surface spike structure, as determined by transmission electron microscopy. Damage to viral proteins and genome was further confirmed by western blotting and RT-qPCR, respectively. The multi-antiviral effects of TiO2-mediated photocatalytic reaction implies universal disinfection potential for different infectious agents. Notably, TiO2 has no adverse effects on human health, and therefore, TiO2-induced photocatalytic reaction is suitable for disinfection of SARS-CoV-2 and other emerging infectious disease-causing agents in human habitation.
... Photocatalytic destruction of SARS-CoV using titanium dioxide nanoparticles was demonstrated by Wei et al. 53 However, it is yet to be determined if SARS-CoV-2 can also be contained by this method. ...
Objective:
This narrative review aims to compile and analyse infection prevention and control (IPAC) practices followed by dental clinics during 3 coronavirus outbreaks: SARS (2002-2004), MERS (2012-2014), and COVID-19 (2019-); and to draw parallels from them for future epidemics.
Methods:
Data were collected from 3 databases: Google Scholar, PubMed, and Embase using search terms "SARS," "MERS," "COVID-19," "infection control," "disinfection," and "sterilization".
Results:
Careful examination of 108 peer-reviewed articles on the 3 outbreaks revealed the following commonalities in the IPAC practices of dental clinics: use of sodium hypochlorite (surface disinfectant), ethanol and 1-propanol (hand hygiene), povidone-iodine (oral rinse), high-volume evacuation (HVE), rubber dam isolation, anti-retraction handpieces, and fogging.
Discussion & conclusion:
Ethanol, 1-propanol, sodium hypochlorite, povidone-iodine, photocatalysis, and fogging have been shown to be effective against various coronaviruses. However, more studies are required to validate the effectiveness of anti-retraction handpieces, rubber dam isolation, HVE, and cold atmospheric plasma specifically in infection control of the current coronavirus strain, SARS-CoV-2.
... Although its antimicrobial activity has only been known since 1985, when its photocatalytic properties were first exploited for sterilization [55], irradiation of TiO 2 with UV light has since proven to be effective against a wide variety of microorganisms, due to its production of reactive oxygen species, which cause cell lysis [16]. TiO 2 has been shown to be effective against many human viruses [56][57][58][59], including SARS [60], which indicates that it may have antiviral activity against SARS-CoV-2. Recent findings show that TiO 2 , induced by UV radiation, was effective on HCoV-NL63, a close genetic relative of SARS-CoV-2 [61]. ...
Facing the deadly pandemic caused by the SARS-CoV-2 virus all over the globe, it is crucial to devote efforts to fighting and preventing this infectious virus. Nanomaterials have gained much attention after the approval of lipid nanoparticle-based COVID-19 vaccines by the United States Food and Drug Administration (USFDA). In light of increasing demands for utilizing nanomaterials in the management of COVID-19, this comprehensive review focuses on the role of nanomaterials in the prevention, diagnostics, therapeutics, and vaccine development of COVID-19. First, we highlight the variety of nanomaterials usage in the prevention of COVID-19. We discuss the advantages of nanomaterials as well as their uses in the production of diagnostic tools and treatment methods. Finally, we review the role of nanomaterials in COVID-19 vaccine development. This review offers direction for creating products based on nanomaterials to combat COVID-19.
... The results showed that viral particle transport was improved by its attractive electrostatic interaction with multi-walled carbon nanotubes, which was inactivated via direct surface oxidation. Photocatalytic titanium apatite filter as a novel material indicated 99.99% inactivation of SARS-CoV-1 after 60 min without UV irradiation [139]. ...
In addition to the numerous health effects caused by the COVID-19 pandemic, the scientific community have considered other emerging effects such as water-related impacts worthy of deep investigation. In this regard, the transmission cycle of the SARS-CoV-2 virus from fecal, vomiting, and sputum routes to sewage has led health authorities to diagnose, prevent, and use novel wastewater treatment technologies. Once they enter the gastrointestinal canal of a healthy person, viral particles can infect via the nominal amount of Angiotensin-Converting Enzyme 2 (ACE2) present in alimentary canal cell surfaces and further infect lung, heart, kidney, and other organs. The current review highlights the detection, status, and fate of SARS-CoV-2 from sewage treatment facilities to water bodies. Besides, it addresses the potential wastewater treatment processes to cope with various viruses, especially SARS-CoV-2. Many processes can manage contaminated wastewater and solid wastes over the long term, including membrane technologies, disinfectants, UV-light and advanced oxidation methods like photocatalysis, ozonation, hydrogen peroxide, nanomaterials, and algae. Future work must focus on implementing the selected actions for the treatment of the wastewater released from the COVID-19 hospitals and self-quarantine centers to better regulate future waves of SARS-CoV-2.
... Photocatalysts are excited by light and exhibit a strong oxidation-reduction reaction generating reactive oxygen species (ROS), such as hydroxyl (·OH) and superoxide radicals (O 2 − ), on their surface [8]. Using this oxidation-reduction reaction, photocatalysts kill microorganisms, such as bacteria and fungi, and inactivate viruses such as influenza virus, hepatitis C virus, vesicular stomatitis virus, enterovirus, herpes virus, Zika virus, human coronavirus, bovine coronavirus, human norovirus, murine norovirus, SARS coronavirus, and bacteriophages [8][9][10][11][12][13][14][15]. Many compounds such as titanium dioxide (TiO 2 ), tungsten trioxide (WO 3 ), zinc oxide (ZnO), cadmium sulfide (CdS), and iron (III) oxide (Fe 2 O 3 ) are known to exhibit photocatalysis and are being actively researched. ...
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019, which has been a global pandemic. Since SARS-CoV-2 is transmitted through contaminated surfaces and aerosols, environmental disinfection is important to block the spread of the virus. Photocatalysts are attractive tools for virus inactivation and are widely used as air purifiers and coating materials. However, photocatalysts are inactive in the dark, and some of them need to be excited with light of a specific wavelength. Therefore, photocatalysts that can effectively inactivate SARS-CoV-2 in indoor environments are needed. Here, we show that a WO3 photocatalyst containing copper inactivated the SARS-CoV-2 WK-521 strain (Pango lineage A) upon irradiation with white light in a time- and concentration-dependent manner. Additionally, this photocatalyst also inactivated SARS-CoV-2 in dark conditions due to the antiviral effect of copper. Furthermore, this photocatalyst inactivated not only the WK-521 strain but also the Omicron variant BA.2. These results indicate that the WO3 photocatalyst containing copper can inactivate indoor SARS-CoV-2 regardless of the variant, in visible light or darkness, making it an effective tool for controlling the spread of SARS-CoV-2.
... The obtained results have shown that the number of cells was reduced up to 54% within 60 min of metal halide lamp irradiation and were further killed after 120 min of exposure. Since then, the application of photocatalysis for water disinfection has grown [132][133][134][135][136]. The use of photocatalyst for various applications including for water treatment process and combatting bacteria and virus including avian influenza H1N1 [136] and SARS-CoV-1 [137] in wastewater have proven that utilization of photocatalyst has been well developed. Many photocatalysts have been studied and reported such as TiO 2 , ZnO, WO 3 , Fe 2 O 3 , CuS, BiOBr, BaTiO 3 , and many more [135,[138][139][140][141]. ...
Consumption of pathogenic contaminated water has claimed the lives of many people. Hence, this scenario has emphasized the urgent need for research methods to avoid, treat and eliminate harmful pathogens in wastewater. Therefore, effective water treatment has become a matter of utmost importance. Membrane technology offers purer, cleaner, and pathogen-free water through the water separation method via a permeable membrane. Advanced membrane technology such as nanocomposite membrane, membrane distillation, membrane bioreactor, and photocatalytic membrane reactor can offer synergistic effects in removing pathogen through the integration of additional functionality and filtration in a single chamber. This paper also comprehensively discussed the application, challenges, and future perspective of the advanced membrane technology as a promising alternative in battling pathogenic microbial contaminants, which will also be beneficial and valuable in managing pandemics in the future as well as protecting human health and the environment. In addition, the potential of membrane technology in battling the ongoing global pandemic of coronavirus disease 2019 (COVID-19) was also discussed briefly.
... Since the earlier studies show that illumination of TiO 2 photocatalysts produces highly reducing/oxidizing free radicals with excellent anti-microbial/viral action against various microbes and also viruses such as influenza virus which are transmitted via aerosol and causes respiratory tract infection, similar to COVID-19 [102,104]. The photocatalytic effect of titanium apatite filter was used to show inactivation of SARS coronavirus long ago [104,105]. However, the antiviral efficacy of TiO 2 against SARS-CoV-2 is still to be investigated in details. ...
The whole world is struggling with current coronavirus pandemic that shows urgent need to develop novel technologies, medical innovations or innovative materials for controlling SARS-CoV-2 infection. The mode of infection of SARS-CoV-2 is still not well known and seems to spread through surface, air, and water. Therefore, the whole surrounding environment needs to be disinfected with continuous function. For that purpose, materials with excellent antiviral properties, cost effective, environmental friendly and practically applicable should be researched. Titanium dioxide (TiO2) under ultraviolet light produces strong oxidative effect and is utilized as photocatalytic disinfectant in biomedical field. TiO2 based photocatalysts are effective antimicrobial/antiviral agents under ambient conditions with potential to be used even in indoor environment for inactivation of bacteria/viruses. Interestingly, recent studies highlight the effective disinfection of SARS-CoV-2 using TiO2 photocatalysts. Here, scope of TiO2 photocatalysts as emerging disinfectant against SARS-CoV-2 infection has been discussed in view of their excellent antibacterial and antiviral activities against various bacteria and viruses (e.g. H1N1, MNV, HSV, NDV, HCoV etc.). The current state of development of TiO2 based nano-photocatalysts as disinfectant shows their potential to combat with SARS-CoV-2 viral infection and are promising for any other such variants or viruses, bacteria in future studies.
... Employing a photocatalytic titanium apatite filter led to an effective inactivation of SARS-CoV-1 coronavirus (which is a large lipid-enveloped and single-stranded RNA virus) under UV irradiation for 6 h. Indeed, the generated ROS damaged the spike proteins leading to the decrease of the viral infectious capacity with 99.99% inactivation efficiency [89,95]. Due to the genome similarities between SARS-CoV-1 and SARS-CoV-2, this latter can be sensitive and affected by disinfectants, like SARS-CoV-1. ...
Obtaining clean and high-quality water free of pathogenic microorganisms is a worldwide challenge. Various techniques have been investigated for achieving an effective removal or inacti-vation of these pathogenic microorganisms. One of those promising techniques is photocatalysis. In recent years, photocatalytic processes used semiconductors as photocatalysts. They were widely studied as a green and safe technology for water disinfection due to their high efficiency, being non-toxic and inexpensive, and their ability to disinfect a wide range of microorganisms under UV or visible light. In this review, we summarized the inactivation mechanisms of different waterborne pathogenic microorganisms by semiconductor photocatalysts. However, the photocatalytic efficiency of semiconductors photocatalysts, especially titanium dioxide, under visible light is limited and hence needs further improvements. Several strategies have been studied to improve their efficiencies which are briefly discussed in this review. With the developing of nanotechnology, doping with nanomaterials can increase and promote the semiconductor's photocatalytic efficiency, which can enhance the deactivation or damage of a large number of waterborne pathogenic microorganisms. Here, we present an overview of antimicrobial effects for a wide range of nano-photocatalysts, including titanium dioxide-based, other metal-containing, and metal-free photocatalysts. Promising future directions and challenges for materials research in photocatalytic water disinfection are also concluded in this review.
... It was able to decompose the virus significantly with 6 h interaction under non-UV irradiation as well as UV irradiation. These photocatalysts when coupled with UV light can damage the spike proteins and decrease the infectious capability of the virus and thus can be helpful against SARS-CoV-2 [94]. ...
In the last few decades, viral infections have caused a greater number of health constraints worldwide. This havoc has created challenges for the healthcare system. Since the pandemic began, COVID-19 has killed more than 2.5 million people across the world. We are still witnessing deaths daily due to the deadly virus SARS-CoV-2 which is the causative agent for COVID-19. Thus, there is an increasing concern about finding an apt way to control the spread of this virus. Recently, the application of nanotechnology-based approaches has emerged as a ground-breaking step in the medical sector owing to their potential for accurate diagnosis and specific treatment in a wide range of health problems, including viral diseases. Therefore, the implementation of nanotechnology can be an articulate strategy to confront the rising distress of COVID-19. The present review particularly emphasizes the perception of several nanoformulation-based approaches as an appropriate means to safeguard mankind against COVID-19.
... 176 A titanium apatite photocatalyst-coated filter inactivated SARS-CoV-1 with an initial infectivity of 10 7.5 PFU mL À1 under UV light irradiation at 1 mW cm À2 for 6 h. 177 A TiO 2 -coated aluminium filter inactivated influenza A virus (H1N1) by reducing aerosolassociated infectivity of (1.2-2.6) Â 10 6 PFU mL À1 to an undetectable level of infectivity (o300 PFU mL À1 ) under 375 nm light irradiation at 10 mW cm À2 for 7 min. ...
The ongoing coronavirus disease 2019 (COVID-19) pandemic has accelerated efforts to develop high-performance antiviral surface coatings while highlighting the need to build a strong mechanistic understanding of the chemical design principles that underpin antiviral surface coatings. Herein, we critically summarize the latest efforts to develop antiviral surface coatings that exhibit virus-inactivating functions through disrupting lipid envelopes or protein capsids. Particular attention is focused on how cutting-edge advances in material science are being applied to engineer antiviral surface coatings with tailored molecular-level properties to inhibit membrane-enveloped and non-enveloped viruses. Key topics covered include surfaces functionalized with organic and inorganic compounds and nanoparticles to inhibit viruses, and self-cleaning surfaces that incorporate photocatalysts and triplet photosensitizers. Application examples to stop COVID-19 are also introduced and demonstrate how the integration of chemical design principles and advanced material fabrication strategies are leading to next-generation surface coatings that can help thwart viral pandemics and other infectious disease threats.
... However, there were also opposite findings (Bogdan et al., 2015). To the best knowledge of the author, there is only one journal article shared the usage photocatalytic titanium apatite filter (PTAF) to combat SARS-CoV-2 (Han et al., 2004). It showed that there is the possibility of using the treatment method. ...
In 2019, a novel type of coronavirus emerged in China called SARS-COV-2, known COVID-19, threatens global health and possesses negative impact on people's quality of life, leading to an urgent need for its diagnosis and remedy. On the other hand, the presence of hazardous infectious waste led to the increase of the risk of transmitting the virus by individuals and by hospitals during the COVID-19 pandemic. Hence, in this review, we survey previous researches on nanomaterials that can be effective for guiding strategies to deal with the current COVID-19 pandemic and also decrease the hazardous infectious waste in the environment. We highlight the contribution of nanomaterials that possess potential to therapy, prevention, detect targeted virus proteins and also can be useful for large population screening, for the development of environmental sensors and filters. Besides, we investigate the possibilities of employing the nanomaterials in antiviral research and treatment development, examining the role of nanomaterials in antiviral- drug design, including the importance of nanomaterials in drug delivery and vaccination, and for the production of medical equipment. Nanomaterials-based technologies not only contribute to the ongoing SARS- CoV-2 research efforts but can also provide platforms and tools for the understanding, protection, detection and treatment of future viral diseases.
... Chlorination technique is one the most common technique for virus disinfection that using chlorine gas, chloramines or hypochlorite solution [21][22][23][24]. Previous study reported chlorination could remove SARS-CoV-1 efficiently [25]. Unfortunately, chlorination was opposed due to generation of mutagenic and carcinogenic disinfection by products. ...
Photocatalytic technology offers powerful virus disinfection in wastewater via oxidative capability with minimum harmful by-products generation. This review paper aims to provide state-of-the-art photocatalytic technology in battling transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater. Prior to that, the advantages and limitations of the existing conventional and advanced oxidation processes for virus disinfection in water systems were thoroughly examined. A wide spectrum of virus degradation by various photocatalysts was then considered to understand the potential mechanism for deactivating this deadly virus. The challenges and future perspectives were comprehensively discussed at the end of this review describing the limitations of current photocatalytic technology and suggesting a realistic outlook on advanced photocatalytic technology as a potential solution in dealing with similar upcoming pandemics. The major finding of this review including discovery of a vision on the possible photocatalytic approaches that have been proven to be outstanding against other viruses and subsequently combatting SARS-CoV-2 in wastewater. This review intends to deliver insightful information and discussion on the potential of photocatalysis in battling COVID-19 transmission through wastewater.
... It may help stop the transfusion of a virus via plasma products [142]. Also, there is a study on the use of photocatalytic titanium apatite filter (PTAF) for inactivation of the SARS-CoV UV and non-UV in the titanium photocatalysis section below [143]. In order to enhance the effectiveness of PDT toward COVID-19, the amalgamation of the latest innovations such as nanotechnology can become more successful. ...
The 2019 novel coronavirus (2019-nCoV; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) has witnessed a rapid and global proliferation since its early identification in patients with severe pneumonia in Wuhan, China. As of 27th May 2020, 2019-nCoV cases have risen to >5 million, with confirmed deaths of 350,000. However, Coronavirus disease (COVID-19) diagnostic and treatment measures are yet to be fully unraveled, given the novelty of this particular coronavirus. Therefore, existing antiviral agents used for severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERSCoV) were repurposed for COVID-19, taking their biological features into consideration. This study provides a concise review of the current and emerging detection and supervision technologies for SARS-CoV-2, which is the viral etiology of COVID19, and their performance characteristics, with emphasis on the novel Nano-based diagnostic tests (protein corona sensor array and magnetic levitation) and treatment measures (treatment protocols based on nano-silver colloids) for COVID-19.
... The big advantage of this method of water purification is the absence of toxic byproducts, the possible use of energy from the sun, as a sustainable and inexpensive source of energy, and the extended ability to kill pathogenic microorganisms. The efficiency of photocatalytic oxidation for inactivation of viruses has been demonstrated, which is very important, since many other types of physicochemical effects disrupt the vital activity of bacteria, microbes, etc., but are not destructive for viruses [15][16][17]19,23,25]. The problem of targeting viruses that enter natural environments has become especially acute this year in connection with the COVID19 pandemic. ...
The dynamics of magnetic separation of TiO2 nanoparticles (25 nm) from water by adding composite magnetic Fe-C-COOH nanoparticles (15 nm) and subsequent magnetic sedimentation or magnetic filtration has been studied. Magnetic sedimentation was carried out in a gradient magnetic field (Hmax = 0.3 T, (gradH)max = 0.13T / m), and magnetic filtration (Hmax = 0.5 T, (gradH)max ∼ 10⁵T / m) was carried out in a column bench filter with a steel wool magnetic matrix. The applied methods of spectrophotometry using the PLS algorithm and nuclear relaxometry made it possible to determine the partial concentrations of the target TiO2 particles and of the magnetic seeds in water. Oppositely charged target TiO2 nanoparticles and magnetic Fe-C-COOH nanoparticles formed heteroaggregates in water, the size of which depended on the pH of the aqueous medium, on the ratio of their concentrations, and on the concentration of the solid phase in water. The maximum efficiency of TiO2 separation from water by both methods was observed at pH = 6, at which the electric charge of the aggregates was minimal. The largest heteroaggregates (with dh ∼ 3 μm) are formed at initial concentrations of TiO2 nanoparticles of 0.1-0.5 g / l and at the 2:1 mass ratio of the nonmagnetic and magnetic components. Magnetic filtration is a more efficient separation process than magnetic sedimentation due to higher magnetic field gradients applied.
It was found that by adding Fe-C-COOH magnetic nanoseeds, the magnetic filtration at a flow rate of 7 * 10⁻³ m / s through a filter of the 50 cm length, leads to the reduction of the TiO2 concentration in water from 0.5 g / l to 3 * 10⁻⁴ g / l for 10 minutes. The results obtained can serve as a basis for designing a magnetic separation unit in photocatalytic reactors for water purification.
... While the antiviral activity was attributed to the viral binding and shielding potential of these sheets due to their sharp edges and binding promoted by the electrostatic attraction between the negative surface charge of GO and the positive charge of the nucleocapsid shell of the viral particles (Sametband et al., 2014;Song et al., 2015;Ye et al., 2015). Furthermore, regardless of the paucity of research on the antiviral effect of titanium dioxide (TiO 2 ), the most described photocatalytic NPs in the literature, a study showed that a titanium apatite filter (PTAF) could inactivate SARS-CoV when exposed to the UV light for 6 h, which was hypothesized to have caused damage to the S protein, resulting in diminished virus infectivity (Han et al., 2004). Therefore, it is indisputable that nano-formulations of the materials mentioned in this section could play promising roles in the context of drug design and vaccine development against COVID-19. ...
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which emerged in December 2019 and caused the coronavirus disease 2019 (COVID-19) pandemic, took the world by surprise with an unprecedented public health emergency. Since this pandemic began, extraordinary efforts have been made by scientists to understand the pathogenesis of COVID-19, and to fight the infection by providing various preventive, diagnostic and treatment opportunities based on either novel hypotheses or past experiences. Despite all the achievements, COVID-19 continues to be an accelerating health threat with no specifically approved vaccine or therapy. This review highlights the recent advances in COVID-19 infection, with a particular emphasis is put on nanomedicine applications that can help to succeed in the development of effective vaccines or therapeutics against COVID-19. A novel future perspective has been proposed in this review based on utilizing polymersome nano-objects for effectively suppressing the cytokine storm, which may reduce the severity of COVID-19 infection.
... Dunlop and colleagues also showed that photocatalytic coated surfaces reduce viability of C. difficile spores and cells within biofilms [32]. Interestingly, studies on viruses including SARS, influenza A/H1N1, norovirus, influenza A/H 3 N 2 also showed that photocatalysis has effects on them [52][53][54][55]. Additionally, it was found that photocatalysis inactivates microbial toxins [56][57][58]. ...
Contaminated surfaces and indoor environments are important sources of infectious spread within hospital and non-hospital facilities. Bacterial infections such as infections with Clostridioides (formerly Clostridium) difficile (C. difficile) and Staphylococcus aureus (S. aureus) and its antibiotic resistant strains continue to pose a significant risk to healthcare workers and patients. Additionally, the recent emergence of the coronavirus disease 2019 (COVID-19) pandemic, which is caused by the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), highlights the need for safe and effective methods to decontaminate surfaces to control infection spread in hospitals and the community. To address these critical needs, we tested a photocatalytic reactor decontamination method to disinfect contaminated surfaces in a hospital and a laboratory setting. By placing the reactor in a test hospital room, growth of S. aureus and C. difficile were significantly reduced compared with a control room. Additionally, using a model enveloped positive-sense single-stranded RNA virus, dengue virus type 2 (DENV2), we showed that the use of the photocatalytic reactor reduces viral infectivity. Collectively, the results demonstrate the potential utility of photocatalytic reactors in reducing the spread of highly contagious bacterial and viral infections through contaminated surfaces and environments.
... TiO 2 was proposed to have an antiviral effect, targeting both DNA and RNA viruses, airborne and bloodborne pathogens. The photocatalytic titanium apatite filter was earlier shown to inactivate SARS coronavirus up to 99.99% after 6 h exposure [38]. Our assay to use TiO 2 coating to efficiently inactivate human coronavirus with UV light through very brief exposure highlights the importance of TNP coatings on publicly used surfaces. ...
The newly identified pathogenic human coronavirus, SARS-CoV-2, led to an atypical pneumonia-like severe acute respiratory syndrome (SARS) outbreak called coronavirus disease 2019 (abbreviated as COVID-19). Currently, nearly 77 million cases have been confirmed worldwide with the highest numbers of COVID-19 cases in the United States. Individuals are getting vaccinated with recently approved vaccines, which are highly protective in suppressing COVID-19 symptoms but there will be a long way before the majority of individuals get vaccinated. In the meantime, safety precautions and effective disease control strategies appear to be vital for preventing the virus spread in public places. Due to the longevity of the virus on smooth surfaces, photocatalytic properties of “self-disinfecting/cleaning” surfaces appear to be a promising tool to help guide disinfection policies for controlling SARS-CoV-2 spread in high-traffic areas such as hospitals, grocery stores, airports, schools, and stadiums. Here, we explored the photocatalytic properties of nanosized TiO2 (TNPs) as induced by the UV radiation, towards virus deactivation. Our preliminary results using a close genetic relative of SAR-CoV-2, HCoV-NL63, showed the virucidal efficacy of photoactive TNPs deposited on glass coverslips, as examined by quantitative RT-qPCR and virus infectivity assays. Efforts to extrapolate the underlying concepts described in this study to SARS-CoV-2 are currently underway.
... TiO2 was proposed to have antiviral effect, targeting both DNA and RNA viruses, airborne and blood borne pathogens. The photocatalytic titanium apatite filter was earlier shown to inactivate SARS coronavirus up to 99.99% after 6 h exposure [34]. Our assay to use TiO2 coating to efficiently inactivate human coronavirus with UV light through very brief exposure highlights the importance of TNP coatings on publicly used surfaces. ...
The newly identified pathogenic human coronavirus, SARS-CoV-2, led to an atypical pneumonia-like severe acute respiratory syndrome (SARS) outbreak called coronavirus disease 2019 (COVID-19). Currently, nearly 23 million cases have been confirmed worldwide with the highest COVID-19 cases been confirmed in the United States. As there is no vaccine or any effective interventions, massive efforts to create a potential vaccine to combat COVID-19 is underway. In the meantime, safety precautions and effective disease control strategies appear to be vital for preventing the virus spread in the public places. Due to the longevity of the virus on smooth surfaces, photocatalytic properties of self-disinfecting/cleaning surfaces appear to be a promising tool to help guide disinfection policies to control infectious SAR-CoV-2 spread in high-traffic areas such as hospitals, grocery stores, airports, schools, and stadiums. Here, we explored the photocatalytic properties of nanosized TiO2 (TNPs) as induced by the UV radiation, towards virus deactivation. Our preliminary results using close genetic relative of SAR-CoV-2, HCoV-NL63, showed the virucidal efficacy of photoactive TNPs deposited on glass coverslips, as examined by quantitative RT-PCR and virus culture assays. Efforts to extrapolate the underlying concepts described in this study to SARS-CoV-2 are currently underway.
... This filter showed effective inactivation of SARS-CoV when exposed for 6 h to UV light. 195 One could also imagine that photocatalysts coupled to UV light could damage spike proteins and lead to decreased infectious capacity of the virus. ...
... Birds Influenza (avian) A/H5N2 [87] Human Hepatitis B virus surface antigen HBsAg [88] Human Influenza A/H1N1 [89] Human Influenza A/H3N2 [90] Human Poliovirus type 1 (ATCC VFR-192) [91] Human SARS coronavirus [92] Antimicrobial photodynamic inactivation in nanomedicine Review of two basic types of nanotubes: multiwalled, referred to as (MWNT and MWCNT) and single-walled, referred to as (SWNT and SWCNT) (Figure 7) [114]. ...
The relentless advance of drug-resistance among pathogenic microbes, mandates a search for alternative approaches that will not cause resistance. Photodynamic inactivation (PDI) involves the combination of nontoxic dyes with harmless visible light to produce reactive oxygen species that can selectively kill microbial cells. PDI can be broad-spectrum in nature and can also destroy microbial cells in biofilms. Many different kinds of nanoparticles have been studied to potentiate antimicrobial PDI by improving photosensitizer solubility, photochemistry, photophysics and targeting. This review will cover photocatalytic disinfection with titania nanoparticles, carbon nanomaterials (fullerenes, carbon nanotubes and graphene), liposomes and polymeric nanoparticles. Natural polymers (chitosan and cellulose), gold and silver plasmonic nanoparticles, mesoporous silica, magnetic and upconverting nanoparticles have all been used for PDI.
... Nonspecific character of AOPs gives rise to assume that the TiO 2 /UV process could efficiently reduce the dissemination of many viruses, e.g., measles, mumps, rubella, or smallpox. Some authors, like Han et al. [54], believe the TiO 2 /UV process can be an efficient tool to reduce the dissemination of the SARS virus, a helical enveloped virus from the (+)ssRNA group. Nakano et al. [55] showed that on the surface covered by a thin layer of nano-TiO 2 , a complete inactivation of influenza virus took place within a short period (approximately 30 min) of the TiO 2 /UV process. ...
Nanotechnology contributes towards a more effective eradication of pathogens that have emerged in hospitals, veterinary clinics, and food processing plants and that are resistant to traditional drugs or disinfectants. Since new methods of pathogens eradication must be invented and implemented, nanotechnology seems to have become the response to that acute need. A remarkable achievement in this field of science was the creation of self-disinfecting surfaces that base on advanced oxidation processes (AOPs). Thus, the phenomenon of photocatalysis was practically applied. Among the AOPs that have been most studied in respect of their ability to eradicate viruses, prions, bacteria, yeasts, and molds, there are the processes of TiO2/UV and ZnO/UV. Titanium dioxide (TiO2) and zinc oxide (ZnO) act as photocatalysts, after they have been powdered to nanoparticles. Ultraviolet (UV) radiation is an agent that determines their excitation. Methods using photocatalytic properties of nanosized TiO2 and ZnO prove to be highly efficient in inactivation of infectious agents. Therefore, they are being applied on a growing scale. AOP-based disinfection is regarded as a very promising tool that might help overcome problems in food hygiene and public health protection. The susceptibility of infectious agents to photocatalylic processes can be generally arranged in the following order: viruses > prions > Gram-negative bacteria > Gram-positive bacteria > yeasts > molds.
Coronavirus disease 2019 (COVID-19) infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global burden to public health that manifests various symptoms, including self-limiting upper respiratory disorder, severe pneumonia, multi-organ failure, and even death. Thus, efficient approaches to tackle the rapid biological diversity and mutations of coronaviruses (CoVs) are required. Recently, nanotechnology approaches have enabled control of virus transmission by offering efficient personal protective equipment, antiviral surface coatings, and disinfectants. Besides, nanotechnology could be used in viral infection sampling, sample processing, amplification, and sensing to create rapid, sensitive, and accurate diagnostic tests. Nanomaterials have been increasingly used to deliver potential therapeutic agents, vaccines, and artificial viruses because of their certain properties such as high surface-to-volume ratio, specific optical, antiviral action, drug encapsulation, nanoscale biorecognition, and controlled release properties. This chapter covers nanotechnology-based approaches for preventing, diagnosing, and treating CoV infections with an emphasis on SARS-CoV-2.
Water is linked to every aspect of our life, and the nexus between water and health is well-documented. Lack of access to clean water and waterborne diseases is a significant cause of human misery. Pesticides are a group of chemicals widely detected in water bodies, mainly due to their indiscriminate use in the agricultural sector. Due to possible entry into human and animal food chains, health hazards posed by pesticides have become a considerable area of concern worldwide. Nevertheless, the production and use of pesticides are increasing, and the global pesticide market is expected to reach 24.6 billion USD by 2020–2024. Given the widespread occurrence and potential toxicity, many treatment technologies are in place to treat pesticide-contaminated water. However, the diverse chemical nature of the pesticides and the stringent regulations in drinking water standards, 0.1 μg/L for a single pesticide and 0.5 μg/L for the sum of all pesticides, limit the use of many existing treatment systems. The advancement in nanoscience and nanotechnology suggests that nanoscale materials, especially nanocarbon and its derivatives, are promising candidates for scavenging pesticides in water. This chapter reviews the literature on various nanoscale carbons with exciting properties and their applications for treating pesticide-laden drinking water. The mechanism of removal, challenges, prospects, and future development in the area is discussed. This chapter also covers the origin, occurrence of pesticides in water bodies, and their human and ecological health impacts.
Clean drinking water is absolutely essential for our survival. Unfortunately, drinking water resources are being polluted in a variety of ways. Conventional water purification technologies are generally not efficient. To mitigate this problem, scientists around the world are working to develop new cost-effective, environment-friendly technologies. Nanomaterials with extraordinary physical, chemical, mechanical, and morphologic properties offer a potential solution to water pollution issues. In this chapter, we point out some basic information on various sources of contamination and their effects on human beings and environment, differences between wastewater and drinking water treatment processes, and limitations of conventional water treatment technologies. We describe how nanophotocatalyst, nanomembrane, nanoreactor, and nanoadsorbent can decontaminate polluted water sources. In addition, we discuss how to remove five selected pollutants (arsenic, lead, pharmaceutical, per- and polyfluoroalkyl substances, and corona viruses) from water by various nanomaterials. Finally, we show some limitations of using nanomaterials for water treatment.
Antiviral hydrophobic cellulose-based cotton or non-woven fabrics containing mesoporous TiO2 particles were developed for potential use in healthcare and in other contaminated environments. Hydrosols made with the sol-gel method using two different amounts of the Ti precursor were applied to cotton and non-woven fabrics and their virucidal effect on Murine Coronavirus (MHV-3) and Human Adenovirus (HAdV-5) was evaluated under indoor light irradiation. The results show 90% reduction of HAdV-5 and up to 99% of MHV-3 in non-woven fabric, and 90% reduction of MHV-3 and no reduction of HAdV-5 in cotton fabric. The antiviral activity was related to the properties of the TiO2 powders and coatings characterized by BET surface area, DRX, DLS, FTIR, DRS, SEM, TEM and water contact angle. The hydrophobic characteristic of the treated fabrics and the high surface area of the TiO2 particles favor interaction with the virus, especially MHV-3. These results demonstrate that non-woven fabric and cotton, coated with TiO2, can be highly effective in preventing contamination with MHV-3 and HAdV-5 viruses, particularly for applications in healthcare indoor environments.
This review addresses the issue of biomedical waste in the form of PPE (personal protection equipment) kit. COVID -19 pandemic has brought life into standstill. It has affected life of each and every person. This includes both direct effect in terms of health and indirect effect in terms of economic loss, business losses which have also resulted into sudden surge in unemployment. But apart from these directly visible effects there is one particular effect which is far sighted but cruel reality of present condition. It is the problem of biomedical wastage arising due to extensive use of PPE kits especially in the form of face mask and isolation gown. As layman is expected to wear face mask all the time, many countries has made it mandatory. It is very important to think about its effective, environment friendly disposal. Similarly isolation gown has also become very common in many medical and non-medical industries. If we dont dispose off used gown properly then the whole purpose of its use will get defeated as it further leads to disease transmission. While selecting method of disposal, it is very important to consider its adverse effect on environment. Incineration, shredding and deep pit burial are some of the common method of disposal of biomedical waste approved by health authorities of different countries, but these are not environment friendly. There are some other disinfection methods like ultra-violet (UV) irradiation, chemical disinfection with the help of them medical isolation gown can be reused but these methods have many disadvantages including being expensive, non-eco-friendly, some methods require expertise in handling machine, some affect the virus barrier ability of gown etc. Considering these problems, this review explored the idea of reusable isolation gown which doesnt require any expertise for its disinfection at the same time it doesnt adversely affect the environment. We proposed the idea of applying layer of photocatalyst which can inhibit the enzymatic activity of cells of microbes which will stop their replication. This can prove very useful in preventing the disease transmission. There are many reports on antimicrobial properties of various semiconductorphotocatalyst which can further be improved by doping it with metal like Cu or Ag which are already popular for their medicinal properties. Major problem with most of the semiconductor photocatalysts is that they show antimicrobial properties within UV range due to their wide band gap. This is not possible just by drying under sun as earth doesnt receive enough ultra violet radiation to start the photocatalysis effectively. This problem is addressed by suggesting different methods/doping to bring photocatalysis range of these photocatalysts within UV-visible range. This would bring major change in isolation gown uses, as people will be able to reuse gown just after drying it under sunlight for some time. This is expected to lower the biomedical waste in the form of gown and mask by manifolds.
The last 50 years have witnessed a growing awareness of the fragile state of most of the planets’ drinking water resources. Access to freshwater will become even more important in the near future, as the world’s population rises from 7 billion today to 9 billion by 2050. The World Health Organization (WHO) has estimated that 80 % of illnesses in the developing world are water related, resulting from poor water quality and lack of sanitation [1]. There are 3.3 million deaths each year from diarrheal diseases caused by bacteria such as Escherichia coli, Salmonella sp. and Cholera sp., parasites and viral pathogens. In the 1990s, the number of children who died of diarrhoea was greater than the sum of people killed in conflicts since World War II [2]. It is also estimated that around 4 billion people worldwide experience to have no or little access to clean and sanitized water supply, and millions of people died of severe waterborne diseases annually [3, 4].
This paper reports the biological effects of TiO2 sol derived from peroxotitanic acid solution (PAS TiO2 sol) on the control of plant diseases and growth regulation. The PAS TiO2 sol is a neutral, viscous aqueous colloid of TiO2 containing 1.6% TiO2 with a size of between 10-50 nm. Experiments were conducted under normal laboratory and greenhouse growing conditions. For the bactericidal effects of the PAS TiO2 experiments, TiO2 coated glass slides were inoculated with pathogenic bacteria in the laboratory. For the Greenhouse experiments on disease control and photosynthesis, all test plants (treatment block and control block) were inoculated with pathogenic bacteria. While plants in the treatment blocks were sprayed with PAS TiO2, plants in the control blocks were sprayed with water. X-ray diffraction (XRD) results demonstrated that the crystal form of TiO2 nano-particles was anatase. Results from greenhouse experiments using cucumbers showed that PAS TiO2 sol formed a well-spread, transparent, and sticky layer of TiO2 photo-catalyst on the plants' surface. The PAS TiO2 photo-catalyst layer prevented pathogenic infection and improved photo synthetic performance. These results suggest that PAS TiO2 sol can be used as a potentially environmentally friendly plant germicide and growth regulator.
The current eight published ISO standards associated with semiconductor photocatalysis are considered. These standards cover: (1) air purification (specifically, the removal of NO, acetaldehyde and toluene), (2) water purification (the photobleaching of methylene blue and oxidation of DMSO) (3) self-cleaning surfaces (the removal of oleic acid and subsequent change in water droplet contact angle), (4) photosterilisation (specifically probing the antibacterial action of semiconductor photocatalyst films) and (5) UV light sources for semiconductor photocatalytic ISO work. For each standard, the background is first considered, followed by a brief discussion of the standard particulars and concluding in a discussion of the pros and cons of the standard, with often recommendations for their improvement. Other possible standards for the future which would either compliment or enhance the current ones are discussed briefly.
Nanocarbons, such as carbon nanohorns (CNH) and carbon nanotubes, are materials of
interest in many fields of science and technology because of their remarkable physical
properties. We report here a novel approach for using NIR laser-driven CNH as an antiviral
agent. NIR laser-driven functional CNH complexes could open the way to a new range of
antiviral materials.
The photocatalytic properties of titanium dioxide are well known and have many applications including the removal of organic contaminants and production of self-cleaning glass. There is an increasing interest in the application of the photocatalytic properties of TiO(2) for disinfection of surfaces, air and water. Reviews of the applications of photocatalysis in disinfection (Gamage and Zhang 2010; Chong et al., Wat Res 44(10):2997-3027, 2010) and of modelling of TiO(2) action have recently been published (Dalrymple et al. , Appl Catal B 98(1-2):27-38, 2010). In this review, we give an overview of the effects of photoactivated TiO(2) on microorganisms. The activity has been shown to be capable of killing a wide range of Gram-negative and Gram-positive bacteria, filamentous and unicellular fungi, algae, protozoa, mammalian viruses and bacteriophage. Resting stages, particularly bacterial endospores, fungal spores and protozoan cysts, are generally more resistant than the vegetative forms, possibly due to the increased cell wall thickness. The killing mechanism involves degradation of the cell wall and cytoplasmic membrane due to the production of reactive oxygen species such as hydroxyl radicals and hydrogen peroxide. This initially leads to leakage of cellular contents then cell lysis and may be followed by complete mineralisation of the organism. Killing is most efficient when there is close contact between the organisms and the TiO(2) catalyst. The killing activity is enhanced by the presence of other antimicrobial agents such as Cu and Ag.
This study was conducted to investigate efficiency of TiO(2) nanomaterial as a novel environment-friendly disinfectant to control avian influenza (AI) by its photochemical sterilization ability. Anatase nano-TiO(2) sol, a neutral, viscous aqueous colloid of 1.6% TiO(2) , was synthesized from peroxotitanic acid solution according to the Ichinose method. Transmission electron microscope images showed that the TiO(2) particles were spindle-shaped with an average size of 50 nm. X-ray diffraction patterns revealed that the crystal phase of TiO(2) particles was anatase type with photocatalytic effect. A photocatalytic film of nano-TiO(2) sol was tested as a means of inactivating H(9) N(2) avian influenza virus (AIV). Inactivation capabilities were examined with 365nm ultraviolet (UV) radiation under black light by adjusting the UV intensity, the UV irradiation time and the quantity of AIV. The titer change of AIV was determined by hemagglutination tests. Cytopathic effect of Madin Darby canine kidney (MDCK) cells was monitored by inverted fluorescence microscope. The results showed that anatase nano-TiO(2) sol significantly inactivated AIV under UV irradiation of 365nm. The inactivation of AIV viruses reached up to 100%. Therefore, anatase nano-TiO(2) sol is a potentially environment-friendly antivirus agent to prevent AI.
Catalytic oxidation is a potential way to disinfect air through a air-condition system. We find that the SARS coronavirus, bacteria and yeast are completely inactivated in 5 min on Ag catalyst surface and in 20 min on Cu catalyst surface at room temperature in air. Scanning electron microscopy (SEM) images show that the yeast cells are dramatically destructed on the Ag/Al2O3 and Cu/Al2O3 surfaces, which indicates that the inactivation is caused by catalytic oxidation rather than by toxicity of heavy metals.
A worldwide outbreak of severe acute respiratory syndrome (SARS) has been associated with exposures originating from a single ill health care worker from Guangdong Province, China. We conducted studies to identify the etiologic agent of this outbreak.
We received clinical specimens from patients in seven countries and tested them, using virus-isolation techniques, electron-microscopical and histologic studies, and molecular and serologic assays, in an attempt to identify a wide range of potential pathogens.
None of the previously described respiratory pathogens were consistently identified. However, a novel coronavirus was isolated from patients who met the case definition of SARS. Cytopathological features were noted in Vero E6 cells inoculated with a throat-swab specimen. Electron-microscopical examination revealed ultrastructural features characteristic of coronaviruses. Immunohistochemical and immunofluorescence staining revealed reactivity with group I coronavirus polyclonal antibodies. Consensus coronavirus primers designed to amplify a fragment of the polymerase gene by reverse transcription-polymerase chain reaction (RT-PCR) were used to obtain a sequence that clearly identified the isolate as a unique coronavirus only distantly related to previously sequenced coronaviruses. With specific diagnostic RT-PCR primers we identified several identical nucleotide sequences in 12 patients from several locations, a finding consistent with a point-source outbreak. Indirect fluorescence antibody tests and enzyme-linked immunosorbent assays made with the new isolate have been used to demonstrate a virus-specific serologic response. This virus may never before have circulated in the U.S. population.
A novel coronavirus is associated with this outbreak, and the evidence indicates that this virus has an etiologic role in SARS. Because of the death of Dr. Carlo Urbani, we propose that our first isolate be named the Urbani strain of SARS-associated coronavirus.
The severe acute respiratory syndrome (SARS) has recently been identified as a new clinical entity. SARS is thought to be caused by an unknown infectious agent.
Clinical specimens from patients with SARS were searched for unknown viruses with the use of cell cultures and molecular techniques.
A novel coronavirus was identified in patients with SARS. The virus was isolated in cell culture, and a sequence 300 nucleotides in length was obtained by a polymerase-chain-reaction (PCR)-based random-amplification procedure. Genetic characterization indicated that the virus is only distantly related to known coronaviruses (identical in 50 to 60 percent of the nucleotide sequence). On the basis of the obtained sequence, conventional and real-time PCR assays for specific and sensitive detection of the novel virus were established. Virus was detected in a variety of clinical specimens from patients with SARS but not in controls. High concentrations of viral RNA of up to 100 million molecules per milliliter were found in sputum. Viral RNA was also detected at extremely low concentrations in plasma during the acute phase and in feces during the late convalescent phase. Infected patients showed seroconversion on the Vero cells in which the virus was isolated.
The novel coronavirus might have a role in causing SARS.
To examine the special features of the antibacterial effect for a thin transparent titanium dioxide (TiO2) film, the photocatalytic degradation of endotoxin, which is a pyrogenic constituent of Escherichia coli (E. coli), as well as its bactericidal activity, was investigated. The TiO2 films were prepared from titanium isopropoxide solution, annealing at 500 °C. The bactericidal activity for E. coli cells was estimated by survival ratio calculated from the number of viable cells which form colonies on the nutrient agar plates. The endotoxin concentration was determined by the Limulus tests. When E. coli cells were killed by the TiO2 photocatalyst under UV irradiation, the endotoxin from the cells was also degraded efficiently. This result shows that the TiO2 photocatalyst has both bactericidal activity and decomposing activity for the endotoxin (i.e., detoxifying activity). The bactericidal effect of the TiO2 thin film results from both inactivating the viability of the bacteria and the destruction of the E. coli cells. This feature renders TiO2 photocatalysts to be applicable to environmental protections, especially in medical facilities where the endotoxin is needed to control.
Titanium dioxide is the most investigated single-crystalline system in the surface science of metal oxides, and the literature on rutile (1 1 0), (1 0 0), (0 0 1), and anatase surfaces is reviewed. This paper starts with a summary of the wide variety of technical fields where TiO2 is of importance. The bulk structure and bulk defects (as far as relevant to the surface properties) are briefly reviewed. Rules to predict stable oxide surfaces are exemplified on rutile (1 1 0). The surface structure of rutile (1 1 0) is discussed in some detail. Theoretically predicted and experimentally determined relaxations of surface geometries are compared, and defects (step edge orientations, point and line defects, impurities, surface manifestations of crystallographic shear planes—CSPs) are discussed, as well as the image contrast in scanning tunneling microscopy (STM). The controversy about the correct model for the (1×2) reconstruction appears to be settled. Different surface preparation methods, such as reoxidation of reduced crystals, can cause a drastic effect on surface geometries and morphology, and recommendations for preparing different TiO2(1 1 0) surfaces are given. The structure of the TiO2(1 0 0)-(1×1) surface is discussed and the proposed models for the (1×3) reconstruction are critically reviewed. Very recent results on anatase (1 0 0) and (1 0 1) surfaces are included.