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Photocatalytic inactivation of influenza virus by titanium dioxide thin film
Abstract
Titanium dioxide (TiO(2)) under ultraviolet (UV) light produces a strong oxidative effect and may therefore be used as a photocatalytic disinfectant. Although many studies on the photocatalytic inactivation of bacteria have been reported, few studies have addressed virus inactivation. In the present study, we demonstrated the inactivation of influenza virus through TiO(2) photocatalysis using TiO(2) nanoparticles immobilized on a glass plate. The influences of the UV intensity, UV irradiation time and bovine serum albumin (BSA) concentration in the viral suspensions on the inactivation kinetics were investigated. Additionally, we also determined whether the International Organization for Standardization (ISO) methodology for the evaluation of antibacterial activity of TiO(2) photocatalysis could be applied to the evaluation of antiviral activity. The viral titers were dramatically reduced by the photocatalytic reaction. Even with a low intensity of UV-A (0.01 mW cm(-2)), a viral reduction of approximately 4-log(10) was observed within a short irradiation time. The viral inactivation kinetics were associated with the exposure time, the UV intensity and the BSA concentration in virus suspensions. These results show that TiO(2) photocatalysis could be used to inactivate the influenza virus. Furthermore, a minor modification of the ISO test method for anti-bacterial effects of TiO(2) photocatalysis could be useful for the evaluation of antiviral activity.
... Although the detailed mechanisms underlying the function of these nanoparticles are not well-studied, the generation of ROS could be the main mechanism responsible for their virucidal effects. Recently, photocatalysts have been studied for their virucidal effects, such as those against SARS-CoV-2 [18], bovine coronavirus [19], influenza virus [20], tobacco mosaic viruses [21], phages [22], human adenovirus [8], human hepatitis B viruses [23], herpes simplex virus [13], as well as prions [24,25]. Viral inactivation using TiO 2 was dependent on the UVA light intensity and exposure time [20]. ...
... Recently, photocatalysts have been studied for their virucidal effects, such as those against SARS-CoV-2 [18], bovine coronavirus [19], influenza virus [20], tobacco mosaic viruses [21], phages [22], human adenovirus [8], human hepatitis B viruses [23], herpes simplex virus [13], as well as prions [24,25]. Viral inactivation using TiO 2 was dependent on the UVA light intensity and exposure time [20]. Inactivation of the virus in suspension was as efficient as that on a TiO 2 -coated glass slide. ...
... Inactivation of the virus in suspension was as efficient as that on a TiO 2 -coated glass slide. Nakano et al. [20] also reported that viral proteins were primarily attacked during photocatalysis. After the destruction of the outer viral protein, the viral RNA was targeted. ...
Ag, Cu, Zn, Ti, and Au nanoparticles show enhanced photocatalytic properties. Efficient indoor disinfection strategies are imperative to manage the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Virucidal agents, such as ethanol, sodium hypochlorite, 222-nm UV light, and electrolyzed water inactivate SARS-CoV-2 in indoor environments. Tungsten trioxide (WO3) photocatalyst and visible light disinfect abiotic surfaces against SARS-CoV-2. The titanium dioxide (TiO2)/UV system inactivates SARS-CoV-2 in aerosols and on deliberately contaminated TiO2-coated glass slide surfaces in photocatalytic chambers, wherein 405-nm UV light treatment for 20 min sterilizes the environment and generates reactive oxygen species (ROS) that inactivate the virus by targeting S and envelope proteins and viral RNA. Mesoscopic calcium bicarbonate solution (CAC-717) inactivates pathogens, such as prions, influenza virus, SARS-CoV-2, and noroviruses, in fluids; it presumably acts similarly on human and animal skin. The molecular complexity of cementitious materials promotes the photocatalysis of microorganisms. In combination, the two methods can reduce the pathogen load in the environment. As photocatalysts and CAC-717 are potent disinfectants for prions, disinfectants against prionoids could be developed by combining photocatalysis, gas plasma methodology, and CAC-717 treatment, especially for surgical devices and instruments.
... The semiconductor photocatalyst that is used in all commercial photocatalytic products, such as self-cleaning glass [7], plastics [8], fabrics [9], tiles [10] and paints [11], is titanium dioxide, TiO 2 . Its popularity lies in the fact that it is inexpensive, chemically inert, biologically non-toxic and very effective as a photocatalyst; not surprisingly, there have been many reports of its use in the photocatalysed destruction of viruses, such as the influenza A [12], herpes simplex [13], norovirus [14], hepatitis B [15] and the SARS-CoV-2 viruses [16][17][18][19]. ...
... Finally, it is useful to compare and contrast the photocatalytic virus inactivation rates reported here with those reported in the literature for other photocatalytic films, i.e. dry TiO 2 powder, colloid or sol-gel coatings on an inert support substrate, using similar viruses. Thus, Table 1 lists key details of these films, including average inactivation rate values and light sources, alongside the results reported here [12,16,17,61,62]. A brief inspection of the values of Δlog[virus]/Δt reported for SARS2 and IAV inactivation in Table 1, indicate that the 30 wt% TiO 2 /LDPE film is more effective than the other cited photocatalytic films. ...
... Reported TiO 2 -based photocatalytic inactivation rates [12,16,17,27,61,62]. ...
A thin, 30 μm, flexible, robust low-density polyethylene, LDPE, film, loaded with 30 wt% P25 TiO2, is extruded and subsequently rendered highly active photocatalytically by exposing it to UVA (352 nm, 1.5 mW cm⁻²) for 144 h. The film was tested for anti-viral activity using four different viruses, namely, two strains of influenza A virus (IAV), WSN, and a recombinant PR8, encephalomyocarditis virus (EMCV), and SARS-CoV-2 (SARS2). The film was irradiated with either UVA radiation (352 nm, 1.5 mW cm⁻²; although only 0.25 mW cm⁻² for SARS2) or with light from a cool white fluorescent lamp (UVA irradiance: 365 nm, 0.047 mW cm⁻²). In all cases the films exhibited an average virus inactivation rate of >1.5log/h. In the case of SARS2, the rates were > 2log/h, with the rate determined using a dedicated, low intensity UVA source (0.25 mW cm⁻²) only 1.3 x's faster than that for a cool white lamp (UVA irradiance = 0.047 mW cm⁻²), which suggests that SARS2 is particularly prone to photocatalytic inactivation even under low UV irradiation conditions, such as found in a room lit with just white fluorescent tubes. This is the first example of a flexible, very thin, photocatalytic plastic film, produced by a scalable process (extrusion), for virus inactivation. The potential of such a film for use as a disposable, self-sterilising thin plastic material alternative to the common, non-photocatalytic, inert equivalent used currently for curtains, aprons and table coverings in healthcare is discussed briefly.
... For example, Ito et al. 10 reported the inactivation of SARS-CoV-2 by cerium molybdates nanoparticles. Among these various solid-state antibacterial and antiviral materials, titanium dioxide (TiO 2 )-based photocatalysts are promising because of their non-toxic, economical (abundant), chemically and/or thermally stable properties 11-13 , and their antiviral effect can be continuously maintained by illuminating ultraviolet (UV) light [14][15][16] . Photogenerated holes in the valence band of TiO 2 have strong oxidation power for decomposing organic molecules; thus, viral components such as surface proteins can be oxidised under UV irradiation, resulting in virus inactivation. ...
... Inactivation of SARS-CoV-2. The photocatalytic antiviral activity of Cu x O/TiO 2 against SARS-CoV-2 virus was evaluated by the method reported in our previous study 15 . Figure 2a shows the inactivation properties of the SARS-CoV-2 virus of wild-type strain under dark and visible light irradiation conditions. ...
... x O/TiO 2 inactivation of SARS-CoV-2 virus. The photocatalytic antiviral activity of Cu x O/TiO 2 against SARS-CoV-2 virus was determined according to ISO 18071:2016 (Fine Ceramics [Advanced Ceramics, Advanced Technical Ceramics]-Determination of antiviral activity of semiconducting photocatalytic materials under indoor lighting environment-Test method using bacteriophage Q-beta) and JIS R 1756 with minor modification from our previous study15 . All experiments were performed in a light-tight box to prevent any influence of indoor light and sunlight. ...
Photocatalysts are promising materials for solid-state antiviral coatings to protect against the spread of pandemic coronavirus disease (COVID-19). This paper reports that copper oxide nanoclusters grafted with titanium dioxide (Cu x O/TiO 2 ) inactivated the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, including its Delta variant, even under dark condition, and further inactivated it under illumination with a white fluorescent bulb. To investigate its inactivation mechanism, the denaturation of spike proteins of SARS-CoV-2 was examined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked immunosorbent assay (ELISA). In addition to spike proteins, fragmentation of ribonucleic acids in SARS-CoV-2 was investigated by real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR). As a result, both spike proteins and RNAs in the SARS-CoV-2 virus were damaged by the Cu x O/TiO 2 photocatalyst even under dark condition and were further damaged under white fluorescent bulb illumination. Based on the present antiviral mechanism, the Cu x O/TiO 2 photocatalyst will be effective in inactivating other potential mutant strains of SARS-CoV-2. The Cu x O/TiO 2 photocatalyst can thus be used to reduce the infectious risk of COVID-19 in an indoor environment, where light illumination is turned on during the day and off during the night.
... Cotton is the most used textile substrate for modification due to the extended surface of cotton fibers resulting in better adhesion of modifiers. acrylamide gel electrophoresis (SDS-PAGE) was used to confirm the degradation of viral proteins [56]. Destruction of virus structures during photocatalytic treatment was also confirmed by the polymer chain reaction (PCR) technique followed by electrophoresis using agarose gel [54]. ...
... As shown in Figure 4a, the detection limit of the PCR technique for this system was achieved after this time. Based on these data and the results of previous studies [56,73], it can be concluded that nanocrystalline TiO 2 in the composition of photoactive material decomposes virus particles under irradiation with UV-A light, with the destruction of the lipid bilayer of the envelope, protein content, and genetic material of the virus ( Figure 5). Long-term irradiation resulted in the decomposition of RNA molecules to fragments, with the number of nucleotides lower than 100 not to be detected using the PCR technique because the primers used for amplification flanked a sequence of ca. 100 nucleotides. ...
Chemical modification of cotton-rich fabrics with TiO2 nanoparticles results in photoactive self-cleaning textiles, which can provide, under UV or solar radiation, complete oxidation of low-molecular compounds, degradation of supramolecular structures, and inactivation of microorganisms due to the photocatalytic effect. In this paper, we describe, based on the example of influenza A (H1N1) virus, a photoinduced antiviral effect of cotton fabric functionalized with nanocrystalline TiO2. Fast inactivation of influenza virus occurs on the irradiated surface of photoactive fabric due to adsorption and photocatalytic degradation. The TiO2 component in the prepared fabric increases the adsorption effect compared to initial cotton due to a high specific area of TiO2 nanocrystallites. Long-term irradiation leads to destruction of all virion structures to the point of RNA molecules. In contrast to pristine cotton, no virus RNA is detected using the polymerase chain reaction (PCR) technique after long-term irradiation of photoactive fabric. The results of this study underline the potential of photoactive self-cleaning fabrics for application in air purification systems and personal protective clothes to provide permanent protection of people against harmful chemical and biological pollutants.
... This mechanism usually occurs with near-infrared radiation adsorption, which is an important factor for antiviral activity of such metal NP [21]. Ag NP and Ti NP interact and destroy the virus envelope [22,23]; Ag NP, Au NP, and Cu NP destroy the viral protein of the virus by physical damage [24][25][26]; and Ti NP binds and destroys viral capsid protein through a photocatalytic effect [27,28]. In the case of the metal oxide form (e.g., TiO2), with UV radiation, surface proteins of the viruses are oxidized through contact with the surface of TiO2 and/or ROS are generated, which are the dominant factors of their antiviral mechanism, leading to degradation of the envelop/capsid, nucleic acid leakage, and virus degradation/virus inactivation [29,30]. ...
... Lanes 2-19 were the treated PET film samples with 10-60 repeats, which showed the lack of virus activity at 15, 30, and 60 min of virus incubation (Figure 7b), indicating that the metal NP on the surface of the PET films prevented coronavirus growth. This was probably due to their binding with the viral envelop protein of the viruses [22,23], photocatalytic oxidation [27,28], and physical damage [24][25][26] that destroyed the viral envelop protein of the viruses [19,20,41]. The PET treated with Zn (30 repeats) was selected to prepare a face shield as a representative application for the COVID-19 pandemic era because the Zn-PET (30 repeats) sample had a high transparency similar to an untreated PET sample, which would have no effect on visual performance of the films. ...
The nano-metal-treated PET films with anti-virus and anti-fogging ability were developed using sparking nano-metal particles of Ag, Zn, and Ti wires on polyethylene terephthalate (PET) films. Ag nanoparticles were detected on the PET surface, while a continuous aggregate morphology was observed with Zn and Ti sparking. The color of the Ag-PET films changed to brown with increasing repeat sparking times, but not with the Zn-PET and Ti-PET films. The water contact angle of the nano-metal-treated PET films decreased with increasing repeat sparking times. The RT-PCR anti-virus test confirmed the high anti-virus efficiency of the nano-metal-treated PET films due to the fine particle distribution, high polarity, and binding of the nano-metal ions to the coronavirus, which was destroyed by heat after UV irradiation. A highly transparent, anti-fogging, and anti-virus face shield was prepared using the Zn-PET film. Sparking was an effective technique to prepare the alternative anti-virus and anti-fogging films for medical biomaterial applications because of their low cost, convenience, and fast processing.
... Nevertheless, there is no ban on the use of TiO 2 nanoparticles in the food industry [202]. There is ample evidence in the literature showing the effects of TiO 2 NPs on such viruses as human norovirus [161], human influenza virus (A/PR8/H1N1) [162], and herpes simplex virus [163]. However, TiO 2 is activated only by UVA photons (λ < 387 nm), which may limit its use in rooms with dominant visible-range lighting. ...
... However, TiO 2 is activated only by UVA photons (λ < 387 nm), which may limit its use in rooms with dominant visible-range lighting. Nakano et al. [162] confirmed that TiO 2 -coated glass exhibited virucidal activity. In turn, the reduction in influenza virus titers below the limit of detection at typical indoor lighting intensity (~0.01 mW·cm −2 ) required an almost 24 h exposure. ...
Metal nanoparticles (NPs) are increasingly being used in many areas, e.g., industry, pharmacy, and biomedical engineering. NPs can be obtained through chemical and biological synthesis or using physical methods. AgNPs, AuNPs, CuNPs, FeNPs, MgNPs, SnO2NPs, TiO2NPs, and ZnONPs are the most commonly synthesized metal nanoparticles. Many of them have anti-microbial properties and documented activity supported by many tests against some species of pathogenic bacteria, viruses, and fungi. AgNPs, which are used for the production of commercial self-sterilizing packages, are one of the best-explored nanoparticles. Moreover, the EFSA has approved the use of small doses of silver nanoparticles (0.05 mg Ag·kg−1) to food products. Recent studies have shown that metal NPs can be used for the production of coatings to prevent the spread of the SARS-CoV-2 virus, which has caused the global pandemic. Some nanoparticles (e.g., ZnONPs and MgONPs) have the Generally Recognized As Safe (GRAS) status, i.e., they are considered safe for consumption and can be used for the production of edible coatings, protecting food against spoilage. Promising results have been obtained in research on the use of more than one type of nanometals, which prevents the development of pathogen resistance through various mechanisms of inactivation thereof.
... Under UV light, the TiO 2 thin film may considerably eradicate the influenza virus in the air by breaking down viral proteins (Nakano et al. 2012). The TiO 2 photocatalysts (λ > 410 nm) loaded with Fe, Mg, and Mn were tested against influenza virus H1N1 under visible-light irradiation (Choi and Cho 2018). ...
A novel ZnO-MoO3-ZnMoO3@graphene GZM composite catalyst prepared by microwave hydrothermal process for personal
protective equipment textiles (PPE) is presented in this study. The results indicated that the GZM with defect vacancy sites
of two types as observed by EPR showed signifcantly superior inactivation of the E. coli bacteria compared to GZM without
the lower defect vacancy sites and concomitant lower electron densities. Photocatalytic activated oxidation by the GZM
composites coatings was observed to proceed in acceptable times as well as the bacterial inactivation (log bact. C/Co> 107
within 3 h). Defect sites in the GZM seem to be important leading to the bacterial inactivation process. DFT calculations
on the GZM with and without catalyst defect sites were carried out. The electron densities were estimated by the Fourier
mapping. The results found in this study showed the potential of GZM-PPE for practical applications
... Under UV light, the TiO 2 thin film may considerably eradicate the influenza virus in the air by breaking down viral proteins (Nakano et al. 2012). The TiO 2 photocatalysts (λ > 410 nm) loaded with Fe, Mg, and Mn were tested against influenza virus H1N1 under visible-light irradiation (Choi and Cho 2018). ...
A novel ZnO-MoO3-ZnMoO3@graphene GZM composite catalyst prepared by microwave hydrothermal process for personal
protective equipment textiles (PPE) is presented in this study. The results indicated that the GZM with defect vacancy sites
of two types as observed by EPR showed signifcantly superior inactivation of the E. coli bacteria compared to GZM without
the lower defect vacancy sites and concomitant lower electron densities. Photocatalytic activated oxidation by the GZM
composites coatings was observed to proceed in acceptable times as well as the bacterial inactivation (log bact. C/Co> 107
within 3 h). Defect sites in the GZM seem to be important leading to the bacterial inactivation process. DFT calculations
on the GZM with and without catalyst defect sites were carried out. The electron densities were estimated by the Fourier
mapping. The results found in this study showed the potential of GZM-PPE for practical applications.
... In particular, the photocatalytic inactivation of viruses has been the subject of intense research due to the increasing global threat of viral outbreaks [11][12][13][14][15]. ...
It is well known that viruses cannot replicate on their own but only inside the cells of target tissues in the organism, resulting in the destruction of the cells or, in some cases, their transformation into cancer cells. While viruses have relatively low resistance in the environment, their ability to survive longer is based on environmental conditions and the type of substrate on which they are deposited. Recently, the potential for safe and efficient viral inactivation by photocatalysis has garnered increasing attention. In this study, the Phenyl carbon nitride/TiO2 heterojunction system, a hybrid organic–inorganic photocatalyst, was utilized to investigate its effectiveness in degrading the flu virus (H1N1). The system was activated by a white-LED lamp, and the process was tested on MDCK cells infected with the flu virus. The results of the study demonstrate the hybrid photocatalyst’s ability to cause the virus to degrade, highlighting its effectiveness for safe and efficient viral inactivation in the visible light range. Additionally, the study underscores the advantages of using this hybrid photocatalyst over traditional inorganic photocatalysts, which typically only work in the ultraviolet range.
... To be used as an antiviral agent and can help prevent the spread of viruses [138,139] Titanium dioxide nanoparticles To make self-cleaning surfaces, which can help prevent the spread of viruses and bacteria [9,[140][141][142][143] Hydrogels To be used in masks and other protective equipment to increase filtration efficiency [67,144,145] Metal-organic frameworks To be used in diagnostic tests to detect the presence of viruses and bacteria [43,146] Magnetic nanoparticles To be used in diagnostic tests and as a drug delivery system [147][148][149][150][151] ...
In December 2019, an outbreak of unknown pneumonia emerged in Wuhan City, Hubei Province, China. It was later identified as the SARS-CoV-2 virus and has since infected over 9 million people in more than 213 countries worldwide. Massive papers on the topic of SARS-CoV-2 that have already been published are necessary to be analyzed and discussed. This paper used the combination of systematic literature network analysis and content analysis to develop a comprehensive discussion related to the use of nanotechnology and materials in environmental and human protection. Its is shown that various efforts have been made to control the transmission of this pandemic. Nanotechnology plays a crucial role in modern vaccine design, as nanomaterials are essential tools for antigen delivery, adjuvants, and mimics of viral structures. In addition, nanomaterials and nanotechnology also reported a crucial role in environmental protection for defence and treating the pandemic. To eradicate pandemics now and in the future, successful treatments must enable rapid discovery, scalable manufacturing, and global distribution. In this review, we discuss the current approaches to COVID-19 development and highlight the critical role of nanotechnology and nanomaterials in combating the virus in the human body and the environment.
... Multiple groups have showed photocatalytic virus inactivation activity of TiO2 coating materials. The TiO2 showed virucidal efficacy against human norovirus and a few norovirus surrogates (murine norovirus, bacteriophage MS2, and feline calicivirus) [147]), human influenza A (A/PR8/H1N1) [148], and herpes simplex virus 1 (HSV-1) [149]. ...
The development of antiviral treatment and anticancer theragnostic agents in recent decades has been associated with nanotechnologies, and primarily with inorganic nanoparticles (INPs) of metal and metal oxides. The large specific surface area and its high activity make it easy to functionalize INPs with various coatings (to increase their stability and reduce toxicity), specific agents (allowing retention of INPs in the affected organ or tissue), and drug molecules (for antitumor and antiviral therapy). The ability of magnetic nanoparticles (MNPs) of iron oxides and ferrites to enhance proton relaxation in specific tissues and serve as magnetic resonance imaging contrast agents is one of the most promising applications of nanomedicine. Activation of MNPs during hyperthermia by an external alternating magnetic field is a promising method for targeted cancer therapy. As therapeutic tools, INPs are promising carriers for targeted delivery of pharmaceuticals (either anticancer or antiviral) via magnetic drug targeting (in case of MNPs), passive or active (by attaching high affinity ligands) targeting. The plasmonic properties of Au nanoparticles (NPs) and their application for plasmonic photothermal and photodynamic therapies have been extensively explored recently in tumor treatment. The Ag NPs alone and in combination with antiviral medicines reveal new possibilities in antiviral therapy. The prospects and possibilities of INPs in relation to magnetic hyperthermia, plasmonic photothermal and photodynamic therapies, magnetic resonance imaging, targeted delivery in the framework of antitumor theragnostic and antiviral therapy are presented in this review.
... Long et al. [6] used nano-TiO 2 as an antibacterial agent to produce antibacterial melamineimpregnated decorative paper and found that it had good inhibitory effects on both Staphylococcus aureus and Escherichia coli. However, nano-TiO 2 is activated by only UVA photons (k \ 387 nm), restricting its utility indoor areas with primarily visible-region lighting [7,8]. Liu [9] found that melamine resin-impregnated paper with added inorganic silver ions had an excellent antibacterial effect. ...
Melamine-impregnated paper is made by impregnating paper with melamine-formaldehyde resin and can be hot-pressed and laminated onto the surface of wood boards. If the paper has antibacterial activity, it can prevent the spread of indoor bacteria, but impregnated paper with a long-term antibacterial effect has not been proposed. Metal–organic frameworks (MOFs) have been studied as a reservoir of metal ions. In this study, a silver-metal organic framework (Ag-BTC) was synthesized by a green and scalable method at 60 °C (A-60) and at room temperature (A-25). The structure and thermal stability of the Ag-BTC were characterized. Compared with A-25, the structure and particle size distribution of A-60 were more regular and uniform. The thermal stability and the compatibility of Ag-BTC and MF resin were suitable for hot-pressing process. Ag-BTC in the cured impregnated paper exhibited the sustained-release performance of Ag⁺. The antibacterial ratio of decorated blockboards with 0.10 wt% A-25 to E. coli and S. aureus exceeded 99.99%, reaching Level I antibacterial grade. Compared with A-60-decorated blockboards, the better antibacterial activity of A-25-decorated blockboards was due to the release of more Ag⁺. This study provides new ideas for the design of antibacterial melamine-impregnated paper.
Graphical abstract
... TiO 2 thin films have been used in a wide application range, as photocatalyst, gas sensing element, optical coatings, in water and air purification applications, corrosion barrier, in solar cells in electrical devices such as varistors and self-cleaning surfaces [9e12]. Another interesting point is the inactivation of bacteria and virus provided by TiO 2 photocatalysis effects, under UV light irradiation [13]. ...
TiO2 thin films obtained through Reactive Magnetron Sputtering (RMS) have been extensively studied in the last decades for several applications as photocatalyst and self-cleaning coats. However, reactive deposition through MS onto large area substrates can be troublesome due to inhomogeneous films thickness and poor adhesion between film and substrate. This paper investigates the deposition of TiO2 thin films on glass substrates through a two steps method, namely: 1- deposition of nanometer thickness Ti metallic films on glass substrate, through triode magnetron sputtering; 2- oxidation of the Ti film through thermal treatment in atmospheric air, to obtain stoichiometric TiO2 layers. The film oxidation was performed concomitantly to the glass thermal treatment carried out at 650 °C. Analysis through XPS depth profile indicates the formation of a chemically graded high entropy interlayer due to the interdiffusion of atoms from substrate to film and vice-versa, during the thermal treatment. The high entropy interface layer contributes to reduces the mismatch between the film and the substrate lattice, resulting in an improvement of film adhesion. The badgap analysis through Tauc method show two energy values, namely 3.2 eV and 2.9 eV, which can be attributed to TiO2-rutile layer and the high entropy zone at interface, composed by [Ca-Na-Si-Ti]Ox oxides. The wettability results show that the contact angle may be as low as 10° between a deionized water drop and the rutile-TiO2 surface, after activation with UV light irradiation, which is characteristic of super-hydrophilic surface.
... UV light removes carbon-containing molecules via two mechanisms: direct decomposition (photolysis) and titanium dioxide-mediated decomposition (photocatalysis) [19,[82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97]. The former is sub-categorized into photochemical and photophysical decomposition. ...
Ultraviolet (UV) photofunctionalization counteracts the biological aging of titanium to increase the bioactivity and osseointegration of titanium implants. However, UV photofunctionalization currently requires long treatment times of between 12 min and 48 h, precluding routine clinical use. Here, we tested the ability of a novel, xenon excimer lamp emitting 172 nm vacuum UV (VUV) to decompose organic molecules coated on titanium as a surrogate of photofunctionalization. Methylene blue as a model organic molecule was coated on grade 4 commercially pure titanium and treated with four UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed 57% of methylene blue compared with 2%, 36%, and 42% for UVC, HUVC, and PUV, respectively. UV dose-dependency testing revealed maximal methylene blue decomposition with VUV within one minute. Equivalent decomposition was observed on grade 5 titanium alloy specimens, and placing titanium specimens in quartz ampoules did not compromise efficacy. Methylene blue was decomposed even on polymethyl methacrylate acrylic specimens at 20–25% lower efficiency than on titanium specimens, indicating a relatively small contribution of titanium dioxide-mediated photocatalytic decomposition to the total decomposition. Load-testing revealed that VUV maintained high efficacy of methylene blue decomposition regardless of the coating density, whereas other UV light sources showed low efficacy with thin coatings and plateauing efficacy with thicker coatings. This study provides foundational data on rapid and efficient VUV-mediated organic decomposition on titanium. In synergy with quartz ampoules used as containers, VUV has the potential to overcome current technical challenges hampering the clinical application of UV photofunctionalization.
... Virus elimination using photocatalysis, which is representative of the AOP, has been studied extensively, and the photocatalytic treatment of bacteriophages has been established by the International Standard Organization (ISO) [76][77][78]. Reports on the photocatalytic elimination of SARS-CoV-2 are also rapidly increasing [53][54][55][56][57][58]; however, the inactivation of viruses is impossible unless bioaerosols are captured on the photocatalytic surface. Although several photocatalytic air purifiers are commercially available, most are photocatalyst-coated filter. ...
We developed a high-speed filterless airflow multistage photocatalytic elbow aerosol removal system for the treatment of bioaerosols such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Human-generated bioaerosols that diffuse into indoor spaces are 1–10 μm in size, and their selective and rapid treatment can reduce the risk of SARS-CoV-2 infection. A high-speed airflow is necessary to treat large volumes of indoor air over a short period. The proposed system can be used to eliminate viruses in aerosols by forcibly depositing aerosols in a high-speed airflow onto a photocatalyst placed inside the system through inertial force and turbulent diffusion. Because the main component of the deposited bioaerosol is water, it evaporates after colliding with the photocatalyst, and the nonvolatile virus remains on the photocatalytic channel wall. The residual virus on the photocatalytic channel wall is mineralized via photocatalytic oxidation with UVA-LED irradiation in the channel. When this system was operated in a 4.5 m³ aerosol chamber, over 99.8% aerosols in the size range of 1–10 μm were removed within 15 min. The system continued delivering such performance with the continuous introduction of aerosols. Because this system exhibits excellent aerosol removal ability at a flow velocity of 5 m/s or higher, it is more suitable than other reactive air purification systems for treating large-volume spaces.
... This led to a significant decrease in the spread of coronaviruses during the initial outbreak of COVID-19 in these regions. Titanium dioxide nanoparticles are also good anti-viral agents used to inhibit the viral activity of influenza viruses (H3N2) [126]. ...
COVID-19 is an epizootic and life-threatening outbreak affecting millions of people globally. Coronavirus variants have emerged in different locations since their origin. Silver and its compounds, including silver nanoparticles (AgNPs), have been used in the medical field for a long period, especially in surgical treatments. The anti-microbial and anti-viral properties of silver are well documented. These properties depend on the size of the particles, concentration, precursor, method of preparation, and the presence of other benefiting compounds. Several experiments were conducted by researchers worldwide to prove the anti-bacterial and anti-viral properties of silver (Ag) and AgNPs, emphasizing that silver can be introduced to multiple organs in the human body and exhibit the expected antiviral characteristics. In this review article, use of silver nanoparticles to
fight the COVID-19 pandemic according with the current information is discussed. The mechanisms involving antiviral activity and toxicity are discussed in detail. This article concludes that strong binding of AgNPs with SARS-CoV-2 virus prevents binding with the host cell, leading to the death of the virus. However, increased cytotoxic effect of the silver compounds at higher concentrations is a matter of concern.
... Using environmentally friendly and cheap inorganic materials alongside sunlight as a natural light source represents a considerable offer for this application of aPDT. One example of such inorganic materials is TiO2, which in the presence of sunlight can induce photo-catalysis for aPDT of viruses [126][127][128]. ...
The deadly viruses, which are spreading worldwide at an alarming rate, are a major challenge for the life sciences. More efficient and cost-effective methods with fewer side effects can provide a good alternative to traditional drug-based methods. Currently, physical phenomena such as light in the form of photodynamic action are increasingly being used to inactivate viruses. Photodynamic inactivation (PDI) uses a photosensitizer (PS), light, and oxygen to generate reactive oxygen species (ROS) to inactivate microorganisms. This article reviews the use of existing PSs, as one of the essential anti-viral agents, and introduces new materials and strategies combined with PDI. Physiochemical properties of PSs and their role in interaction with virus components are discussed. Furthermore, the effectiveness of optical sensitizers with radiation methods to inactivate viruses is highlighted.
... Conversely, solid-state antiviral metal compounds may be helpful because of their porous translucency, strength and feasibility for use as coating weak light materials. Among various antiviral materials, photocatalysts based TiO 2 are promising (10)(11)(12)(13), because the antiviral effect is functioned under ultraviolet (UV) light irradiation (14,15). ...
Viral infections mainly occur in indoor environments, it is suggested that visible light-sensitive antiviral photocatalyst is highly desired. Here we developed a photocatalysis system based on zinc hydroxide (Zn(OH) 2 ) to efficiently generate antiviral radicals on mask surface under weak visible light. The weak visible light induced the Zn(OH) 2 photocatalysis and completed the inactivation of H 1 N 1 virus for short time. In addition, the inactivating efficiency was improved greatly by adding a natural washing agent layer. Our system could inactivate H 1 N 1 influenza virus completely rapidly under the irradiation of weak visible light. The discovery will open up a new research field, and enrich and promote the development of photocatalysis theory and practice.
... Conversely, solid-state antiviral metal compounds may be helpful because of their porous translucency, strength and feasibility for use as coating weak light materials. Among various antiviral materials, photocatalysts based TiO 2 are promising (10)(11)(12)(13), because the antiviral effect is functioned under ultraviolet (UV) light irradiation (14,15). Photos generate holes in the valence band of TiO 2 and they exhibit strong oxidation power for decomposing organic molecules (16-18), thus virus components such as surface shell proteins are oxidized under UV irradiation, resulting in virus disinfection (11). ...
Viral infections mainly occur in indoor environments, it is suggested that visible light-sensitive antiviral photocatalyst is highly desired. Here we developed a photocatalysis system based on zinc hydroxide (Zn(OH) 2 ) to efficiently generate antiviral radicals on mask surface under weak visible light. The weak visible light induced the Zn(OH) 2 photocatalysis and completed the inactivation of H 1 N 1 virus for short time. In addition, the inactivating efficiency was improved greatly by adding a natural washing agent layer. Our system could inactivate H 1 N 1 influenza virus completely rapidly under the irradiation of weak visible light. The discovery will open up a new research field, and enrich and promote the development of photocatalysis theory and practice.
... 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.
... In addition, when ROS is formed as a result of the excitation created by UV light exposure, the photocatalytic action occurs [50]. Nakano et al. [52], reported on the photochemical activity of titanium dioxide NPs (TiO 2 ) to inactivate influenza virus. As previously stated, the formation of ROS can result in antiviral action against coronaviruses; consequently, NPs having photo-catalytic characteristics could be another route to coronavirus inactivation. ...
The COVID-19 is a pandemic caused by the SARS-CoV-2 virus, has instigated major health problems and prompted WHO to proclaim a worldwide medical emergency. The knowledge of SARS-CoV-2 fundamental structure, aetiology, its entrance mechanism, membrane hijacking and immune response against the virus, are important parameters to develop effective vaccines and medicines. Liquid crystals integrated nano-techniques and various nanoformulations were applied to tackle the severity of the virus. It was reported that nanoformulations have helped to enhance the effectiveness of presently accessible antiviral medicines or to elicit a fast immunological response against COVID-19 virus. Applications of liquid crystals, nanostructures, nanoformulations and nanotechnology in diagnosis, prevention, treatment and tailored vaccine administration against COVID-19 which will help in establishing the framework for a successful pandemic combat are reviewed. This review also focuses on limitations associated with liquid crystal-nanotechnology based systems and suggests the possible ways to address these limitations. Also, topical advancements in the ground of liquid crystals and nanostructures established diagnostics (nanosensor/biosensor) are discussed in detail.
... Nano-materials possess interesting physical (e.g., size, shape, specific surface area, aspect ratio, aggregation state size distribution surface morphology/topography, crystallinity, and solubility) and chemical properties (such as molecular structure, purity, enormous reactive sites, catalytic properties, etc.). Such properties have facilitated the extensive application of nano-materials to control disasters in wide areas such as environmental, energy, and health sectors [12][13][14]. Therefore, this chapter aims to provide an overview of the potential role of nanotechnology in disaster management by highlighting roles of nano-materials in major areas like agriculture, energy production, health sector, pollution control (water, air, light, etc.), corrosion protection, and prevention as well as therapy of pandemics [8,15]. ...
“The natural and man-made catastrophic events negatively influence human life by damaging the sustainability agenda of nations, shortening the supply of basic necessities to people (e.g., clean water, food, and medicines). Such disasters can also destroy human fatalities and infrastructure massively. The past three decades of research in the development of nanotechnology has resulted in the designing, fabrication, and application of diverse engineered nanomaterials. These nano-scale materials possess outstanding characteristics that differ from their bulk counterparts. These properties include tunable surface properties, high reactivity, and tailorable structures, facilitating their potential applications in prevention of different crises and disasters such as health (pandemics), energy, food (agricultural), environment. Therefore, this chapter aims to provide a brief introduction on utilization of nanotechnology to prevent such crises.”
... e pH of nourishment changes at the beginning of the corruption preparation; this move is one of the measures of product quality. Packaging with a pH pointer could be a security measure that can mean the consistency of the nourishment at the time of buying or earlier than utilization [56]. ...
Abstract
Hydrogel refers to a three-dimensional cross-linked polymeric network made of synthetic or natural polymers that can hold water in its porous structure. The inclusion of hydrophilic groups in the polymer chains, such as amino, carboxyl, and hydroxyl groups, contributes to the hydrogel’s water-holding ability. At physiological temperature and pH, these polymeric materials do not dissolve in water, but they do swell significantly in aqueous media. Hydrogel can be manufactured out of almost any water-soluble polymer, and it comes in a variety of chemical compositions and bulk physical properties. Hydrogel can also be made in a variety of ways. Hydrogel comes in a variety of physical shapes, including slabs, microparticles, nanoparticles, coatings, and films. Due to its ease of manufacture and self-application in clinical and fundamental applications, hydrogel has been widely exploited as a drug carrier. Contact lenses, artificial corneas, wound dressing, suture coating, catheters, and electrode sensors are some of the biomedical applications of hydrogels. The pigment color changes were observed from colorless to pale pink followed by dark reddish-pink. Anthocyanin was produced in large quantities and tested using a UV-visible spectrophotometer. At 450–550 nm, the largest peak (absorbance) was detected, indicating the presence of anthocyanin. The FTIR analysis of this study shows the different stretches of bonds at different peaks: 2918.309 (-C-H alkane stretch), 2812.12 (-C-H aldehyde weak intensity), 192320.37/cm (C-O bend), 21915.50, 2029.08/cm (-C=C arene group), 1906.94/cm (=C-H aromatics), 1797.78/cm (=C-H), 1707.94 (-C=O ketene), 1579.70, 1382.96 (C-H alkane strong bend), 889.18/cm (C-H aromatics plane bend), and 412.77/cm (-C-CI strong bond). The spectra of the PVA/chitosan film depict the peak’s formation: 1571.88, 1529.55, 1500.62/cm (C-H alkene strong bend), 1492.90, 1483.26, 1467.83/cm (C-H alkene strong bond), 670.48, 443.63, 412.77/cm (-O-H carboxylic acids with great intensity), 1708.93 (-C=O ketone), and 1656.0/cm (alkenyl C=C stretch strong bond).
... Nakano et al. [61] demonstrated the photocatalytic properties of TiO 2 nanoparticles by immobilizing them on glass plates and successfully inactivating the influenza virus. UVrays do not limit these excellent antibacterial and antiviral activities. ...
Design of antimicrobial tiles seems necessary to combat against contagious diseases, especially COVID-19. In addition to personal hygiene, this technology facilitates public hygiene as antimicrobial tiles can be installed at hospitals, schools, banks, offices, lobbies, railway stations, etc. This review is primarily focused on preparing antimicrobial tiles using an antimicrobial layer or coatings that fight against germs. The salient features and working mechanisms of antimicrobial tiles are highlighted. This challenge is a component of the exploratory nature of nanoarchitectonics, that also extends farther than the realm of nanotechnology. This nanoarchitectonics has been successful at the laboratory scale as antimicrobial metal nanoparticles are mainly used as additives in preparing tiles. A detailed description of various materials for developing unique antimicrobial tiles is reported here. Pure metal (Ag, Zn) nanoparticles and a mixture of nanoparticles with other inorganic materials (SiO2, TiO2, anatase, nepheline) have been predominantly used to combat microbes. The developed antimicrobial tiles have shown
excellent activity against a wide range of Gram-positive and Gram-negative bacteria. The last section discussed a hypothetical overview of utilizing the antimicrobial tiles against SARS-CoV-2. Overall, this review gives descriptive knowledge about the importance of antimicrobial tiles to create a clean and sustainable environment.
... 79,80 TiO 2 −NPs under ultraviolet (UV) light produce a strong oxidative effect and utilizing the property can be used as a photocatalytic disinfectant. 81 TiO 2 −NPs activate during the photocatalytic reaction and generate hydrogen peroxide and hydroxyl radicals, thus reducing glycosylation of the main protease of the virus. ...
The COVID-19 pandemic caused by the SARS-CoV-2, a Ribonucleic acid (RNA) virus that emerged less than two years but has caused nearly 6.1 million deaths to date. Recently developed variants of the SARS-CoV-2 virus have been shown to be more potent and expanded at a faster rate. Till now there is no specific and effective treatment for SARS-CoV-2 in terms of reliable and sustainable recovery. Precaution, prevention, and vaccinations are the only ways to keep the pandemic situation under control. Medical and scientific professionals are now focusing on the repurposing of previous technology and trying to develop more fruitful methodologies to detect the presence of viruses, treat the patients, precautionary items, and vaccine developments. Nanomedicine or nano-based platforms can play a crucial role in these fronts. Researchers are working on many effective approaches by nanosized particles to combat SARS-CoV-2. The role of a nano-based platform to combat SARS- CoV-2 is extremely diverse (i.e., mark to personal protective suit, rapid diagnostic tool to targeted treatment, and vaccine developments). Although there are many theoretical possibilities of a nano- based platform to combat SARS-CoV-2, till now there is an inadequate number of research targeting SARS-CoV-2 to explore such scenarios. This unique mini-review aims to compile and elaborate on the recent advances of nano-based approaches from prevention, diagnostics, treatment to vaccine developments against SARS-CoV-2 and associated challenges.
... Nakano et al. [61] demonstrated the photocatalytic properties of TiO 2 nanoparticles by immobilizing them on glass plates and successfully inactivating the influenza virus. UVrays do not limit these excellent antibacterial and antiviral activities. ...
Design of antimicrobial tiles seems necessary to combat against contagious diseases, especially COVID-19. In addition to personal hygiene, this technology facilitates public hygiene as antimicrobial tiles can be installed at hospitals, schools, banks, offices, lobbies, railway stations, etc. This review is primarily focused on preparing antimicrobial tiles using an antimicrobial layer or coatings that fight against germs. The salient features and working mechanisms of antimicrobial tiles are highlighted. This challenge is a component of the exploratory nature of nanoarchitectonics, that also extends farther than the realm of nanotechnology. This nanoarchitectonics has been successful at the laboratory scale as antimicrobial metal nanoparticles are mainly used as additives in preparing tiles. A detailed description of various materials for developing unique antimicrobial tiles is reported here. Pure metal (Ag, Zn) nanoparticles and a mixture of nanoparticles with other inorganic materials (SiO2,, TiO2, anatase, nepheline) have been predominantly used to combat microbes. The developed antimicrobial tiles have shown excellent activity against a wide range of Gram-positive and Gram-negative bacteria. The last section discussed a hypothetical overview of utilizing the antimicrobial tiles against SARS-CoV-2. Overall, this review gives descriptive knowledge about the importance of antimicrobial tiles to create a clean and sustainable environment.
Graphical Abstract
... Once exposed to UV, these materials can produce ROS and develop antiviral efficacy [110][111][112]. Nakano et al [113]. produced a TiO 2 thin film through spin-coating. ...
The routine disinfection and sanitization of surfaces, objects, and textiles has become a time-consuming but necessary task for managing the COVID-19 pandemic. Nonetheless, the excessive use of sanitizers and disinfectants promotes the development of antibiotic-resistant microbes. Moreover, that improper disinfection could lead to more virus transfer, which leads to more viral mutations. Recently developed antiviral surface coatings can reduce the reliance on traditional disinfectants. These surfaces remain actively antimicrobial between periods of active cleaning of the surfaces, allowing a much more limited and optimized use of disinfectants. The novel nature of these surfaces has led, however, to many inconsistencies within the rapidly growing literature. Here we provide tools to guide the design and development of antimicrobial and antiviral surfaces and coatings. We describe how engineers can best choose testing options and propose new avenues for antiviral testing. After defining testing protocols, we summarize potential inorganic and organic materials able to serve as antiviral surfaces and present their antiviral mechanisms. We discuss the main limitations to their application, including issues related to toxicity, antimicrobial resistance, and environmental concerns. We propose solutions to counter these limitations and highlight how the context of specific use of an antiviral surface must guide material selection. Finally, we discuss how the use of coatings that combine multiple antimicrobial mechanisms can avoid the development of antibiotic resistance and improve the antiviral properties of these surfaces.
... Finalmente, los radicales hidroxilos se forman de la interacción de agua del ambiente y un hueco. Este principio ha inactivado al virus de la influenza, el virus de la hepatitis C, SARS-CoV-2 y bacteriófagos (Nakano et al., 2012;Syngouna et al., 2017;Khaiboullina et al., 2020;Tong et al., 2021). Incluso se ha estudiado ampliamente el fotocatalizador TiO2 para la purificación del aire por contaminantes gaseosos, incluidos compuestos orgánicos volátiles, Por ejemplo, óxidos de nitrógeno, óxidos de azufre, óxidos de cobre y óxidos de hierro (Talaiekhozani et al., 2021;Muangmora et al., 2021). ...
La fotocatálisis es una reacción química inducida por la absorción de un material sólido, o fotocatalizador. La excitación del sólido desencadena dos reacciones que conducen a la formación casi instantánea de radicales hidroxilos y aniones superóxido (llamadas especies reactivas de oxígeno; ROS). Los ROS producen daño oxidativo en diversos microorganismos incluyendo al virus SARS-CoV2, favoreciendo la desintegración de la conformación proteica de la cápside, cambios en la permeabilidad y daños de la membrana del virión que finalmente conduce a rotura del ADN, sin la oportunidad de reparación. Incluso, la reacción fotocatalítica causa la degradación oxidativa contra materiales peligrosos orgánicos y/o inorgánicos en el aire para convertirlos en sustancias no dañinas como agua o dióxido de carbono.
... The virostatic agents are accelerated in the very early stages of virus infection to reduce the RNA replication rate and their functioning is centered on the binding mechanism of surface proteins. However, virucidal agents are the agents that have the potential to deactivate the nanovirus permanently and almost completely (Rabiee et al., 2020;Zan et al., 2007;Nakano et al., 2012). Photoactive metal oxides are much potentially lethal for various viruses by disrupting proteins, genomic RNA, cell membrane etc. ...
Nanotechnology holds huge potential for the prevention of various viral outbreaks that have increased at a disquieting rate over the past decades. Metal oxide nanomaterials with oxidative capability are the effective materials that provide platforms as well as tools for the well understanding of the mechanism, its detection, and treatment of various viral diseases like measles, influenza, herpes, ebola, current COVID-19 etc. In this inclusive review, we survey various previous research articles on different notable photoactive transition metal oxides that possess enough potential to act as antiviral agents for the deactivation of harmful viruses. We investigated and highlighted the plausible photocatalytic oxidative mechanism of photoactive transition metal oxides in degrading viral coatings, genomic RNA using suitable free radical generation. The key finding of the present review article including the discovery of a vision on the suitable photocatalytic transition metal oxides that have been proven to be excellent against harmful viruses and consequently combatting deadly CoV-2 in the environment. This review intends to provide conclusive remarks and a realistic outlook on other advanced photocatalytic metal oxides as a potential solution in battling other similar upcoming pandemics.
Allergies to dogs and cats can cause enormous damage to human health and the economy. Dog and cat allergens are mainly found in dog and cat dander and are present in small particles in the air and in carpets in homes with dogs and cats. Cleaning houses and washing pets are the main methods for reducing allergens in homes; however, it is difficult to eliminate them completely. Therefore, we aimed to investigate whether a TiO2 photocatalyst could degrade dog and cat allergens. Under wet conditions, exposure to the TiO2 photocatalyst for 24 h degraded Can f1, which is a major dog allergen extracted from dog dander, by 98.3%, and Fel d1, which is a major cat allergen extracted from cat dander, by 93.6–94.4%. Furthermore, under dry conditions, the TiO2 photocatalyst degraded Can f1 and Fel d1 by 92.8% and 59.2–68.4%, respectively. The TiO2 photocatalyst abolished the binding of dog and cat allergens to human IgE by 104.6% and 108.6%, respectively. The results indicated that the TiO2 photocatalyst degraded dog and cat allergens, causing a loss in their allergenicity. Our results suggest that TiO2 photocatalysis can be useful for removing indoor pet allergens and improving the partnership between humans and pets.
Even to this date, oral drug delivery in the form of tablets, capsules, and syrups is considered as the most accepted one. However, oral delivery as a methodology requires that the active molecules and their formulations are water-soluble. Nasal drug delivery is characterized by ease of permeability through the epithelial mucosa, low enzyme activity, and a wide range of immunocompetent cells. For the transfer of drugs and active molecules through the nasal route, it is often essential to resort to nanodelivery methods, such as liposomes, microspheres, nanoemulsions, and so on. The use of nanodelivery vehicles has become more important in the modern context of viral infections, including those of the respiratory tract. Nanoformulations are developed in the form of nasal gels, sprays, drops, rinses, etc. Nanoformulations of antigens, vaccine and immune adjuvants, and antivirals are now gaining importance. There are promising reports on nanoparticles of metals, metal oxides, polymers, and so on that have the potential to detect and inhibit viruses by themselves. This review looks into the nasal nanoformulations in detail and provides an insight into how their efficacy can be improved. To overcome known drawbacks, such as degradation and active mucociliary clearance by antigenpresenting cells at the site of administration, polymers, such as PEG, are incorporated in the nanoformulation. Polymeric systems also provide better tunability of physicochemical properties. The mechanism of nasal spray-based drug delivery systems is also discussed in this paper. The review, thus, provides a detailed insight into the way forward for the development of nasal formulations.
According to World Health Organization, air pollution kills millions of people worldwide every year. In addition, several epidemiological findings have uncovered the impacts of air pollution on respiratory and cardiovascular systems. This chapter presents current knowledge of human health concerns caused by volatile organic compounds (VOCs) and biological contaminants. These contaminants contribute to air pollutants that impair all environmental elements. Heterogeneous photocatalytic processes using semiconductor photocatalyst would serve as a promising technology and an efficient approach for removing VOCs and airborne pathogens. Considering the potentially toxic effect of these air pollutants, emerging mitigation approaches such as the photocatalysis process are explained elaborately in this chapter, including fundamental principles of photocatalysis, reaction mechanism, reaction kinetics, and photoreactor designs suitable for air purification. Furthermore, the photocatalytic process as a paradigm explores existing techniques utilized in research and commercial applications. Significant efforts have been made to include information from worldwide sources for this investigation.KeywordsAirborne pathogensAir pollutionHydroxyl radicalPhotocatalysisPhotoreactorPMROSTiO2VOCs
The COVID-19 pandemic is the largest global public health outbreak in the 21 st century so far. It has contributed to a significant increase in the generation of waste, particularly personal protective equipment and hazardous medical, as it can contribute to environmental pollution and expose individuals to various hazards. To minimize the risk of infection, the entire surrounding environment should be disinfected or neutralized regularly. Effective medical waste management can add value by reducing the spread of COVID-19 and increasing the recyclability of materials instead of sending them to landfill. Developing an antiviral coating for the surface of objects frequently used by the public could be a practical solution to prevent the spread of virus particles and the inactivation of virus transmission. Relying on an abundance of engineered materials identifiable by their useful physicochemical properties through versatile chemical functionalization, nanotechnology offers a number of approaches to address this emergency. Here, through a multidisciplinary perspective encompassing various fields such as virology, biology, medicine, engineering, chemistry, materials science, and computer science, we describe how nanotechnology-based strategies can support the fight against COVID-19 well as infectious diseases in general, including future pandemics. In this review, the design of the antiviral coating to combat the spread of COVID-19 was discussed, and technological attempts to minimize the coronavirus outbreak were highlighted. Environmental signicance The COVID-19 pandemic has signicantly impacted waste generation, particularly in the form of personal protective equipment. Proper management of such waste is essential to prevent the spread of infectious agents and protect public health. This review article examines the potential applications of nanotechnology to reduce the environmental risks of waste associated with the COVID-19 pandemic.
Single-phase powders of γ-Ce2Mo3O13, Ce8Mo12O49, and Ce2Mo4O15 were prepared using the solid-phase method. Then, the antiviral activity of these powders against the non-enveloped virus bacteriophage Qβ and the enveloped virus bacteriophage Φ6 were evaluated. Moreover, H2O2 assay and catalase inactivation test were performed. Regarding the antiviral activity of the prepared samples, the activity against bacteriophage Φ6 was higher than the activity against bacteriophage Qβ. The antiviral activity order for bacteriophage Φ6 was correlated with the amount of H2O2 generated and the catalase inactivation rate. It depended also on the eluted Ce/Mo ratio. These results imply that the antiviral activity on bacteriophage Qβ is influenced by neutralization of the negative charge of capsid by rare earth ions and by adsorption of heteropolyacids to specific sites of the virus. Results suggest that the oxidation reaction of Ce (IV) or of the H2O2, and the adsorption of heteropolyacids formed by Ce and molybdate ions affect the antiviral activity against bacteriophage Φ6. Among the compounds examined this time, γ-Ce2Mo3O13 exhibited the highest antiviral activity against bacteriophage Φ6.
The present world continues to face unprecedented challenges caused by the COVID-19 pandemic. Collaboration between researchers of multiple disciplines is the need of the hour. There is a need to develop antiviral agents capable of inhibiting viruses and tailoring existing antiviral drugs for efficient delivery to prevent a surge in deaths caused by viruses globally. Biocompatible systems have been designed using nanotechnological principles which showed appreciable results against a wide range of viruses. Many nanoparticles can act as antiviral therapeutic agents if synthesized by the correct approach. Moreover, nanoparticles can act as carriers of antiviral drugs while overcoming their inherent drawbacks such as low solubility, poor bioavailability, uncontrolled release, and side effects. This review highlights the potential of nanomaterials in antiviral applications by discussing various studies and their results regarding antiviral potential of nanoparticles while also suggesting future directions to researchers.
A prominent feature of the SARS-CoV-2 virus is the presence of a large glycoprotein spike protruding from the virus envelope. The spike determines the interaction of the virus with the environment and the host. Here, we used an all-atom molecular dynamics simulation method to investigate the interaction of up- and down-conformations of the S1 subunit of the SARS-CoV-2 spike with the (100) surface of Au, Ag, and Cu. Our results revealed that the spike protein is adsorbed onto the surface of these metals, with Cu being the metal with the highest interaction with the spike. In our simulations, we considered the spike protein in both its up-conformation Sup (one receptor binding domain exposed) and down-conformation Sdown (no exposed receptor binding domain). We found that the affinity of the metals for the up-conformation was higher than their affinity for the down-conformation. The structural changes in the spike in the up-conformation were also larger than the changes in the down-conformation. Comparing the present results for metals with those obtained in our previous MD simulations of Sup with other materials (cellulose, graphite, and human skin models), we see that Au induces the highest structural change in Sup, larger than those obtained in our previous studies.
Upon the tremendous spread of coronavirus, there is a need to develop biodegradable, multifunctional, antiviral masks that can be safely used without polluting the environment as conventional surgical masks do. In this study, a three-layered mask filter is designed and fabricated. The first two layers contain electrospun polyamide with dispersed nanoparticles (NPs) of TiO2 and ZnO prepared via breakdown anodization. The third layer is composed of Nigella sativa oil (black seed oil) electrospun with polyamide and blended with chitosan to form an effective antiviral three-layered mask filter. The morphological characterization revealed the nanoscale features of the fabricated nanofibers with the ZnO and TiO2 NPs being embedded in the polymeric matrix. The specimens showed good wettability, which is necessary for virus attachment and its subsequent decay. The assembled mask has shown very good mechanical properties. The cytotoxicity results revealed that the proposed mask filter has less cytotoxic effect on the A549 cell line than the commercial KN95 mask filter with maintaining a cell viability of 65.3%. The antiviral activity test showed a variable virucidal effect against human adenovirus on A549 cells. The proposed mask showed the highest effect on the virus followed by PA-ZnO and PA-TiO2 films, which supports the assumption that the used NPs may have broad and promising effects on viruses when combined with the electrospun films.
Surface dielectric barrier discharge (SDBD) was used to inactivate the infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) trapped in a polypropylene (PP) melt-blown filter. We used a dielectric barrier made of polyimide films with hexagonal holes through which air flowed. In a cylindrical wind tunnel, the SDBD device supplied reactive oxygen species such as ozone to the SARS-CoV-2 trapped in the PP filter. A plaque assay showed that SDBD at an ozone concentration of approximately 51.6 ppm and exposure time of 30 min induced more than 99.78% reduction for filter-adhered SARS-CoV-2. A carbon catalyst after SDBD effectively reduced ozone exhaust below 0.05 ppm. The combination of SDBD, PP filter, and catalyst could be a promising way to decrease the risk of secondary infection due to indoor air purifiers.
In the current situation of the global pandemic COVID 19, there is a worldwide demand for the protection of regular handling surfaces from the viral transmission to restrict the spread of COVID 19 infection. To tackle this challenge, researchers and scientists are continuously working on novel antiviral nanocoating's to make various substrates capable of arresting the spread of pathogens. Such nanocoatings system include metal/metal oxide nanoparticles, electrospun antiviral polymer nanofibers, antiviral polymer nanoparticles, graphene family nanomaterials, and etched nanostructures. The antiviral mechanism of these systems involves depletion of the spike glycoprotein that anchors to surfaces by the nanocoating and makes the spike glycoprotein and viral nucleotides inactive; however, the nature of interaction between the spike proteins and virus depends on the type of nanostructure and surface charge over the coating surface. In this review article, I have discussed the current scenario of COVID 19 and how it can be tackled using antiviral nanocoatings from further transmission of SARS‐CoV‐2 along with their different mode of actions. Additionally, I also highlighted different types of nanocoatings developed for various substrates to encounter transmission of SARS‐CoV‐2, future research areas along with the current challenges related to it, and how these challenges can be resolved. This article is protected by copyright. All rights reserved
Photocatalyst is widely used as an antibacterial and antivirus material. Since typical photocatalysts such as TiO2, can indiscriminately inactivate various microorganisms, they are effective to remove harmful microorganisms. On the other hand, photocatalysts can be applied in a broad area if specific microorganisms are inactivated with photocatalyst. In this article, we show unique photocatalysts for which selective microbial inactivation was observed. We focus on the protein of phage as a virus model and clarify the mechanism of inactivation by comparison with model protein.
We describe the details and concrete analysis of selective microorganism inactivation mechanism with photocatalyst.
A full-color white light source is continuously required for general lighting applications. Herein, the white electroluminescence (EL) from Tb 3+-singly doped CaSiO3 (CSO) thin film on a silicon substrate has been reported for the first time. The EL device has a metal-oxide-semiconductor (MOS) structure which consists of two CSO and SiOx oxide layers on silicon wafer. Above the threshold voltage in AC power, it shows a full-color white EL spectrum with two dominant emission groups of ultraviolet-blue and green-red peaks from the f-f intra-transition of Tb 3+ ions without the cross-relaxation effect in the four blue peaks which suffers from their severe cross-relaxation quenching in its photoluminescence spectrum. It is attributed to the strong electric field splitting (Stark effect) which prevents the resonance energy transfer due to energy perturbation. With increasing Tb 3+ concentrations, the blue bands get more dominant along with increasing the threshold voltage. Furthermore, we demonstrate the EL-voltage transient behavior with a large hysteresis in a positive voltage polarity.
The COVID‐19 pandemic has inspired large research investments from the global scientific community in the study of viral properties and antiviral technologies (e.g., self‐cleaning surfaces, virucides, antiviral drugs, and vaccines). Emerging viruses are a constant threat due to the substantial variation in viral structures, limiting the potential for expanded broad‐spectrum antiviral agent development, and the complexity of targeting multiple and diverse viral species with unique characteristics involving their virulence. Multiple, more infectious variants of SARS‐CoV2 (e.g., Delta, Omicron) have already appeared, necessitating research into versatile, robust control strategies in response to the looming threat of future viruses. Nanotechnology and nanomaterials have played a vital role in addressing current viral threats, from mRNA‐based vaccines to nanoparticle‐based drugs and nanotechnology enhanced disinfection methods. Rapid progress in the field has prompted a review of the current literature primarily focused on nanotechnology‐based virucides and antivirals. In this review, a brief description of antiviral drugs is provided first as background with most of the discussion focused on key design considerations for high‐efficacy antiviral nanomaterials (e.g., nanopharmaceuticals) as determined from published studies as well as related modes of biological activity. Insights into potential future research directions are also provided with a section devoted specifically to the SARS‐CoV2 virus.
This article is categorized under: Toxicology and Regulatory Issues in Nanomediciney > Toxicology of Nanomaterials
Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease
Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease
In this study, we expose various techniques based on cold plasma discharge (CPD), and more precisely aqueous-phase plasma-aided grafting (APPAG), to efficiently modify the surface of polymers as well as fabric made of natural fibers. Several directions were investigated to ultimately add a functional coating providing an antimicrobial effect to textiles. Our strategy relies on the immobilization of silver nanoparticles (AgNPs) and Bi2MoO6 (BMO) – a robust inorganic photocatalyst that can be activated by visible light – microflowers, at the surface of cotton fabric fibers. Notably, an in situ complexation-assisted precipitation route (ISCAP – an original method derived from CPD) was successfully employed to generate a very uniform coating of silver nanoparticles at the surface of organic substrates. As we demonstrate in this study, the surface functionalization with BMO and silver provides a significant protection against bacteria in dark conditions, through a bacteriostatic effect of nano silver, and under low-intensity artificial visible light (thanks to the photocatalytic effect of BMO/Ag), hence suitable for an indoor environment such as hospitals. Our composite nanomaterial, cotton/BMO/AgNPs, was assessed through antibacterial testing with Escherichia coli (E. coli) and Staphylococcus aureus (S. Aureus), showing a pronounced antimicrobial effect with both strains. This study opens prospects for the functionalization of natural or artificial fiber materials with possible applications in the field of biomedical protective equipment such as bandages, masks or technical cloths; or even photocatalysis.
An ozone-assisted photocatalytic water-purification unit using a TiO2 modified titanium-mesh sheet (TMiP) was investigated. Significant decomposition of biological and chemical contaminants has been achieved by highly active intermediates formed by catalyticdecomposition and photocatalysis.
The role of the water cycle in spreading human pathogenic influenza viruses is poorly studied and is not considered to be significant. However, gastrointestinal symptoms developed in a large proportion of influenza A (H1N1) 2009 virus infected people during the pandemic in 2009 and fecal shedding was reported. This fecal route could potentially play a role in the entry of human pathogenic influenza viruses in to the water cycle. Monitoring of influenza viruses in sewage and surface water during the pandemic in 2009 showed that influenza A viruses were detected in sewage and surface water. However, the pandemic influenza A (H1N1) 2009 virus was not detected. These findings imply that the water cycle did not play a relevant role in spreading the pandemic influenza virus during the epidemic in the Netherlands in 2009. Analyses of deliberately contaminated water samples confirmed the ability of quantitative RT-PCR to detect influenza viruses in sewage samples whereas the analysis of large volumes of surface water was strongly hampered by the presence of PCR-inhibiting substances.
The carcinogenic potential of chlorine disinfection by-products and recent changes in water quality regulations have led to a greater emphasis on alternative disinfection mechanisms. In this study, the efficacy of bench-scale and pilot-scale titanium dioxide (TiO(2)) photocatalytic disinfection was explored using four bacteriophages (MS2, PRD1, phi-X174, and fr). The optimized bench-scale experiments indicated that 1 mg/L of Degussa P25 TiO(2) irradiated by low-pressure ultraviolet (UV) light reduced the dose requirements for viral inactivation in comparison to UV light alone. The highest UV dose reductions for 4-log inactivation of PRD1, MS2, phi-X174, and fr were 19%, 15%, 6%, and 0%, respectively. Bench-scale photocatalysis was inhibited by limited adsorption of the viruses onto the TiO(2) nanoparticles, as indicated by the poor results for high TiO(2) concentrations. Subsequently, pilot-scale experiments were completed using the Photo-Cat Lab from Purifics. The annular reactor configuration and increased viral adsorption dramatically improved photocatalytic inactivation for samples with high TiO(2) concentrations. Using the Photo-Cat Lab, 2-log inactivation of the bacteriophages was achieved with 400 mg/L of Degussa P25 TiO(2) and a UV dose of approximately 34 mJ/cm(2) (energy consumption of 0.33 kWh/m(3))-a 700-fold decrease in energy use compared to bench-scale photocatalysis.
The maintenance of infectivity of influenza viruses on the surfaces of personal protective equipment and clothing is an important factor in terms of controlling viral cross-infection in the environment and preventing contact infection. The aim of this study was to determine if laboratory-grown influenza A (H1N1) virus maintained infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings.
Influenza A virus (0.5 mL) was deposited on the surface of a rubber glove, an N95 particulate respirator, a surgical mask made of non-woven fabric, a gown made of Dupont Tyvek, a coated wooden desk, and stainless steel. Each sample was left for 1, 8, and 24 h, and hemagglutination (HA) and 50% tissue culture infective dose (TCID(50))/mL were measured.
The HA titer of this influenza A virus did not decrease in any of the materials tested even after 24 h. The infectivity of influenza A virus measured by TCID(50) was maintained for 8 h on the surface of all materials, with the exception of the rubber glove for which virus infectivity was maintained for 24 h.
Our results indicate that the replacement/renewal of personal protective equipment and clothing by healthcare professionals in cases of exposure to secretions and droplets containing viruses spread by patients is an appropriate procedure to prevent cross-infection.
The efficacy of vapor-phase hydrogen peroxide in a pass-through box for the decontamination of equipment and inanimate materials potentially contaminated with exotic animal viruses was evaluated. Tests were conducted with a variety of viral agents, which included representatives of several virus families (Orthomyxoviridae, Reoviridae, Flaviviridae, Paramyxoviridae, Herpesviridae, Picornaviridae, Caliciviridae, and Rhabdoviridae) from both avian and mammalian species, with particular emphasis on animal viruses exotic to Canada. The effects of the gas on a variety of laboratory equipment were also studied. Virus suspensions in cell culture media, egg fluid, or blood were dried onto glass and stainless steel. Virus viability was assessed after exposure to vaporphase hydrogen peroxide for 30 min. For all viruses tested and under all conditions (except one), the decontamination process reduced the virus titer to 0 embryo-lethal doses for the avian viruses (avian influenza and Newcastle disease viruses) or less than 10 tissue culture infective doses for the mammalian viruses (African swine fever, bluetongue, hog cholera, pseudorabies, swine vesicular disease, vesicular exanthema, and vesicular stomatitis viruses). The laboratory equipment exposed to the gas appeared to suffer no adverse effects. Vaporphase hydrogen peroxide decontamination can be recommended as a safe and efficacious way of removing potentially virus-contaminated objects from biocontainment level III laboratories in which exotic animal disease virus agents are handled.
When titanium dioxide (TiO(2)) is irradiated with near-UV light, this semiconductor exhibits strong bactericidal activity. In this paper, we present the first evidence that the lipid peroxidation reaction is the underlying mechanism of death of Escherichia coli K-12 cells that are irradiated in the presence of the TiO(2) photocatalyst. Using production of malondialdehyde (MDA) as an index to assess cell membrane damage by lipid peroxidation, we observed that there was an exponential increase in the production of MDA, whose concentration reached 1.1 to 2.4 nmol. mg (dry weight) of cells(-1) after 30 min of illumination, and that the kinetics of this process paralleled cell death. Under these conditions, concomitant losses of 77 to 93% of the cell respiratory activity were also detected, as measured by both oxygen uptake and reduction of 2,3,5-triphenyltetrazolium chloride from succinate as the electron donor. The occurrence of lipid peroxidation and the simultaneous losses of both membrane-dependent respiratory activity and cell viability depended strictly on the presence of both light and TiO(2). We concluded that TiO(2) photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane. Subsequently, essential functions that rely on intact cell membrane architecture, such as respiratory activity, were lost, and cell death was inevitable.
Photocatalytic inactivation of virus by immobilized TiO2 was investigated using RNA phage Qβ as a model. TiO2-coated tiles, developed for interior sterilisation, were used as immobilized photocatalyst. 2.2 log Qβ was inactivated by immobilized TiO2 mediated photocatalysis by 1h irradiation with near UV black light at an intensity of 3.6×10−3W/cm2. Experiments with a slurry TiO2 reactor were also performed as a reference for the inactivation kinetics study. Photocatalytic Qβ inactivation was expressed by first-order kinetics as the initial concentration of the phage Qβ varied. The inactivation rate constant was proportional to the light intensity in the range of 3–8×10−3W/cm2 of black light with immobilized TiO2 photocatalyst. Broth introduced with phage into the reaction solution inhibited inactivation. No noticeable difference in inactivation was observed between germicidal lamp irradiation with and without immobilized TiO2.
SYPRO Ruby dye is a permanent stain comprised of ruthenium as part of an organic complex that interacts noncovalently with proteins. SYPRO Ruby Protein Gel Stain provides a sensitive, gentle, fluorescence-based method for detecting proteins in one-dimensional and two-dimensional sodium dodecyl sulfate-polyacrylamide gels. Proteins are fixed, stained from 3h to overnight and then rinsed in deionized water or dilute methanol/acetic acid solution for 30 min. The stain can be visualized using a wide range of excitation sources commonly used in image analysis systems including a 302 nm UV-B transilluminator, 473 nm second harmonic generation (SHG) laser, 488 nm argon-ion laser, 532 nm yttrium-aluminum-garnet (YAG) laser, xenon arc lamp, blue fluorescent light bulb or blue light-emitting diode (LED). The sensitivity of SYPRO Ruby Protein Gel Stain is superior to colloidal Coomassie Brilliant Blue (CBB) stain or monobromobimane labeling and comparable with the highest sensitivity silver or zinc-imidazole staining procedures available. The linear dynamic range of SYPRO Ruby Protein Gel stain extends over three orders of magnitude, which is vastly superior to silver, zinc-imidazole, monobromobimane and CBB stain. The fluorescent stain does not contain superfluous chemicals (formaldehyde, glutaraldehyde, Tween-20) that frequently interfere with peptide identification in mass spectrometry. While peptide mass profiles are severely altered in protein samples prelabeled with monobromobimane, successful identification of proteins by peptide mass profiling using matrix-assisted laser desorption/ionization mass spectrometry was easily performed after protein detection with SYPRO Ruby Protein Gel stain.
The purpose of this review is to examine current methods of estimation of influenza-related morbidity and mortality from the perspective of surveillance of seven seasons (1974-1981) of influenza virus activity and related disease by the Influenza Research Center in Houston Texas. Virologic surveillance was designed to monitor influenza virus activity in all socioeconomic strata of the population of Harris County Texas which increased from about 2.0 to 2.4 million persons during the study period. The surveillance program has provided some measure of the contribution of influenza virus infections to medically attended acute respiratory illnesses while defining the period of influenza virus prevalence for each season. Nonvirological indexes of epidemic influenza that have been used for regional and national surveillance are evaluated. "Preliminary observations suggest that the number of hospitalizations for acute respiratory illnesses observed in this framework provides a better estimate of impact than data derived from death certificates." (EXCERPT)
Photocatalytic inactivation of virus by immobilized TiO2 was investigated using RNA phage QB as a model. TiO2-coated tiles, developed for interior sterilisation, were used as immobilized phoocatalyst. 2.2 log QB was inactivated by immobilized TiO2 mediated photocatalysis by 1h irradiation with near UV black light at an intensity of 3.6×10−3W/cm2. Experiments with a slurry TiO2 reactor were also performed as a reference for the inactivation kinetics study. Photocatalytic QB inactivation was expressed by first-order kinetics as the initial concentration of the phage QB varied. The inactivation rate constant was proportional to the light intensity in the range of 3–8×10−3W/cm2 of black light with immobilized TiO2 photocatalyst. Broth introduced with phage into the reaction solution inhibited Inactivation. No noticeable difference in inactivation was observed between germicidal lamp irradiation with and without immobilized TiO2.
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.
Photocatalytic sterilization of Escherichia coli cells with TiO2 particles is examined using a rectangular bubble-column reactor irradiated with three kinds of artificial light sources. The three types of used lamps were a black light fluorescent (BL-F) lamp, a blue actinic fluorescent (BB-F) lamp and a daylight fluorescent (DL-F) lamp. Under the conditions of TiO2 concentration of 1 x 10(-2) kg/m(3) and initial cell concentration of 1 x 10(11) cells/m(3), average light intensities in the reactor were varied in the range of 0 to 22 W/m(2), 0 to 14 W/m(2) and 0 to 1.1 W/m(2) with the BL-F, BA-F and DL-F lamps, respectively, The apparent sterilization rate constants of E. coli cells for these lamps are determined on the basis of a series-event model, and are compared with those obtained in experiments with a high pressure mercury lamp. Irrespective of the examined lamps, the rate constants can be correlated with the light quantities absorbed by TiO2 slurry, which are evaluated by taking into account both the dependency of absorbance of TiO2 slurry on light wavelengths and the spectral distributions of light rays from the respective lamps. From the results obtained in experiments using the artificial light sources, the sterilization rate constants of E. coli under the sunlight can be predicted, The experimental data are in good agreement with the predicted results in the reactor illuminated with sunlight at average light intensities of 14 and 23 W/m(2).
The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight. During the past 20 years, it has become an extremely well researched field due to practical interest in air and water remediation, self-cleaning surfaces, and self-sterilizing surfaces. During the same period, there has also been a strong effort to use photocatalysis for light-assisted production of hydrogen. The fundamental aspects of photocatalysis on the most studied photocatalyst, titania, are still being actively researched and have recently become quite well understood. The mechanisms by which certain types of organic compounds are decomposed completely to carbon dioxide and water, for example, have been delineated. However, certain aspects, such as the photo-induced wetting phenomenon, remain controversial, with some groups maintaining that the effect is a simple one in which organic contaminants are decomposed, while other groups maintain that there are additional effects in which the intrinsic surface properties are modified by light. During the past several years, powerful tools such as surface spectroscopic techniques and scanning probe techniques performed on single crystals in ultra-high vacuum, and ultrafast pulsed laser spectroscopic techniques have been brought to bear on these problems, and new insights have become possible. Quantum chemical calculations have also provided new insights. New materials have recently been developed based on titania, and the sensitivity to visible light has improved. The new information available is staggering, but we hope to Offer an overview of some of the recent highlights, as well as to review some of the origins and indicate some possible new directions. (C) 2008 Elsevier B.V. All rights reserved
The destruction of toxic halogenated hydrocarbons in waste water effuents or ground water wells is a problem of growing importance in our industrial society. Since conventional methods such as chemical oxidation or microbial treatment are often not efficient for the destruction of these toxins, alternative routes for detoxification are required. It has been shown that semiconductor particles can be used as photocatalysts which are capable of inducing the complete mineralization of many of these hazardous compounds. Detailed mechanistic studies are presented here which have been carried out to investigate the potential use of concentrated solar illumination as the source of irridiance in those photocatalytic systems. Thus the influence of light intensity, temperature and pH on the overall yield of the destruction of halogenated hydrocarbons in aqueous suspensions containing titanium dioxide powder has been studied in detail. Models are presented to explain the observations made with chloroform as the probe molecule and to enable predictions of the efficiency of this method for “real world” applications.
Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO2), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with some fundamental aspects. A novel photoinduced superhydrophilic phenomenon involving TiO2 and its applications are presented.
The inactivation of coliform bacteria and poliovirus 1 was studied in secondary wastewater effluent containing suspensions of titanium dioxide (250 mg 1−1) irradiated with either F40BL fluorescent lights or sunlight. Approximately 150 min were required to achieve two-log inactivation of coliform bacteria under laboratory lights, while the two-log inactivation of poliovirus 1 occurred in approximately 30 min. No differences in photocatalytic disinfection rates were found when the assays were conducted in the pH range of 5–8. The results show that poliovirus 1 was effectively inactivated by titanium dioxide photocatalysis, and the rates were more rapid than for the inactivation of coliform bacteria. However, the photocatalytic disinfection of effluents using titanium dioxide under sunlight may be limited due to the relatively low inactivation rates and resulting long contact times compared to conventional disinfection methods.
Irradiation of suspensions of Escherichia coli ([approximately] 10[sup 6] cells/mL) and TiO[sub 2] (anatase) with UV-visible light of wave-lengths longer than 380 nm resulted in the killing of the bacteria within minutes. Oxygen was found to be a prerequisite for the bactericidal properties of the photocatalyst. Bacterial killing was found to adhere to first-order kinetics. The rate constant was proportional to the square root of the concentration of TiO[sub 2] and proportional to the incident light intensity in the range [approximately] 180- [approximately] 1660 [mu]E s[sup [minus]1] m[sup [minus]2]. The trends in these simulated laboratory experiments were mimicked by outdoor tests conducted under the summer noonday sun in Texas. The implications of these results as well as those of previous investigations in terms of practical applicability to solar-assisted water treatment and disinfection at remote sites are discussed relative to water technologies currently considered as viable as alternatives to chlorination. 24 refs., 8 figs.
The International Organization for Standardization (ISO) was used to evaluate antibacterial activity by titanium dioxide (TiO(2)) photocatalysis since 2006. We evaluated photocatalytic inactivation of Qβ and T4 bacteriophages induced by low-intensity, long-wavelength ultraviolet A (UVA; 0.1 mW cm(-2) and 0.001 mW cm(-2)) irradiation on a TiO(2)-coated glass plate using the ISO methodology. The results indicated that both bacteriophages were inactivated at 0.001 mW cm(-2) UVA. The intensity of UV light, including long-wavelength light (UVA), is very low in an actual indoor environment. Thus, TiO(2) photocatalysis can be beneficial for inactivating viruses in an indoor environment. Experiments using qPCR and bovine serum albumin degradation assume that viral inactivation is caused by outer viral protein disorder and not by viral RNA reduction by reactive oxygen species produced during TiO(2) photocatalysis. Furthermore, we showed that the ISO methodology for standard testing of antibacterial activity by TiO(2) photocatalysis can be applied to assess antiviral activity.
Since 2003, there has been significant concern about the possibility of an outbreak of avian influenza virus subtype H5N1. Moreover, in the last few months, a pandemic of a novel swine-origin influenza A virus, namely A(H1N1), has already caused hundreds of thousands of human cases of illness and thousands of deaths. As those viruses could possibly contaminate water resources through wild birds excreta or through sewage, the aim of our work was to find out whether the treatment processes in use in the drinking water industry are suitable for eradicating them. The effectiveness of physical treatments (coagulation–flocculation–settling, membrane ultrafiltration and ultraviolet) was assessed on H5N1, and that of disinfectants (monochloramine, chlorine dioxide, chlorine, and ozone) was established for both the H5N1 and H1N1 viruses.
Simple assay systems for infectivity titrations of avian infectious bronchitis virus (IBV) in chicken embryo trachea organ cultures (OC) were developed using plastic multiplate wells with one tracheal ring per well; these assays appeared to be much more satisfactory than the conventional rolled-tube method. The medium, 0.05 M HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered Eagle minimal essential medium was not changed during observation. A medium containing 0.4% bovine serum albumin did not influence the virus yield, but did stabilize virus viability during storage. Reproducibility of results obtained in the OC system was confirmed by performing replicate titrations of the Beaudette strain with three different passage histories. The mean virus titers in the OC were lower than those in chicken embryos, depending on the IBV passage histories. The time required for ciliostasis was related not only to the concentration of virus, but also to the IBV passage history. Application of OC techniques for the constant serum-variable virus neutralization test gave low neutralization indexes with excellent reproducibility as compared with those obtained in the chicken embryo assay system. Also, the slopes of neutralization curves obtained by assays in OC were less steep than those seen in the chicken embryo system.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
We report a novel photochemical sterilization system in which Escherichia coli cells were sterilized with photosemiconductor powders (titanium oxide). For sterilization that could be used in practice, it was necessary to separate the TiO2 powders from the cell suspension. Therefore, semiconductor powders were immobilized on acetylcellulose membranes. We constructed a continuous-sterilization system consisting of a TiO2-immobilized acetylcellulose membrane reactor, a mercury lamp, and a masterflex pump. As a result, under the various sterilization conditions examined, E. coli (10(2) cells per ml) was sterilized to less than 1% survival when the cell suspension flowed in this system at a mean residence time of 16.0 min under irradiation (1,800 microeinsteins/m2 per s). We found that this system was reusable.
Using an improved method of gel electrophoresis, many hitherto unknown
proteins have been found in bacteriophage T4 and some of these have been
identified with specific gene products. Four major components of the
head are cleaved during the process of assembly, apparently after the
precursor proteins have assembled into some large intermediate
structure.
To investigate the transmission of influenza viruses via hands and environmental surfaces, the survival of laboratory-grown
influenza A and influenza B viruses on various surfaces was studied. Both influenza A and B viruses survived for 24–48 hr
on hard, nonporous surfaces such as stainless steel and plastic but survived for <8–12 hr on cloth, paper, and tissues. Measurable
quantities of influenza A virus were transferred from stainless steel surfaces to hands for 24 hr and from tissues to hands
for up to 15 min. Virus survived on hands for up to 5 min after transfer from the environmental surfaces. These observations
suggest that the transmission of virus from donors who are shedding large amounts could occur for 2–8 hr via stainless steel
surfaces and for a few minutes via paper tissues. Thus, under conditions of heavy environmental contamination, the transmission
of influenza virus via fomites may be possible.
The purpose of this review is to examine current methods of estimation of influenza-related morbidity and mortality from the perspective of surveillance of seven seasons (1974-1981) of influenza virus activity and related disease by the Influenza Research Center in Houston, Texas. Virologic surveillance was designed to monitor influenza virus activity in all socioeconomic strata of the population of Harris County, Texas, which increased from about 2.0 to 2.4 million persons during the study period. The surveillance program has provided some measure of the contribution of influenza virus infections to medically attended acute respiratory illnesses while defining the period of influenza virus prevalence for each season. Definition of the epidemic has allowed examination of related events which may be used to measure the frequency of serious morbidity and mortality. Preliminary observations suggest that the number of hospitalizations for acute respiratory illnesses observed in this framework provides a better estimate of impact than data derived from death certificates.
The semiconductor TiO2 is known to have photobiological activity in prokaryotic and eukaryotic cells. Applications of this photobiological activity have been suggested including sterilization of waste water and phototherapy of malignant cells. Here, several model and cellular systems were used to study the mechanism of photocatalysis by TiO2. Treatment of TiO2 (anatase, 0.45 microns), suspended in water containing a spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), with UV radiation (320 nm) resulted in an electron spin resonance (ESR) signal characteristic of the hydroxyl radical. Irradiation of solutions containing calf thymus DNA and TiO2 with UVA (320-400 nm) radiation resulted in hydroxylation of guanine bases. The degree of hydroxylation was dependent on both UVA fluence and amount of TiO2 in suspension. Human skin fibroblasts, preincubated 18 h with 10 micrograms/cm2 TiO2 and then UVA-irradiated (0-58 KJ/m2), showed dose dependent photocytoxicity. RNA, isolated from similarly treated fibroblasts, contained significant levels of photooxidation, measured as hydroxylation of guanine bases. However, no oxidative damage was detectable in cellular DNA. These results suggest that nucleic acids are a potential target for photooxidative damage sensitized by TiO2, and support the view that TiO2 photocatalyzes free radical formation.
SYPRO Ruby dye is a permanent stain comprised of ruthenium as part of an organic complex that interacts noncovalently with proteins. SYPRO Ruby Protein Gel Stain provides a sensitive, gentle, fluorescence-based method for detecting proteins in one-dimensional and two-dimensional sodium dodecyl sulfate-polyacrylamide gels. Proteins are fixed, stained from 3h to overnight and then rinsed in deionized water or dilute methanol/acetic acid solution for 30 min. The stain can be visualized using a wide range of excitation sources commonly used in image analysis systems including a 302 nm UV-B transilluminator, 473 nm second harmonic generation (SHG) laser, 488 nm argon-ion laser, 532 nm yttrium-aluminum-garnet (YAG) laser, xenon arc lamp, blue fluorescent light bulb or blue light-emitting diode (LED). The sensitivity of SYPRO Ruby Protein Gel Stain is superior to colloidal Coomassie Brilliant Blue (CBB) stain or monobromobimane labeling and comparable with the highest sensitivity silver or zinc-imidazole staining procedures available. The linear dynamic range of SYPRO Ruby Protein Gel stain extends over three orders of magnitude, which is vastly superior to silver, zinc-imidazole, monobromobimane and CBB stain. The fluorescent stain does not contain superfluous chemicals (formaldehyde, glutaraldehyde, Tween-20) that frequently interfere with peptide identification in mass spectrometry. While peptide mass profiles are severely altered in protein samples prelabeled with monobromobimane, successful identification of proteins by peptide mass profiling using matrix-assisted laser desorption/ionization mass spectrometry was easily performed after protein detection with SYPRO Ruby Protein Gel stain.
Respiratory viruses in the home exploit multiple modes of transmission. RSV is transmitted primarily by contact with ill children and contaminated objects in the environment. Influenza appears to be spread mainly by airborne droplet nuclei. Despite many years of study, from the plains of Salisbury, to the hills of Virginia, to the collegiate environment of Madison, WI, the precise routes rhinovirus takes to inflict the misery of the common cold on a susceptible population remain controversial.
The antiviral effect of anti-influenza drugs such as zanamivir may be demonstrated in patients as an increased rate of decline in viral load over a time course of treatment as compared with placebo. Historically this was measured using plaque assays, or Culture Enhanced Enzyme Linked Immunosorbent Assay (CE-ELISA).
to develop and characterise real time quantitative PCR (qPCR) assays to measure influenza A and B viral load in clinical samples, that offer improvements over existing methods, in particular virus infectivity assays.
The dynamic range and robustness were established for the real time qPCR assays along with stability of the assay components. Cross validation of the real time PCR assays with CE-ELISA was performed by parallel testing of both serial dilutions of three different subtypes of cultured virus and a panel of influenza positive throat swab specimens.
the assays were specific for influenza A and B and the dynamic ranges were at least seven logs. The assay variability was within acceptable limits but increased towards the lower limit of quantification, which was 3.33 log(10) viral cDNA copies/ml of virus transport medium (ten viral RNA copies/PCR). The components of the assay were robust enough to withstand extended storage and several freeze-thaw cycles. For the real time PCR assays the limit of quantification was equivalent to the virus infectivity cut off, which equates to a 93-fold increase in sensitivity.
Well characterised real time PCR assays offer significant improvements over the existing methods for measuring the viral load of strains of influenza A and B in clinical specimens.
New pathogens and antimicrobial-resistant forms of older pathogens continue to emerge, some with the potential for rapid, global spread and high morbidity and mortality. Pathogens can emerge either through introduction into a new population or when the interaction with the vector changes; emergence is also influenced by microbiological adaptation and change, global travel patterns, domestic and wild animal contact and other variants in human ecology and behaviour. Quick, decisive action to detect and control novel pathogens, and thereby contain outbreaks and prevent further transmission, is frequently hampered by incomplete or inadequate data about a new or re-emerging pathogen. Three examples of pathogens that are current causes for human health concern are avian influenza, West Nile virus (WNV) and the severe acute respiratory syndrome (SARS) coronavirus. Pathogens directly or indirectly transmitted by aerosolized droplets, such as avian influenza and SARS, pose considerable containment challenges. Rapid screening tests for other newly described pathogens such as WNV require time for development and may be <100% reliable. The importance of vigilance in the detection and control of newly recognized infectious threats cannot be overstressed. The presence of infectious agents in the blood supply could again have a significant impact on the safe use of both blood and blood-derived products in the care of patients with haemophilia, as did the human immunodeficiency virus in the 1980s. Emerging pathogens will continue to be a reality requiring the collaborative efforts of public health and individual healthcare providers worldwide to contain outbreaks and prevent transmission.
The biocidal action of the TiO2 photocatalyst has been now well recognized from massive experimental evidences, which demonstrates that the photocatalytic disinfection process could be technically feasible. However, the understanding on the photochemical mechanism of the biocidal action largely remains unclear. In particular, the identity of main acting photooxidants and their roles in the mechanism of killing microorganisms is under active investigation. It is generally accepted that reactive oxygen species (ROS) and OH radicals play the role. The aim of this study is to determine how the OH radical, acting either independently or in collaboration with other ROS, is quantitatively related to the inactivation of E. coli. The steady-state concentrations of OH radicals ([*OH]ss) in UV-illuminated TiO2 suspensions could be quantified from the measured photocatalytic degradation rates of p-chlorobenzoic acid (a probe compound) and its literature bimolecular rate constant with OH radicals. The results demonstrated an excellent linear correlation between [*OH]ss and the rates of E. coli inactivation, which indicates that the OH radical is the primary oxidant species responsible for inactivating E. coli in the UV/TiO2 process. The CT value of OH radical for achieving 2 log E. coli inactivation was initially found to be 0.8x10(-5) mg min/l, as predicted by the delayed Chick-Watson model. Although the primary role of OH radicals in photocatalytic disinfection processes has been frequently assumed, this is the first quantitative demonstration that the concentration of OH radicals and the biocidal activity is linearly correlated.
A process scheme for the harvesting and concentration of cell culture-derived human influenza A virus is presented. The scheme comprises two static filtration steps, chemical inactivation by beta-propiolactone and cross-flow ultrafiltration. Human influenza A virus A/PR/8/34 (H1N1) was produced in roller bottles with serum-free medium using MDCK cells as a host. Cultivations resulted in specific hemagglutination (HA) activities of 393 HAU (100 microL)(-1) and turbidities of 0.479 OD measured as the extinction of light at 700 nm (mean values are presented). The concentrations of soluble protein and DNA in the harvests were 72 microg/mL and 5.73 microg/mL, respectively. An average product yield of 79% based on HA activity was achieved after clarification by depth (85%) and microfiltration (93%). The turbidities of cell culture supernatants were reduced to 2% of their initial value. Concentration with 750 kDa hollow-fiber modules by a factor of 20 resulted in 97% recovery of the product when operated at a constant flux of 28 L/(m(2) h) and a wall shear rate of 9,500 s(-1). The amount of protein and DNA could be reduced to 16% and 33% of their initial amount, respectively. An overall product yield of 77% was achieved. Clarified supernatants and concentrates were further analyzed by non-reducing SDS-PAGE and agarose gel electrophoresis. Particle volume distributions of concentrates were obtained by dynamic light scattering analysis. From the results it can be concluded that the suggested process scheme is well suited for the harvesting and concentration of cell culture-derived influenza A virus.