Prospects of TiO2-based photocatalytic degradation of microplastic leachates related disposable facemask, a major COVID-19 waste

COVID-19 is one of the serious catastrophes that have a substantial influence on human health and the environment. Diverse preventive actions were implemented globally to limit its spread and transmission. Personnel protective equipment (PPE) was an important part of these control approaches. But unfortunately, these types of PPE mainly comprise plastics, which sparked challenges in the management of plastic waste. Disposable face masks (DFM) are one of the efficient strategies used across the world to ward off disease transmission. DFMs can contribute to micro and nano plastic pollution as the plastic present in the mask may degrade when exposed to certain environmental conditions. Microplastics (MPs) can enter the food chain and devastate human health. Recognizing the possible environmental risks associated with the inappropriate disposal of masks, it is crucial to avert it from becoming the next plastic crisis. To address this environmental threat, titanium dioxide (TiO2)-based photocatalytic degradation (PCD) of MPs is one of the promising approaches. TiO2-based photocatalysts exhibit excellent plastic degradation potential due to their outstanding photocatalytic ability, cost efficiency, chemical, and thermal stability. In this review, we have discussed the reports on COVID-19 waste generation, the limitation of current waste management techniques, and the environmental impact of MPs leachates from DFMs. Mainly, the prominence of TiO2 in the PCD and the applications of TiO2-based photocatalysts in MPs degradation are the prime highlights of this review. Additionally, various synthesis methods to enhance the photocatalytic performance of TiO2 and the mechanism of PCD are also discussed. Furthermore, current challenges and the future research perspective on the improvement of this approach have been proposed.

Advanced Oxidation Processes of Amoxicillin Based on Visible Light Active Nitrogen-Doped TiO2 Photocatalyst

Environmental consequences during the COVID-19 pandemic have attracted attention due to the excessive use of antibiotics which lead to the release of the drug's residue, such as amoxicillin (AMX), into the environment. In this work, an advanced oxidation process based on a visible, active N-doped TiO2 photocatalyst was carried out to eliminate AMX. Nitrogen with different initial doping concentrations (15, 30, 45% w/w) was doped into TiO2 by the sol-gel method. The characterization technique such as XRD, FTIR, UV-SRS, and SEM-EDX revealed that nitrogen with 30% doping concentration improved the TiO2 response in the visible region, attributed to the lower band gap energy (2.97 eV). In the photodegradation processes, the TiO2-N (30%) photocatalyst possessed higher AMX degradation than undoped TiO2 for both UV and visible light irradiation. In an aqueous solution, the degradation percentage of AMX by TiO2-N (30%) was 68.5 and 84.12%, while the degradation percentage of AMX by TiO2 was 38.7 and 78.01% under visible and UV light, respectively. © Kusuma Putri Suwondo et al.

Using visible light to activate antiviral and antimicrobial properties of TiO2 nanoparticles in paints and coatings: focus on new developments for frequent-touch surfaces in hospitals.

The COVID-19 pandemic refocused scientists the world over to produce technologies that will be able to prevent the spread of such diseases in the future. One area that deservedly receives much attention is the disinfection of health facilities like hospitals, public areas like bathrooms and train stations, and cleaning areas in the food industry. Microorganisms and viruses can attach to and survive on surfaces for a long time in most cases, increasing the risk for infection. One of the most attractive disinfection methods is paints and coatings containing nanoparticles that act as photocatalysts. Of these, titanium dioxide is appealing due to its low cost and photoreactivity. However, on its own, it can only be activated under high-energy UV light due to the high band gap and fast recombination of photogenerated species. The ideal material or coating should be activated under artificial light conditions to impact indoor areas, especially considering wall paints or frequent-touch areas like door handles and elevator buttons. By introducing dopants to TiO2 NPs, the bandgap can be lowered to a state of visible-light photocatalysis occurring. Naturally, many researchers are exploring this property now. This review article highlights the most recent advancements and research on visible-light activation of TiO2-doped NPs in coatings and paints. The progress in fighting air pollution and personal protective equipment is also briefly discussed. Graphical Abstract: Indoor visible-light photocatalytic activation of reactive oxygen species (ROS) over TiO2 nanoparticles in paint to kill bacteria and coat frequently touched surfaces in the medical and food industries.

A novel photoelectrochemical immunosensor based on TiO2@Bi2WO6 hollow microspheres and Ag2S for sensitive detection of SARS-COV-2 nucleocapsid protein.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) is a cluster of ß coronaviruses. The 2019 coronavirus disease (COVID-19) caused by SARS-COV-2 is emerging as a global pandemic. Thus, early diagnosis of SARS-COV-2 is essential to prevent severe outbreaks of the disease. In this experiment, a novel label-free photoelectrochemical (PEC) immunosensor was obtained based on silver sulfide (Ag2S) sensitized titanium dioxide@bismuth tungstate (TiO2@Bi2WO6) nanocomposite for quantitative detection of SARS-COV-2 nucleocapsid protein. The constructed TiO2@Bi2WO6 hollow microspheres had large specific surface area and could produce high photocurrent intensity under visible light illumination. Ag2S was in-situ grown on the surface of thioglycolic acid (TGA) modified TiO2@Bi2WO6. In particular, TiO2@Bi2WO6 and Ag2S formed a good energy level match, which could effectively enhance the photocurrent conversion efficiency and strength the photocurrent response. Ascorbic acid (AA) acted as an effective electron donor to effectively eliminate photogenerated holes. Under optimal experimental conditions, the constructed immunosensor presented a supersensitive response to SARS-COV-2 nucleocapsid protein, with a desirable linear relationship ranged from 0.001 to 50 ng/mL for nucleocapsid protein and a lower detection limit of 0.38 pg/mL. The fabricated sensor exhibited a wide linear range, excellent selectivity, specificity and stability, which provided a valuable referential idea for the detection of SARS-COV-2.

Photocatalytic Degradation of Paracetamol under Simulated Sunlight by Four TiO2 Commercial Powders: An Insight into the Performance of Two Sub-Micrometric Anatase and Rutile Powders and a Nanometric Brookite Powder

The photocatalytic degradation of the emerging contaminant paracetamol in aqueous solution has been studied under 1 SUN (~1000 W m−2) in the presence of four commercial TiO2 powders, namely sub-micrometric anatase and rutile, and nanometric brookite and P25 (the popular anatase/rutile mixture used as a benchmark in most papers). The rutile powder showed low activity, whereas, interestingly, the anatase and the brookite powders outperformed P25 in terms of total paracetamol conversion to carboxylic acids, which, according to the literature, are the final products of its degradation. To explain such results, the physicochemical properties of the powders were studied by applying a multi-technique approach. Among the physicochemical properties usually affecting the photocatalytic performance of TiO2, the presence of some surface impurities likely deriving from K3PO4 (used as crystallization agent) was found to significantly affect the percentage of paracetamol degradation obtained with the sub-micrometric anatase powder. To confirm the role of phosphate, a sample of anatase, obtained by a lab synthesis procedure and having a "clean” surface, was used as a control, though characterized by nanometric particles and higher surface area. The sample was less active than the commercial anatase, but it was more active after impregnation with K3PO4. Conversely, the presence of Cl at the surface of the rutile did not sizably affect the (overall poor) photocatalytic activity of the powder. The remarkable photocatalytic activity of the brookite nanometric powder was ascribed to a combination of several physicochemical properties, including its band structure and nanoparticles size.

Production of nano filter mask as a Covid-19 prevention effort by using an integrated nanofiltration membrane nanosilver-TiO2-chitosan

The current Covid-19 (SARS-CoV-2) pandemic is causing a tremendous impact on all people in the world. The use of masks is part of preventive measures in spreading certain respiratory viral diseases, including Covid-19. One way to prevent viruses is to use fabric masks, but there is still a shortage that nano filters are needed as a material mask layer. The purpose of this research is to examine the effect of nanosilver concentration and nano-TiO2 concentration on mechanical strength, chemical composition, mixtures, morphology, mechanical strength, and effectiveness of the resulting nano-filter filtration. The nano filters are produced by mixing part of the chitosan solution (2% by weight), nanosilver activated carbon, and the nano-TiO2 solution is added and stirred until homogeneous. Based on the mechanical strength analysis, the best nano filter was obtained at an Ag 3% TiO2 4% concentration with a tensile strength of 7,471 Mpa and an elongation of 7%. The results of the FTIR test showed that nano filters with a concentration of Ag 3% and TiO2 4% found the highest absorption of the primary amine groups N-H2 and OH-. The results of SEM confirmed that the addition of Ag caused a decrease in the porosity of the nano filter. The results of the XRD showed the consistency of the presence of Ag and TiO2 nanoparticles. In addition, nano filters with a concentration of Ag 3% and TiO2 4% have a better rejection condition than other concentrations with a percentage of 77.54%. © 2023 Author(s).

A photoelectrochemical immunosensor based on magnetic all-solid-state Z-scheme heterojunction for SARS-CoV-2 nucleocapsid protein detection.

Rapid, convenient and accurate detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is urgently needed to timely diagnosis of coronavirus pandemic (COVID-19) and control of the epidemic. In this study, a signal-off photoelectrochemical (PEC) immunosensor was constructed for SARS-CoV-2 nucleocapsid (N) protein detection based on a magnetic all-solid-state Z-scheme heterojunction (Fe3O4@SiO2@TiO2@CdS/Au, FSTCA). Integrating the advantages of magnetic materials and all-solid-state Z-scheme heterostructures, FSTCA was implemented to ligate the capture antibody to form magnetic capture probe (FSTCA/Ab1). It can simplify the separation and washing process to improve reproducibility and stability, while allowing immune recognition to be performed in the liquid phase instead of the traditional solid-liquid interface to improve anti-interference. Besides, the heterojunction inhibited the recombination of photogenerated electron/hole (e-/h+) and promoted the light absorption to provide superior photoelectric substrate signal. The mechanism of photogenerated e-/h+ transfer of FSTCA were investigated by the electron spin resonance (ESR) spectroscopy. SiO2 spheres loaded with Au NPs utilized as an efficient signal quencher. The steric hindrance effect of SiO2@Au labeled detection antibodies (SiO2@Au-Ab2) conjugates significantly diminished light absorption and hindered the transfer of photogenerated electrons, further amplifying the signal change value. Based on the above merits, the elaborated immunosensor had a wide linear range of 10 pg mL-1-100 ng mL-1 and a low detection limit down to 2.9 pg mL-1 (S/N = 3). The fabricated PEC immunosensor demonstrated strong anti-interference, easy operation, and high sensitivity, showing enormous potential in clinical diagnosis of SARS-CoV-2.

Adsorption and Inactivation of SARS-CoV-2 on the Surface of Anatase TiO2(101).

We investigated the adsorption of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), the virus responsible for the current pandemic, on the surface of the model catalyst TiO2(101) using atomic force microscopy, transmission electron microscopy, fluorescence microscopy, and X-ray photoelectron spectroscopy, accompanied by density functional theory calculations. Three different methods were employed to inactivate the virus after it was loaded on the surface of TiO2(101): (i) ethanol, (ii) thermal, and (iii) UV treatments. Microscopic studies demonstrate that the denatured spike proteins and other proteins in the virus structure readsorb on the surface of TiO2 under thermal and UV treatments. The interaction of the virus with the surface of TiO2 was different for the thermally and UV treated samples compared to the sample inactivated via ethanol treatment. AFM and TEM results on the UV-treated sample suggested that the adsorbed viral particles undergo damage and photocatalytic oxidation at the surface of TiO2(101) which can affect the structural proteins of SARS-CoV-2 and denature the spike proteins in 30 min. The role of Pd nanoparticles (NPs) was investigated in the interaction between SARS-CoV-2 and TiO2(101). The presence of Pd NPs enhanced the adsorption of the virus due to the possible interaction of the spike protein with the NPs. This study is the first investigation of the interaction of SARS-CoV-2 with the surface of single crystalline TiO2(101) as a potential candidate for virus deactivation applications. Clarification of the interaction of the virus with the surface of semiconductor oxides will aid in obtaining a deeper understanding of the chemical processes involved in photoinactivation of microorganisms, which is important for the design of effective photocatalysts for air purification and self-cleaning materials.

Nano-sized Metal Oxides and Their use as a Surface Disinfectant Against COVID-19: (Review and Perspective)

Contamination of surfaces has long been identified as a significant factor in viral transmission. Therefore, sustained efforts are required to address this issue. This work aims to build a scientific database on nano-sized metal oxides as intelligent materials for surface disinfection against corona viruses, synthesize and characterize nano-sized MgO, and discuss the possibility of using it in virus eradication. The MgO nanoparticle was prepared through the heating method. Meanwhile, XRD diffractometer, Scan electron microscope, and nitrogen adsorption were used to characterize the MgO nanoparticle. The synthesized MgO nanoparticle showed an average crystallite size of 18.55nm, lattice strain 0.0053, surface area 27.56 m(2)/g and d-spacing 2.1092. The outcomes of this review highlight the advantage and challenges of AgO, CuO, ZnO, TiO2 and MgO nanoparticles and their utilization for surface disinfection against coronaviruses.

Spectral selective composite mask media for personal cooling and efficient PM 2.5 removal

Face masks are commonly used to protect an individual's respiratory system from inhaling fine particulate matter (PM2.5) in polluted air, as well as the airborne pathogens, especially during the ongoing coronavirus disease 2019 (COVID-19) pandemic. However, all conventional masks with anti-PM2.5 function suffer from insufficient facial thermal comfort, particularly in a hot and humid environment. Herein, we demonstrated a novel infrared-transmittance visible-opaque PM2.5 media for radiative cooling utilizing rutile titanium dioxide particle-embedded polyamide 6 (PA6-TiO2). The transmission of visible light and infrared and PM2.5 removal performance of composite media containing a variety of microstructures, such as TiO2 particles of varying sizes, shapes, and contents, were numerically examined to determine the optimal ranges. Then the PA6-TiO2 media was effectively electrospun by controlling the arrangement of fibers and the morphology of TiO2 particles. By transmitting more than 85% of the thermal radiation from the human body and selectively blocking solar irradiance, the developed PA6-TiO2(flower-shaped) media cooled the simulative skin by 10.3°C as compared with commercial masks under strong solar irradiance. Additionally, they demonstrated a high PM2.5 removal efficiency of 95.3%, a low air resistance of 22.5 Pa (at 5.3 cm/s), and a sound water vapor transmission rate of 0.0169 g cm−2 h−1. This study presents an effective strategy for making thermally comfortable anti-PM2.5 masks, which will significantly benefit the public health prevention and control. © The Author(s) 2022.

CdTe QDs-sensitized TiO2 nanocomposite for magnetic-assisted photoelectrochemical immunoassay of SARS-CoV-2 nucleocapsid protein.

A sensitive, reliable, and cost-effective detection for SARS-CoV-2 was urgently needed due to the rapid spread of COVID-19. Here, a "signal-on" magnetic-assisted PEC immunosensor was constructed for the quantitative detection of SARS-CoV-2 nucleocapsid (N) protein based on Z-scheme heterojunction. Fe3O4@SiO2@Au was used to connect the capture antibody to act as a capture probe (Fe3O4@SiO2@Au/Ab1). It can extract target analytes selectively in complex samples and multiple electrode rinsing and assembly steps were avoided effectively. CdTe QDs sensitized TiO2 coated on the surface of SiO2 spheres to form Z-scheme heterojunction (SiO2@TiO2@CdTe QDs), which broadened the optical absorption range and inhibited the quick recombination of photogenerated electron/hole of the composite. With fascinating photoelectric conversion performance, SiO2@TiO2@CdTe QDs were utilized as a signal label, thus further realizing signal amplification. The migration mechanism of photogenerated electrons was further deduced by active material quenching experiment and electron spin resonance (ESR) measurement. The elaborated immunosensor can detect SARS-CoV-2 N protein in the linear range of 0.005-50 ng mL-1 with a low detection limit of 1.8 pg mL-1 (S/N = 3). The immunosensor displays extraordinary sensitivity, strong anti-interference, and high reproducibility in detecting SARS-CoV-2 N protein, which envisages its potential application in the clinical diagnosis of COVID-19.

Utilization of Medical Mask Wastes as Filter Material for Air Purification Units

The COVID-19 pandemic significantly increased the amount of infectious medical wastes produced, with medical mask wastes being one of the largest contributors. Present research focuses on trying to turn medical mask waste into a functioning air filter by modifying it with CuO/TiO2 to reduce the amount of infectious medical wastes laying around. Synthesis of CuO/TiO2 was confirmed with FESEM-EDX, UV-Vis DRS and XRD techniques. The optimum amount of Cu added (1%wt of TiO2) was determined by assessing the degradation performance of the modified medical mask wastes against an organic pollutant (methylene blue) and a biological pollutant (S. aureus). The filter was then integrated into a simple air purifying unit and complemented with a UV-C germicidal lamp and a plasma ion generator. The prototype of the simple air purifying unit was able to degrade 100% tobacco smoke in less than 15 min and 30.8% CO gas in 30 min. © 2022 Chemical Publishing Co.. All rights reserved.

Efficient degradation of doxycycline and ofloxacin in an aqueous environment using Fe and Cu doped TiO2-SiO2 photocatalyst under sunlight

Several drugs have sparked interest as potential COVID-19 treatment options. Doxycycline (DOX) has been widely used with other potential agents to reduce COVID-19-induced inflammation. DOX and OFLX, both well-known antimicrobial and anti-inflammatory drugs, were chosen as model pollutants. Fe, Cu-codoped TiO2-SiO2 was synthesised as a novel photocatalyst active under sunlight irradiation to treat model pollutants. The synthesised catalyst samples were meticulously characterised using various techniques to evaluate their morphological, optical, and structural properties. The results of BET analysis showed that the TSFC1 sample has a large specific surface area of 288 m(2)g(-1). Maximum degradation of DOX and OFLX (about 98%) was achieved with the TSFC1 catalyst. The photocatalytic reusability was investigated for up to seven successive cycles, and the composite particles maintained their high photodegradation activity for DOX and OFLX. TFSC1 composite, in particular, demonstrated high catalytic activity as well as excellent recovery potential, and its combination with solar light, silica, and dopants can be introduced as a promising strategy for efficiently destroying both DOX and OFLX antibiotics. This study highlights the feasibility of hybridising doped dual semiconductor nanostructures in implementing solar light-powered pharmaceutical wastewater degradation.

Inactivation of SARS-CoV-2 and Other Human Coronaviruses Aided by Photocatalytic One-Dimensional Titania Nanotube Films as a Self-Disinfecting Surface.

SARS-CoV-2 and its variants that continue to emerge have necessitated the implementation of effective disinfection strategies. Developing self-disinfecting surfaces can be a potential route for reducing fomite transmissions of infectious viruses. We show the effectiveness of TiO2 nanotubes (T_NTs) on photocatalytic inactivation of human coronavirus, HCoV-OC43, as well as SARS-CoV-2. T_NTs were synthesized by the anodization process, and their impact on photocatalytic inactivation was evaluated by the detection of residual viral genome copies (quantitative real-time quantitative reverse transcription polymerase chain reaction) and infectious viruses (infectivity assays). T_NTs with different structural morphologies, wall thicknesses, diameters, and lengths were prepared by varying the time and applied potential during anodization. The virucidal efficacy was tested under different UV-C exposure times to understand the photocatalytic reaction's kinetics. We showed that the T_NT presence boosts the inactivation process and demonstrated complete inactivation of SARS-CoV-2 as well as HCoV-OC43 within 30 s of UV-C illumination. The remarkable cyclic stability of these T_NTs was revealed through a reusability experiment. The spectroscopic and electrochemical analyses have been reported to correlate and quantify the effects of the physical features of T_NT with photoactivity. We anticipate that the proposed one-dimensional T_NT will be applicable for studying the surface inactivation of other coronaviruses including SARS-CoV-2 variants due to similarities in their genomic structure.

Development of a high-speed bioaerosol elimination system for treatment of indoor air.

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.

Evaluation of degradation performance toward antiviral drug ribavirin using advanced oxidation process and its relations to ecotoxicity evolution.

The rapid spread of coronavirus disease 2019 has increased the consumption of some antiviral drugs, wherein these are discharged into wastewater, posing risks to the ecosystem and human health. Therefore, efforts are being made for the development of advanced oxidation processes (AOPs) to remediate water containing these pharmaceuticals. Here, the toxicity evolution of the antiviral drug ribavirin (RBV) was systematically investigated during its degradation via the UV/TiO2/H2O2 advanced oxidation process. Under optimal conditions, RBV was almost completely eliminated within 20 min, although the mineralization rate was inadequate. Zebrafish embryo testing revealed that the ecotoxicity of the treated RBV solutions increased at some stages and decreased as the reaction time increased, which may be attributed to the formation and decomposition of various transformation products (TPs). Liquid chromatography-mass spectrometry analysis along with density functional theory calculations helped identify possible toxicity increase-causing TPs, and quantitative structure activity relationship prediction revealed that most TPs exhibit higher toxicity than the parent compound. The findings of this study suggest that, in addition to the removal rate of organics, the potential ecotoxicity of treated effluents should also be considered when AOPs are applied in wastewater treatment.

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

Legionella pneumophila (L. pneumophila) is the causative agent of Legionnaires’ disease and Pontiac fever, collectively known as legionellosis. L. pneumophila infection occurs through inhalation of contaminated aerosols from water systems in workplaces and institutions. The development of disinfectants that can eliminate L. pneumophila in such water systems without evacuating people is needed to prevent the spread of L. pneumophila. Photocatalysts are attractive disinfectants that do not harm human health. In particular, the TiO2 photocatalyst kills L. pneumophila under various conditions, but its mode of action is unknown. Here, we confirmed the high performance of TiO2 photocatalyst containing PtO2 via the degradation of methylene blue (half-value period: 19.2 min) and bactericidal activity against Escherichia coli (half-value period: 15.1 min) in water. Using transmission electron microscopy, we demonstrate that the disinfection of L. pneumophila (half-value period: 6.7 min) by TiO2 photocatalyst in water is accompanied by remarkable cellular membrane and internal damage to L. pneumophila. Assays with limulus amebocyte lysate and silver staining showed the release of endotoxin from L. pneumophila due to membrane damage and photocatalytic degradation of this endotoxin. This is the first study to demonstrate the disinfection mechanisms of TiO2 photocatalyst, namely, via morphological changes and membrane damage of L. pneumophila. Our results suggest that TiO2 photocatalyst might be effective in controlling the spread of L. pneumophila.

Antimicrobial Activity of a Titanium Dioxide Additivated Thermoset

The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.

Semiconductor Technology based Air Sterilizer (STAS) for Indoor Air in Hospital/Clinic Rooms

Since the outbreak covid-19, the exposure of bacteria, fungi, and virus is a hazardous situation in outpatient clinics and hospital wards. Moreover, air pollution is a serious health issue that can impact the individuals differently. The major concern of these health issues is not only the polluted air of outdoor atmosphere but also contaminated air is spread inside the houses in urban as well as rural areas. In this regard, this paper proposes a Semiconductor Technology based Air Sterilizer (STAS) that integrated several layers of filtration, purification, sterilization and air freshening. Proposed STAS device is able to purify indoor pollutants and also lower down the amount of other harmful materials like, formaldehyde, moulds etc. simultaneously it can also kill organic substances and bacilli in air. The results have been tested in a hospital of Ghaziabad and the obtained data aftersterilization showed that the application of semiconductor technology used in STAS significantly reduced the concentration harmful gas particles, bacteria, and fungi in the installed environment and shifted the peak of the size distribution of particulate matter particles into coarser particles.

Delta SARS-CoV-2 inactivation and bactericidal performance of cotton wipes decorated with TiO2/Ag nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora.

The current pandemic of Coronavirus Disease 2019 (COVID-19) raised several concerns about using conventional textiles for manufacturing personal protective equipment without self-disinfecting properties since the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is transmitted mainly by aerosols that can transpose cotton masks. Therefore, developing new cotton fibers with high self-disinfecting ability is essential to avoid a new pandemic due to new SARS-CoV-2 variants. Herein, we developed cotton wipes (CFs) with fibers coated by Ag, TiO2, and Ag/TiO2 hybrid nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora by a sonochemical approach. Moreover, the coated CFs present high antimicrobial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), being able to inactivate infectious SARS-CoV-2 (Delta variant) by the destruction of the spike, membrane, and nucleocapsid proteins while the viral RNA is not significantly affected, according to the molecular biological findings.