Antimicrobial Effect of Silver Nanoparticle-Based Thin Films

The global pandemic of disease COVID-19 caused by the pathogenic SARS-Cov-2 virus brought more interest in the public health community for known silver with its potential antimicrobial properties to fight infection. One of the ways to stop virus to protect community transmission is the application of nanotechnology of silver nanoparticles on the exposed surfaces of daily used materials in public, e.g., transportation, community spaces, hospitals, and everywhere where the potential infection load is increased. Published technology to coat AgNPs on surfaces differs in the preparation of nanocomposites and substrates, which results in different mechanical and antimicrobial properties. In our study, we focused on the properties of AgNPs prepared by HiTUS and PVD technology with a challenge to test the antimicrobial effect towards the model of gram-negative bacteria (Escherichia coli), fungi (Trichoderma harzianum) and related enteroviruses (Poliovirus and Coxsackie). All tested materials showed 59% or more growth inhibition of E. coli. Growth of T. harzianum was inhibited by 16% in the presence of AgTiB2 50W, and other materials caused 37% to 68% inhibition. Enteroviruses infection was completely inhibited after 1 hour of AgNPs treatment. Only Coxsackie A7 retained infection capability after 30 minutes of treatment with AgNPs. Moreover, the ICP-OES-measured amounts of silver released in cultivation media are lower than most published studies of silver nanoparticles with a comparable antimicrobial effect. Keeping silver concentration at the lowest possible limit is one of the most critical factors for producing environmentally safe antimicrobial materials for everyday use.

THE USED SURGICAL MASKS: FROM WASTE TO RESOURCE

The general focus of research is the development of recycling protocols for disposable surgical masks into new raw materials for different possible applications. Separation of various constituent materials was performed by manual procedure or by water floating. The potentially targeted end applications are thin film and glass fibre composites. Polypropylene thin-films with a thickness of 100 micron were produced by compounding the face mask polymer with different content of a virgin PP, in the range 20-80 wt%. Face mask polypropylene (FM-PP) composites containing glass fibre of 15 wt% and 30 wt% were also prepared, evidencing an improvement of stiffness and strength, furtherly increased in presence of coupling agent. © 2022 Fambri et al.

Sensitivity enhanced tunable plasmonic biosensor using two-dimensional twisted bilayer graphene superlattice

This study theoretically demonstrated an insight for designing a novel tunable plasmonic biosensor, which was created by simply stacking a twisted bilayer graphene (TBG) superlattice onto a plasmonic gold thin film. To achieve ultrasensitive biosensing, the plasmonic biosensor was modulated by Goos-Hänchen (GH) shift. Interestingly, our proposed biosensor exhibited tunable biosensing ability, largely depending on the twisted angle. When the relative twisted angle was optimized to be 55.3°, such a configuration: 44 nm Au film/1-TBG superlattice could produce an ultralow reflectivity of 2.2038 × 10-9and ultra-large GH shift of 4.4785 × 104μm. For a small refractive index (RI) increment of 0.0012 RIU (refractive index unit) in sensing interface, the optimal configuration could offer an ultra-high GH shift detection sensitivity of 3.9570 × 107μm/RIU. More importantly, the optimal plasmonic configuration demonstrated a theoretical possibility of quantitatively monitoring severe acute respiratory syndrome coronavirus (SARS-CoV-2) and human hemoglobin. Considering an extremely small RI change as little as 3 × 10-7RIU, a good linear response between detection concentration of SARS-CoV-2 and changes in differential GH shift was studied. For SARS-CoV-2, a linear detection interval was obtained from 0 to 2 nM. For human hemoglobin, a linear detection range was achieved from 0 to 0.002 g/L. Our work will be important to develop novel TBG-enhanced biosensors for quantitatively detecting microorganisms and biomolecules in biomedical application. © 2023 the author(s), published by De Gruyter, Berlin/Boston 2023.

Durability and Surface Oxidation States of Antiviral Nano-Columnar Copper Thin Films.

Antiviral coatings that inactivate a broad spectrum of viruses are important in combating the evolution and emergence of viruses. In this study, nano-columnar Cu thin films have been proposed, inspired by cicada wings (which exhibit mechano-bactericidal activity). Nano-columnar thin films of Cu and its oxides were fabricated by the sputtering method, and their antiviral activities were evaluated against envelope-type bacteriophage Φ6 and non-envelope-type bacteriophage Qß. Among all of the fabricated films, Cu thin films showed the highest antiviral activity. The infectious activity of the bacteriophages was reduced by 5 orders of magnitude within 30 min by the Cu thin films, by 3 orders of magnitude by the Cu2O thin films, and by less than 1 order of magnitude by the CuO thin films. After exposure to ambient air for 1 month, the antiviral activity of the Cu2O thin film decreased by 1 order of magnitude; the Cu thin films consistently maintained a higher antiviral activity than the Cu2O thin films. Subsequently, the surface oxidation states of the thin films were analyzed by X-ray photoelectron spectroscopy; Cu thin films exhibited slower oxidation to the CuO than Cu2O thin films. This oxidation resistance could be a characteristic property of nanostructured Cu fabricated by the sputtering method. Finally, the antiviral activity of the nano-columnar Cu thin films against infectious viruses in humans was demonstrated by the binding inhibition of the SARS-CoV-2 spike protein to the angiotensin-converting enzyme 2 receptor within 10 min.

Electrochemical Immunosensors Based on Zinc Oxide Nanorods for Detection of Antibodies Against SARS-CoV-2 Spike Protein in Convalescent and Vaccinated Individuals

Even after over 2 years of the COVID-19 pandemic, research on rapid, inexpensive, and accurate tests remains essential for controlling and avoiding the global spread of SARS-CoV-2 across the planet during a potential reappearance in future global waves or regional outbreaks. Assessment of serological responses for COVID-19 can be beneficial for population-level surveillance purposes, supporting the development of novel vaccines and evaluating the efficacy of different immunization programs. This can be especially relevant for broadly used inactivated whole virus vaccines, such as CoronaVac, which produced lower titers of neutralizing antibodies. and showed lower efficacy for specific groups such as the elderly and immunocompromised. We developed an impedimetric biosensor based on the immobilization of SARS-CoV-2 recombinant trimeric spike protein (S protein) on zinc oxide nanorod (ZnONR)-modified fluorine-doped tin oxide substrates for COVID-19 serology testing. Due to electrostatic interactions, the negatively charged S protein was immobilized via physical adsorption. The electrochemical response of the immunosensor was measured at each modification step and characterized by scanning electron microscopy and electrochemical techniques. We successfully evaluated the applicability of the modified ZnONR electrodes using serum samples from COVID-19 convalescent individuals, CoronaVac-vaccinated with or without positive results for SARS-CoV-2 infection, and pre-pandemic samples from healthy volunteers as controls. ELISA for IgG anti-SARS-CoV-2 spike protein was performed for comparison, and ELISA for IgG anti-RBDs of seasonal coronavirus (HCoVs) was used to test the specificity of immunosensor detection. No cross-reactivity with HCoVs was detected using the ZnONR immunosensor, and more interestingly, the sensor presented higher sensitivity when compared to negative ELISA results. The results demonstrate that the ZnONRs/spike-modified electrode displayed sensitive results for convalescents and vaccinated samples and shows excellent potential as a tool for the population's assessment and monitoring of seroconversion and seroprevalence.

Docking of COVID-19 Main Protease and TD-DFT/DMOl3 Simulated method, Synthesis, and Characterization with hybrid nanocomposite thin films and its applications

Using the precipitation polymerization method copolymer poly methyl methacrylate co acrylonitrile was synthesized. Hybrid nanocomposite thin films [P(MMA-co-AN)/ZnO]HNC were prepared using the dip casting method by adding ZnO nanoparticles by the ratios 0.25, 0.20, 0.15, and 0.10 according to the weight of P(MMA-co-AN). Fourier Transform Infrared Spectroscopy (FTIR), UV-Vis optical properties, and laser photoluminescence PL characterization techniques were used to study [P(MMA-co-AN)/ZnO]HNC films. In addition, density functional theory (DFT), optimization via TD-DFTD/Mol3, and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) were used to perform the geometrical study. FTIR spectra from [P(MMA-co-AN)/ZnO]HNC indicates the interaction between the copolymer and ZnO nanoparticles. In the wavelength range of 190 – 800 nm, the optical properties of [P(MMA-co-AN)/ZnO]HNC were considered. The direct energy band gap was found to be changed from 4.1 eV for P (MMA – co – AN) to 3.19 eV for 0.25 ZnO, while the concentration of 0.20 ZnO was the highest in the Urbach energy with 0.17 eV. The refractive index nλ=700 ranges from 1.48 to 1.81 for the concentration of 0.15 ZnO. Three emission peaks at 393 nm, 527 nm, and 775 nm were figured in the laser photoluminescence spectra of [P(MMA-co-AN)/ZnO]HNC films. In order to attain the restrained action of studied ligands (hybrid nanocomposite) novel coronavirus (COVID 19) main protest (6LU7) molecular docking studies were performed. The predicted energy gab by TD-DFT/DMOl3 was found to be agreed with the experimental data in a good manner.

Atomic layer deposition of chalcogenide thin films: processes, film properties, applications, and bibliometric prospect

The use of atomic layer deposition (ALD) for the deposition of chalcogenide thin films have offered great potential applications in numerous research areas such as change-memory storage, sensors, solar cells, photocatalysis, and batteries, but advancing in these fields of research without understanding the previous developments may not be possible. In this review, both qualitative and quantitative methods were used to establish the development of ALD chalcogenide thin films research for the first time. The qualitative approach was used to study several investigations that utilized the ALD technique in fabricating different chalcogenide thin film materials. The thin films deposition processes, properties, and ap-plications were emphasized. It established the fact that ALD can produce quality chalco-genide thin films for different applications. Similarly, the bibliometrics which is a quantitative method was utilized to analyze ALD chalcogenide thin films based on the published documents retrieved from the Scopus database between the period 1993 and 2021. The influence and quality of published documents were assessed based on the ranking of several authors, authors' countries, institutions, and journals through various indicators like numbers of the published article, total citation and average citation per year, impact factor, and h_index. The bibliometric study revealed the highest annual publication was in 2019 and was found to decrease gradually in 2020 and 2021, which may be due to the outbreak of the covid-19 pandemic. It concluded by creating the prospect for researchers to have knowledge about ALD chalcogenide thin films research, allowing more research focus and selecting an appropriate research collaborative network. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Development and applications of diffusive gradients in thin films for monitoring pharmaceuticals in surface waters.

Pharmaceutical contaminants in surface water have raised significant concerns because of their potential ecological risks. In particular, coronavirus disease 2019 (COVID-19)-related pharmaceuticals can be released to surface water and reduce environmental water quality. Therefore, reliable and robust sampling tools are required for monitoring pharmaceuticals. In this study, passive sampling devices of diffusive gradients in thin films (DGTs) were developed for sampling 35 pharmaceuticals in surface waters. The results demonstrated that hydrophilic-lipophilic balance (HLB) was more suitable for DGT-based devices compared with XAD18 and XDA1 resins. For most pharmaceuticals, the performance of the HLB-DGT devices were independent of pH (5.0-9.0), ionic strength (0.001-0.5 M), and flow velocity (0-400 rpm). The HLB-DGT devices exhibited linear pharmaceutical accumulation for 7 days, and time-weighted average concentrations provided by the HLB-DGT were comparable to those measured by conventional grab sampling. Compared to previous studies, we extended DGT monitoring to include three antiviral drugs used for COVID-19 treatment, which may inspire further exploration on identifying the effects of COVID-19 on ecological and human health.

Growth of a fluid-infused patch from droplet drainage into a thin porous layer

Growth of a fluid-infused patch on a thin porous layer, e.g. on a piece of paper or cloth, is related to the transmission of virus particles through exhaled droplets and aerosols. We present a theoretical model to describe how a wet patch develops gradually through imbibition, once a sessile droplet attaches at a permeable surface and drains gradually into a thin porous layer. Two limiting cases are considered based on different assumptions on the motion of the contact line during the coupled process of drop drainage and patch growth: (i) the apparent contact angle remains unchanged, so the radius of a sessile droplet decreases with time;and (ii) the location of the contact line remains pinned, so the contact angle decreases as time progresses. The model leads to evolution pathways for both the droplet and the fluid film within the porous layer, without introducing arbitrary fitting parameters. Potential implications of the model and its solutions are also discussed briefly in the context of the outspread of COVID-19, employing physical parameters for exhaled droplets, paper and cloth.

Direct Sunlight Driven In2S3 Thin Film Based Water Treatment Proto-Type

A multi-faceted energy intensive technology that can be used for water disinfection and synthesis of electrolysed water (EW) is the need of the hour to achieve a sustainable post COVID 19 water management strategy. Direct sunlight driven processes are legislatively green technologies and hold the key in environmental sustenance. The development of a laboratory proto type reactor powered by a photovoltaic module for the treatment open source river water is described in this paper. This paper reports on the efficacy of the developed proto type technology for multipurpose application namely: (1) the production of Electrolysed water (EW) in a cost efficient manner using direct sunlight and (2) the removal of organic impurity from water using direct sunlight without the use of any photo catalyst or membrane. The prototype reactor utilizes chemical spray pyrolysis deposited highly photo-conducting indium sulphide thin films grown on fluorine doped tin oxide (F:SnO2) substrate (coated using chemical spray pyrolysis technique in-house) as the photo electrode. Dissolved organic matter arising in river water has distinctive fluorescence properties, and this research has utilized it to identify dissolved organic substances in both random samples and treated water. The work proves that photovoltaic module powered electrolytic reactors consisting of In2S3 electrodes can be used for treatment of river water. A diaphragm free, energy intensive route for the production of electrolysed water with the use of non-hazardous NaCl as the electrolyte has been demonstrated here. We conclude that In2S3 electrodes can be used for non-photo catalytic reduction of humic-derived impurities in river water. These results are also encouraging on the prospects of treating Nitrates present in the river water. The likes of techniques as described in this report that do not use photo catalyst or membranes may pave way for real time photovoltaic module powered floating reactors that can decontaminate water bodies on a large scale. The technique used by us demonstrates that a chlorine free route can be optimized for the synthesis of EW eliminating the production of large amounts of wastewater with high levels of biological oxygen demand (BOD).

Gold-coated iron oxide core-shell nanostructures for the oxidation of indoles and the synthesis of uracil-derived spirooxindoles

Encapsulation of iron oxide (Fe3O4)-based nanoparticles (NPs) with Au NPs holds a promising scope for catalysis, which overcomes the hindrance of the inherent hydrophilic surface of iron species and facilitates the easy separation of colloidal Au NPs. As such, iron oxide-based NPs were encapsulated by Au NPs to form core-shell structures (Fe3O4/Au NPs) followed by further immobilization on in situ synthesized reduced graphene oxide (rGO) to yield Fe3O4/Au NPs-rGO for increased stability. Fe3O4/Au NPs-rGO was evaluated for the oxidation of NH-free indoles to synthesize isatins, potential precursors of SARS-CoV-2 protease inhibitors. Furthermore, the application of isatin was explored with the Fe3O4/Au NPs-rGO catalysed synthesis of uracil-based spirooxindoles (potential precursors of anti-cancer compounds) via mild reaction conditions and short reaction times with high yields.

SnS2 Nanoparticles and Thin Film for Application as an Adsorbent and Photovoltaic Buffer.

Energy consumption and environmental pollution are major issues faced by the world. The present study introduces a single solution using SnS2 for these two major global problems. SnS2 nanoparticles and thin films were explored as an adsorbent to remove organic toxic materials (Rhodamine B (RhB)) from water and an alternative to the toxic cadmium sulfide (CdS) buffer for thin-film solar cells, respectively. Primary characterization tools such as X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), and UV-Vis-NIR spectroscopy were used to analyze the SnS2 nanoparticles and thin films. At a reaction time of 180 min, 0.4 g/L of SnS2 nanoparticles showed the highest adsorption capacity of 85% for RhB (10 ppm), indicating that SnS2 is an appropriate adsorbent. The fabricated Cu(In,Ga)Se2 (CIGS) device with SnS2 as a buffer showed a conversion efficiency (~5.1%) close to that (~7.5%) of a device fabricated with the conventional CdS buffer, suggesting that SnS2 has potential as an alternative buffer.

Current advances in solar-blind photodetection technology: using Ga2O3 and AlGaN

The rapid spread of the novel coronavirus disease (COVID-19) and emergence of different variants worldwide have caused a pandemic. With the sudden outbreak of this virus, ultraviolet-C (UV-C) sterilizing devices are significantly employed to destroy around 99% of these viruses. However, continuous exposure to UV-C may harm the environment and humans, leading to an increased risk of skin cancer, DNA damage, cataracts and many more severe health complications, which may result in another pandemic situation. Thus, it is highly necessary to monitor the intensity of UV-C exposure and limit the radiation in the environment. It is advisable to employ a highly sensitive solar-blind (SB) UV photodetector (PD) together with UV-C radiation devices. Among the various ultra-wide bandgap semiconductors, AlGaN and Ga2O3 have emerged as the most suitable materials for application in solar-blind photodetection devices due to their high radiation hardness and high chemical and thermal stability. In lieu of exploring efficient SB UV detection systems, herein, we present a comprehensive review of the latest progress in solar-blind UV PDs based on the device architecture and the accompanying physical mechanisms. Further, the technical issues related to material synthesis and device fabrication, which limit the large-scale implementation of these detectors, are also addressed. Finally, a perspective for the future integration of these semiconducting materials with emerging two-dimensional materials towards highly sensitive SB detection devices is given.

Synthesis and characterization of ZnO nanorods-Zn2SiO4 nanoparticles-PMMA nanocomposites for UV-C protection

Nowadays, UV-C is used in a variety of applications, such as disinfection and sterilization of air, surface, and liquids. In particular, its application against the pandemic COVID-19 virus is of great interest. On the other hand, it must be remarked that UV-C is harmful to the eyes, face, head, ears, and skin of engaged employees or personnel but studies on the UV-C range are rare. To the best of our knowledge, studies on zinc silicate as UV-absorber are very rare. In this research, flexible and transparent ZnO nanorods-Zn2SiO4 nanoparticles-PMMA nanocomposite thin films were made for protecting against UV-C radiation. To find the most suitable morphology, the effect of pH variation on the morphology and structural properties of the prepared ZnO–Zn2SiO4 composites were studied. Here we show that the most regular morphology of composites consisting of ZnO nanorods decorated with Zn2SiO4 nanoparticles was obtained at pH 12.5. The UV–vis spectra show that ZnO–Zn2SiO4-PMMA nanocomposite thin films prepared at pH 12.5 exhibit optical transparency in the visible-wavelength region and a prominent UV-C absorbing capability.

Polarity-Dominated Stable N97 Respirators for Airborne Virus Capture Based on Nanofibrous Membranes.

The longevity and reusability of N95-grade filtering facepiece respirators (N95 FFRs) are limited by consecutive donning and disinfection treatments. Herein, we developed stable N97 nanofibrous respirators based on chemically modified surface to enable remarkable filtration characteristics via polarity driven interaction. This was achieved by a thin-film coated polyacrylonitrile nanofibrous membrane (TFPNM), giving an overall long-lasting filtration performance with high quality factor at 0.42 Pa-1 (filtration efficiency: over 97 %; pressure drop: around 10 Pa), which is higher than that of the commercial N95 FFRs (0.10-0.41 Pa-1 ) tested with a flow rate of 5 L min-1 and the 0.26 µm NaCl aerosol. A coxsackie B4 virus filtration test demonstrated that TFPNM also had strong virus capture capacity of 97.67 %. As compared with N95 FFRs, the TFPNM was more resistant to a wider variety of disinfection protocols, and the overall filtration characteristics remained N97 standard.

Tailoring magnetism in spinel vanadate CoV2O4epitaxial thin films.

Near itinerant cubic bulk CoV2O4is at variance with other spinel vanadates by not showing orbital ordering down to low temperature, albeit it displays fragile anomalies related to spin, and lattice structure, signaling a spin/orbital glass transition around 95 K. We investigate tetragonal-like epitaxial CoV2O4films on SrTiO3and (La0.3Sr0.7)(Al0.65Ta0.35)O3substrates that exhibit pronounced signature of spin reorientation transition from toa/bplane around 90 K unlike its bulk counterpart. Using in-plane and out-of-plane magnetic measurements, we demonstrate the intricate link between Co2+and V3+sublattice magnetizations that give rise to anisotropic magnetic switching. In-plane magnetic measurements reveal a wasp-waist shapedM(H) loop below reorientation transition temperature, while the out-of-plane follows antiferromagnet-likeM(H) response. The wasp-waist shaped feature could be linked to in-plane spin-canted (anti)ferromagnetism induced by canting away of V-spins away from antiferromagnetically coupled Co-spin direction below reorientation transition temperature. Further, we uncover the evidence for slow relaxation over a period of ∼104 s at 20 K and memory effect that indicates the possible existence for magnetic glassy phase in the low temperature regime. Using epitaxial strain as a control knob, our results inspire future study to manipulate orbital states, spin texture and itinerant electron character in tailored CoV2O4films away from cubic lattice symmetry.