Comparative Study of the Antimicrobial Effects of Tungsten Nanoparticles and Tungsten Nanocomposite Fibres on Hospital Acquired Bacterial and Viral Pathogens

© 2020 The Author(s). This is an open access article distributed under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.A significant proportion of patients acquire hospital associated infections as a result of care within the NHS each year. Numerous antimicrobial strategies, such as antibiotics and surface modifications to medical facilities and instruments, have been devised in an attempt to reduce the incidence of nosocomial infections, but most have been proven unsuccessful and unsustainable due to antibiotic resistance. Therefore, the need to discover novel materials that can combat pathogenic microorganisms is ongoing. Novel technologies, such as the potential use of nanomaterials and nanocomposites, hold promise for reducing these infections in the fight against antimicrobial resistance. In this study, the antimicrobial activity of tungsten, tungsten carbide and tungsten oxide nanoparticles were tested against Escherichia coli, Staphylococcus aureus and bacteriophage T4 (DNA virus). The most potent nanoparticles, tungsten oxide, were incorporated into polymeric fibres using pressurised gyration and characterised using scanning electron microscopy and energy dispersive X-ray spectroscopy. The antimicrobial activity of tungsten oxide/polymer nanocomposite fibres was also studied. The results suggest the materials in this study promote mediation of the inhibition of microbial growth in suspension.Peer reviewe

Antiviral properties of porous graphene, graphene oxide and graphene foam ultrafine fibers against Phi6 bacteriophage

As the world has experienced in the Coronavirus Disease 2019 pandemic, viral infections have devastating effects on public health. Personal protective equipment with high antiviral features has become popular among healthcare staff, researchers, immunocompromised people and more to minimize this effect. Graphene and its derivatives have been included in many antimicrobial studies due to their exceptional physicochemical properties. However, scientific studies on antiviral graphene are much more limited than antibacterial and antifungal studies. The aim of this study was to produce nanocomposite fibers with high antiviral properties that can be used for personal protective equipment and biomedical devices. In this work, 10 wt% polycaprolactone-based fibers were prepared with different concentrations (0.1, 0.5, 1, 2, 4 w/w%) of porous graphene, graphene oxide and graphene foam in acetone by using electrospinning. SEM, FTIR and XRD characterizations were applied to understand the structure of fibers and the presence of materials. According to SEM results, the mean diameters of the porous graphene, graphene oxide and graphene foam nanofibers formed were around 390, 470, and 520 nm, respectively. FTIR and XRD characterization results for 2 w/w% concentration nanofibers demonstrated the presence of graphene oxide, porous graphene and graphene foam nanomaterials in the fiber. The antiviral properties of the formed fibers were tested against Pseudomonas phage Phi6. According to the results, concentration-dependent antiviral activity was observed, and the strongest viral inhibition graphene oxide-loaded nanofibers were 33.08 ± 1.21% at the end of 24 h

Exploiting the antiviral potential of intermetallic nanoparticles

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Viral pandemic outbreaks cause a significant burden on global health as well as healthcare expenditure. The use of antiviral agents not only reduces the spread of viral pathogens but also diminishes the likelihood of them causing infection. The antiviral properties of novel copper-silver and copper-zinc intermetallic nanoparticles against Escherichia coli bacteriophage MS2 (RNA virus) and Escherichia coli bacteriophage T4 (DNA virus) are presented. The intermetallic nanoparticles were spherical in shape and were between 90 and 120 nm. Antiviral activity was assessed at concentrations ranging from 0.05 to 2.0 wt/v% for 3 and 24 h using DNA and RNA virus model organisms. Both types of nanoparticles demonstrated strong potency towards RNA viruses (> 89% viral reduction), whilst copper-silver nanoparticles were slightly more toxic towards DNA viruses when compared to copper-zinc nanoparticles. Both nanoparticles were then incorporated into polymeric fibres (carrier) to investigate their antiviral effectiveness when composited into polymeric matrices. Fibres containing copper-silver nanoparticles exhibited favourable antiviral properties, with a viral reduction of 75% after 3 h of exposure. The excellent antiviral properties of the intermetallic nanoparticles reported in this study against both types of viruses together with their unique material properties can make them significant alternatives to conventional antiviral therapies and decontamination agents.Final Published versio

Applied Methods to Assess the Antimicrobial Activity of Metallic-Based Nanoparticles

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/With the rise of antibiotic resistance, the drive to discover novel antimicrobial substances and standard testing methods with the aim of controlling transmissive diseases are substantially high. In healthcare sectors and industries, although methods for testing antibiotics and other aqueous-based reagents are well established, methods for testing nanomaterials, non-polar and other particle-based suspensions are still debatable. Hence, utilities of ISO standard validations of such substances have been recalled where corrective actions had to be taken. This paper reports a serial analysis obtained from testing the antimicrobial activities of 10 metallic-based nanomaterials against 10 different pathogens using five different in vitro assays, where the technique, limitation and robustness of each method were evaluated. To confirm antimicrobial activities of metallic-based nanomaterial suspensions, it was found that at least two methods must be used, one being the agar well diffusion method, which was found to be the most reliable method. The agar well diffusion method provided not only information on antimicrobial efficacy through the size of the inhibitory zones, but it also identified antimicrobial ions and synergistic effects released by the test materials. To ascertain the effective inhibitory concentration of nanoparticles, the resazurin broth dilution method is recommended, as MIC can be determined visually without utilising any equipment. This method also overcomes the limit of detection (LoD) and absorbance interference issues, which are often found in the overexpression of cell debris and nanoparticles or quantum dots with optical profiles. In this study, bimetallic AgCu was found to be the most effective antimicrobial nanoparticle tested against across the bacterial (MIC 7 µg/mL) and fungal (MIC 62.5 µg/mL) species.Peer reviewe

A Portable Device for the Generation of Drug-Loaded Three-Compartmental Fibers Containing Metronidazole and Iodine for Topical Application

The use of combination therapies for the treatment of a range of conditions is now well established, with the component drugs usually being delivered either as distinct medicaments or combination products that contain physical mixes of the two active ingredients. There is, however, a compelling argument for the development of compartmentalised systems whereby the release, stability and incorporation environment of the different drugs may be tailored. Here we outline the development of polymeric fine fiber systems whereby two drugs used for the treatment of wounds may be separately incorporated. Fibers were delivered using a newly developed handheld electrospinning device that allows treatment at the site of need. Crucially, the delivery system is portable and may be used for the administration of drug-loaded fibers directly into the wound in situ, thereby potentially allowing domiciliary or site-of-trauma administration. The three-layered fiber developed in this study has polyethylene glycol as the outermost layer, serving as a structural support for the inner layers. The inner layers comprised iodine complexed with polyvinylpyrrolidone (PVP) and metronidazole dispersed in polycaprolactone (PCL) as a slow release core. The systems were characterized in terms of structure and architecture using scanning electron microscopy, transmission electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy and diffractometry. As antibacterial creams are still used for managing infected wounds, the performance of our trilayered fiber was studied in comparison with creams containing similar active drugs. Drug release was measured by UV analysis, while antimicrobial efficiency was measured using agar diffusion and suspension methods. It was found that the trilayered systems, averaging 3.16 µm in diameter, released more drug over the study period and were confirmed by the microbacterial studies to be more effective against P. aeruginosa, a bacterium commonly implicated in infected wounds. Overall, the portable system has been shown to be capable of not only incorporating the two drugs in distinct layers but also of delivering adequate amounts of drugs for a more effective antibacterial activity. The portability of the device and its ability to generate distinct layers of multiple active ingredients make it promising for further development for wound healing applications in terms of both practical applicability and antimicrobial efficacy

Characterisation of chemical composition and structural features of novel antimicrobial nanoparticles

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the Creative Commons Attribution License (CC BY 4.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Three antimicrobial nanoparticle types (AMNP0, AMNP1 and AMNP2) produced using the TesimaTM thermal plasma technology were investigated and their compositions determined using a combination of analytical methods. Scanning electron micrograph provided the morphology of these particles with observed sizes ranging from 10 – 50 nm. Whilst FTIR spectra confirmed the absence of polar bonds and organic impurities, strong Raman active vibrational bands at ca. 1604 and 1311 cm-1 ascribed to C-C vibrational motions were observed. Carbon signals resonated at δC126 ppm in solid state NMR spectra confirmed sp2 hybridised carbons were present in high concentration in two of the nanoparticle types (AMNP1 and AMNP2). X-ray powder diffraction suggested AMNP0 contains single phase WC in a high state of purity and multiple phases of WC/WC1-x were identified in both AMNP1 and AMNP2. Finally, XPS surface analyses revealed and quantified the elemental ratios in these composite formulations.Peer reviewe

Macromol. Mater. Eng. 3/2018

Bacterial cellulose blended polymeric fibrous bandages made in a novel way, from a solution subjected to gyration under pressure to directly weave the bandages. The products show cellular attraction, mechanical and swelling properties in preliminary tests and heralds a very promising new route for the manufacture of wound care bandages. This is reported by Esra Altun, Mehmet Onur Aydogdu, Fatma Koc, Maryam Crabbe‐Mann, Francis Brako, Rupy Kaur‐Matharu, Gunes Ozen, Serap Erdem Kuruca, Ursula Edirisinghe, Oguzhan Gunduz, and Mohan Edirisinghein

Novel Making of Bacterial Cellulose Blended Polymeric Fiber Bandages

Bacterial cellulose (BC) is a very promising biological material. However, at present its utilization is limited by difficulties in shape forming it. In this Communication, it is shown how this can be overcome by blending it with poly(methylmethacrylate) (PMMA) polymer. BC:PMMA fibers are produced by pressurized gyration of blended BC:PMMA solutions. Subsequently, BC:PMMA bandage‐like scaffolds are generated with different blends. The products are investigated to determine their morphological and chemical features. Cell culture and proliferation tests are performed to obtain information on biocompatibility of the scaffolds

Production of Antimicrobial Filters for Water Systems using Novel Gyratory Techniques

Diseases caused by the direct and indirect exposure to waterborne pathogens, pose a serious threat to human health. Such microorganisms spread in a non-uniform manner in water supplies and are extremely difficult to eradicate. This research focuses on the manufacture of antimicrobial fibrous membranes to be used in water filtration systems at the point-of-use. In this thesis a cross-disciplinary approach was taken, using knowledge from material science and microbiology, to investigate the antimicrobial activity of tellurium, tungsten, tungsten oxide, tungsten carbide, copper-silver, copper-zinc, graphene oxide nanosheets and graphene nanoplatelets against bacterial and viral microorganisms. By varying the nanomaterial concentration, the agents showed dose-dependent microbicidal characteristics. Carbonaceous based nanomaterials exhibited the strongest potency with a minimum inhibitory concentration of 2 w/v%. At this concentration graphene oxide nanosheets and graphene nanoplatelets killed 96.1 ±4.4% and 63.1 ±4.4% of Escherichia coli populations, respectively, 99% of Staphylococcus aureus populations and 100% of bacteriophage T4 populations. Both copper-based intermetallic materials also showed antimicrobial activity, with copper-silver nanoparticles deactivating 99.0 ±2.2% of E. coli, 75.4 ±1.0% of S. aureus and 100% of bacteriophage T4 populations at 2 w/v%, and copper-zinc nanoparticles deactivating 98.1 ±1.7 % of E. coli, 90.1 ±3.8% of S. aureus and 96.9 0.3±% of bacteriophage T4 populations at 2 w/v%. The solubility and spinnability of poly(methyl methacrylate) (PMMA) in seven different organic solvents was investigated using theoretical and experimental techniques. The effect of applied pressure on the formed fibres was also investigated. Halogenated solvents were identified as the most favourable for the dissolution of PMMA. Increasing the applied pressure was shown to alter fibre morphology and surface pore size as a trade-off between pore formation and solvent evaporation was identified. Pressurised gyration of 20 w/v% PMMA in chloroform at maximum speed and 0.1 MPa applied pressure was outlined as optimal as it yielded fibres with a diameter of 3.3 ±1.2 µm and average surface pore size of 126 ±18 nm. Graphene oxide nanosheets and graphene nanoplatelets were incorporated into PMMA fibres at four different concentrations and their antimicrobial properties were assessed. Fibre morphology was found to be influenced by nanoparticle concentration, as a positive correlation between nanoparticle loading and fibre diameter was observed. Of the prepared composite fibres, 8 wt% graphene oxide/PMMA fibres were found to have the strongest antimicrobial activity as they deactivated 85 ±20% of the E. coli, 95 ±3% of the S. aureus and 39 ±1% of the bacteriophage T4 populations following 24 hours of exposure. These fibres were characterised using Scanning Electron Microscopy, Raman mapping, Fourier Transform Infrared and Stimulated Raman Spectroscopy to confirm the presence of graphene oxide nanosheets on the fibre surface. Microbial cytotoxicity was attributed to oxidative stress, as demonstrated by reactive oxygen species studies. The microbial filtration efficiency of 8 wt% graphene oxide/PMMA fibrous membranes to decontaminate water at the point-of-use was studied. Results showed the membranes to deactivate 83.8 ±1.2% of Gram-negative bacteria, 95.0 ±2.5% Gram-positive bacteria and 32.1 ±2.9% of virions. This thesis shows the implementation of nanocomposite fibrous filter membranes as a viable solution to waterborne diseases

Viral filtration using carbon-based materials

Viral infections alone are a significant cause of morbidity and mortality worldwide and have a detrimental impact on global healthcare and socioeconomic development. The discovery of novel antiviral treatments has gained tremendous attention and support with the rising number of viral outbreaks. In this work, carbonaceous materials, including graphene nanoplatelets and graphene oxide nanosheets, were investigated for antiviral properties. The materials were characterised using scanning electron microscopy and transmission electron microscopy. Analysis showed the materials to be two-dimensional with lateral dimensions ranging between 1 - 4 µm for graphene oxide, 110 ± 0.11nm for graphene nanoplatelets. Antiviral properties were assessed against a DNA virus model microorganism at concentrations of 0.5, 1.0 and 2.0 wt/v%. Both carbonaceous nanomaterials exhibited potent antiviral properties and gave rise to a viral reduction of 100% across all concentrations tested. Graphene oxide nanosheets were then incorporated into polymeric fibres and their antiviral behaviour was examined after 3 and 24 hours. A viral reduction of ~39% was observed after 24 hours of exposure. The research presented here showcases, for the first time, the antiviral potential of several carbonaceous nanomaterials, also included in a carrier polymer. These outcomes can be translated and implemented in many fields and devices to prevent viral spread and infection