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

Pressure-Spun Fibrous Surgical Sutures for Localized Antibacterial Delivery: Development, Characterization, and In Vitro Evaluation

Surgical sutures designed to prevent infection are critical in addressing antibiotic-resistant pathogens that cause surgical site infections. Instead of antibiotics, alternative materials such as biocides have been assessed for coating commercially used sutures due to emerging antibiotic resistance concerns worldwide. This study has a new approach to the development of fibrous surgical sutures with the ability to deliver localized antibacterial agents. A new manufacturing process based on pressure spinning was used for the first time in the production of fibrous surgical sutures by physically blending antibacterial triclosan (Tri) agent with poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene oxide) (PEO) polymers. Fibrous surgical sutures with virgin PLGA, virgin PEO, different ratios of PLGA-PEO, and different ratios of Tri-loaded PLGA-PEO fibrous sutures were produced to mimic the FDA- and NICE-approved PLGA-based sutures available in the market and compared for their characteristics. They were also tested simultaneously with commercially available sutures to compare their in vitro biodegradation, antibacterial, drug release, and cytotoxicity properties. After in vitro antibacterial testing for 24 h, sutures having 285 ± 12 μg/mg Tri loading were selected as a model for further testing as they exhibited antibacterial activity against all tested bacteria strains. The selected model of antibacterial fibrous sutures exhibited an initial burst of Tri release within 24 h, followed by a sustained release for the remaining time until the sutures completely degraded within 21 days. The cell viability assay showed that these surgical sutures had no cytotoxic effect on mammalian cells

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

Findings and Guidance for Airborne Infection Resilience

This guidance provides insights into airborne infection risks and proposes mitigation measures to improve airborne infection resilience of indoor and semi-outdoor spaces. In some poorly-ventilated and/or highly occupied spaces, the provision of increased ventilation performance can be the key to reducing airborne infection risk down to 'acceptable' (although currently undefined) levels.This is a complex area of study with many areas of uncertainty that form the basis of ongoing research. That said, the AIRBODS programme, in the context of the global research efforts associated with the COVID-19 pandemic, has generated a sound basis for improving airborne infection resilience. Key aspects of the guide with its many recommendations include:• Experiments carried out in a test chamber showing how screens can improve or, even, worsen airborne infection risk.• Field studies undertaken as part of the Events Research Programme which underpinned the opening up of the UK hospitality sector in summer of 2021. Good practice advice is provided on how to drive high resolution CO2 and microbiological studies and then appropriately interpret results.• Analytical models were developed to understand how infection risk, using a mass balance approach with many different parameters, might be mitigated in some circumstances when compared to reference spaces. These models were then developed into a 'full building' tool which can be downloaded as part of this guidance.• Computational fluid dynamics (CFD) models were developed to provide insights into the physics of droplets or aerosols at microscale. Following completion of a test chamber validation exercise, models were developed to investigate breathing or coughing mannequins at single human moving towards audience or crowd scale.Local ventilation effectiveness and associated airborne infection risk aspects of some real spaces may significantly differ from assumed 'fully-mixed' equivalent spaces. This, along with a number of other issues, will form part of ongoing research activities.• Focus groups were also used to provide some wider context and support some of our recommendations.AIRBODS has produced a repository of data and modelling methods with the mindset of enabling building professionals to inform their design and operation decisions towards improving airborne infection resilience in their buildings