Non-thermal plasma technology for the development of antimicrobial surfaces: a review

Antimicrobial coatings are in high demand in many fields including the biomaterials and healthcare sectors. Within recent progress in nanoscience and engineering at the nanoscale, preparation of nanocomposite films containing metal nanoparticles ( such as silver nanoparticles, copper nanoparticles, zinc oxide nanoparticles) is becoming an important step in manufacturing biomaterials with high antimicrobial activity. Controlled release of antibiotic agents and eliminating free nanoparticles are of equal importance for engineering antimicrobial nanocomposite materials. Compared to traditional chemical 'wet' methods, plasma deposition and plasma polymerization are promising approaches for the fabrication of nanocomposite films with the advantages of gas phase dry processes, effective use of chemicals and applicability to various substrates. In this article, we present a short overview of state-of-the-art engineering of antimicrobial materials based on the use of non-thermal plasmas at low and atmospheric pressure

Control of ion density distribution by magnetic traps for plasma electrons

The effect of a magnetic field of two magnetic coils on the ion current density distribution in the setup for low-temperature plasma deposition is investigated. The substrate of 400 mm diameter is placed at a distance of 325 mm from the plasma duct exit, with the two magnetic coils mounted symmetrically under the substrate at a distance of 140 mm relative to the substrate centre. A planar probe is used to measure the ion current density distribution along the plasma flux cross-sections at distances of 150, 230, and 325 mm from the plasma duct exit. It is shown that the magnetic field strongly affects the ion current density distribution. Transparent plastic films are used to investigate qualitatively the ion density distribution profiles and the effect of the magnetic field. A theoretical model is developed to describe the interaction of the ion fluxes with the negative space charge regions associated with the magnetic trapping of the plasma electrons. Theoretical results are compared with the experimental measurements, and a reasonable agreement is demonstrated. © 2012 American Institute of Physics

Characterization of a DC-driven microplasma between a capillary tube and water surface

A microplasma generated between a stainless-steel capillary and water surface in ambient air with flowing argon as working gas appears as a bright spot at the tube orifice and expands to form a larger footprint on the water surface, and the dimensions of the bell-shaped microplasma are all below 1 mm. The electron density of the microplasma is estimated to be ranging from 5.32 × 109 cm−3 to 2.02 × 1014 cm−3 for the different operating conditions, which is desirable for generating abundant amounts of reactive species. A computational technique is adopted to fit the experimental emission from the N2 second positive system with simulation results. It is concluded that the vibrational temperature (more than 2000 K) is more than twice the gas temperature (more than 800 K), which indicates the non-equilibrium state of the microplasma. Both temperatures showed dependence on the discharge parameters (i.e., gas flow and discharge current). Such a plasma device could be arranged in arrays for applications utilizing plasmainduced liquid chemistry

Plasma-laser assisted synthesis of nanoparticles for antibacterial coatings

The “green synthesis” of colloidal nanoparticles and their application for the antibacterial coatings is based on the plasma-laser assisted ablation in liquids. Nanoparticles are synthesized through the process of laser ablation of target in water, which enables additional advantages in comparison with the other standard wet chemical synthesis, such as simplicity and complete utilization of materials. Furthermore, these nanoparticles are used and tested for antibacterial coatings on polymers, where they are grafted or imbedded through atmospheric pressure plasma assisted processes. The advantages of different coatings made from those nanoparticles are presented as well.Plasmatexinfo:eu-repo/semantics/publishedVersio

Dense Plasmas in Magnetic Traps: Generation of Focused Ion Beams With Controlled Ion-to-Neutral Flux Ratios

Customized magnetic traps were developed to produce a domain of dense plasmas with a narrow ion beam directed to a particular area of the processed substrate. A planar magnetron coupled with an arc discharge source created the magnetic traps to confine the plasma electrons and generate the ion beam with the controlled ratio of ion-to-neutral fluxes. Images of the plasma jet patterns and numerical vizualizations help explaining the observed phenomena

Protein retention on plasma-treated hierarchical nanoscale gold-silver platform

Dense arrays of gold-supported silver nanowires of about 100 nm in diameter grown directly in the channels of nanoporous aluminium oxide membrane were fabricated and tested as a novel platform for the immobilization and retention of BSA proteins in the microbial-protective environments. Additional treatment of the silver nanowires using low-temperature plasmas in the inductively-coupled plasma reactor and an atmospheric-pressure plasma jet have demonstrated that the morphology of the nanowire array can be controlled and the amount of the retained protein may be increased due to the plasma effect. A combination of the neutral gold sublayer with the antimicrobial properties of silver nanowires could significantly enhance the efficiency of the platforms used in various biotechnological processes

Atmospheric pressure plasma and depositions of antibacterial coatings

Healthcare-associated infections (HCAI) are complications of healthcare that result in elevated patient morbidity and mortality. HCAI present a huge financial burden for patients, hospitals and insurers due to extended hospitalisation and associated care. According to the estimations, in the US alone, HCAI affects approximately 2 million patients annually, of whom approximately 90.000 patients die, with an estimated annual cost estimated to range from 28 billion to 45 billion US$. [1] European Union is facing the similar situation, the European Centre for Disease Prevention and control (ECDC) advice that approximately 4.1 million acute care patients acquire a HCAI annually, with 37.000 deaths directly attributed to HCAI. With increasing prevalence of HCAI across European countries and threatening development of antimicrobial resistance to widely used antibiotics, there is a recognised need for novel approach in battle against this healthcare burden [2]. One of the approaches involves a development and fabrication of materials with antimicrobial properties. Usually, these are coatings with integrated antibacterial agent that is responsible for the elimination of microorganisms that come into contact with active surface. There is a variety of different antibacterial compounds integrated in such coatings, such as different antibiotics, chemical compounds, peptides. Recently, metal nanoparticles (NPs) have been increasingly used in designing coatings with antibacterial properties due to their large surface-to-volume ration, physiochemical properties and biological multi-target mechanism of actions. Besides all beneficial properties of NPs their emergence of cytotoxicity is limiting their practical applications in human body. [3-4] To overcome this drawback it is important to design a new class of antibacterial coatings with firmly embedded NPs that allows controlled release of antimicrobial agent into the microenvironment. Atmospheric pressure plasma technology has shown a big promise as an alternative and cost-efficient method for deposition of coatings with antibacterial properties. This contribution explores the potential of plasma-assisted approach for fabrication of antibacterial coatings, containing different metal NPs on medical textiles. Plasma-assisted deposition of coatings was carried out with so-called ˝sandwich technique˝, where nanoparticles were embedded between two layers in order to tailor the desirable ion release and to prolong antibacterial effect of fabrics. Antibacterial effects of different nano-coatings were tested against G+ and G- bacterial species, Staphylococcus aureus and Escherichia coli, respectively. Besides antibacterial properties, potential cytotoxic effects were also studied. The study demonstrates that atmospheric pressure plasma can be an efficient technique for deposition of antibacterial coatings containing metal NPs. Medical textiles with plasma-assisted nano-coatings showed effective antibacterial properties. The choice of proper metal antimicrobial agent and optimal concentration of NPs should be considered in regards to potential cytotoxic effects when these materials would be used in medical environments.info:eu-repo/semantics/publishedVersio

Atmospheric-pressure plasma spray deposition of silver/HMDSO nanocomposite on polyamide 6,6 with controllable antibacterial activity

"Paper presented at the ICON2019 conferences in Çorlu, Tekirdağ, Turkey April 17-19, 2019"Novel coatings containing silver nanoparticles (AgNPs) with strong bonding and controllable antibacterial activity on polyamide 6,6 fabric were produced by dielectric barrier discharge (DBD) plasmaassisted deposition at atmospheric pressure and hexamethyldisiloxane (HMDSO) layers. Silver ion release was tuned using a “sandwich” coating structure to prolong the antibacterial effect. The novel spray-assisted deposition increased deposition rates of AgNPs using atmospheric pressure DBD plasma treatment when an HMDSO layer was applied. An increase in AgNPs deposition in plasma treated samples and antimicrobial activity against Gram-negative (Escherichia coli) for samples with an additional HMDSO layer was observed. These coatings allow the development of new and safe wound dressings able to switch the antimicrobial effect against Gram- positive and Gram-negative bacteria by washing the dressing at high temperature (75 oC) before application.This work was funded by European Regional Development funds (FEDER) through the Competitiveness and Internationalization Operational Program (POCI) – COMPETE and by National Funds through Portuguese Fundação para a Ciência e Tecnologia (FCT) under the project UID/ CTM/00264/2019. Ana Ribeiro acknowledges FCT for its doctoral grant SFRH/BD/137668/2018. Andrea Zille also acknowledges fnancial support of the FCT through an Investigator FCT Research contract (IF/00071/2015) and the project PTDC/CTM-TEX/28295/2017 fnanced by FCT, FEDER, and POCI in the frame of the Portugal 2020 program

DBD plasma treatment and chitosan layers - A green method for stabilization of silver nanoparticles on polyamide 6.6

The addition of silver nanoparticles (AgNPs) to biomedical textiles can be of great interest to protect the materials against microorganisms and prevent their spread. However, the human and environmental over‐exposure to AgNPs is leading to numerous concerns due to their toxicity. In this work, AgNPs were stabilized onto polyamide 6.6 fabrics (PA66) through atmospheric dielectric barrier discharge (DBD) plasma treatment and the use of chitosan (Ch) layers applied by spray. DBD plasma treatment revealed a crucial role in AgNPs adhesion (4.8 and 6.3 At%). A first layer of Ch decreased the AgNPs adhesion in both untreated and DBD plasma‐treated samples but treated samples show higher concentration (1.7 and 4.1 At%). The antibacterial activity was evaluated against Staphylococcus aureus and Escherichia coli after 2 and 24 h, showing a superior action in all samples with DBD plasma treatment after 24 h. The Ch in the first layers of the composites delayed the antimicrobial action of the samples but it also may enhance antimicrobial action. The obtained coatings will allow the development of novel and safe wound dressings with improved AgNPs deposition, controlled ions released and consequently, manage the antimicrobial performance and minimize the AgNPs side effects