ORCID Profile
0000-0002-5165-1490
Current Organisation
University of South Australia
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Publisher: American Vacuum Society
Date: 24-04-2015
DOI: 10.1116/1.4918765
Abstract: The transport of plasma generated reactive oxygen species (ROS) across a simple phospholipid membrane mimic of a (real) cell was investigated. Experiments were performed in cell culture media (Dulbecco's modified Eagle's medium, DMEM), with and without 10% serum. A (broad spectrum) ROS reporter dye, 2,7-dichlorodihydrofluorescein (DCFH), was used to detect the generation of ROS by a helium (He) plasma jet in DMEM using free DCFH and with DCFH encapsulated inside phospholipid membrane vesicles dispersed in DMEM. The authors focus on the concentration and on the relative rates (arbitrary units) for oxidation of DCFH [or the appearance of the oxidized product 2,7-dichlorofluorescein (DCF)] both in solution and within vesicles. In the first 1 h following plasma exposure, the concentration of free DCF in DMEM was ∼15× greater in the presence of serum (cf. to the serum-free DMEM control). The DCF in vesicles was ∼2× greater in DMEM containing serum compared to the serum-free DMEM control. These data show that serum enhances plasma ROS generation in DMEM. As expected, the role of the phospholipid membrane was to reduce the rate of oxidation of the encapsulated DCFH (with and without serum). And the efficiency of ROS transport into vesicles was lower in DMEM containing serum (at 4% efficiency) when compared to serum-free DMEM (at 32% efficiency). After 1 h, the rate of DCFH oxidation was found to have significantly reduced. Based upon a synthesis of these data with results from the open literature, the authors speculate on how the components of biological fluid and cellular membranes might affect the kinetics of consumption of plasma generated ROS.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.JHIN.2012.01.008
Abstract: Current methods used for the detection of residual proteinaceous contamination vary in sensitivity and specificity. This is of concern because it increases the risk for transmission of neurodegenerative diseases such as spongiform encephalopathies. To determine the effectiveness of electrolysis-assisted sonication (EAS) for removing residual proteinaceous contamination from surgical grade stainless steel. EAS was used to clean surgical grade 316L stainless steel that had been contaminated with the protein bovine serum albumin. Using nitrogen, an abundant element in proteins, as a marker for the presence of protein, X-ray photoelectron spectroscopy (XPS) was used to quantify the amount of protein remaining on the substrate surface. Cathodic, anodic and dual polarization modes of EAS were investigated using 0.1% NaCl solution (w/v, in deionized water) as the electrolyte medium and 13 V as the polarization voltage. EAS under dual polarization was found to be the most effective method for removing the residual protein layer down to an estimated XPS detection limit of 10 ng/cm(2). Surface roughness and hardness of the stainless steel remained unchanged following EAS treatment, indicating that the procedure does not compromise the material's properties. This relatively inexpensive and quick method of cleaning medical devices using an easily accessible salt-based electrolyte solution may offer a cost-effective strategy for cleaning medical and dental devices made of stainless steel in the future.
Publisher: SPIE
Date: 11-2002
DOI: 10.1117/12.468658
Publisher: IOP Publishing
Date: 22-10-2020
Abstract: To investigate the potential role of the hydroxyl radical ( • OH) in cold atmospheric plasma (CAP) jet treatment, two fluorescence-based methodologies are utilised to measure DNA strand breaks. The first comprises a model system of a double-stranded DNA oligomer, where the respective strand ends are tagged with fluorophore and quencher molecules and the second, a cell culture system reporting DNA strand breaks using the γ -H2AX assay. During the various CAP jet treatments, optical emission spectroscopy is used to detect the • OH in the gas phase and electron spin resonance is used to detect the • OH in solution. The CAP jet production of the • OH is shown to correlate to CAP jet induced DNA damage both with the DNA model and in biological cells. Results indicate that the CAP jet induces a higher degree of DNA damage when the CAP plume is in contact with the target solution. The potential of a ‘plasma screen’ based upon a hydrogel film, as a method to remove the DNA-damaging • OH species from reaching skin cells, is shown to significantly reduce DNA damage whilst facilitating the delivery of hydrogen peroxide. These findings could aid in the development of CAP jet-based applications where DNA damage is the objective (e.g. in cancer treatment) and others where it is to be avoided, e.g. in open-wound treatment and dermatology.
Publisher: SPIE
Date: 21-12-2011
DOI: 10.1117/12.903293
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 11-2010
Publisher: American Physical Society (APS)
Date: 15-12-1985
Publisher: Hindawi Limited
Date: 2012
DOI: 10.1155/2012/839053
Abstract: We present a novel substrate suitable for the high-throughput analysis of cell response to variations in surface chemistry and nanotopography. Electrochemical etching was used to produce silicon wafers with nanopores between 10 and 100 nm in diameter. Over this substrate and flat silicon wafers, a gradient film ranging from hydrocarbon to carboxylic acid plasma polymer was deposited, with the concentration of surface carboxylic acid groups varying between 0.7 and 3% as measured by XPS. MG63 osteoblast-like cells were then cultured on these substrates and showed greatest cell spreading and adhesion onto porous silicon with a carboxylic acid group concentration between 2-3%. This method has great potential for high-throughput screening of cell-material interaction with particular relevance to tissue engineering.
Publisher: Elsevier BV
Date: 09-1984
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3RA42025F
Publisher: IOP Publishing
Date: 13-11-2017
Publisher: Elsevier BV
Date: 04-2010
Publisher: AIP Publishing
Date: 2015
DOI: 10.1063/1.4913367
Abstract: Spatially varied surface treatment of a fluorescently labeled Bovine Serum Albumin (BSA) protein, on the walls of a closed (sealed) microchannel is achieved via a well-defined gradient in plasma intensity. The microchips comprised a microchannel positioned in-between two microelectrodes (embedded in the chip) with a variable electrode separation along the length of the channel. The channel and electrodes were 50 μm and 100 μm wide, respectively, 50 μm deep, and adjacent to the channel for a length of 18 mm. The electrode separation distance was varied linearly from 50 μm at one end of the channel to a maximum distance of 150, 300, 500, or 1000 μm to generate a gradient in helium plasma intensity. Plasma ignition was achieved at a helium flow rate of 2.5 ml/min, 8.5 kVpk-pk, and 10 kHz. It is shown that the plasma intensity decreases with increasing electrode separation and is directly related to the residual amount of BSA left after the treatment. The plasma intensity and surface protein gradient, for the different electrode gradients studied, collapse onto master curves when plotted against electrode separation. This precise spatial control is expected to enable the surface protein gradient to be tuned for a range of applications, including high-throughput screening and cell-biomolecule-biomaterial interactions.
Publisher: Springer Science and Business Media LLC
Date: 08-2017
Publisher: World Scientific Pub Co Pte Lt
Date: 05-1986
DOI: 10.1142/S0217732386000142
Abstract: Covariant quantization of Fermi-Bose supersymmetric gauge theories is formulated within an enlarged superspace (x µ , θ α , ξ m ) with manifest ξ-supertranslation (=extended BRST) and Sp(2) invariance. In Wess-Zumino gauges, the correct ghost and auxiliary field structure emerges by counting arguments for the (N=1) super-Yang-Mills, conformal and Einstein supergravity cases. The super-Yang-Mills case is analyzed in detail for both supercovariant and Wess-Zumino gauge-fixing, with particular emphasis on the Sp(2) assignments of the ghost superfields.
Publisher: IOP Publishing
Date: 08-12-2017
Publisher: AIP Publishing
Date: 07-09-2015
DOI: 10.1063/1.4930874
Abstract: The influence of protein and molecular, ground state oxygen (O2) on the plasma generation, and transport of reactive oxygen and nitrogen species (RONS) in tissue are investigated. A tissue target, comprising a 1 mm thick gelatin film (a surrogate for real tissue), is placed on top of a 96-well plate each well is filled with phosphate buffered saline (PBS, pH 7.4) containing one fluorescent or colorimetric reporter that is specific for one of three RONS (i.e., H2O2, NO2−, or OH•) or a broad spectrum reactive oxygen species reporter (2,7-dichlorodihydrofluorescein). A helium cold atmospheric plasma (CAP) jet contacts the top of the gelatin surface, and the concentrations of RONS generated in PBS are measured on a microplate reader. The data show that H2O2, NO2−, or OH• are generated in PBS underneath the target. Independently, measurements are made of the O2 concentration in the PBS with and without the gelatin target. Adding bovine serum albumin protein to the PBS or gelatin shows that protein either raises or inhibits RONS depending upon the O2 concentration. Our results are discussed in the context of plasma-soft tissue interactions that are important in the development of CAP technology for medicine, biology, and food manufacturing.
Publisher: American Chemical Society (ACS)
Date: 10-03-2023
Publisher: IOP Publishing
Date: 23-11-2018
Publisher: Wiley
Date: 06-01-2017
Publisher: Springer Science and Business Media LLC
Date: 20-06-2017
DOI: 10.1038/S41598-017-03754-1
Abstract: Despite growing interest in the application of atmospheric plasma jets as medical treatment strategies, there has been comparatively little research on the potential genotoxic and cytotoxic effects of plasma jet treatment. In this study, we have employed the cytokinesis block micronucleus cytome (CBMN-Cyt) assay with WIL2-NS B lymphoblastoid cells to test the potential genotoxicity, as well as the cytotoxicity, of toxic species generated in cell culture media by an argon (Ar) plasma jet. Elevated levels of cell death (necrosis) and occurrence of chromosomal damage (micronuclei MN, nculeoplasmic bridge NPBs and nuclear bus, Nbuds) were observed when cells were exposed to plasma jet-treated media. These results provide a first insight into how we might measure the genotoxic and cytotoxic effect of plasma jet treatments (both indirect and direct) in iding human cells.
Publisher: IOP Publishing
Date: 13-12-2022
Abstract: An unresolved issue in the physics of lightning is an explanation for lightning proceeding to the ground by successive luminous steps separated by ‘dark’ times of many microseconds. There is also no explanation of the structure of the dark column connecting the streamer step with the cloud that can be km in length, is electrically conducting, yet has a very low sustaining electric field. It is proposed that these two processes can be explained by the accumulation of singlet delta metastable oxygen molecules excited in the corona pulses of lightning. The step time is necessary for the excitation of large metastable densities to produce significant metastable detachment of electrons from negative ions. The detached electrons form a highly conducting step, initially luminous, that causes a redistribution of electric fields and an increase in the potential and electric fields at the end of the step to make possible a further step by ionization. These features are supported by calculations of densities of electrons, positive ions, negative ions and singlet delta metastable oxygen molecules for the first 7 μ s of a discharge chosen to be initiated by a 50 cm sphere of charged hail particles. The calculated corona streamers produce metastable densities of 10 17 cm −3 near the corona source. These metastables, by electron detachment, produce a conducting cylinder 10 m long with a radius of 1 cm and an electron density ∼10 12 cm −3 that is attributed to being the first step and a lightning ‘leader’. These conducting regions develop within them very low electric fields. Successive steps are likely to combine to form the long conductive columns of lightning that exist before the return stroke. Electron densities in the leader and the column are an equilibrium between electron production by metastable detachment and electron loss by attachment to neutral oxygen molecules, requiring no electric field.
Publisher: Elsevier BV
Date: 02-1985
Publisher: IOP Publishing
Date: 06-1982
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.TIBTECH.2017.07.012
Abstract: Electrically generated cold atmospheric plasma is being intensively researched for novel applications in biology and medicine. Significant attention is being given to reactive oxygen and nitrogen species (RONS), initially generated upon plasma-air interactions, and subsequently delivered to biological systems. Effects of plasma exposure are observed to millimeter depths within tissue. However, the exact nature of the initial plasma-tissue interactions remains unknown, including RONS speciation and delivery depth, or how plasma-derived RONS intervene in biological processes. Herein, we focus on current research using tissue and cell models to learn more about the plasma delivery of RONS into biological environments. We argue that this research is vital in underpinning the knowledge required to realize the full potential of plasma in biology and medicine.
Publisher: IOP Publishing
Date: 16-04-2015
Publisher: Elsevier BV
Date: 12-2011
Publisher: Technical Association of Photopolymers, Japan
Date: 2017
Publisher: MDPI AG
Date: 13-10-2022
Abstract: The study compares how acetyl donor molecules tetraacetylethylenediamine (TAED) and pentaacetate glucose (PAG) improve the antibacterial efficacy of solutions activated with a low-temperature atmospheric-pressure argon plasma jet. Plasma activation of solubilised TAED and PAG produce solutions with different chemical compositions and oxidative potentials. Both acetyl donor molecules enhance the hydrogen peroxide (H2O2) concentration in solution with TAED being more effective compared to PAG. However, PAG is more effective at forming peracetic acid (PAA) from reaction of its acetyl donor groups with plasma generated H2O2. The enhanced oxidative potential of plasma activated TAED and PAG solutions were shown to significantly improve bactericidal activity against common wound pathogens Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus compared to plasma activated water produced without acetyl donors. Furthermore, the oxidative capacity of plasma activated PAG was least affected by the bacterial oxidative defence enzyme catalase, attributed to the high concentration of PAA produced in this formulation. Overall, the above data show that acetyl donors may help improve next generation of antimicrobial formulations produced by plasma, which might help combat increasing problems of antimicrobial resistance.
Publisher: IOP Publishing
Date: 18-04-2013
Publisher: American Chemical Society (ACS)
Date: 21-12-2015
DOI: 10.1021/ACS.LANGMUIR.5B03794
Abstract: This paper reports on the fabrication of a pSi-based drug delivery system, functionalized with an initiated chemical vapor deposition (iCVD) polymer film, for the sustainable and temperature-dependent delivery of drugs. The devices were prepared by loading biodegradable porous silicon (pSi) with a fluorescent anticancer drug c tothecin (CPT) and coating the surface with temperature-responsive poly(N-isopropylacrylamide-co-diethylene glycol inyl ether) (pNIPAM-co-DEGDVE) or non-stimulus-responsive poly(aminostyrene) (pAS) via iCVD. CPT released from the uncoated oxidized pSi control with a burst release fashion (∼21 nmol/(cm(2) h)), and this was almost identical at temperatures both above (37 °C) and below (25 °C) the lower critical solution temperature (LCST) of the switchable polymer used, pNIPAM-co-DEGDVE (28.5 °C). In comparison, the burst release rate from the pSi-pNIPAM-co-DEGDVE s le was substantially slower at 6.12 and 9.19 nmol/(cm(2) h) at 25 and 37 °C, respectively. The final amount of CPT released over 16 h was 10% higher at 37 °C compared to 25 °C for pSi coated with pNIPAM-co-DEGDVE (46.29% vs 35.67%), indicating that this material can be used to deliver drugs on-demand at elevated temperatures. pSi coated with pAS also displayed sustainable drug delivery profiles, but these were independent of the release temperature. These data show that sustainable and temperature-responsive delivery systems can be produced by functionalization of pSi with iCVD polymer films. Benefits of the iCVD approach include the application of the iCVD coating after drug loading without causing degradation of the drug commonly caused by exposure to factors such as solvents or high temperatures. Importantly, the iCVD process is applicable to a wide array of surfaces as the process is independent of the surface chemistry and pore size of the nanoporous matrix being coated.
Publisher: Elsevier
Date: 2011
Publisher: IOP Publishing
Date: 11-07-2016
Publisher: Wiley
Date: 05-03-2012
Publisher: SPIE
Date: 21-12-2008
DOI: 10.1117/12.759260
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0LC00339E
Abstract: A rapid, high-precision method for localised plasma-treatment of bonded PDMS microchannels is demonstrated. Patterned electrodes were prepared by injection of molten gallium into preformed microchannel guides. The electrode guides were prepared without any additional fabrication steps compared to conventional microchannel fabrication. Alignment of the "injected" electrodes is precisely controlled by the photomask design, rather than positioning accuracy of alignment tools. Surface modification is detected using a fluorescent dye (Rhodamine B), revealing a well-defined micropattern with regions less than 100 µm along the length of the microchannel.
Publisher: Elsevier BV
Date: 06-2015
Publisher: Elsevier BV
Date: 06-2004
Publisher: Elsevier BV
Date: 07-2008
Publisher: Wiley
Date: 06-12-2010
Publisher: Wiley
Date: 03-11-2005
DOI: 10.1002/JBM.A.30514
Abstract: Adherent and optically semitransparent thin calcium phosphate (CaP) films were electrochemically deposited on titanium substrates in a modified simulated body fluid at 37 degrees C. Coatings deposited by using periodic pulsed potentials showed better adhesion and better mechanical properties than coatings deposited with use of a constant potential. Scanning electron microscopy was used to study the morphology of the coatings. The coatings displayed a polydispersed porous structure with pores in the range of a few nanometers to 1 mum. Furthermore, X-ray diffractometry and the O(1s) satellite peaks in X-ray photoelectron spectroscopy indicated that the coatings possessed a similar surface chemistry to that of natural bone minerals. These results were confirmed by inductively coupled plasma optical emission spectrometry, which yielded a Ca:P ratio of 1.65, close to that of hydroxyapatite. Contact mode atomic force microscopy (AFM) showed the average thickness of the coatings was in the order of 200 nm. Root-mean-square (RMS) roughness values, also derived by AFM, were shown to be much higher on the titanium-CaP surfaces in comparison with untreated titanium substrates, with RMS values of about 300 and 110 nm, respectively. Cell culture experiments showed that the CaP surfaces are nontoxic to MG63 osteoblastic cells in vitro and were able to support cell growth for up to 4 days, outperforming the untreated titanium surface in a direct comparison. These easily prepared coatings show promise for hard-tissue biomaterials.
Publisher: American Scientific Publishers
Date: 06-2018
Publisher: AIP Publishing
Date: 14-11-2016
DOI: 10.1063/1.4967880
Abstract: The effect of oxidation, oxygenation, and de-oxygenation arising from He gas jet and He plasma jet treatments on the viability of skin cells cultured in vitro has been investigated. He gas jet treatment de-oxygenated cell culture medium in a process referred to as “sparging.” He plasma jet treatments oxidized, as well as oxygenated or de-oxygenated cell culture medium depending on the dissolved oxygen concentration at the time of treatment. He gas and plasma jets were shown to have beneficial or deleterious effects on skin cells depending on the concentration of dissolved oxygen and other oxidative molecules at the time of treatment. Different combinations of treatments with He gas and plasma jets can be used to modulate the concentrations of dissolved oxygen and other oxidative molecules to influence cell viability. This study highlights the importance of a priori knowledge of the concentration of dissolved oxygen at the time of plasma jet treatment, given the potential for significant impact on the biological or medical outcome. Monitoring and controlling the dynamic changes in dissolved oxygen is essential in order to develop effective strategies for the use of cold atmospheric plasma jets in biology and medicine.
Publisher: Elsevier BV
Date: 11-1983
Publisher: AIP Publishing
Date: 04-03-2019
DOI: 10.1063/1.5086522
Abstract: Cold atmospheric pressure plasma jets (plasma) operated in ambient air provide a rich source of reactive oxygen and nitrogen species (RONS), which are known to influence biological processes important in disease. In the plasma treatment of diseased tissue such as subcutaneous cancer tumors, plasma RONS need to first traverse an interface between the plasma-skin surface and second be transported to millimeter depths in order to reach deep-seated diseased cells. However, the mechanisms in the plasma generation of RONS within soft tissues are not understood. In this study, we track the plasma jet delivery of RONS into a tissue model target and we delineate two processes: through target delivery of RONS generated (primarily) in the plasma jet and in situ RONS generation by UV photolysis within the target. We demonstrate that UV photolysis promotes the rapid generation of RONS in the tissue model target's surface after which the RONS are transported to millimeter depths via a slower molecular process. Our results imply that the flux of UV photons from plasma jets is important for delivering RONS through seemingly impenetrable barriers such as skin. The findings have implications not only in treatments of living tissues but also in the functionalization of soft hydrated biomaterials such as hydrogels and extracellular matrix derived tissue scaffolds.
Publisher: American Chemical Society (ACS)
Date: 22-04-2010
DOI: 10.1021/AC100455X
Abstract: There is considerable interest in the highly parallelized mass spectrometry analysis of complex s le mixtures without any time-consuming prepurification. Porous silicon-based laser desorption/ionization mass spectrometry (pSi LDI-MS) is enabling technology for such analysis. Previous studies have focused on pSi surface functionalization to enhance sensitivity of detection and engineer surfaces for s le capture and enrichment in LDI-MS analysis. In this report, we build on this work by showing that surface functionalization of thin pSi films can be extended to the covalent immobilization of antibodies, producing a porous immunoaffinity surface. We demonstrate highly selective mass spectrometric detection of illicit drugs (benzodiazepines) on pSi films displaying antibenzodiazepine antibodies covalently immobilized via isocyanate chemistry. The effects of antibody immobilization conditions, antibody concentration, and surface blocking on LDI-MS performance and selectivity were studied. X-ray photoelectron spectroscopy (XPS) was instrumental in characterizing surface chemistry and optimizing LDI-MS performance. Overall, our approach is suitable for rapid and sensitive confirmatory analysis in forensic toxicology requiring only minimal s le volume and may be applied to other areas requiring small molecular analysis such as metabolomics and pharmacology.
Publisher: IOP Publishing
Date: 28-12-2021
Abstract: This study investigates how addition of a 2nd ground electrode in an argon plasma jet influences the production of hydrogen peroxide (H 2 O 2 ) in deionised water (DIW). Briefly, plasma is ignited by purging argon gas through a quartz tube at 1 l min −1 and applying a sinusoidal voltage of 7 kV (peak–peak) at 23.5 kHz to a high voltage stainless steel needle electrode sealed inside the quartz tube surrounded by one or two copper ring(s) that served as the ground electrode(s) situated downstream of the high voltage electrode. The mechanisms of H 2 O 2 production are investigated through the electrical and optical plasma properties and chemical analysis of the treated DIW. We discover that the addition of a 2nd ground electrode results in higher accumulation of charges on the inner wall surface of the quartz tube of the plasma jet assembly resulting in an increase in the discharge current and dissipated power. This further leads to an increase in the electron temperature that more than doubles the H 2 O 2 production through dissociative recombination of water vapour molecules, whilst still maintaining a biological tissue tolerable gas temperature. The double ground electrode plasma jet is shown to be highly effective at reducing the growth of common wound pathogens ( Pseudomonas aeruginosa and Staphylococcus aureus ) in both planktonic and biofilm states whilst inducing a low level of cytotoxicity in HaCaT keratinocyte skin-like cells under certain conditions. The information provided in this study is useful in understanding the complex physicochemical processes that influence H 2 O 2 production in plasma jets, which is needed to optimise the development of plasma sources for clinical applications.
Publisher: American Chemical Society (ACS)
Date: 21-06-2012
DOI: 10.1021/AM300621K
Abstract: We describe a pH responsive drug delivery system which was fabricated using a novel approach to functionalize biodegradeable porous silicon (pSi) by initiated chemical vapor deposition (iCVD). The assembly involved first loading a model drug (c tothecin, CPT) into the pores of the pSi matrix followed by capping the pores with a thin pH responsive copolymer film of poly(methacrylic acid-co-ethylene dimethacrylate) (p(MAA-co-EDMA)) via iCVD. Release of CPT from uncoated pSi was identical in two buffers at pH 1.8 and pH 7.4. In contrast, the linear release rate of CPT from the pSi matrix with the p(MAA-co-EDMA) coating was dependent on the pH release of CPT was more than four times faster at pH 7.4 (13.1 nmol/(cm(2) h)) than at pH 1.8 (3.0 nmol/(cm(2) h)). The key advantage of this drug delivery approach over existing ones based on pSi is that the iCVD coating can be applied to the pSi matrix after drug loading without degradation of the drug because the process does not expose the drug to harmful solvents or high temperatures and is independent of the surface chemistry and pore size of the nanoporous matrix.
Publisher: MDPI AG
Date: 27-02-2023
Abstract: Low-temperature atmospheric-pressure plasma jets are generally considered a safe medical technology with no significant long-term side effects in clinical studies reported to date. However, there are studies emerging that show plasma jets can cause significant side effects in the form of skin burns under certain conditions. Therefore, with a view of developing safer plasma treatment approaches, in this study we have set out to provide new insights into the cause of these skin burns and how to tailor plasma treatments to mitigate these effects. We discovered that joule heating by the plasma bullet currents is responsible for creating skin burns during helium plasma jet treatment of live mice. These burns can be mitigated by treating the mice at a further distance so that the visible plasma plume does not contact the skin. Under these treatment conditions we also show that the plasma jet treatment still retains its medically beneficial property of producing reactive oxygen species in vivo. Therefore, treatment distance is an important parameter for consideration when assessing the safety of medical plasma treatments.
Publisher: Wiley
Date: 09-07-2020
Publisher: IOP Publishing
Date: 12-11-2015
Publisher: American Physical Society (APS)
Date: 15-04-1985
Publisher: Frontiers Media SA
Date: 03-02-2017
Publisher: AIP Publishing
Date: 02-08-2021
DOI: 10.1063/5.0062787
Abstract: Antibiotics are commonly used as the first line of defense in the treatment of infectious diseases. However, the rise of antimicrobial resistance (AMR) is rendering many antibiotics less effective. Consequently, effective non-antibiotic antimicrobial strategies are urgently needed to combat AMR. This paper presents a strategy utilizing cold plasma for the “on-demand” activation of acetyl donor molecules. The process generates an aqueous-based antimicrobial formulation comprising a rich mixture of highly oxidizing molecules: peracetic acid, hydrogen peroxide, and other reactive oxygen and nitrogen species. The synergistic potent oxidative action between these molecules is shown to be highly effective at eradicating common wound pathogenic bacteria (Pseudomonas aeruginosa and Staphylococcus aureus) and at inactivating a virus (SARS-CoV-2).
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CP03520F
Abstract: The combination of phospholipid vesicle experiments and molecular dynamics (MD) simulations illustrate how lipid oxidation, lipid packing and rafts formation may influence the response of healthy and diseased cell membranes to plasma-derived RONS.
Publisher: Technical Association of Photopolymers, Japan
Date: 2015
Publisher: IOP Publishing
Date: 21-08-2014
Publisher: SPIE
Date: 21-12-2011
DOI: 10.1117/12.903304
Publisher: IOP Publishing
Date: 15-06-2017
Publisher: IOP Publishing
Date: 27-03-2014
Publisher: Begell House
Date: 2015
Publisher: Wiley
Date: 11-08-2011
Publisher: IOP Publishing
Date: 03-2021
Abstract: We explore how to configure an argon atmospheric-pressure plasma jet for enhancing its production of hydrogen peroxide (H 2 O 2 ) in deionised water (DIW). The plasma jet consists of a quartz tube of 1.5 mm inner diameter and 3 mm outer diameter, with an upstream internal needle electrode (within the tube) and a downstream external cylindrical electrode (surrounding the tube). The plasma is operated by purging argon through the glass tube and applying a sinusoidal AC voltage to the internal needle electrode at 10 kV (peak–peak) with a frequency of 23.5 kHz. We study how the following operational parameters influence the production rate of H 2 O 2 in water: tube length, inter-electrode separation distance, distance of the ground electrode from the tube orifice, distance between tube orifice and the DIW, argon flow rate and treatment time. By examining the electrical and optical properties of the plasma jet, we determine how the above operational parameters influence the major plasma processes that promote H 2 O 2 generation through electron-induced dissociation reactions and UV photolysis within the plasma core and in the plasma afterglow but with a caveat being that these processes are highly dependent on the water vapour content from the argon gas supply and ambient environment. We then demonstrate how the synergistic action between H 2 O 2 and other plasma generated molecules at a plasma induced low pH in the DIW is highly effective at decontaminating common wound pathogens Gram-positive Staphylococus aureus and Gram-negative Pseudomonas aeruginosa . The information presented in this study is relevant in the design of medical plasma devices where production of plasma reactive species such as H 2 O 2 at physiologically useful concentrations is needed to help realise the full clinical potential of the technology.
Publisher: Elsevier BV
Date: 07-1983
Publisher: AIP Publishing
Date: 22-08-2022
DOI: 10.1063/5.0104481
Abstract: A conical assembly of six plasma jets arranged in a rectangular pattern for biomedical applications is presented. The conical configuration increases the separation distance between in idual tubes within the assembly that reduces interference between in idual plasma jets and enables the jets to converge at the output, facilitating more uniform treatment as opposed to plasma jet arrays operated in parallel. Electrical and optical diagnostics of the plasma discharges and measurements of H2O2 and NO2− production in de-ionized water are used to characterize the potential suitability of the device for biomedical applications. Particularly, it was found that the efficiency in H2O2 (an important bacterial disinfection agent) production by the conical assembly of six plasma jets was more than nine-fold higher compared to its single plasma jet counterpart and that this could be achieved at a biocompatible temperature of below 300 K. Therefore, the device may find use in biomedical applications, particularly where larger area treatments are required such as for certain wounds and cancer tumors that can span areas of tens of cm2.
Publisher: Elsevier BV
Date: 05-2009
Publisher: World Scientific Pub Co Pte Lt
Date: 10-1986
DOI: 10.1142/S0217732386000579
Abstract: A general procedure for defining gauge-invariant fields is presented. In this way it is possible to associate gauge-variant Green functions, in some particular gauge, with gauge-invariant quantities. This construction can be done regardless of whether a mass shell exists or not and should be useful for the colored sector in quantum chromodynamics.
Publisher: Wiley
Date: 07-06-2018
Abstract: Chronic wounds are a major socio-economic problem. Bacterial infections in such wounds are a major contributor to lack of wound healing. An early indicator of wound infection is an increase in pH of the wound fluid. Herein, we describe the development of a pH-responsive drug delivery device that can potentially be used for wound decontamination in situ and on-demand in response to an increase in the pH of the wound environment. The device is based on a porous silicon film that provides a reservoir for encapsulation of an antibiotic within the pores. Loaded porous silicon is capped with dual plasma polymer layers of poly(1,7-octadiene) and poly(acrylic acid), which provide a pH-responsive barrier for on-demand release of the antibiotic. We demonstrate that release of the antibiotic is inhibited in aqueous buffer at pH 5, whereas the drug is released in a sustainable manner at pH 8. Importantly, the released drug was bacteriostatic against the Pseudomonas aeruginosa wound pathogen. In the future, incorporation of the delivery device into wound dressings could potentially be utilized for non-invasive decontamination of wounds.
Publisher: Informa UK Limited
Date: 2010
Publisher: Begell House
Date: 2021
Publisher: AIP Publishing
Date: 24-11-2021
DOI: 10.1063/5.0078076
Publisher: Informa UK Limited
Date: 2010
No related grants have been discovered for Endre Szili.