ORCID Profile
0000-0003-4529-2257
Current Organisation
University of South Australia
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Publisher: IOP Publishing
Date: 18-04-2013
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: IOP Publishing
Date: 11-07-2016
Publisher: Elsevier BV
Date: 09-2013
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: 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: 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: IOP Publishing
Date: 12-11-2015
Publisher: IOP Publishing
Date: 08-12-2017
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.BIOS.2011.08.028
Abstract: A new methodology for detecting the microbiological state of a wound dressing in terms of its colonization with pathogenic bacteria such as Staphylococcus aureus or Pseudomonas aeruginosa has been developed. Here we report how stabilized lipid vesicles containing self-quenched carboxyfluorescein dye are sensitive to lysis only by toxins/virulence factors from P. aeruginosa and S. aureus but not by a non-toxic Escherichia coli species. The development of the stabilized vesicles is discussed and their response to detergent (triton), bacterial toxin (α-hemolysin) and lipases (phospholipase A(2)). Finally, fabrics with stabilized vesicles attached via plasma deposited maleic anhydride coupling are shown visibly responding to S. aureus (MSSA 476) and P. aeruginosa (PAO1) but not E. coli DH5α in a prototype dressing.
Publisher: Elsevier BV
Date: 09-2011
Publisher: American Chemical Society (ACS)
Date: 28-05-2013
DOI: 10.1021/LA401679U
Abstract: Phospholipid vesicles have been the focus of attention as potential vehicles for drug delivery, as they are biomimetic, easy to produce, and contain an aqueous compartment which can be used to carry hydrophilic material, such as drugs or dyes. Lipid vesicles used for this purpose present a particular challenge, as they are not especially stable and can rapidly break down and release their contents away from the target area, especially at physiological temperatures/environments. This study aims to investigate optimum methods for vesicle stabilization where the vesicles are employed as part of a system or technology that signals the presence of pathogenic bacteria via the effect of secreted cytolytic virulence factors on a sensor interface. A number of approaches have been investigated and are presented here as a systematic study of the long-term (14 day) stability at 37 °C, and at various pHs. The response of vesicles, both in suspension and within hydrogels, to Staphylococcus aureus (RN 4282) and Pseudomonas aeruginosa (PAO1) whole bacteria, and supernatants from overnight cultures of both (containing secreted proteins but free of cells), was measured via a sensitive encapsulated carboxyfluorescein release assay. The results showed that lipid chain length, cholesterol concentration, and stabilization via photopolymer stable components were critical in achieving stability. Finally, dispersion of the optimum vesicle formulation in hydrogel matrixes was investigated, culminating in the in vivo demonstration of a simple prototype wound dressing.
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: 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: IOP Publishing
Date: 21-08-2014
Publisher: Technical Association of Photopolymers, Japan
Date: 2015
Publisher: IOP Publishing
Date: 15-06-2017
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: Begell House
Date: 2015
Publisher: Wiley
Date: 19-02-2020
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.BIOS.2012.09.019
Abstract: This paper describes a biosensing concept for exotoxins secreted by Staphylococcus aureus and Pseudomonas aeruginosa based on the toxin mediated breakdown and subsequent fluorescent dye release from phospholipid vesicles (liposomes). The sensitivity of vesicles to toxins was tuned by altering the lipid and fatty acid composition of the membranes such that vesicles could be engineered to respond to toxins/enzymes from S. aureus only P. aeruginosa only and both S. aureus and P. aeruginosa. Nineteen types of vesicle were made with varying compositions of phosphocholine (PC), phosphoethanolamine (PE), cholesterol and the photo-polymerizable iphile 10,12-tricosadiynoic acid (TCDA). The selectivity of the vesicles was measured via a simple fluorescence "switch on" assay. Sensitivity of the vesicles to 40 clinically derived strains of S. aureus and P. aeruginosa was also demonstrated. This work suggests that this technology could be utilised in a diagnostic tool to discriminate between the species of S. aureus and P. aeruginosa in wound dressings.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-05-2020
Abstract: Wave-controlled transport in fluid provides a novel method to shape and promote biofilm formation for bioengineering applications.
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: 10-12-2015
Publisher: IOP Publishing
Date: 16-04-2015
Publisher: Technical Association of Photopolymers, Japan
Date: 2017
No related grants have been discovered for Sung Ha Hong.