Showing papers in "Plasma Processes and Polymers in 2014"
TL;DR: Plasma-based cancer treatment may be a powerful and practical anti-cancer agent, acting either alone or in combination with other therapies, and there are hints that combining nitrosative stress with oxidative stress via air plasma might avoid this problem.
Abstract: Cold atmospheric plasmas (CAP) formed in air generate reactive oxygen and nitrogen species (RONS). RONS are biologically and therapeutically active agents and experimental evidence suggests that air plasmas shrink tumors by increasing oxidative and nitrosative stress on neoplastic tissue. Most mainline anti-cancer therapies – including ionizing radiation and chemotherapies – also operate primarily via this pro-oxidant, oxidative, and nitrosative stress mechanism. The main disadvantage of these conventional therapies is the development of treatment-resistant cells. A key question for plasma cancer therapies is therefore whether or not cold plasma will lead to similar oxidative stress resistance. However, there are hints that combining nitrosative stress with oxidative stress via air plasma might avoid this problem. Plasma-based cancer treatment may be a powerful and practical anti-cancer agent, acting either alone or in combination with other therapies.
229 citations
TL;DR: These effects support the potential direct (CAP) and indirect (CAP-activated media) applications for adjuvant anti-cancer therapeutics, in a combination with the chemo-, radio-, and nano-therapies.
Abstract: Cold atmospheric plasma (CAP) has just recently been showing promising anti-cancer activities supported by ability to induce cell death via apoptosis and cell cycle arrest leading to tumor cell destruction in vitro, and in vivo. Several studies showed the ability of CAP-activated media to modulate the tumor cell environment a link between the generation of reactive oxygen species/reactive nitrogen species and cancer cell death following CAP treatment. Targeting cancer cells through ROS-mediated mechanisms has become an attractive strategy for effective and selective cancer treatment by exploiting the aberrant redox characteristics of cancer cells. These effects support the potential direct (CAP) and indirect (CAP-activated media) applications for adjuvant anti-cancer therapeutics, in a combination with the chemo-, radio-, and nano-therapies.
165 citations
114 citations
101 citations
TL;DR: Combinations of plasma deposition and treatment processes have been employed to create chemical gradients inside polycaprolactone porous scaffolds, whose micro-morphology has been finely characterized with synchrotron radiation computed micro-tomography and has successfully allowed the increase of cell viability with respect to untreated materials.
Abstract: The improvement of scaffold performances as cell carriers in a tissue implant is still a challenge in tissue engineering. Since cells in contact with a scaffold firstly sense its top surface before interacting with its macro-/micro-porous structure, the insertion of chemical motifs within the body of the scaffold could improve cell colonization through its entire structure. In this study, combinations of plasma deposition and treatment processes have been employed to create chemical gradients inside polycaprolactone porous scaffolds, whose micro-morphology has been finely characterized with synchrotron radiation computed micro-tomography. The graded chemical composition of these scaffolds has successfully allowed the increase of cell viability with respect to untreated materials.
79 citations
TL;DR: The influence of the charged particles in PC and NC on the cell inactivation is caused by different electrophysical effects, which lead nevertheless to an identical consequence: the cell membrane becomes more transparent for neutral reactive species.
Abstract: Inactivation of microorganisms by plasma of a positive (PC) and negative corona (NC) discharge in air at atmospheric pressure was investigated. Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Pseudomonas aeruginosa were chosen for the discharge inactivation. PC and NC produce three types of bactericidal agents, which are ultraviolet radiation (UV), neutral reactive species (R), and electric field and charged particles (E), respectively. We elucidated the contribution of each bioactive agent to the inactivation of S. aureus and P. aeruginosa. The influence of the charged particles in PC and NC on the cell inactivation is caused by different electrophysical effects, which lead nevertheless to an identical consequence: the cell membrane becomes more transparent for neutral reactive species. It gives additional possibility for neutral reactive species to increase the inactivation of cell by biochemical mechanisms. Due to that, total UV + R + E bactericidal effect in PC and NC is approximately the same and great – only a few tens of seconds is enough to inactivate completely S. aureus and P. aeruginosa cells.
68 citations
TL;DR: Findings indicate a significant level of apoptosis in plasma-treated lymphoma cells, which lends insight into progress toward an appropriate therapy for blood cancers using non-thermal DBD plasma.
Abstract: In this paper, we demonstrate the effect of dielectric barrier discharge (DBD) plasma on lymphoma and normal blood mononuclear cells Results indicates enhanced level of reactive oxygen species in U937 cells, which presented a compromised redox status evident from increased NADP+/NADPH levels, reduced GSH/GSSG ratios and decreases in the total endogenous antioxidant activity of cells A plasma treatment drastically reduces cell viability, causing more severe damage to DNA and mitochondria, as determined by means of apoptosis indicators and related genes expression Taken together, these findings indicate a significant level of apoptosis in plasma-treated lymphoma cells This report lends insight into progress toward an appropriate therapy for blood cancers using non-thermal DBD plasma
65 citations
TL;DR: High concentrations of nitrite and nitrate were detected in growth media exposed to the plasma and were found to increase in a time dependent manner post exposure, which indicates a slow release of reactive nitrogen species into the growth media, which is likely to influence cellular response to plasma exposure.
Abstract: The effect of a radio-frequency driven, microscale non thermal atmospheric pressure plasma jet operated in helium with vol. 0.3% molecular oxygen gas admixture, on PC-3 prostate cancer cells has been investigated. The viability of cells exposed to the plasma was found to decrease with increasing plasma exposure time, with apoptosis through caspase and PARP cleavage being observed. High concentrations of nitrite and nitrate were detected in growth media exposed to the plasma and were found to increase in a time dependent manner post exposure. This indicates a slow release of reactive nitrogen species into the growth media, which is likely to influence cellular response to plasma exposure.
60 citations
TL;DR: Treatment with nanosecond-pulsed non-thermal dielectric barrier discharge enhances migration of macrophages in vitro, which is a key initial step towards defense against diseases.
Abstract: Plasma has been shown to be effective against cancer cells both in vitro and in vivo. Several studies have documented the selectivity of plasma against cancer cells with minimal or reduced damage to normal cells. However, complete remission of cancer following plasma treatment has not been achieved yet. In the body, the immune system plays a vital role in the prevention and control of cancer. Presence of cells of the adaptive immune system in the tumor microenvironment is usually an indicator of good prognosis.[1] Since immune cell migration is a key initial step towards defense against diseases, it is important to evaluate the influence of plasma treatment on such cellular functions. Here we show that treatment with nanosecond-pulsed non-thermal dielectric barrier discharge enhances migration of macrophages in vitro.
57 citations
TL;DR: A cell viability assay, which can act as standard procedure to compare plasma sources by the biological effectiveness is proposed and can easily be performed with a minimum of technical equipment, allows the estimation of the biological impact of a plasma source.
Abstract: Commonly, non-thermal plasma sources for medical applications are compared by the quantity of reactive components they produce Here, a different perspective is chosen: A cell viability assay, which can act as standard procedure to compare plasma sources by the biological effectiveness is proposed This assay can easily be performed with a minimum of technical equipment It allows the estimation of the biological impact of a plasma source For maximum flexibility, an indirect plasma treatment procedure is combined with a dilution method The applicability of the assay is demonstrated by assessing the impact of different non-thermal plasma sources (kINPen & kINPen med, µAPPJ, water discharge, DBE) and the use of a series of human cell lines and their response to a kINPen treatment (HaCaT, MV3, Jurkat, THP-1, MRC-5)
55 citations
TL;DR: Results show an enhancement of scaffold biocompatibility, demonstrating that atmospheric plasma technology is a flexible process that can be integrated in “in-line” procedures of biomaterial fabrication and functionalization.
Abstract: In this study, atmospheric pressure non-thermal plasma treatment of electrospun poly(L-lactic acid) scaffolds is used to improve scaffold hydrophilicity and to introduce carboxyl groups on scaffold surface Thermo-mechanical properties, morphology, hydrophilicity, and water uptake of the plasma-treated scaffolds are studied The amount of carboxyl functional groups on the scaffold surface is evaluated using fluorescein isothiocyanate conjugation and microdensitometry The effect of plasma treatment on mouse embryonic fibroblast morphology is assessed through image analysis Results show an enhancement of scaffold biocompatibility, demonstrating that atmospheric plasma technology is a flexible process that can be integrated in “in-line” procedures of biomaterial fabrication and functionalization
TL;DR: In this article, a cyclopropylamine (CPA) polymerization in pulsed and continuous wave radio frequency (RF) discharges leads to the proposition of conditions at which CPA-rich films exhibit a good stability in contact with water.
Abstract: The present investigation of cyclopropylamine (CPA) plasma
polymerization in pulsed and continuous wave radio frequency
(RF) discharges leads to the proposition of conditions at which
amine-rich films exhibit a good stability in contact with
water. The analyses reveal complex structure of CPA plasma
polymers containing hydrocarbon chains, primary and secondary
amines, nitriles and possibly imines. The decomposition of the
monomer in plasma is progressing with the composite parameter
W/F (RF power over monomer flow rate) but, in pulsed
discharges, it is possible to deposit the films with N/C ratio
above 0.24 using higher monomer flow rate. At the optimized
monomer flow rate the 280nm thick film exhibits only 20%
thickness loss after 48h immersion in water and still contains
about 5at% of the NHx environment.
TL;DR: In this paper, an innovative antibacterial thin film with imbedded silver nanoparticles (AgNPs) was investigated through atmospheric pressure plasma deposition, where AgNPs are fed directly into the discharge zone.
Abstract: An innovative antibacterial thin film with imbedded silver nanoparticles (AgNPs) is investigated through atmospheric pressure plasma deposition. The process is based on a single-step fabrication of nanocomposite films where AgNPs are fed directly into the discharge zone. The morphology and stoichiometry of the thin films, characterized with SEM/EDX, GD-OES, and XPS, can be tailored by the plasma parameters and the quantity of introduced AgNPs. An exceptional 32 at% of AgNPs is reached in the work. The antibacterial assays using Escherichia coli and Staphylococcus aureus strains show effective antibacterial activity of the films and indicate that the fabrication of nanocomposite films using atmospheric pressure plasma represents a feasible way to overcome the issue of device related infection.
TL;DR: In this article, the authors investigated the biocidal effect of a plasma jet in a microhollow cathode discharge geometry when operated with air and a dc voltage, and found that NO is the dominant long-lived reaction product with concentrations of several hundreds of ppm.
Abstract: Chemical species that are generated by a plasma jet in a microhollow cathode discharge geometry when operated with air and a dc voltage were investigated. Nitric oxide (NO) is found as the dominant long-lived reaction product with concentrations of several hundreds of ppm. In comparison, the concentrations observed for nitric dioxide (NO2) and ozone (O3) are negligible. The concentrations of NO are increasing with increasing electric power but decreasing with increasing flow rates. Simultaneously, NO2 concentrations are increasing slightly. The results suggest that the observed far reaching biocidal effect of the plasma jet depends on the generation of nitric oxide.
TL;DR: In this paper, it was shown that by adding 3% of H2 and 2% of CH4 most of the oxygen can be trapped at a CO2 conversion of � 2.5%.
Abstract: A crucial step in the plasma splitting of carbon dioxide is the separation of the conversion products, and this is not straightforward, especially for separating O2 from CO2 and CO. In this work the trapping of atomic oxygen by adding a hydrogen source, which enhances the chemical conversion into water, is demonstrated. The experimentaland modellingresults show that by adding 3% of H2 and 2% of CH4 most of the oxygen can be trapped at a CO2 conversion of � 2.5%. The identified products formed by the addition of CH4 or H2 are mainly H2O and in the case of CH4 also H2. Adding a hydrogen source thus leads to the removal of O2, leaving behind a gas mixture that can be more easily separated.
TL;DR: The generated ROS/RNS signals stimulated the burn wound healing process, which were correlated with the angiogenesis and epithelialization processes, and a possible in vivo mechanism for the enhancement of the processes in the plasma-exposed mice is proposed.
Abstract: Non-thermal 0.5% N2/Ar micro-plasma treatment with relatively high NO content was conducted on mice with second-degree burn wounds. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) concentrations in the plasma-exposed tissue lysate were measured. The wound closure kinetics, inflammatory responses, proliferation phase, blood flow, and formation of blood vessels in the mice were then assessed. The results showed that the wound contraction in the plasma-exposed mice occurred five days earlier than that in the control group. The generated ROS/RNS signals stimulated the burn wound healing process, which were correlated with the angiogenesis and epithelialization processes. A possible in vivo mechanism for the enhancement of the processes in the plasma-exposed mice is thereafter proposed.
TL;DR: In this paper, a statistical study on the relationship between the chemical-physical properties of CNTs, which vary by changing the conditions of purification and plasma treatment, and the macroscopic properties of PC-based nanocomposites was performed.
Abstract: This work reports a statistical study on the relationship between the chemical–physical properties of CNTs, which vary by changing the conditions of purification and plasma treatment, and the macroscopic properties of PC-based nanocomposites. CNTs are synthesized and then purified in two different ways and used as fillers for the preparation of PC/CNTs nanocomposites. In some cases, oxygen plasma treatment is carried out to improve their affinity to the matrix. The CNTs are characterized by TGA, ICP/OES, and FT-Raman spectroscopy, titration and morphological analysis. Mechanical, dynamic-mechanical, electrical, and morphological tests are used for characterizing PC/CNTs nanocomposites.
TL;DR: In this article, XPS and FTIR analyses of pps from triisopropyl phosphite (TIP) and diethyl phosphite (DEP) reveal the presence of phosphate and polyphosphate groups, while phosphonate and phosphate are found in pps of co-polymerized 1,7-octadiene and TIP.
Abstract: Phosphate groups are part of biological molecules involved in bio-interfacial phenomena but monomers containing these groups are not volatile enough to be plasma polymerized (pp). Hence monomers with lower oxidation states of P are needed which then does not enable prediction of the oxidation state(s) of P in the pps, nor of possible aging effects. XPS and FTIR analyses of pps from triisopropyl phosphite (TIP) and diethyl phosphite (DEP) reveal the presence of phosphate and polyphosphate groups, while phosphonate and phosphate are found in pps of co-polymerized 1,7-octadiene and TIP. Post-plasma aging and electrical biasing have negligible effects on the oxidation state of P in TIP pps.
TL;DR: The results show that the inactivation efficiencies of C. fulvum are dependent on the plasma density and treatment time, and the APPJ can also provide a novel approach to decrease the rotting rates ofC.
Abstract: Plant diseases resulting from plant pathogens are profoundly affecting crops worldwide. In this study, the tomato pathogen Cladosporium fulvum (C. fulvum) have been inactivated by using the atmospheric-pressure plasma jet (APPJ). The results show that the inactivation efficiencies of C. fulvum are dependent on the plasma density and treatment time. The APPJ with a relatively high plasma density can completely kill the resistant C. fulvum within the treatment time of 60 s. Due to plasma generating electrostatic force, the outer membrane of C. fulvum is disrupted and the cytoplasm is released to the surrounding medium. Both protein and DNA molecules can be destroyed during the plasma inactivation. Meanwhile, the APPJ can also provide a novel approach to decrease the rotting rates of C. fulvum-infected tomato seeds.
TL;DR: Caspase-3 assays reveal that plasma can activate the cells' apoptotic pathways and alter cell morphology, cell reattachment, and kill SCaBER cells in an exposure time dependent and delayed manner.
Abstract: The efficacy of the plasma pencil is studied for its cancer therapeutics effects against the SCaBER cell line. First, the SCaBER cells in media were treated with different exposure times of low temperature plasma (LTP). Secondly, LTP activated media was generated by treating the media prior to adding it to the cells. Cell viability was assayed at 0, 24, 48, and 72 h after treatments. The results indicate that both treatments alter cell morphology, cell reattachment, and kill SCaBER cells in an exposure time dependent and delayed manner. Caspase-3 assays reveal that plasma can activate the cells' apoptotic pathways.
TL;DR: Several examples of reactive molecular dynamics simulations are presented, which contribute to a better understanding of the underlying mechanisms in plasma medicine on the atomic scale, and the interaction of important reactive oxygen plasma species with the outer cell wall of both gram-positive and gram-negative bacteria, and with lipids present in human skin.
Abstract: In this review paper, we present several examples of reactive molecular dynamics simulations, which contribute to a better understanding of the underlying mechanisms in plasma medicine on the atomic scale. This includes the interaction of important reactive oxygen plasma species with the outer cell wall of both gram-positive and gram-negative bacteria, and with lipids present in human skin. Moreover, as most biomolecules are surrounded by a liquid biofilm, the behavior of these plasma species in a liquid (water) layer is presented as well. Finally, a perspective for future atomic scale modeling studies is given, in the field of plasma medicine in general, and for cancer treatment in particular.
TL;DR: In this paper, polyethylene terephthalate (PET) was functionalized using Ar/O2 and NH3/C2H4 plasmas followed by incubation in simulated body fluids (SBF).
Abstract: In this study polyethylene terephthalate (PET) were functionalized using Ar/O2 and NH3/C2H4 plasmas followed by incubation in simulated body fluids (SBF). Hydroxyapatite (HAp) formed on sheets was investigated with the aid of infrared spectroscopy (IR), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and X-ray diffraction (XRD). IR spectra showed that plasma pre-treatments increased the reactivity of PET toward the SBF by generation of polar domains. SEM images indicated that there is a thin and uniform porous layer of HAp with needle-like nanocrystals covering the surface of plasma treated sheets. Amorphous HAp films closely resembled bone compositions which may suggest Ar/O2 and NH3/C2H4 plasmas as potentially useful tools for bone tissue regeneration procedures.
TL;DR: In this article, the catalytic effect of the electrode surface was investigated in a dielectric barrier discharge of CO2 and CH4 at atmospheric pressure, and an increased production of carboxylic acids, especially formic acid, was observed for copper and nickel electrodes.
Abstract: The catalytic effect of the electrode surface is investigated in a dielectric barrier discharge of CO2 and CH4 at atmospheric pressure. An increased production of carboxylic acids, especially formic acid, is observed for copper and nickel electrodes. This suggests the occurrence of CO2 hydrogenation reactions on the metal surface.
TL;DR: In this article, the inactivation efficacy of microwave plasma processed air against vegetative bacteria and bacterial endospores was investigated and the gained results provide inactivation rates up to 6 log in total treatment times (15-30 min) comparable to sterilization treatment times of thermo-sensitive medical devices with ethylene oxide, formaldehyde or H2O2.
Abstract: Plasma is used as a common technology for the treatment and modification of surfaces in a variety of industrial branches. Decontamination of inorganic materials by plasma is possible with deterioration of the materials properties of a few nanometres. The inactivation efficacy of microwave plasma processed air against vegetative bacteria and bacterial endospores was investigated. The gained results provide inactivation rates up to 6 log in total treatment times (15–30 min) comparable to sterilization treatment times of thermo-sensitive medical devices with ethylene oxide, formaldehyde or H2O2. Additions like O2 or O3 did not promote the antimicrobial efficacy. Moreover, this new method is characterized by advantages like no thermal influence, no toxicity for human and environment and low costs.
TL;DR: In this paper, the use of non-thermal plasma to improve the electrospinnability of poly(L-lactic acid) (PLLA) was focused on using the plume of a jet driven by high voltage pulses with rise rate of several kV n−1.
Abstract: This work is focused on the use of non-thermal plasma to improve the electrospinnability of poly(L-lactic acid) (PLLA). The use of toxic high boiling point solvents is minimized to produce high quality solvent free nanofibrous scaffolds for biomedical applications. PLLA polymeric solutions dissolved in pure dichloromethane are exposed to the plasma plume of a jet developed by some of the authors and driven by high voltage pulses with rise rate of several kV ns−1. The effects of peak voltage, pulse repetition frequency, volume of the solution and treatment time on the morphology of electrospun fibers are investigated by means of scanning electron microscope. Electrospinning is performed at different time lapses after the plasma treatment to study the durability of the induced effects.
TL;DR: In this paper, the Junta de Andalucia and the Spanish MINECO have provided financial support for the work of the authors of this paper. But they did not specify the type of financial support.
Abstract: We thank the Junta de Andalucia (Projects
P09-CTS-5189, TEP5283, P12-FQM-2265 and FQM-6900) and
the Spanish MINECO (Projects CONSOLIDER CSD2008-00023,
MAT2010-21228, MAT2010-18447, MAT2011-29194-C02-01) for
financial support.
TL;DR: In this paper, a one-step method for the rapid synthesis of colloidal silver nanoparticles (AgNPs) forbacterial disinfection was presented, and the results showed that the AgNPs had a significant antibacterial activity against those bacteria cells and the minimum inhibition concentration was associated with the type of bacteria and initial bacterial concentration.
Abstract: This paper presents a one-step method for the rapid synthesis of colloidal silver nanoparticles (AgNPs) forbacterialdisinfection.Silverions were electrochemicallyreducedto silveratoms in an AgNO3 solution with the assistance of an atmospheric argon microplasma jet. Dextran was used to stabilize the AgNPs in the liquid solution. Ultraviolet–visible spectroscopy, transmission electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy were used to characterize the synthesized AgNPs. It was found that the size of the nanoparticles can be controlled by adjusting the dextran monomer/ Ag þ molar ratio in the solution. Furthermore, antibacterial activity of the as-synthesized AgNPs against Escherichia coli and Staphylococcus aureus was carried out in liquid as well as on solid growth media, as a function of the AgNPs concentration. The results showed that the AgNPs had a significant antibacterial activity against those bacteria cells and the minimum inhibition concentration was associated with the type of bacteria and initial bacterial concentration.
TL;DR: In this paper, a dielectric barrier discharge (DBD) was fed with a commercial methacrylic anhydride precursor, bearing an anhydric function and two methacrylates groups aiming at producing a highly cross-linked deposit.
Abstract: In this paper, we focused our attention on the elaboration of a hydrolyzable plasma-polymer produced by aerosol-assisted atmospheric pressure plasma process. A dielectric barrier discharge (DBD) was hence fed with a commercial methacrylic anhydride precursor – bearing an anhydride hydrolyzable function and two methacrylates groups aiming at producing a highly cross-linked deposit – to produce thin coatings of plasma-polymerized (pp) methacrylic anhydride. IR and NMR were performed to highlight the retention of the hydrolyzable group. After immersion in water, mass spectrometry analysis was conducted on the aqueous medium to characterize the end-products and consequently confirm the occurrence of a hydrolytic degradation. A huge 80% thickness decrease was finally pointed out by nanoscratch measurements after 10 days.
TL;DR: In this paper, a dielectric barrier discharge system was used for the coatings deposition, coupled with an atomizer for the lactic acid/elastin aerosol feeding.
Abstract: Atmospheric pressure plasmas are acquiring more interest in biomedical applications where synthetic biodegradable polymers modified to impart cells adhesion properties play a crucial role. This paper shows a new approach for the bio functionalization of such materials: inclusion of a biomolecule during the plasma deposition. A dielectric barrier discharge system was used for the coatings deposition, coupled with an atomizer for the lactic acid/elastin aerosol feeding. ATR-FTIR, XPS, and UV–VIS were used to investigate the chemical composition of the coatings. By properly tuning plasma parameters, a good retention of the monomer chemical structure could be obtained in the coatings, as well as the inclusion of elastin in its structure.
TL;DR: The strong correlation between the bactericidal efficacy and the ozone concentration measured by optical absorption spectroscopy suggests that ozone generated by the SMD plasma is the major agent for the bacterial inactivation under the investigated conditions.
Abstract: The composition of the gas for the Surface Micro-Discharge (SMD) plasma system is changed by applying variety of binary mixtures with oxygen, nitrogen and argon. Gram-negative Escherichia coli and gram-positive Enterococcus mundtii bacteria strains are inoculated on agar and exposed to the plasma using different gas mixture ratios either with a fixed applied voltage or with a fixed dissipated power. No bacterial reduction is observed in the absence of oxygen. Higher bactericidal efficacy is observed with higher oxygen fraction in the gas composition for the plasma. A threshold of the oxygen fraction is found where the bacterial reduction does not change much. The strong correlation between the bactericidal efficacy and the ozone concentration measured by optical absorption spectroscopy suggests that ozone generated by the SMD plasma is the major agent for the bacterial inactivation under the investigated conditions.