Plasma-inspired biomaterials

The first questions which arise when one looks at the title of this special issue are what are plasma-inspired biomaterials, and what is this Special Issue of Journal of Physics D: Applied Physics (JPhysD) all about? Peculiar as it may seem, from a philosophical point of view 'inspiration' is something that influences by idea or is a good idea that connects two at first glance opposite things—plasma and biomaterials. On the one hand, plasma as a discharge state of the gas is considered nowadays as a cutting edge tool which can manipulate objects at the atomic or molecular scale (figure 1). On the other hand, biomaterials are substances that are engineered to possess certain properties which can control the interactions with components of living systems, inducing favourable response from the biological entities, and as such can direct the course of a therapy or diagnostic procedure [1]. In this respect, plasmas can be used to initiating even more favourable or selective responses, making the biomaterials even more suitable for their interaction biological entitiesPeer ReviewedPostprint (author's final draft

Regulating the antibiotic drug release from ß-tricalcium phosphate ceramics by atmospheric plasma surface engineering

Calcium phosphate (CaP) ceramics are of interest in bone substitution due to their good biocompatibility and bioresorbability. Currently certain CaPs in the market are loaded with antibiotics in order to prevent infections but further control is needed over antibiotic release patterns. Cold plasmas have emerged as a useful means of modifying the interactions with drugs through surface modification of polymer materials. In this work we explore the possibility of using atmospheric pressure plasmas as a tool for the surface modification of these CaP materials with newly populated bonds and charges, with views on enabling higher loading and controlled drug release. Herein the surface modification of ß-tricalcium phosphate ceramics is investigated using an atmospheric pressure helium plasma jet as a tool for tuning the controlled release of the antibiotic doxycycline hyclate, employed as a drug model. The surface chemistry is tailored mainly by plasma jet surface interaction with an increasing O/C ratio without changes in the topography as well as by build-up of surface charges. With this surface tailoring it is demonstrated that the atmospheric plasma jet is a new promising tool that leads to the design of a control for drug release from bioceramic matrices.Peer ReviewedPostprint (author's final draft

Reversible carrier-type transition in gas-sensing oxides and nanostructures

Despite many important applications of a-Fe2O3 and Fe doped SnO2 in semiconductors, catalysis, sensors, clinical diagnosis and treatments, one fundamental issue that is crucial to these applications remains theoretically equivocal- the reversible carrier-type transition between n- and p-type conductivities during gas-sensing operations. Here, we give unambiguous and rigorous theoretical analysis in order to explain why and how the oxygen vacancies affect the n-type semiconductors, a-Fe2O3 and Fe doped SnO2 in which they are both electronically and chemically transformed into a p-type semiconductor. Furthermore, this reversible transition also occurs on the oxide surfaces during gas-sensing operation due to physisorbed gas molecules (without any chemical reaction). We make use of the ionization energy theory and its renormalized ionic displacement polarizability functional to reclassify, generalize and to explain the concept of carrier-type transition in solids, and during gas-sensing operation. The origin of such a transition is associated to the change in ionic polarizability and the valence states of cations in the presence of (a) oxygen vacancies and (b) physisorped gas molecules.Comment: To be published in ChemPhysChe

White paper on the future of plasma science and technology in plastics and textiles

This is the peer reviewed version of the following article: “Uros, C., Walsh, J., Cernák, M., Labay, C., Canal, J.M., Canal, C. (2019) White paper on the future of plasma science and technology in plastics and textiles. Plasma processes and polymers, 16 1 which has been published in final form at [doi: 10.1002/ppap.201700228]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."This white paper considers the future of plasma science and technology related to the manufacturing and modifications of plastics and textiles, summarizing existing efforts and the current state‐of‐art for major topics related to plasma processing techniques. It draws on the frontier of plasma technologies in order to see beyond and identify the grand challenges which we face in the following 5–10 years. To progress and move the frontier forward, the paper highlights the major enabling technologies and topics related to the design of surfaces, coatings and materials with non‐equilibrium plasmas. The aim is to progress the field of plastics and textile production using advanced plasma processing as the key enabling technology which is environmentally friendly, cost efficient, and offers high‐speed processingPeer ReviewedPostprint (author's final draft

On diagnostics of an annular-shape radio-frequency plasma jet operating in argon at atmospheric conditions

One of the driving forces behind the development of cold plasma sources at atmospheric pressure is their application in the biomedical field. In this respect, radio-frequency (RF) plasma jets are of particular importance due to their possible safe operation on humans and the generation of the high amount of reactive species. For this reason, we designed an RF plasma jet in co-axial geometry with the possibility of aerosol introduction, where its characteristics were evaluated by electrical diagnostics, optical emission and laser scattering spectroscopy. The RF plasma jet operation and stability of diffuse mode were analysed based on energy balance. It was observed that alpha-mode diffuse discharge characterised by an effluent length up to 5 mm was sustained at a power density below 30 W cm(-3). The gas and rotational temperature were determined by means of spectroscopy methods and compared with the results of direct laser scattering. It was established that the gas temperature obtained from N-2 emission of transition C(3)n(u) -> B(3)n(g) (0, 2) is highly overestimated whereas the gas temperature estimated from OH transition A(2)sigma+ -> X(2)n(i) (0, 0) gave a reasonable agreement with both Rayleigh and Raman spectroscopy. Based on the Rayleigh scattering method, uniform gas temperature distribution in the discharge effluent was found at a power below 15 W with the average temperature below 340 15 K. The low gas temperature of argon plasma jets would allow use of this source in temperature-sensitive material applications including skin treatments

Plasma-induced selectivity in bone cancer cells death

Background Current therapies for bone cancers - either primary or metastatic – are difficult to implement and unfortunately not completely effective. An alternative therapy could be found in cold plasmas generated at atmospheric pressure which have already demonstrated selective anti-tumor action in a number of carcinomas and in more relatively rare brain tumors. However, its effects on bone cancer are still unknown. Methods Herein, we employed an atmospheric pressure plasma jet (APPJ) to validate its selectivity towards osteosarcoma cell line vs. osteoblasts & human mesenchymal stem cells. Results Cytotoxicity following direct interaction of APPJ with cells is comparable to indirect interaction when only liquid medium is treated and subsequently added to the cells, especially on the long-term (72 h of cell culture). Moreover, following contact of the APPJ treated medium with cells, delayed effects are observed which lead to 100% bone cancer cell death through apoptosis (decreased cell viability with incubation time in contact with APPJ treated medium from 24 h to 72 h), while healthy cells remain fully viable and unaffected by the treatment. Conclusions The high efficiency of the indirect treatment indicates that an important role is played by the reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the gaseous plasma stage and then transmitted to the liquid phase, which overall lead to lethal and selective action towards osteosarcoma cells. These findings open new pathways for treatment of metastatic bone disease with a minimally invasive approach.Peer ReviewedPostprint (author's final draft

Plasma deposition of antibacterial nano-coatings on polymeric materials

Non-woven textile materials with antimicrobial properties are of high demands for applications ranging from medical dressing to everyday cleaning products. A plasma assisted route to engineer antimicrobial nano-composite coatings is proposed. Nano-particles of Ag, Cu and ZnO are tested as antimicrobial agents with average nano-particle size of 20-50 nm. Nanoparticles are incorporated in between two layers of an organosilicon film. The effect of the barrier coating on nano-particles release is determined by XPS. Antibacterial efficiency of the samples against P. aeruginosa ATCC 9027 and S. aureus M u50 bacteria shows that all treated samples exhibit higher antibacterial efficiency against S. aureus. The antibacterial efficiency of AgNPs and CuNPs is above 90% which is practically interesting for medical application while ZnONPs shows lower antibacterial efficiency.This work is supported by the M.Era-Net project IWT 140812 “PlasmaTex”.info:eu-repo/semantics/publishedVersio

Non-square-well potential profile and non-blinking effect in graded CdZnSe/ZnSe nanocrystals: An ionization-energy theoretic study

Randomly blinking nanocrystals have given rise to numerous and intense theoretical and experimental investigations recently. An experimental breakthrough was finally made by fabricating the non-blinking Cd$_{1-x}$Zn$_x$Se/ZnSe graded nanocrystal [Nature 459 (2009) 686]. Here, we report (1) an unequivocal and detailed theoretical investigation to understand the properties of the potential-well and the distribution of Zn content with respect to the nanocrystal radius and (2) develop a strategy to find the relationship between the photoluminescence (PL) energy peaks and the potential-well due to Zn distribution in nanocrystals. We found that the non-square-well potential can be varied in such a way that one can indeed control the PL intensity and the energy-level difference (PL energy peaks) in any non-free-electron nanocrystals accurately. This implies that we can either suppress the blinking altogether, or alternatively, manipulate the PL energy peaks and intensities systematically to give non-random blinking. Our theoretical strategy developed here is generic and can be applied to any non-free-electron nanocrystals.Comment: Published online in Nanoscale (2010). Different from published versio

Effect of dispersion solvent on the deposition of PVP-Silver nanoparticles onto DBD plasma-treated polyamide 6,6 fabric and Its antimicrobial efficiency

Supplementary Material: https://www.mdpi.com/2079-4991/10/4/607/s1Polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) dispersed in ethanol, water and water/alginate were used to functionalize untreated and dielectric barrier discharge (DBD) plasma-treated polyamide 6,6 fabric (PA66). The PVP-AgNPs dispersions were deposited onto PA66 by spray and exhaustion methods. The exhaustion method showed a higher amount of deposited AgNPs. Water and water-alginate dispersions presented similar results. Ethanol amphiphilic character showed more affinity to AgNPs and PA66 fabric, allowing better uniform surface distribution of nanoparticles. Antimicrobial effect in E. coli showed good results in all the samples obtained by exhaustion method but using spray method only the DBD plasma treated samples displayed antimicrobial activity (log reduction of 5). Despite the better distribution achieved using ethanol as a solvent, water dispersion samples with DBD plasma treatment displayed better antimicrobial activity against S. aureus bacteria in both exhaustion (log reduction of 1.9) and spray (methods log reduction of 1.6) due to the different oxidation states of PA66 surface interacting with PVP-AgNPs, as demonstrated by X-Ray Photoelectron Spectroscopy (XPS) analysis. Spray method using the water-suspended PVP-AgNPs onto DBD plasma-treated samples is much faster, less agglomerating and uses 10 times less PVP-AgNPs dispersion than the exhaustion method to obtain an antimicrobial effect in both S. aureus and E. coli.This research was funded by FEDER funds through the Operational Competitiveness Program – COMPETE and by National Funds through Fundação para a Ciênciae Tecnologia (FCT) under the project POCI01-0145-FEDER-007136 and UID/CTM/00264/2019. A. Zille also acknowledges financial support of the FCT project PTDC/CTM-TEX/28295/2017 financed by FCT, FEDER and POCI.Isabel Ribeiro (SFRH/BD/137668/2018) acknowledges FCT, Portugal, for its doctoral grant financial support. A. Zille also acknowledges financial support of the FCT project PTDC/CTM-TEX/28295/2017 financed by FCT, FEDER and POCI