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Successful plasma-polymerization of acrylic acid (AA), aimed at depositing plasma-polymerized polyacrylic acid (pPAA) coatings stable upon water contact with a high amount of carboxyl groups, using a non-equilibrium atmospheric pressure nanopulsed plasma jet is reported. Special attention is devoted to the surface chemical characterization of the pPAA coatings deposited on pristine and plasma pretreated polymeric substrates. The investigation of the pPAA chemical structure is performed by means of attenuated total reflectance-Fourier transform infrared and X-ray photoelectron spectroscopies. Insights on the morphological characteristics of the coatings are also provided by optical microscopy. An acrylic acid plasma polymerization process, for the deposition of plasma-polymerized polyacryilic acid coatings stable upon water contact with high amount of carboxyl groups, by means of a non-equilibrium atmospheric pressure nanopulsed plasma jet is reported. A thorough characterization of the chemical structure of the coatings, jointly to some insights on their morphological characteristics, is presented.

A single step process for the deposition of nanocomposite coatings with silver nanoparticles (AgNPs) embedded in a plasma-polymerized polyacrylic acid (pPAA) matrix and performed using a non-equilibrium atmospheric pressure plasma jet is presented. Acrylic acid (AA) and AgNPs dispersed in ethanol (EtOH) are used as precursors and are separately injected in the plasma region directly; Ar is used as plasma gas and also as carrier gas for both precursors. Scanning electron microscopy (SEM) and ATR-FTIR analysis show the deposition of a micrometric pPAA coating on the polyethylene (PE) film used as substrate; AgNPs embedded in the polymeric matrix are visible in SEM pictures and their presence is confirmed by XPS and EDS analysis. X-ray photoelectron spectroscopy (XPS) also highlights a high retention of carboxylic groups in the pPAA chemical structure and the surface oxidation of AgNPs. Preliminary results of the antibacterial activity of the co-deposited coatings are presented.

In this work, the effectiveness of atmospheric pressure non-equilibrium plasma, generated by a dielectric barrier discharge and operated in air, in successfully crosslinking water soluble pullulan electrospun fibers is demonstrated. After being exposed to plasma, the fibers show a remarkable capability to preserve structural stability and fiber morphology upon water exposure. The gel fraction and the water absorption are quantified to evaluate the crosslinking efficiency of different plasma operating conditions, and ATR-FTIR characterization provided some insights into plasma-induced modification of pullulan chemical structure.

Atmospheric non-equilibrium plasma is drawing interest as a promising tool for cancer treatment due to its blend of physical and chemical components that can exert anti-tumor effects. In this work, we investigate the effects of plasma treatment, performed by means of a wand electrode DBD driven by nanosecond high voltage pulses, on the viability, proliferation, and cell-cycle distribution of cells of mouse lymphoma. Results for direct treatment, with cell exposed to plasma while suspended in culture medium, and indirect treatment, where cells were added to culture medium previously activated by plasma treatment, are compared. A qualitative characterization by means of high-speed and iCCD imaging of the plasma discharges produced for the different operating conditions adopted in biological experiments, as well as a semi-quantitative study of the reactive species produced by plasma treatment in the culture medium, are also presented.

Widely employed for a steadily increasing number of industrial processes and experimental studies, plasma can be considered as one of the most pervasive and promising technology of our time. Differently from thermal plasmas, the potentialities offered by non-equilibrium plasmas, especially if working at atmospheric pressure, are still far away to be totally understood, since the surprising and sometimes unpredictable results, coming from studies carried out all over the world, bring out the growing versatility of this technology and its suitability for many applications intersecting our daily lives. The present dissertation, organized in two parts, is focused to present and discuss the results obtained from the Ph.D research activities carried out in the wide field of plasma and materials. The first part of the work is mainly aimed at investigating the potentialities of cold atmospheric plasmas (CAP) for the modification of materials, coating deposition and crosslinking of polymers. In the first two chapters, the conventional techniques and the CAP approaches most employed to carry out the processes will be briefly summarized. In the other chapters, organized by topic, the results achieved during the Ph.D research activities in the fields of surface material modification, coating deposition and crosslinking of polymers will be presented and discussed. The second part of the dissertation is linked to the investigation of the potentialities of plasma-induced chemistry in a liquid environment for the synthesis of nanostructures. Similarly to the first one, the second part of the dissertation will present an overview on the conventional and CAP assisted methods for nanostructures synthesis; moreover, in the second part of the last chapter, the Ph.D experimental activities aimed at synthesising CuO quantum dots in a liquid environment will be illustrated.

The use of Plasma Activated Water (PAW) on plants has been reported as a promising tool for the improvement of plants growth [1]; moreover, plasma treatment of water is known to induce the formation of nitrates, nitrites and peroxides and a change in pH, producing PAW with antimicrobial properties [2]. Indeed, conventional management of plant diseases caused by bacteria has been mainly focused on the use of copper compounds and a few biofungicides or, in the case of phytoplasmas, on insect vector chemical control and on infected plant rouging. Treatment of infected plants with PAW represents an innovative alternative in the control of plant diseases caused by phytopathogens. Fundamental investigations are needed to understand the antimicrobial activity of PAW on plants and the possible phytotoxicity induced by such a treatment. In this work, the antibacterial properties of PAW have been investigated with in vivo tests. Experiments were carried out using Sterile Distilled Water (SDW) treated for 10 minutes by means of a dielectric barrier discharge driven by nanosecond pulses with a peak voltage of 19 kV and a pulse repetition frequency of 1 kHz. PAW antibacterial effects were tested on two vegetal models: experimentally infected tomato plants and periwinkles micropropagated shoots. In the case of tomato plants, the roots were soaked for 10 min into PAW or into SDW (positive control); then, the plants were experimentally inoculated by spraying a water suspension of Xanthomonas vesicatoria (Xv) on the leaves and the disease severity was assessed 21 days after. A reduction of the number of leaf spots caused by Xv was observed in the tomatoes plants soaked in PAW compared to positive control. Moreover, no phytotoxicity effect has been detected on treated plants. In the second model, periwinkle micropropagated shoots, maintained in tubes containing MS agar-solidified medium [3] infected with ‘Candidatus phytoplasma asteris’ were treated adding 1 ml of PAW to the surface of the agar in the micropropagation tubes. Preliminary results indicate that treatment by PAW does not induce shoot toxicity and allows an improved detection of phytoplasma presence in shoots and also in liquid phytoplasma isolation medium [4], indeed, after direct PCR, amplicons of the expected lengths were obtained from all the treated shoot, while the use of nested-PCR was required to obtain specific primers amplification from untreated shoots. The reduced symptomatology and the lack of bacterial endophytic colony formation from liquid isolation medium inoculated with treated shoots, induce to speculate that PAW interacts with phytoplasmas and/or with endophytes viability.

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. Non-thermal atmospheric pressure plasma is applied for surface modification of nanofibrous electrospun PLLA scaffolds. The plasma treatment causes a notable increase of scaffold hydrophilicity and wettability and the introduction of carboxylic functional groups. Mouse embryonic fibroblast cells cultured on plasma treated scaffolds show a more elongated and dendritic morphology and a higher vitality than cells cultured on pristine scaffolds.

The bacterial plant disease control is nowadays limited to copper compounds, few resistance inducers and biocontrol agents, but prophylaxis still remains the most important control measure that is poorly explored. Experiments were carried out using sterile distilled water (SDW) treated by a nanopulsed dielectric barrier discharge. The electrodes of the plasma source consisted of aluminum foils, covered by 1 mm thick polystyrene as dielectric; one of the polystyrene dielectrics was shaped with edges in order to contain water to be treated Ten minutes treatment with a peak voltage of 19 kV and a pulse repetition frequency of 1,000 Hz induced in plasma activated water (PAW) the presence of nitrates, nitrites and peroxides, and a pH decrease. After the treatment, PAW was firstly assayed in in vitro experiments, using diffusion and dilution methods, to evaluate its direct efficacy against selected bacterial pathogens such as Erwinia amylovora, Pseudomonas syringae pv. actinidiae and Xanthomonas arboricola pv. pruni. PAW was then assayed in greenhouse trial to evaluate its ability to induce resistance in tomato plants against X. vesicatoria (Xv). PAW was applied at the root apparatus five days before and two days after Xv experimental inoculation; negative and positive controls were Bion®, streptomycin sulphate and SDW, respectively. In in vitro experiments, PAW did not show bacterial inhibition neither using diffusion nor dilution method. In greenhouse no phytotoxicity was detected on tomato plants, disease severity (DS) assessments highlighted a significant disease inhibition and a relative protection of approximately 35%.

This research is part of a wider International study realized starting from 2009 in different European countries (France, Great Britain, Greece, Italy and Romania) among the activities of the “Mediterranean Center for the study of Social Representaions (CeMeRS)” of Naples. The aim of this study, placed in the Structural approach, is to investigate the social representations of the economic crisis among different social groups. The objectives of the research are: a) verify if there are differences between social representations constructed by different social groups; b) explore if and how the social representation of economic crisis has been transformed from 2009 to 2012; c) identify the differences between social representations of economic crisis (SRsEc) in different cultural contexts. It has been used a mixed method approach, useful to investigate both the SRsEc structure and content, in both a synchronic and diachronic perspective. In particular the Hierarchized Evocation method, integrated with a questionnaire of characterization (in 2012), was made to reach the structure, while a semi-structured interview (in 2009) and a structured interview (in 2012) was realized to explore the content. Data were collected in two periods, 2009 and 2012, on the same group of subjects, interviewed at the same time in each country. The participants were 120 subjects for each country involved (30 for each group, balanced on gender), equally distributed in four social categories: university students (second/third year; Faculty of Economics); bank clerks of medium level; shopkeepers; laypeople. Obtained data were treated with the Analysis of Hierarchized Evocations and Similitude Analysis (Evoc/Simi2005); categorial-frequencial content analysis (Atlas.ti); mono and multivariate analysis (SPSS). Results showed that, unless a diffuse salience of Job loss and Uncertainty, fear of future, the different Italian groups of participants had a different social representation of crisis, especially in the case of shopkeepers. This difference was traced also between the three “expert” categories and laypeople as regards the evolutive phase of their representation. A difference was found also between Italian and Greek social representations of crisis, with reference to the meaning of the salient elements and their organization.