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This work introduces an innovative new method to transport gold nanoparticles (Au-NPs) toward specific organs using as transporter the M13 filamentous phage. The aim is to improve the radiotherapy efficiency by injecting gold nanoparticles in the tumor tissues in order to increase the effective atomic number and, consequently, to produce higher locally deposited doses. The biocompatible Au-NPs can be bonded to the phage surface for their transport in the biological fluids and tissues. M13 phages can be prepared to arrive in specific tissues and organs depending on their biochemical preparation and functionalization. Evidence about the real attachment of spherical Au-NPs, 10 nm in diameter, to the M13 phages is obtained using different microscopies. Other analyses have been also performed to evaluate the number of gold nanoparticles that can be transported by M13 phages inside the organism. Our results on the study of the spherical Au-NP size distribution, deduced by AFM, EFM, and TEM analyses, have indicated that in average, 2 couples of Au-NPs are attached to each phage. Moreover, the size of the NPs ranges between 10 and 30 nm, demonstrating a little aggregation of the nanoparticles, which remain usefully sized to be vehicled with the blood flux towards specific organs.

A Nd:YAG laser operating at 1064 nm was used to irradiate, at different intensities, graphene oxide foils placed in vacuum and in air. The laser irradiated GO foils were analysed successively by using different techniques such as 2.0 MeV alpha particle Rutherford backscattering spectrometry, X-ray photoemission spectroscopy and SEM-EDX. In particular, in vacuum irradiated graphene oxide samples the oxygen reduction has been observed with increment of the carbon content. In air irradiated GO samples an increase in oxygen has instead been highlighted. Furthermore thermal and chemical effects are induced by the photon irradiation. Results will be presented and discussed.

Gold nanoparticles are more and more used in bio-medical field for their advantages to be employed as contrast medium for diagnostic images and as targets of disease cells in which thermal-therapy or radiotherapy must be applied. In this contest, a suitable concentration of nanoparticles was added to human blood to study in vitro some physical properties of the treated liquid which is prepared to transport the nanoparticles to the different organs where they can be accumulated by metabolic effects. Measurements indicated that the insertion of gold nanoparticles in the human blood improves the blood wetting ability. In particular, the wetting ability of the blood containing or not gold nanoparticles, with respect to different biocompatible solid surfaces, was investigated. Also, the density, tension surface, and viscosity of the solution at room temperature were measured. Results demonstrated that the introduction of gold nanoparticles in the blood, with size distribution centered at about 50 nm, generally improves the wetting ability and changes other properties of the solution, due to the different distributions of the cohesion and adhesion forces.

An evaluation of the improvement in radiotherapy obtained using gold nanoparticles embedded in the tumor tissues is presented for traditional treatments using X-rays and electrons and for innovative proton therapy. The possible nanoparticles’ preparation via physical, by laser ablation in liquids, and chemical techniques is presented. The use of functionalized gold nanoparticles is discussed and results from the study of uptake and decay from mice living systems are reported. The improvement obtainable in medical images and in the dose distribution enhancement in disease tissues with respect to healthy ones is investigated.

We propose very promising gold nanoparticles for medicinal diagnostic and therapy. The synthesis of gold nanoparticles by using laser ablation in liquids and their physical characterization, jointed with their surface plasmon resonance absorptions, high density and atomic number, and high biocompatibility, is presented in the first part of the article. The second part describes aspects of X-ray absorption enhancement due to the presence of gold nanoparticles in the biological liquids and tissues. The third part of the manuscript shows the applications of gold nanoparticles as contrast medium for X-ray diagnostic imaging. We also discuss possibilities of improvement of the radio therapeutic dose released to disease tissues, to which the gold nanoparticles can be locally absorbed, transported, or injected.

An overview of results is given for laser ion sources based on the expanding laser plasma. All these experiments serve as a base for studies of possible, but not yet unambiguously determined mechanisms of ion production under various experimental conditions. The thermal ambipolar acceleration of ions guided either by thermal or suprathermal electrons, are assumed to be responsible for the ion streams expanding backward from the massive targets and registered by standard corpuscular diagnostics methods. A multi peak structure of the ion energy spectra is the most conspicuous phenomenon suggesting the presence of several fast electron groups guiding the plasma expansion and assisting the charge freezing due to the enhanced acceleration. The frequently observed asymmetry of the ion with respect to the laser caustic can be interpreted as the onset of self focusing of the heating laser beam inside the self-created plasma of the developing laser corona (or a pre-pulse plasma either formed by a double pulse or generated spontaneously in the case of a low contrast of the heating pulse) with a dramatic increase in the power density impinging on the target.

Abstract

A study of the laser ablation of a ZnO target has been carried out in vacuum, by using a Nd:Yag laser with a pulse duration of 3 ns, a wavelength of 532 nm and a maximum pulse energy of 150 mJ. The measurements of ablation yields, crater profiles and fast CCD plasma imaging allowed the evaluation of the plasma density. Time-of-flight (TOF) measurements have been also utilized to monitor the ion emission by using a special ion collector placed along the normal to the target surface. Coulomb-Boltzmann-shifted ion energy distributions have been obtained depending on the ions charge states. The plasma temperature was evaluated by such ion energy distributions of the experimental data. A special attention has been devoted to the ion acceleration processes due to the high electric fields generated inside the non-equilibrium plasma. The characterization of the latter and the deposition of ZnO thin films are correlated and discussed.

The nonthermal and nonlinear coupling of strong laser light wave with plasma transfers a part of laser energy into hot electrons and fast ions. The efficiency of these effects depends on the characteristics of a laser pulse, target properties and irradiation geometry.

A Nd:Yag laser operating at 1064?nm, 900?mJ maximum pulse energy and 9?ns pulse duration, is employed to irradiate solid tin targets placed in a high vacuum (10?7?mbar). The Sn plasma produced on the target surface is investigated with different analysis techniques, such as ion collectors, mass quadrupole spectrometry, electron microscopy and surface profilers. Measurements of ablation threshold, ablation yield, atomic and molecular emission, ion and neutral emission are reported. A time-of-flight technique is employed to calculate the velocity and the kinetic energy of the ion emission from the plasma. The angular distributions of the ejected ion species and of their kinetic energy are strongly peaked along the normal to the target surface. A valuation of the electric field generated inside the non-equilibrium plasma is given and discussed.

Laser-beam interaction with expanding plasma was investigated using the PALS high-power iodine-laser system. The interaction conditions are significantly changing with the laser focus spot position. The decisive role of the laser-beam self-focusing, participating in the production of ions with the highest charge states, was proved.

If a laser plasma generated on a slab target with a high Z is left to expand it becomes a very efficient source of highly charged ions. Depending on the parameters of the laser driver, ions with charge states from 1+ up to more than 50+ can be produced, with ion energies ranging from tens of electronvolts up to tens of megaelectronvolts, with no external acceleration. The ion current density may reach tens of milliamperes per square centimetres in a distance of 1 m from the target. They can be used either for a direct accelerator injection, for a hybrid ion source based on the coupling of a laser with an electron cyclotron resonance ion source for an easier evaporation and a pre-ionization of the target material with a subsequent charge state enhancement or for a direct ion implantation, as substrates for the implantation metallic and polymer materials are usually exposed to the laser produced ion streams with an appropriate tuning of the implantation regime to modify their surface properties. Although the interaction of the laser beam with the plasma is a fairly complex process certain fundamental phenomena have been identified based on a careful analysis of the charge–energy spectra of the outgoing ions.

We report on the results concerning the characteristics and the behavior of expanding plasma generated by a Laser Ion Source (LIS). The LIS technique is an efficient means in producing of multi-charged ions utilizing pulsed laser beams. In order to extract Cu ions, in this experiment an XeCl excimer UV laser was employed, providing a power density on the target surface up to 5 × 108 W/cm2. Two typologies of diagnostic systems were developed in order to detect the plasma current and the ion energy. The time-of-flight (TOF) measurements were performed exploiting either a Faraday cup or an Ion Energy Analyzer (IEA). This latter allowed getting quantitative information about the relative ion abundances, their kinetic energy and their charge state. To study the plasma characteristics we measured the total etched material per pulse at 70 mJ. It was 0.235 μg and the overall degree of ionization, 16%. The angular distribution of the ablated material was monitored by optical transmission analysis of the deposited film as a function of the angle with respect to the normal to the target surface. Applying a high voltage to an extraction gap a multi-charged ion beam was obtained; different peaks could be distinguished in the TOF spectrum, resulting from the separation of ions of hydrogen, adsorbed compounds in the target and copper.

The PERUN and PALS iodine laser systems and a Nd : YAG laser have been used for studies of ions emitted from various single element laser plasmas, at both low (I_L~10⁹ W cm⁻²) and high (I_L~10¹⁶ W cm⁻²) laser intensities. Sufficiently high current densities of low-charge ions, with energies only of hundreds of electronvolt, were produced for starting tests of a considered new hybrid ion source, based on coupling of laser ion source to electron cyclotron resonance plasma. Highly charged ions with charge states about 50+ and with energies even higher than 20 MeV were generated at the highest laser intensities (I_L>2×10¹⁴ W cm⁻²). Seven ion sub-groups at least (faster and slower) were recorded and distinguished at these conditions. The existence of an `optimum focus position' in front of the target surface is consistent with the idea that laser interaction with a prepulse-produced plasma improves the conditions for self-focusing. The experimental arrangements and ion diagnostics used for the various laser ion generation experiments are briefly reviewed, as well as our both older and more recent results on the characteristics of the ions, produced at the various laser irradiances, are presented. The results of laser ion implantation experiments using these ions directly (without additional electrostatic acceleration) are also mentioned.

Over the last 20 years the JAK/STAT signal transduction pathway has been extensively studied. An enormous amount of data on different cell signal transduction pathways is now available. The JAK/STAT signal transduction pathway is one of the intracellular signaling pathways activated by cytokines and growth factors that was first studied in the hematopoietic system, but recent data demonstrate that this signal transduction is also greatly utilized by other systems. The JAK/STAT pathway is a signaling cascade that links the activation of specific cell membrane receptors to nuclear gene expression. This review is focused on the role of JAK/STAT signal transduction pathway activation in the central nervous system (CNS).

The experimental results of the investigations on the influence of external magnetic and electric fields on the characteristics of a tungsten ion stream emitted from a plasma produced by the Nd:glass laser (1 J, 1 ns) performed at IPPLM, Warsaw are presented. A negatively biased target up to −15 kV and a magnetic field up to 0.45 T were used in the experiment. A set of ion collectors and an electrostatic cylindrical ion energy analyzer located at small angles with respect to the laser beam axis and at large distances from the target were applied for ion measurements. The effect of an external magnetic field is essential to plasma expansion, but the effect of the retarding potential of the target is very weak in our experimental conditions. The aim of the studies was to prove the possibility of the optimization of ion beam parameters from laser-produced plasma for the particular application as a laser ion source coupled with the electron cyclotron resonance ion source for particle accelerators.

AbstractPolyvinyltoluene is an organic polymer based on a structure of benzenic rings bonded to methylic and vinylic groups. This molecular structure has peculiar luminescent properties in the visible and near ultraviolet wavelength range. The fluorescence induced by photons is investigated as a function of the polymer irradiation with keV–MeV ion beams.Because the luminescence yield is proportional to the radiation energy released by the incident ions to the polymer, these organic materials are employed as scintillators to detect energetic particle in nuclear physics.A significant damage induced by radiation at high stopping power reduces the luminescence yield and degrades the polymer properties. The radiation damage increases with the stopping power of the incident particles. A luminescence yield reduction of about 90% is obtained with an absorbed ion dose of the order of 1014/cm2.

Fluorine-doped polyvinyltoluene (PVT) shows a luminescence peak emission at 432 nm under proton beam irradiation. The conversion efficiency, typically 2% at 60 MeV, has been investigated in the 5–62 MeV proton energy range. The luminescence yield has been measured as a function of the ionization energy loss. The energy loss has been evaluated through a thin ionization chamber in the range 1–10 MeV mm−1. No dose-rate effect has been detected in the adopted proton flux 106–4×108cm−2s−1. The experimental data are discussed by modelling the interaction between proton–organic molecules as electronic excitations, including recombination processes up to the second order.

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AbstractIon beam irradiation of polyvinyltoluene (PVT) induces strong chemical and physical modifications. Using 50—300 keV proton, helium and nitrogen beams, at low doses, below 1012ions/cm2, dehydrogenation and molecular emission of CxHygroups occurs. At higher doses the irradiation induces surface roughness and density increase of the polymer. Main emitted species are H2, C2H2and C3H5. At high ion doses the polymer density may reach 195% of its initial value and the roughness may reach micron dimensions. The densification process is investigated as a function of the ion fluency and ion stopping power.

Duplications of chromosome 15 have been reported in individuals with atypical autism, varying degrees of mental retardation, and epilepsy. The authors report the molecular analysis, neurophysiologic, and clinical evaluation of a 12-year-old boy with atypical autism and epilepsy due to a maternally derived 15q11-q13 duplication. Their findings suggest that this chromosomal region harbors genes for autism and possibly for partial epilepsy that may act in a dose-dependent manner.

Swift ions with 50 MeV energy are used to irradiate bio-polymeric films. Lithium, carbon and oxygen beams, with fluencies ranging between 108and 1013ions/cm2, are swept on large surfaces of hydrogenated and fluorated polymers. The electronic stopping power of the ion induces high rates of ionization, excitation and radical formation along the ion path with production of chain-scission and cross-linking processes which can be investigated by the molecular emission from the irradiated polymer. The radiation damage increases the chemical solubility of the material around the ion track up to distances of the order of 100 nm. A suitable chemical etching removes the damaged material leaving micrometric holes in the polymeric film. This process gives rise to micro-perforated films which can be used as microfilters, with sub-micrometric pore dimension, high selectivity and controllable porosity. Their use is very interesting for special applications in ultra- and micro filtration of biological liquids.

Nitrogen implantation and thermal nitridation processes are investigated to improve the wear resistance of titanium medical devices. Ion implantation uses 80 keV nitrogen ions and doses ranging between 1 × 1017and 5 × 1017/cm2to modify the surface layers up to 140 nm depth. Stable surface layers are obtained at high ion doses by post-annealing at 550°C for 30 min. Thermal processes are developed as a function of the time (20–90 min) and annealing temperature (950–1100°C) in a dry nitrogen atmosphere. The amount of titanium nitride formed dwing the thermal process increases with the annealing temperature and time. Samples are analysed by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). Ion implantation and thermal nitridation processes increase the surface hardness and wear resistance improving the mechanical properties of titanium used for movable devices for total joint replacements, such as the hip and knee protheses.

Metallic screws are becoming more and more useful to join bones or for prothesis support in orthopaedic and dental surgery. High biocompatible materials such as titanium alloys and hydroxyapatite ceramics are making possible the realization of stable fixation devices utilizable in load-bearing applications. The mechanical and biological anchorage of metallic screws to the bone depends on many factors: mechanical screws-bone thread matching, use of cements between bone and screw, chemical-physical treatments of screw surface, use of screw coverage films based on osteointegrating ceramics or active bioglasses, use of porous coverage films to induce bone ingrowth into the pore, and so on. The first step of the research, the aim of the present paper, is the comparison among screws of different shapes and geometric characteristics in order to find the best macromechanical system versus the different load conditions. Static and dynamic tests are applied to the screws mounted on segments of pig spine, in order to measure the mechanical characteristics of the system under tension (pull-out), bending on the principal planes along the axis of the screw and fatigue loads. Physical analysis, obtained using energetic charged particles, such as SEM, RBS, and AES, are used to charactelize the screw surface compositions and morphology.

Thin films of bio-polymers, such as polymethylmetacrylate, polytetrafluoroethylene, polyethylene-terephthalate and polyimide, are efficiently etched in air by UV laser pulses. A different sharp laser fluence threshold for significant etching is measured for each polymer. The thresholds are correlated to the chemical structure and to the wavelength-dependent absorption coefficient of the irradiated polymer. The polymers, having low absorption coefficients, show thresholds of the order of some J/cm2, about one order magnitude higher than polymers having high absorption coefficients. Measurements on the polymer etching rates, in terms of removed molecules per eV at the used 347 nm wavelength, and a discussion on the laser-polymer interaction are presented.An interesting application of the laser ablation process to bio-polymers, concerning the ability to realize microfilters for the bio-medical field by irradiating the polymer surface through a perforated metal mask, is discussed.

Pulsed laser deposition of hydroxyapatite is applied to cover titanium medical prothesis. Laser irradiation of ceramics by power-pulsed ruby laser produces high velocity micron-size particles emission with a narrow ejection plume directed normally to the target surface. Photoemitted particles are deposited on a metal surface at 400°C to obtain a granular film, stoichiometric, polycrystalline, and very adherent to the substrate. Deposited films are highly biocompatible and may be used to induce osteointegration processes of the implanted prothesis with the bone tissues. The comparison between laser and plasma spray depositions of biocerarnics is discussed.

Experimental results on erosion of thin sulphur layers at various temperatures (77-300 K) by MeV He beams are presented. We find a yield of Y=10.5 S-atoms/ion for samples at low temperatures (77 K) and Y∼102 to 103 for samples at RT (300 K). We interpret the results at low temperatures as "true" erosion, i.e. related to the energy transfer from incoming ion to electronic excitations in the target atoms. The enormous yield measured at room temperature as well as those previously published for thick sulphur targets,1,2 can be ascribed to beam-induced heating of the bombarded sulphur.

The effect of keV ion irradiation on the electronic structure of highly oriented pyrolytic graphite has been investigated by means of electronic spectroscopies. Samples were irradiated by a 0.5 keV Ar+ beam with fluences from 3 × 1014 up to 3 × 1015 ions/cm2. In order to investigate the relationship between initial (crystalline) and final (amorphous) structure in ion beam processing, we have compared the electronic states of graphite with those of damaged diamond and polystyrene. Results indicate that the process of amorphization by ion beam is very fast and it stabilizes after a dose corresponding to about one atomic monolayer, producing the same type of amorphous carbon regardless of the virgin material.

The thickness of ice (H2O) layers accreted on a cold finger has been measured by detecting the interference pattern of a He-Ne laser beam (632.8 nm) reflected from the ice surface and from the underlying substrate.Sublimation and/or sputtering from the ice surface have been induced by bombarding the ice layers with 200 keV He+ ion beams. Sublimation rates and sputtering yields have been measured. It has been shown that if sublimation dominates then ice erosion is uniform and no light scattering is observed. If sputtering dominates, surface roughening, evidenced by light scattering, is observed.

Experimental results on erosion of thin sulphur layers by 1.0 MeV He ions are presented in the temperature range between 77 and 300 K.At the lower temperatures (< 200 K) the erosion yield Y is constant and equal to ∼10 atoms per He ion. Y does not depend on the ion current (0.1-3 μA/cm2), while at the higher temperatures (> 200 K) the erosion yield increases strongly up to two orders of magnitude and it depends on the ion current testifying for sublimation induced by beam heating.The method to prepare in situ the sulphur films and analysis techniques used for thickness measurements have been discussed in detail.

Polyvinylidene fluoride (PVDF) films were bombarded with 50-350 keV ion beams with fluences of about 1 × 1015 ions/cm2. Structural modifications induced by the ion beam irradiation were studied 'in situ' by monitoring the desorbed gases from the irradiated polymer by quadrupole mass spectrometry and 'ex situ' by X-ray diffractometry analysis. The chemical yields of the emitted H2 and HF molecules are of the order of 1 desorbed molecule per 100 eV incident energy. The chemical yields of these molecules were investigated as a function of the irradiation conditions and ion fluences. The experimental results are discussed from the standpoint of the chemical evolution induced by ion energy deposition in the bio-polymer.

AbstractRadiation damage of polymethylmetacrylate (PMMA) is investigated irradiating thin films with 100–300 keV helium beams. The damage is deduced by measuring in situthe molecular ejection from the irradiated polymer with a quadrupole mass spectrometer. The main ejected molecular masses are 2, 15, 16, 18, 26, 28 and 44, corresponding to H2, CH3, CH4, H2O, C2H2and CO2, respectively. The heavier ejected masses are 60 and 70, corresponding to C2O2H4and C3O2H2groups, respectively.The molecular ejected yields, in terms of removed molecules per incident ion, and the chemical yields, in terms of ejected molecules per 100 eV deposited energy, are given.The damage induced by ion beams in PMMA is discussed and correlated to the effects produced in plastic scintillators for charged particles detection.

AbstractPolyvinyltoluene (PVT) is an organic polymer employed as base material for many plastic scintillators useful to detect charged particles. Radiation damage in PVT is investigated irradiating the polymer in vacuum with different ion beams (H+, He+, N+and Ar+) as a function of their ion stopping power. The structural modifications indced in the polymer are deduced by monitoring in situ, during the ion irradiation, the molecular desorption from the polymer by a highly sensitive mass-quadrupole spectrometer. The desorbed molecules are detected in the mass range 1–100 amu and the chemical yields are measured with respect to the calibrated gas leaks. Main emitted species are H2, C2H2and C3H5, the yields of which strongly depend on the ion stopping power.As will be discussed, the investigation of radiation damage in PVT permits to extend the results to the damage undergone by plastic scintillators during the detection of charged particles at high energy, such as protons of 10–100 MeV, an energy range useful in nuclear physics and in proton-therapy.

Polyvinylidene fluoride (PVDF) is strongly modified by ion irradiation. PVDF films were bombarded with helium beams, 50-350 keV in energy and ion doses ranging between 1012 and 1015 ion/cm2. Irradiations were performed in vacuum at different temperatures from-150 up to +100°C. Ion irradiation of the fluropolymer produces H2 and HF gas desorption, which yields are proportional to the temperature, as detected 'in situ' by a quadrupole mass spectrometer. The results can be qualitatively explained by assuming that free radicals of hydrogen and fluorine, produced along the ion track, can diffuse throughout the sample, react, and the resulting melecules desorbed from the polymer surface. Residual irradiated polymer remains drastically modified and rich in carbon content.

AbstractPolyvinyltoluene (PVT), a base polymer used for plastic scintillators, has been irradiated with 50–400 keV helium beam with fluency ranging between 109-1015ions/ (cm2s). Structural modifications induced by the ion bombardment are studied in situby monitoring the desorbed species from the irradiated polymer films by a mass quadrupole spectrometer. The main desorbed chemical species are detected at the masses between 2 and 41 but even heavier masses such as monomers, are detected. The chemical yields of the emitted species depend on the molecular mass and, generally, are within 0.01–1 desorbed molecules per 100 eV of deposited energy.The experimental results are discussed from the standpoint of the chemical evolution induced by the ion energy deposition in the scintillating polymeric material.

A new method of dental fluorine prophylaxis based on the chemical reaction induced by UV irradiation in dental enamel has been presented. Fluorine ions from a gel topic can be retained to the dental apatite in the lamp-irradiated samples at about 70% and in the laser-irradiated samples at about 80% of the maximum deposited value. The19F(p,α)16O nuclear reaction was used to measure the fluorine concentrations in the first 3 μm of the enamel of healthy teeth before and after the gel topic applications with and without UV irradiation. This method of dental prefenction resolves the problem of the traditional fluorine prophylaxis which brings fluorine in the enamel without binding the apatite. Con questo lavoro viene presentato un nuovo metodo di fluoroprofilassi dentale basato su una reazione chimica indotta da irraggiamento UV dello smalto dentario. Gli ioni fluoro di un gel applicato topicamente sullo smalto vengono ritenuti dall'apatite dentaria al 70% ed all'80% del valore di massima deposizione per campioni irradiati con lampada o con luce laser, rispettivamente. La reazione nucleare19F(p,α)16O è stata adoperata per misurare le concentrazioni di fluoro nei primi 3 μm dello smalto dio denti sani prima e dopo l'applicazione del gel con e senza irraggiamento UV. Questo metodo di prevenzione dentale risolve il problema della tradizionale fluoroprofilassi che apporta fluoro allo smalto senza legarlo all'apatite. Предлагается новый метод зубной фторовой профилактики, основанной на химической реакции, индуцированной ультрафиолетовым облучением зубной эмали. Ионы фтора могут удерживатжся из геля в зубном апатите при облучении лампой на 70% и при облучении лазером на 80% от максимальной нанесенной величины. Используется ядерная реакция19F(p,α)16O для измерения концентраций фтора в первых 3 мкм эмали здоровых зубов до и после нанесения гелия с и без ультрафиолетового облучения. Этот метод решает проблему традиционной фторовой профилактики, который позволяет вносить фтор в эмаль без повреждения апатита.