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Polydimethylsiloxane (PDMS) has been irradiated by a ns pulsed IR laser in vacuum and the radiation effects induced by the coherent radiation, above a threshold fluence, produce a non-equilibrium plasma and material ablation. The laser absorption can be enhanced using gold nanoparticles (AuNPs) embedded in the polymer. The laser-generated plasma has been characterized, whereas the ion emission from both the virgin PDMS and the PDMS + AuNPs sheets has been analysed both in mass and energy. Morphological investigations, optical spectroscopy and compositional analyses have been performed. The adopted laser treatment can be employed to modify the properties of PDMS with and without AuNPs inducing a local enrichment of microcrystalline silicon in both cases.

Spherical gold nanoparticles (NPs), 10 nm in diameter, have been dispersed in a type of polydimethylsiloxane, whose polymerisation requires accurate temperature control. At the temperature of 100°C, the polymerisation of the polydimethylsiloxane matrix is completed in 15 min, whereas at room temperature (∼20°C), it takes about 24–48 h. Gold NPs were incorporated into polydimethylsiloxane after which the resulting nanocomposites were placed in an oven preheated to 100°C for different curing times. Both porous and bulk nanocomposites were obtained using a bottom-up approach. Polydimethylsiloxane (PDMS) nanocomposites with the weight-percentage concentration of 0.2% of Au NPs were cured for 15, 30 and 45 min. Different curing times have affected the Au-NP properties. The network of porous PDMS nanocomposite promotes a uniform anchoring of the gold NPs. The porous PDMS nanocomposite samples, prepared using the sugar-template method, have been compared with the bulk counterpart to obtain a full characterisation of the material. The dependence of the morphological and electrical properties of gold NPs on their size has been studied by atomic-force microscopy and two-point-probe electrical-conductivity measurement. The optical performance of the bulk PDMS nanocomposites has been analysed by ultraviolet–visible (UV–vis) spectroscopy in the transmission mode. An enhancement of the absorption was observed after the increase of both the nanocomposite-curing time and the percentage of the Au NPs used as fillers. The fabricated nanocomposite can be used to manufacture optical-sensing devices, switches in optoelectronics and optical waveguides.

A compressible capacitive mechanical pressure sensor has been developed. Porous polydimethylsiloxane (p-PDMS) has been chosen as dielectric insulator because of its dielectric constant value. Gold nanoparticles have been embedded in p-PDMS to change the dielectric properties and to tune its elasticity. p-PDMS and its nanocomposite have been synthesized using the sugar leaching process. The p-PDMS physical characterization, with and without the gold nanoparticles, has been conducted to investigate its elastic response to compressive stresses as a function of both the polymer preparation thermal treatment and the gold nanoparticle concentration. A sensor operating in a low-pressure range between about 100 Pa and 10 kPa with a strain ranging between about 5% and 95% has been realized. Dielectric constant and electrical resistivity measurements have been performed using samples with a starting volume of the order of 1 cm3. The relationship between the dielectric constant, the electrical resistivity and the compressive stress/strain has been also deduced. The described sensor is flexible, biocompatible, water equivalent and can have applications in biomedicine (orthopedic, dentistry), engineering (stress–strain measurements, robotics), and microelectronics (microbalances, stress test on electronic devices).

The INFN-CIMA project deals with the employment of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) for applications in Nuclear Physics. In particular, the project aim is that to use ...

Reduced graphene oxide (rGO) is a two-dimensional material, which is attracting increasing attention due to its special properties. It can be obtained by laser or ion beam irradiations of pristine ...

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.

Different ion beams, with energy from 2 MeV up to 16 MeV at different atomic number, have been employed to irradiate graphene oxide (GO) foils in vacuum. Due to effects of electron and nuclear ion stopping powers, the ion energy deposition reduces the irradiated GO foils and structurally modifies them. The ion bombarded GO foils X-ray diffraction (XRD) investigations have permitted to shed light on the different structural phases induced by the ion energy deposition. The changes in the GO foils pristine structure shift the diffraction main peak towards larger angles and produce new diffraction peaks indicating the presence of new phases, such as reduced GO (rGO), carbon nanotubes (CNT), amorphous carbon (a-C), onion like carbon (OLC) and probably new carbon allotropes. The obtained results indicate that the inner structure of the GO foils becomes more and more compact and dense with the absorbed dose, suggesting that the removal of the functional oxygen groups leads to a near graphite structure with a significant increase of the material mass density. The different structural phase modifications induced by the different ion beams as a function of the stopping power, fluence and dose will be presented and discussed in detail.

Different ion beams, from protons up to gold ions, with energy from 2 MeV up to 16 MeV, have been employed to irradiate graphene oxide (GO) foils in vacuum. The ion energy deposition reduces GO releasing functional oxygen groups. The effect of radiating ions – GO foils interaction has been investigated by Raman spectroscopy, X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). All the performed analyses show that both reduction and damaging depend on the fluence, the energy and the type of radiating ions. In the regime of electron stopping power the reduction is linearly dependent on the absorbed dose, while in the regime of nuclear stopping power an intense damage is produced in GO, altering the Raman spectrum and producing defects and amorphization of the material. The achieved goal was to quantify the GO's response to ionizing radiation with the aim of using the GO foil as a dosimeter for high energy ion beams.

In this paper, the synthesis of macro-porous polydimethylsiloxane (PDMS) sponges decorated with reduced graphene oxide and graphene is described using a top-down approach based on the sugar templating process. Among the multiple assets enjoyed by PDMS, its elasticity and porosity make possible the uniform dispersion of embedded graphene-based material into its structure. Where possible, the optical, surface and morphology properties of both porous PDMS composites and their not porous (bulk) counterparts have been studied. Scanning transmission ion microscopy (STIM), based on the reciprocity between the beam energy loss and the sample areal density, has been used to obtain the images of the sponge internal part. A detailed spatial resolution of the PDMS microstructure has been deduced by the areal density map. The homogeneous dispersion of the fillers was observed by scanning electron microscopy (SEM) and indirectly by light transmittance measures performed in several regions of the PDMS bulk. The reduced graphene oxide and graphene introduced into PDMS significantly improve its electrical conductivity. The porosity of the presented hybrid material holds a key role for good performances in microelectronics and biomedicine.

The presented work deals with the uptake of gold nanoparticles (Au NPs) by M13 phages in solutions. In particular, the Au NPs uptake modalities and their localization in the filamentous phages are evaluated and measured. Gold spherical nanoparticles (with an average diameter of the order of 10 nm) are obtained by laser ablation in water with a sodium citrated surfactant. The interest of such application comes from the possibility to employ living biological structures to transport heavy metallic nanoparticles inside cells of tumoral tissues. Indeed, phages have the capability to introduce Au NPs in the proximity to the cell nucleus, increasing the efficiency of DNA destruction in the tumoral cells by employing low doses of ionizing radiation during radiotherapy and hyperthermia treatments. Several analyses and microscopy characterizations of the prepared phages samples embedding gold nanoparticles are presented, demonstrating that the presence of Au NPs increases the phages imaging contrast.

Measurements of nitrogen diffusion coefficient in graphene oxide (GO) and reduced graphene oxide (rGO) have been performed at different temperatures ranging between 21 °C and 101 °C. GO and rGO foils have been prepared as thin foils with 15 μm in thickness, total surface of about 5 cm2 and active diffusion surface of about 20 mm2. The rGO foils have been obtained by thermal annealing at 170 °C for 30 min in air. The measured room temperature diffusion coefficients, of 3.43 × 10−4 cm2/s for GO and 5.1 × 10−4 cm2/s for rGO, and, at 101 °C, of 5.22 × 10−4 cm2/s for GO and 10.7 × 10−4 cm2/s for rGO, have been obtained with a simple experimental set-up measuring the gas pressure gradient applied to the two faces of the thin foils versus the time. The rGO foils show a significant increasing of the diffusion coefficients with respect to the pristine GO due to the removing of water and some functional oxygen groups which determines the aperture of nanochannels through which the N2 gas diffuses. The thermal activation energy of nitrogen diffusion is evaluated for the two investigated materials. The experimental apparatus to measure the diffusion coefficients, the obtained results, their correlation with the graphene sheets structure and the comparison with the literature data are presented and discussed.

A simple, cost-effective approach to realize a sensitive temperature sensor based on IR laser reduced graphene oxide (IRLrGO) is reported. The sensor has been obtained by irradiating a graphene oxide (GO) film, placed between two thin glass substrates, with a continuous wave diode laser operating at 970 nm along its entire length. A conductive strip, 13 mm long, 300 μm wide and 7 μm thick, has been generated by moving the GO film on an X-Y translator stage with a given velocity with respect to the fixed laser fiber tip position. The laser treatment has given rise to the GO reduction confirmed by the resistance R measurements as well as from SEM, EDX, ATR-FTIR and Raman analyses. The temperature dependence of the conductive strip resistance has been measured in air from 30ˆC to 80ˆC and in high vacuum from 80 K to 300 K. The sample acts as a sensitive and low mass Resistance Temperature Detector (RTD). Such a sensor is biocompatible and requires a very low bias (

Graphene oxide (GO) micrometric foils have been prepared using a graphene oxide solution. A pulsed IR laser at 970 nm wavelength, with a 100 ms pulse duration and an energy between 50 mJ and 0.7 J, has been employed to irradiate the micrometric GO foils in air. Pulsed IR laser irradiation of GO foils promotes the GO reduction in air and, when the GO foils are tightened between two transparent and thin flat glasses, it permits to realize electrically conductive strips, labelled as rGO. Measurements of laser ablation yield in air as a function of the pulse energy, analysis of elemental composition of the samples before and after the irradiation and morphological characterization have been performed. An estimation of both the temperature induced by the laser treatment and the penetration depth is presented. The so-obtained rGO foils can find many interesting applications in microelectronics, engineering and bio-medicine as sensors, detectors, ion strippers and dosimeters.

A new type of ion dosimeter based on graphene oxide (GO) foils is presented and discussed. GO is biocompatible, stable, tissue equivalent and has special chemical and physical properties. The ion i...

A hybrid material incorporating gold nanoparticles (Au-NPs) in polydimethylsiloxane (PDMS) has been synthesized. Gold nanoparticles gained wide interest for their optical, chemical and physical properties, such as surface plasmon oscillations resonant absorption, chemical structure, imaging and sensing. Au-NPs can be conjugated with several functionalizing agents, such as polymeric chains, improving their properties and performances. PDMS composites with weight percentages ranging between 0.1 and 0.2% of spherical Au-NPs (10 nm diameter), were produced. In this work, we report on different dispersion effects of gold nanoparticles in PDMS. The surface morphology was investigated by atomic force microscopy (AFM) and wetting ability analyses. The presence of structures inside both virgin and hybrid PDMS containing Au-NPs was preliminary investigated by Small Angle X-ray Scattering (SAXS). The optical performance of such hybrid material was studied by UV-VIS spectroscopy, in transmission mode. An enhancement of the absorption was reported as a function of increasing percentage of gold nanoparticles and changing the nanoparticles dispersion approach. The presented hybrid material could be promising for many useful applications, such as optical waveguides, sensors and switches in optoelectronics.

The oxygen content in graphene oxide (GO) can be reduced by the ion beam irradiation in high vacuum conditions. The reduction changes the C/O atomic ratio that increases with the absorbed ion dose. Moreover, as the level of reduction increases, the surface flattens and the material becomes denser. At high absorbed doses, greater than about 100 MGy, the material is affected by the high energy deposited with damage radiation effects which make the C/O ratio not proportional to the dose. At low doses, less than about 100 MGy, the C/O atomic ratio shows an optimal linearity with the ion dose and is independent of the ion stopping power, thus assuming the characteristics of a good biocompatible water-tissue equivalent dosimeter. The aim of the work was that to explore the possibility to use GO as ionizing radiation dosimeter for energetic ion beams by the measure of the compositional C/O atomic ratio.

The suitability of graphene oxide (GO) foils as radiation sensitive materials for soft X-ray irradiation is investigated by means of X-ray photoelectron spectroscopy (XPS). In particular GO micrometric foils have been irradiated by soft X-rays at a 1486.6 eV energy at high flux (>1012 photons/cm2s) in ultra-high vacuum. The XPS analysis of the carbon-carbon (CC) and the carbon-oxygen links (CO) characterizes the composition of the first layers of the GO foils. The CC/CO ratio of the high-resolution C1s XPS spectrum is used as dosimetric index. The incident X-ray photons, proportionally to their fluence, partially reduce GO foils decreasing the amount of oxygen groups chemically bonded to carbon network. This decrease causes an increase on the CC/CO ratio that is correlated to the irradiation time, i.e. to the dose absorbed by the GO foil, showing a linear increment with the dose. Our preliminary investigations indicate that GO can be employed to realize a thin foil dosimeter giving a linear response to the absorbed dose in the (275.76 kGy ÷ 8.02 MGy) range. The absorbed dose can be also evaluated by measuring the C/O ratio from the C1s and O1s XPS spectra analysis or with different techniques, as discussed in the paper.

Two well-established electrical insulators, graphene oxide and poly(methylmethacrylate) (PMMA) have been selectively exposed to controlled energy and fluence of ions. Ion micro beam has been propos...

The helical geometry of virus capsid allows simple self-assembly of identical protein subunits with a low request of free energy and a similar spiral path to virus nucleic acid. Consequently, small variations in protein subunits can affect the stability of the entire phage particle. Previously, we observed that rearrangement in the capsid structure of M13 engineered phages affected the resistance to UV-C exposure, while that to H2O2 was mainly ascribable to the amino acids’ sequence of the foreign peptide. Based on these findings, in this work, the resistance to accelerated proton beam exposure (5.0 MeV energy) of the same phage clones was determined at different absorbed doses and dose rates. Then, the number of viral particles able to infect and replicate in the natural host, Escherichia coli F+, was evaluated. By comparing the results with the M13 wild-type vector (pC89), we observed that 12III1 phage clones, with the foreign peptide containing amino acids favorable to carbonylation, exhibited the highest reduction in phage titer associated with a radiation damage (RD) of 35 × 10−3/Gy at 50 dose Gy. On the other hand, P9b phage clones, containing amino acids unfavorable to carbonylation, showed the lowest reduction with an RD of 4.83 × 10−3/Gy at 500 dose Gy. These findings could improve the understanding of the molecular mechanisms underlying the radiation resistance of viruses

Graphene oxide (GO) is an electrical insulator as most of the carbon atoms in this material are sp3-hybridized. Its physical, optical and chemical properties depend on the type and degree of reduction process. Presently, copper ion irradiation of GO foil has been performed at Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf to investigate the behavior of a set of GO foils under this irradiation at low energy and different fluences up to 5 × 1016 ions/cm2. The compositional and optical properties of graphene oxide have been studied as a function of the fluences of implanted copper ions in the wavelength range 400–1000 nm. The results of ellipsometry microscopy, helium Rutherford backscattering spectroscopy, elastic recoil detection analysis, Raman spectroscopy and SEM-EDX measurements will be presented and discussed.

Measurements of electrical conductivity were carried out at temperatures ranging between 77 K and 450 K on high vacuum thermal reduced graphene oxide (rGO) films. The investigated samples were characterized in composition and structure before being analyzed in terms of electrical conduction. Their electrical conductivity was also measured in air at room temperature. Measurements have demonstrated that at first graphene oxide (GO) was not stable both in air and vacuum. It stabilized after having been subjected to 7 thermal cycles under high vacuum conditions, about 10−7 torr, up to a Tmax of 450 K. At room temperature the initial GO material had a very low conductivity, of the order of 10−10 Ω−1 x cm−1, which increased to about 2.5 Ω−1x cm−1 when it was thermal stabilized in rGO. The stabilization process, induced by the high vacuum heating procedure, seems due to a good reduction of GO, which gives rise to such expansion of the conjugated π-electron system that a band-like transport with small thermal activation energies (Ea = 10–50 meV) occurs. The performed electrical conductivity measurements are presented and discussed.

Reduced graphene oxide (rGO) films can be employed as ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivity, low density, high mechanical resistance and high stability. Thin graphene oxide (GO) films with a sub-micron thickness have been synthesized and transformed into reduced GO (rGO) by ion beam irradiations. Physical characterizations of the pristine and ion irradiated GO films have been performed. Measurements of stripping efficiency have been carried out by using helium, lithium, carbon and oxygen ion beams. The rGO stripper films demonstrate a significantly high charge production, comparable to that of the graphite films but with the advantage of a longer lifetime.

In recent years graphene and its derivatives, have attracted scientific interest due to their unique properties. This study is to explore the quality of synthesized graphene oxide and reduced graphene oxide foils under the irradiation of protons and helium ions of the same energy and current. Fully characterizations by Raman spectroscopy, Rutherford backscattering spectrometry and Elastic recoil detection analysis and the relative results are presented. The effects of parameters, such as type of ions, their current and irradiation time, are studied. The quality of large-scale fabrication of graphene oxide and reduced graphene oxide (rGO) is important for industrial and research applications of these materials. An overview on the changes in the optical property and electron conductivity of graphene oxide and reduced graphene oxide under irradiation by protons, helium and carbon ions are also summarized.

Modifications induced by nanosecond Nd:YAG laser irradiation in the graphene oxide properties were investigated. To correlate the effects of laser irradiation with the modifications of the structural, chemical and electrical properties of graphene oxide, 2.5 MeV alpha particle and 2.0 MeV proton beams in Rutherford backscattering spectrometry and elastic recoil detection analysis, and also X-ray photoemission spectroscopy, have been employed. A high ratio of carbon to oxygen atoms was measured in the irradiated graphene oxide, with respect to the virgin one. The localized reduction of graphene oxide film is promising for patterning techniques useful for the graphene-based devices production.

Reduced graphene oxide (rGO) films can be employed as thin ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivities, low density, high mechanical resistance and high stability. The preparation method of the graphene-based films and their physical characterization are presented and discussed. Thin graphene oxide (GO) films with a thickness of from 0.5 up to 2.0 μm have been synthesized and studied to be used as an ion extractor (stripper) in the 3.0 MV Tandetron of the CANAM Laboratory at the Nuclear Physics Institute in Rez, Czech Republic. GO is transformed to rGO also by low ion beam doses. Measurements of stripper efficiency, as the ion transmission factor of films, have been carried out by accelerating different ions, from helium to carbon, having energies from 1.0 up to 16 MeV, and by using different charge states and a current density ranging between about 10 nA/cm2 and 2 μA/cm2. The ion fluence at which the so-obtained graphene oxide films can be undergone exceeds a dose of 1 × 1016 particles/cm2. Furthermore, these stripper films have demonstrated a significantly high charge production, comparable to that of the graphite films. However, the higher mechanical resistance represents an undiscussed advantage with respect to the graphite films.

This work is aimed at studying the growing process of nanostructures electrodeposited from molybdate aqueous solutions at different pH values into pores of polycarbonate membrane templates. The challenging issue was the opportunity to investigate a rather complex deposition process in a confined ambient, where electrochemical conditions are quite different from those usually established for deposition on a flat substrate. Nanostructures were grown from a bath containing Mo7O246– (NH4)6Mo7O24·4H2O) at different concentrations (50–100 g/L), at a constant cathodic current density of 2 mA/cm2 (electrodeposition area ∼8 cm2). Nanostructured deposit was characterized by XRD, EDS, Raman, XPS, and photoelectrochemical spectroscopy. Several parameters have been investigated, such as electrodeposition time, concentration of Mo precursor, and pH. These parameters do not influence the nature of deposit that always consists of mixed valence molybdenum oxides, whereas the nanostructure morphology changes with pH. Nanos...