Mask-Assisted Deposition of Ti on Cyclic Olefin Copolymer Foil by Pulsed Laser Deposition

Cyclic olefin copolymer (COC) is a novel type of thermoplastic polymer gaining the attention of the scientific community in electronic, optoelectronic, biomedicine and packaging applications. Despite the benefits in the use of COC such as undoubted optical transparency, chemical stability, a good water-vapor barrier and biocompatibility, its original hydrophobicity restricts its wider applicability and optimization of its performances. Presently, we report on the optical and morphological properties of the films of COC covered with Ti in selected areas. The layer of Ti on COC was deposited by pulsed lased deposition processing. The Ti/COC film was characterized by UV-Vis spectroscopy indicating that its transmittance in the visible region decreased by about 20% with respect to the pristine polymer. The quality of the deposited Ti was assessed with the morphology by scanning electron (SEM) and atomic force microscopies (AFM). The modification of the wettability was observed by the sessile drop method indicating a reduction of the native hydrophilicity.

Compositional and Structural Modifications by Ion Beam in Graphene Oxide for Radiation Detection Studies

In the present study, graphene oxide foils 10 μm thick have been irradiated in vacuum using same charge state (one charge state) ions, such as protons, helium and oxygen ions, at the same energies (3 MeV) and fluences (from 5 × 10¹¹ ion/cm² to 5 × 10¹⁴ ion/cm²). The structural changes generated by the ion energy deposition and investigated by X-ray diffraction have suggested the generation of new phases, as reduced GO, GO quantum dots and graphitic nanofibers, carbon nanotubes, amorphous carbon and stacked-cup carbon nanofibers. Further analyses, based on Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis, have indicated a reduction of GO connected to the atomic number of implanted ions. The morphological changes in the ion irradiated GO foils have been monitored by Transmission Electron, Atomic Force and Scanning Electron microscopies. The present study aims to better structurally, compositionally and morphologically characterize the GO foils irradiated by different ions at the same conditions and at very low ion fluencies to validate the use of GO for radiation detection and propose it as a promising dosimeter. It has been observed that GO quantum dots are produced on the GO foil when it is irradiated by proton, helium and oxygen ions and their number increases with the atomic number of beam gaseous ion.

Nanoparticles embedded in a sponge of polydimethylsiloxane by laser ablation in liquid

This work describes the preparation of polydimethylsiloxane (PDMS) sponge with pore sizes of about 50 and 900 µm. The sponges synthetized by the sugar template process were embedded with graphene oxide (GO) and gold nanoparticles (AuNPs) previously produced by laser ablation in liquid. The suspension containing graphene oxide and gold nanoparticles were optically characterized by UV-ViS spectroscopy. The dispersion of the nanoparticles in the PDMS sponges was observed by the Scanning Electron Microscopy (SEM). The biocompatibility of virgin PDMS, PDMS filled with graphene oxide, and with graphene oxide and gold nanoparticles was studied for different types of cell cultures. This study has allowed us to confirm that the PDMS sponge is a good matrix for embedding AuNPs and has highlighted as the presence of GO hinders the aggregation of AuNPs avoiding the use of surfactant and allowing their use in biological applications.

Synthesis of Porous Polydimethylsiloxane Gold Nanoparticles Composites by a Single Step Laser Ablation Process

Typically, polymeric composites containing nanoparticles are realized by incorporating pre-made nanoparticles into a polymer matrix by using blending solvent or by the reduction of metal salt dispersed in the polymeric matrix. Generally, the production of pre-made Au NPs occurs in liquids with two-step processes: producing the gold nanoparticles first and then adding them to the liquid polymer. A reproducible method to synthetize Au nanoparticles (NPs) into polydimethylsiloxane (PDMS) without any external reducing or stabilizing agent is a challenge. In this paper, a single-step method is proposed to synthetize nanoparticles (NPs) and at the same time to realize reproducible porous and bulk composites using laser ablation in liquid. With this single-step process, the gold nanoparticles are therefore produced directly in the liquid polymer. The optical properties of the suspensions of AuNPs in distilled water and in the curing agent have been analyzed by the UV-VIS spectroscopy, employed in the transmission mode, and compared with those of the pure curing agent. The electrical dc conductivity of the porous PDMS/Au NPs nanocomposites has been evaluated by the I–V characteristics. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis have monitored the composition and morphology of the so-obtained composites and the size of the fabricated Au nanoparticles. Atomic force microscopy (AFM) has been used to determine the roughness of the bulk PDMS and its Au NP composites.

Role of Phage Capsid in the Resistance to UV-C Radiations

The conformational variation of the viral capsid structure plays an essential role both for the environmental resistance and acid nuclear release during cellular infection. The aim of this study was to evaluate how capsid rearrangement in engineered phages of M13 protects viral DNA and peptide bonds from damage induced by UV-C radiation. From in silico 3D modelling analysis, two M13 engineered phage clones, namely P9b and 12III1, were chosen for (i) chemical features of amino acids sequences, (ii) rearrangements in the secondary structure of their pVIII proteins and (iii) in turn the interactions involved in phage capsid. Then, their resistance to UV-C radiation and hydrogen peroxide (H2O2) was compared to M13 wild-type vector (pC89) without peptide insert. Results showed that both the phage clones acquired an advantage against direct radiation damage, due to a reorganization of interactions in the capsid for an increase of H-bond and steric interactions. However, only P9b had an increase in resistance against H2O2. These results could help to understand the molecular mechanisms involved in the stability of new virus variants, also providing quick and necessary information to develop effective protocols in the virus inactivation for human activities, such as safety foods and animal-derived materials.

Physical investigations on the radiation damage of graphene oxide by IR pulsed laser

Graphene oxide foils were irradiated by Nd:YAG laser at the moderated intensities of the order of 108 W/cm2 in vacuum. Measurements of atomic emission during the laser irradiation were performed with ion collectors and mass spectrometry, demonstrating a strong emission of carbon, oxygen and hydrogen atoms. Further investigations of the irradiated graphene oxide foils were carried out on pristine and laser irradiated samples by using Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. Results indicate that graphene oxide losses oxygen and hydrogen during the irradiation, changing its carbon content and its chemical and physical properties.