Optical Properties of Amorphous Carbon Thin Films Fabricated Using a High-Energy-Impulse Magnetron-Sputtering Technique.

This paper reports the results of amorphous carbon thin films fabricated by using the gas-impulse-injection magnetron-sputtering method and differing the accelerating voltage (1.0-1.4 kV). The obtained layers were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XRD), and spectroscopic ellipsometry (SE). The analysis of the Raman and XPS spectra point to the significant content of sp3 hybridization in the synthesized materials (above 54-73%). The refractive index of the films is very high-above 2.45 in the infrared spectral range. The band-gap energy (determined using the inversed-logarithmic-derivative method) depends on the discharging voltage and is in the range from 1.58 eV (785 nm) to 2.45 eV (506 nm). Based on the obtained results, we have elaborated a model explaining the a-C layers' formation process.

Synthesis of Copper Nitride Layers by the Pulsed Magnetron Sputtering Method Carried out under Various Operating Conditions.

Copper nitride shows various properties that depend on the structure of the material and is influenced by the change in technical parameters. In the present work, Cu-N layers were synthesized using the pulsed magnetron sputtering method. The synthesis was performed under different operating conditions: direct current (DC) or alternating current (AC) power supply, and various atmospheres: pure Ar and a mixture of Ar + N2. The structural properties of the deposited layers were characterized by X-ray diffraction measurements, and Raman spectroscopy and scanning electron microscopy have been performed. Optical properties were also evaluated. The obtained layers showed tightly packed columnar grain features. The kinetics of the layer growth in the AC mode was lower than that observed in the DC mode, and the layers were thinner and more fine-grained. The copper nitride layers were characterized by the one-phase and two-phase polycrystalline structure of the Cu3N phase with the preferred growth orientation (100). The lattice constant oscillates between 3.808 and 3.815 Å for one-phase and has a value of 3.828 Å for a two-phase structure. Phase composition results were correlated with Raman spectroscopy measurements. Raman spectra exhibited a broad, diffused, and intense signal of Cu3N phase, with Raman shift located at 628-635 cm-1. Studies on optical properties showed that the energy gap ranged from 2.17 to 2.47 eV. The results showed that controlling technical parameters gives a possibility to optimize the structure and phase composition of deposited layers. The reported changes were discussed and attributed to the properties of the material layers and technology method.

Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50µF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp3/sp2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp3/sp2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.

Diamond, graphite, and graphene oxide nanoparticles decrease migration and invasiveness in glioblastoma cell lines by impairing extracellular adhesion.

The highly invasive nature of glioblastoma is one of the most significant problems regarding the treatment of this tumor. Diamond nanoparticles (ND), graphite nanoparticles (NG), and graphene oxide nanoplatelets (nGO) have been explored for their biomedical applications, especially for drug delivery. The objective of this research was to assess changes in the adhesion, migration, and invasiveness of two glioblastoma cell lines, U87 and U118, after ND, NG, and nGO treatment. All treatments affected the cell surface structure, adhesion-dependent EGFR/AKT/mTOR, and ß-catenin signaling pathways, decreasing the migration and invasiveness of both glioblastoma cell lines. The examined nanoparticles did not show strong toxicity but effectively deregulated cell migration. ND was effectively taken up by cells, whereas nGO and NG strongly interacted with the cell surface. These results indicate that nanoparticles could be used in biomedical applications as a low toxicity active compound for glioblastoma treatment.