Although Titanium and its alloys are generally used for the manufacturing of dental implant abutments, they are typically prone to bacterial infection, due to their implantation in the transgingival region. In close contact with the soft surrounding tissue, the surface may be functionalized in order to improve connective tissue cells adhesion while preventing bacterial penetration at the interface. Ultrafast laser processing of dental implants has demonstrated the potential to obtain unique surface features, down to the nanoscale. With this study, we introduce the possibility to generate laser-induced periodic surface structures (LIPSS) by picosecond laser processing, with periodicity of about 500 nm on large-scale surfaces, in a contamination-free approach. By changing the applied laser dose, different surface coloring of TiAl6V4 samples is obtained due to a gradual surface oxidation, as revealed by depth-profile compositional analyses. In the same time, an increase of the irradiation dose induced the formation of thicker oxide layers, the oxygen content increasing up to ten times. The response of human mesenchymal stem cells (hMSCs) in contact with laser processed surfaces was evaluated to assess samples cytocompatibility. It was demonstrated that large-scale, uniform LIPSS distributed on whole TiAl6V4 surface are beneficial to hMSCs viability and proliferation.
We fabricated hierarchical glass biochips with interior characteristics that can be tailored by adjusting process parameters. By a new derived processing method, termed Femtosecond Laser Assisted chemical Etching Nanoscale Glass Deformation (FLAE-NGD), we have developed graded and hierarchical configurations with dimensions from several hundred micrometers to several hundred nanometers as relevant glass model platforms that mimic cancer cell intravasation-extravasation processes. We were able to control the dimensions of both the widths and lengths of the channels as well as shape and curvatures of interior glass pillars. Various curvatures were successfully prepared for the study of the migration and invasion processes of cancer. We have further evaluated the effect of x-ray exposure on melanoma cells grown in glass biochips and determined the increase of intracellular reactive oxygen species production and cellular DNA breaks with the applied irradiation dose.
Three dimensionally (3D) engineered scaffolds are a viable alternative to investigate cells in physiologically relevant configurations. Two photon polymerization (TPP) is a 3D maskless laser direct writing technology that employs a focused femtosecond (fs) laser beam to produce a localized chemical reaction with high precision that ultimately leads to polymerization of a photosensitive material inside the focal volume. TPP has the capability of creating synthetic polymer constructs with 3D complex architectures and high resolution far beyond the diffraction limit. TPP was demonstrated to fulfill technical requirements necessary for fabricating personalized 3D scaffolds for tissue engineering and regenerative medicine applications. Herein, we propose the use of polymeric scaffolds fabricated by TPP for cancer research, specifically as model structures for cancer cell invasion assessment in 3D environments. In particular, the aim is to evaluate cancer cell interaction with confined spaces developed in a woodpile-like polymeric scaffold with pore dimensions less than 1 μm in microchannel cross-section. TPP of negative photoresist SU-8 was conducted using a 3D Lithography platform produced by Nanoscribe GmbH. Scaffolds with uniform networks of pores with sizes down to 0.66 μm were successfully produced, which were then used for melanoma cancer cell invasion assays. The scaffolds demonstrated potential for use in testing the invasion potential of melanoma cancer cells in comparison to normal melanocytes. Time-lapse microscopy observations were carried out to assess the optimal intervals for cell analysis in interaction with scaffolds. Preliminary in vitro tests suggested that melanoma-melanocytes co-culture may exhibit a more invasive potential in narrower spaces as compared to normal melanocytes alone, while an inhibitory effect on melanocyte invasion may be attributed to melanoma cells present in co-culture.
The structure and optical properties of AlN thin films synthesized at 800°C by Pulsed Laser Deposition were studied in
terms of ambient nitrogen pressure (10-4-10 Pa) and post-deposition cooling rate (5-25°C/min). X-ray diffraction
patterns showed the films were polycrystalline with predominantly cubic phase and small-sized crystallites. The
refractive index and oscillator energies values were also characteristic of the polycrystalline AlN with cubic structure.
In the present paper, a study concerning the in-vitro behaviour of Hydroxyapatite films obtained by Pulsed Laser
Deposition technique on titanium under different conditions was performed. The structures were immersed in Hank's
Solution for 21 days in accurately controlled environment conditions. Both film and immersion solution changes were
analyzed by means of XRD, SEM, EDX and X-Ray fluorescence respectively.
The obtained results point to an excellent behaviour of the obtained films as bioactive structures, recommending this type
of covering for further analysis in view of its use in orthopedic and dental implantology.
The half-metallic ferromagnetic chromium dioxide (Tc = 390 K) is a prospective material for spintronics applications. We employed pulsed laser deposition (PLD) to grow thin films of various chromium oxides. The experiments have been carried out in oxygen at different dynamical pressures, using a KrF* laser source (λ = 248 nm, τFWHM ≥ 30 ns), various chromium oxide targets, such as CrO3, Cr8O21 (the latter ones both pure and doped with Y and Sb respectively, for stabilization purposes) and sapphire substrates (c-cut). We optimized the laser fluence. To avoid CrO2 reduction to Cr2O3 in very thin films when kept in atmospheric air, we applied a protection with gold. X-ray diffraction, electron microscopy and Raman spectroscopy evidence uniform films containing CrO2.
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