170,256 research outputs found
Optical response and ultrafast carrier dynamics of silicene on silver
No full textSilicene can be stabilized in various forms on Ag(111) surface and was recently integrated in field-effect transistors (FET) showing high mobility when Ag is withdrawn. However, strong hybridization effects in silicene superstructures on silver have been invoked as responsible for the disruption of its peculiar electronic properties.
We investigate the role of the Ag(111) metallic support in determining the physical properties of the Si/Ag interface, by means of theoretical calculations of the optical response of the supported system. Ab initio simulations based on density functional theory show that the silicene/Ag(111) absorption spectra are strongly non-additive, while the presence of the silicene layer still produces a clear signature. Individual contributions to the spectra are singled out, allowing us to quantify the role of electronic transitions involving silver and silicon states. Silver states, in particular, are found to provide a huge contribution to the optical absorption of silicene on silver, compatible with a strong Si-Ag hybridization. The same conclusions are derived for amorphous two-dimensional Si layers. The results point to a dimensionality-driven peculiar dielectric response of the silicon/silver interface, which is confirmed by means of measurements by Transient-Reflectance spectroscopy. These observations show a metallic-like carrier dynamics, both for silicene and ultra-thin amorphous silicon, hence providing an optical demonstration of the strong hybridization arising in silicene/Ag(111) systems [1].
[1] E. Cinquanta, G. Fratesi, S. dal Conte, C. Grazianetti, F. Scotognella, S. Stagira, C. Vozzi, G. Onida, and A. Molle, Phys. Rev. B 92, 165427 (2015
Design, characterization and modeling of microfabricated Soft-MI for ophthalmologic applications.
No full textSOFT-MI: Integration of Soft-Lythography and Molecular Imprinting such as a Novel Microfabrication Technique
No full textInfluence on shear stress on cell morphology and of endothelin-1 release using a laminar flow bioreactor
No full text
Influence of physical and structural stimuli on cell morphology and on Endothelin-1/nitric Oxide release
No full textGelatin and carbon-based nanotubes scaffold for cardiac tissue engineering: A preliminary study
No full textObjectives: A realistic goal for cardiac muscle engineering is the design of a scaffold able to mimic both the tissue-specific architecture and mechanical properties as well as the main physiological functions. The aim of this study was the set up of gelatin and carbon nanotubes (CNT) scaffolds for cardiac tissue engineering applications.
Materials and methods: Gelatin-based scaffolds (Sc) and CNT in percentage of 0.3% and 0.9% (n = 12), cross-linked with genepin 0.2%, were prepared. H9c2 cell line was cultured for 10 days in DMEM, supplemented with 10% of FBS (C10%, n = 10). Myoblast differentiation was induced by adding 1% FBS (C1%, n = 6), while cardiac phenotype by 10 nM all trans-retinoic acid (CRA, n = 6). Cell viability, citotoxicity, phenotype differentiation and immunohistochemical assay were performed. After 10 days cells and Sc were collected in tri-reagent and RNA was extracted for RealTime PCR analysis. In order to evaluate cardiac phenotype, the natriuretic peptide (NP) and endothelin (ET) system were studied. To confirm cellular interaction by gap junction formation, connexin (CX)-43 was measured.
Results: Immunohystochemistry study revealed that C1% showed the presence of elongated myotubes, typical of skeletal phenotype and dissimilar from myoblast of control condition. CRA was induced to cardiac phenotype showing round and multinucleated nuclei. Data were also confirmed by a significantly increased expression of NP system in CRA with respect to C10% and C1% except for NP receptor-C that significantly decreased in CRA. Furthermore, CRA revealed an increased of both ET-A and ET-B receptors in parallel with a decreased ET-1 expression with respect to C10% and C1%. In CNT Sc cell viability was similar both at 0.3% than and 0.9% and resulted decreased at 3 days probably for adapting at the Sc. NP and ET system expression decreased in CNT0.3% and CNT0.9% with respect to C10% as well as CX43 mRNA (p < 0.01), mainly due to a lacking of complete differentiation in cardiac phenotype during these few days.
Conclusions: In this study the addition of retinoic acid during serum reduction favours a cardiac phenotype at the expense of skeletal muscle trans-differentiation, confirmed by NP and ET system expression. Moreover, the lacking of a complete differentiation of cells on CNT-Sc highlights the need of more day of culture to realize this process. Nevertheless further analysis on novel biomaterials to enhance cell growth/proliferation and to support the damaged heart will be needed to bring heart tissue engineering into clinical application, these results are a useful starting point to develop new Sc-based biomaterials
Pressure-activated microsyringe composite scaffold of poly(L-lactic acid) and carbon nanotubes for bone tissue engineering
No full textTissue engineering is an innovative interdisciplinary field in which bioengineers and life scientists try to regenerate and reproduce natural tissues through the use of biodegradable structures, called scaffolds, with the aim of mimicking the specific tissue extracellular matrix (ECM). Carbon nanotubes (CNTs) offer a natural platform for obtaining composite microfabricated scaffolds thanks to their excellent mechanical properties and their good biocompatibility. In this study, we microfabricated three‐dimensional (3D) scaffolds by mixing poly(L‐lactic acid) (PLLA) and multiwalled carbon nanotubes (MWCNTs) for bone tissue engineering. We measured their mechanical properties and studied their biocompatibility with human fetal osteoblasts (hFOB 1.19). The 3D microfabricated PLLA/MWCNTs nanocomposite scaffolds showed higher stiffness and cell viability than the pure 3D microfabricated PLLA scaffolds. The results of this preliminary work suggest that biopolymer/CNT microcomposites and nanocomposites could be used as effective building blocks to replace ECMs in bone tissue engineering applications. The final goal is the creation of innovative scaffolds for implants and tissue regeneration
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