Biomimetic electrochemical sensor integrated in flexible polymeric devices for cancer diagnosis

The authors gratefully acknowledge to the project IBEROS, Instituto de Bioingeniería en Red para el Envejecimiento Saludable, PROGRAMA INTERREG 2014-2020, reference POCTEP/0245_IBEROS_1_E and the financial support to CANCER Project through Norte 2020 – Programa Operacional Regional do Norte, reference NORTE-01-0145-FEDER-000029.info:eu-repo/semantics/publishedVersio

Multi-stacks of epitaxial GeSn self-assembled dots in Si: Structural analysis

We report on the growth and structural and morphologic characterization of stacked layers of self-assembled GeSn dots grown on Si (100) substrates by molecular beam epitaxy at low substrate temperature T = 350 °C. Samples consist of layers (from 1 up to 10) of Ge0.96Sn0.04 self-assembled dots separated by Si spacer layers, 10 nm thick. Their structural analysis was performed based on transmission electron microscopy, atomic force microscopy and Raman scattering. We found that up to 4 stacks of dots could be grown with good dot layer homogeneity, making the GeSn dots interesting candidates for optoelectronic device applications.This work was partly supported by the Portuguese Foundation for Science and Technology (FCT) through Strategic Project PEst-C/FIS/UI0607/2013 and PhD Fellowship (F. Oliveira)

Estudio de la citotoxicidad de cerámicas biomórficas de SiC recubiertas con vidrio bioactivo

La necesidad de desarrollar nuevos implantes basados en materiales bioactivos que sean capaces de soportar grandes cargas mecánicas ha llevado a la producción de sustratos metálicos recubiertos con cerámicas bioactivas. Recientemente se ha propuesto un dispositivo alternativo que consiste en un sustrato de carburo de silicio (SiC) biomórfico recubierto con vidrio bioactivo, mediante la técnica de Depósito por Láser Pulsado (PLD), y que dispone de la resistencia mecánica adecuada, además de gran ligereza y una porosidad intrínseca muy favorable de cara a la implantación. En este trabajo se presenta un estudio interdisciplinar de este nuevo material centrado en la morfología y porosidad de sustratos de SiC provenientes de diferentes maderas, la bioactividad de los recubrimientos producidos por PLD y en la evaluación in vitro con células de osteosarcoma MG-63 con la que se ha determinado la citotoxicidad de estos materiales y se ha estudiado la influencia de los mismos en la adhesión y la proliferación celular.In the past years there was a need to develop new tough bioactive materials capable to resist high loads when implanted in the body, that led to the production of bioactive coatings on metallic substrates. A new approach, which consists of biomorphic silicon carbide (SiC) coated with bioactive glass by Pulsed Laser Deposition (PLD), was recently presented. This new material joins the high mechanical strength, lightness and porosity of biomorphic SiC and the bioactive properties of PLD glass films. In this work, a multiple evaluation of this new material is presented starting from the biomorphic SiC morphology and porosity, following with the bioactivity in simulated body fluid of the coatings, and ending with a deep in vitro study with MG-63 cells. The citotoxicity of the SiC coated and uncoated and the cell proliferation and attachment were studied

Extensive studies on biomorphic SiC ceramics properties for medical applications

Biomorphic silicon carbide ceramics are light, tough and high-strength materials with interesting biomedical applications. The fabrication method of the biomorphic SiC is based in the infiltration of molten-Si in carbon preforms with open porosity. The final product is a biostructure formed by a tangle of SiC fibers. This innovative process allows the fabrication of complex shapes and the tailoring of SiC ceramics with optimised properties and controllable microstructures that will match the biomechanical requirements of the natural host tissue. An interdisciplinary approach of the biomorphic SiC fabricated from beech, sapelly and eucalyptus is presented. Their mechanical properties, microstructure and chemical composition were evaluated. The biocompatible behaviour of these materials has been tested in vitro

Photoluminescence from ultrathin Ge-rich multi-quantum wells observed up to room-temperature: experiments and modeling

Employing a low-temperature growth-mode, we fabricated ultrathin Si1-xGex/Si multiple quantum well (QW) structures with a well thickness of less than 1.5 nm and a Ge concentration above 60 % directly on a Si substrate. We identified an unusual temperature-dependent blueshift of the photoluminescence (PL) and an exceptionally low thermal quenching. We find that this behavior is related to the relative intensities of the no-phonon (NP) peak and a phonon-assisted replica that are the main contributors to the total PL signal. In order to investigate these aspects in more detail, we developed a strategy to calculate the PL spectrum employing a self-consistent multi-valley effective mass model in combination with second-order perturbation theory. According to our investigation, we find that while the phonon-assisted feature decreases with temperature, the NP feature shows a strong increase in the recombination rate. Besides leading to the observed robustness against thermal quenching, this causes the observed blueshift of the total PL signal.T.W. and K.B. were supported by the Stiftung der Deutschen Wirtschaft (sdw) and by the Deutsche Forschungsgemeinschaft (DFG) through project B10 within the Collaborative Research Center (CRC) 951 Hybrid Inorganic/Organic Systems for Opto-Electronics. HRTEM measurements were financed by Xunta de Galica Grant No. GRC2014/008

Raman shifts in MBE‐grown SixGe1 − x − ySny alloys with large Si content

We examine the Raman shift in silicon–germanium–tin alloys with high silicon content grown on a germanium virtual substrate by molecular beam epitaxy. The Raman shifts of the three most prominent modes, Si–Si, Si–Ge, and Ge–Ge, are measured and compared with results in previous literature. We analyze and fit the dependence of the three modes on the composition and strain of the semiconductor alloys. We also demonstrate the calculation of the composition and strain of SixGe1 − x − ySny from the Raman shifts alone, based on the fitted relationships. Our analysis extends previous results to samples lattice matched on Ge and with higher Si content than in prior comprehensive Raman analyses, thus making Raman measurements as a local, fast, and nondestructive characterization technique accessible for a wider compositional range of these ternary alloys for silicon-based photonic and microelectronic devices.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Peer Reviewe

Device-Compatible Chiroptical Surfaces through Self-Assembly of Enantiopure Allenes

Chiroptical methods have been proven to be superior compared to their achiral counterparts for the structural elucidation of many compounds. To expand the use of chiroptical systems to everyday applications, the development of functional materials exhibiting intense chiroptical responses is essential. Particularly, tailored and robust interfaces compatible with standard device operation conditions are required. Herein, we present the design and synthesis of chiral allenes and their use for the functionalization of gold surfaces. The self-assembly results in a monolayer-thin room-temperature-stable upstanding chiral architecture as ascertained by ellipsometry, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure. Moreover, these nanostructures anchored to device-compatible substrates feature intense chiroptical second harmonic generation. Both straightforward preparation of the device-compatible interfaces along with their chiroptical nature provide major prospects for everyday applications

Device-Compatible Chiroptical Surfaces through Self-Assembly of Enantiopure Allenes

Chiroptical methods have been proven to be superior compared to their achiral counterparts for the structural elucidation of many compounds. To expand the use of chiroptical systems to everyday applications, the development of functional materials exhibiting intense chiroptical responses is essential. Particularly, tailored and robust interfaces compatible with standard device operation conditions are required. Herein, we present the design and synthesis of chiral allenes and their use for the functionalization of gold surfaces. The self-assembly results in a monolayer-thin room-temperature-stable upstanding chiral architecture as ascertained by ellipsometry, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure. Moreover, these nanostructures anchored to device-compatible substrates feature intense chiroptical second harmonic generation. Both straightforward preparation of the device-compatible interfaces along with their chiroptical nature provide major prospects for everyday applications.</p