The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with ...controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials.
This work present structural, morphological, magnetic, and electrical properties of GaSb/Mn multilayer deposited via DC magnetron sputtering at room temperature and at 423 K. The samples are ...characterized by forming layers of 3, 6 and 12 periods of the GaSb/Mn structure. Through XRD patterns, it was possible to stablish the formation of GaSb, Mn
Ga, and Mn
Sb
phases. FTIR measurements present an optical interference associated with periodicity and the homogenous thickness of the layers. HR-SEM shows the multilayer architecture with columnar microstructure in the formation of layers with grain nucleation on the surface. A ferromagnetic-like behavior was observed in the multilayers at room temperature related to the domains and interlayers interaction. Additionally, the hysteresis curves present shifts attributed to the effect of exchange bias coupling. I-V curves show RESET-SET states of the multilayer system with bipolar resistive behavior, which can be modified by external magnetic fields. The resistive switching evidenced corresponds to the conductive mechanism based on the capacitive conductance and the formation of conductive filaments in multilayer structure.
•ZnO:Ag films grown by DC Co-Sputtering Magnetron from Zn and Ag independent targets.•Detailed composition and structural analysis by RBS and XRD, respectively.•After annealing, Ag cubic phase and ...amorphous ZnO appear in the samples with higher Ag content.•PL results point out the Ag segregation and great defects reduction after annealing.•Plasmonic effect and an increase in conductivity are identified in annealed samples.
The ZnO semiconductor is probably among the most mentioned compounds in the scientific literature during the last decade, which is mainly due to its wide spectrum of applications. Compounds based on ZnO (in doped or composite form) are of great relevance for the development of high-tech devices. In this work, we present the growth and characterization of samples deposited by DC Magnetron co-sputtering from two pure Zn and Ag targets in an O2 / Ar atmosphere. The samples were characterized as deposited and after an annealing treatment in a reducing atmosphere. We have used XRD, RBS, ellipsometry, UV visible photoluminescence, and electrical measurements for sample characterization. The results revealed the amorphization of ZnO when the Ag content increases and, after annealing, a mixture of crystalline phases was detected for the samples with higher Ag content. It is also demonstrated the strong effect of the presence of Ag atoms in the stimulated optical and electrical responses from ZnO:Ag compounds obtained in this work.
•Wetting of Ti6Al4V is modified by ion irradiation.•Pitting in HF after selective irradiation leads to nanotopographic contrasts.•Concentration/surface tension of HF electrolyte influence Ti6Al4V ...etching.•Etching in HF increases surface concentration of alumina.•Pitting conditioned adhesion leads to ensheathing glia cell polarization.
We have modified Ti6Al4V at the micro and nanoscale by using ion beam irradiation with 5 MeV Si+ ions through 1D micromasks. The passivation layer on irradiated areas inhibits hydrofluoric acid induced etching, leading to pitting contrasts. Surface microscopies and spectroscopies reveal that the nanotopographic modification correlates with a preferential titanium etching, and lead to dual surface free energy properties. The patterns are able to induce guidance of olfactory ensheathing glia cells, mainly through inhibition of adhesion on nanostructured areas, and could be attractive substrates for the induction of stimuli to neural cells under non voltaic polarization.
A multi-particulate fixed-dose combination product, consisting of a combination of two alkalising salts formulated as prolonged-release granules, ADV7103, was developed to obtain a sustained and ...prolonged alkalising effect. The specific release of both types of granules was shown in vitro through their dissolution profiles, which indicated that potassium citrate was released within the first 2-3 h and potassium bicarbonate up to 10-12 h after administration. The long-lasting coverage of ADV7103 was confirmed through a randomised, placebo-controlled, double-blind, two-period study, measuring its effect on urine pH in healthy adults (n = 16) at doses of alkalising agent ranging between 0.98 and 2.88 meq/kg/day. A significant increase of urine pH with a positive dose-response in healthy adult subjects was shown. Urine pH above 7 was maintained during 24 h with a dosing equivalent to 1.44 meq/kg twice a day, while urine pH was below 6 most of the time with placebo. The effect observed was non-saturating within the range of doses evaluated and the formulation presented a good safety profile. ADV7103 provided an effective prolonged release of alkalising salts to cover a 12-h effect with adequate tolerability and could afford a twice a day (morning and evening) dosing in patients requiring long-term treatment.
The multilayer structure is a well-studied architecture for electronic and optoelectronic applications and more recently in spintronic devices. In this work, we present the structural, morphological, ...topographical, and magnetic properties of GaSb/Mn multilayers deposited via DC magnetron sputtering at room temperature and 423 K. Raman measurements evidence the formation of p-type GaSb layers with a contribution of electrons in the multilayer due to the neighboring Mn layer and the formation of effective interlayers. HR-SEM measurements show the multilayer architecture with columnar microstructure in the layer’s formation, while AFM micrographs allowed observing the changes in grain sizes (between 129 and 187 nm) and roughness (between 1.47 nm and 6.28 nm) with increasing number of layers. The formation of the interlayers between the GaSb and Mn layer was assayed in-depth spectroscopically via Rutherford backscattering studies. These interlayers were associated with diffusion processes during deposition and contributed to the magnetic behavior of multilayers. A ferromagnetic-like behavior was observed in the multilayers.
•Impedimetric platform based on interdigitated NiCr/porous silicon platforms.•Sandwich bioassay for detection of prostate specific antigen.•Au nanoparticle decreases equivalent series resistance at ...increasing biomarker concentration.•Dark field microscopy analysis allows a parallel optoplasmonic detection.•Dual sensing allows biomarker detection with an internal control.
A porous silicon (PSi) platform with interdigitated NiCr electrodes has been used for the impedimetric biosensing of prostate specific antigen (PSA), a cancer biomarker. The first step involved the formation of a conductive PSi structure through the ion beam creation of 250 nm deep interdigitated slots, followed by their filling with NiCr electrodes deposited by plasma sputtering. In the second step, a biorecognition interface was formed by modification of the PSi surface with (3-Glycidyloxypropyl)-trimethoxysilane. A sandwich assay was performed in which PSA was first recognized by a surface-anchored antibody and then by a secondary antibody tethered to 100 nm gold nanoparticles (GNPs). The changes in the impedance upon analyte binding at different concentrations have been monitored showing that the PSA concentration exhibits a linear dependence with the series resistance defined from the device equivalent circuit. A limit of detection in the range of 1 ng/mL PSA has been determined. A dark-field study of the PSi surface after the sandwich bioassay allowed an optoplasmonic demonstration of the increasing density of GNPs at higher PSA concentrations, which was confirmed by using scanning electron microscopy. The results confirm the dual optoplasmonic-electric labelling effect of the 100 nm GNPs and their role in an internally controlled detection of PSA.
This work presents a study of bilayer and multilayer systems of GaSb/Mn, obtained via DC magnetron sputtering at room temperature for memories applications. These architectures were observed through ...HR-SEM, which determined that the GaSb and Mn layers had an average thickness of 186,01±5,582 nm and 10,71±0,323 nm, respectively. Through the deconvolution of AES spectra, it was possible to identify the chemical element concentration profiles for each system and propose a model of diffusion layers. The GaSb/Mn systems were analyzed in two cases; in the cases of Mn deposited on the surface of GaSb wafer and bilayer systems, the Mn diffusion process was studied by the conventional Fick’s second law, considering the Mn layer as a constant source, and the Mn diffusion coefficient values correspond to 1,6×10−15cm2/s and 5,8×10−15cm2/s, respectively. The superposition of Fick´s second law solutions in each section of the multilayer architecture was used to describe the experimental concentration profile. Through, the model proposed to calculate the different diffusion coefficients of Mn layers, the description of the diffusion process in the bilayer and multilayer systems and their correlation with synthesis parameters, such as deposition time, has been satisfactory. In the multilayer architecture case, the Mn diffusion coefficients have been reported, considering the Mn layer position, and their values corresponding are 1,105×10−14cm2/s and 6,5×10−15cm2/s for Mn inner and middle layer respectively. Finally, the resistive behavior of the multilayers was studied through I-V curves. It was possible to establish the bipolar resistive behavior of the multilayer and contribution to the formation of conductive filaments or the space charge limited current like conductive mechanism of the multilayer thin films.
•Bilayer and GaSb/Mn3 multilayer type nanostructures have been obtained by DC magnetron sputtering.•Mn diffusion process was studied through two cases, Mn and GaSb wafer, and GaSb/Mn structure.•The different diffusion coefficients in each section of the multilayer system were calculated using the Fick’s second law.•The room temperature of the substrate and the growth mechanism contributed to the diffusion process.
Columnar mesoporous silicon (PSi) with hydrophobic vs. hydrophilic chemistries was chosen as a model for the local (pore-by-pore) study of water-pore interactions. Tomographic reconstructions ...provided a 3D view of the ramified pore structure. An in situ study of PSi wetting was conducted for categorized pore diameters by environmental scanning TEM. An appropriate setting of the contrast allows for the normalization of the gray scale in the images as a function of relative humidity (RH). This allows constructing an isotherm for each single pore and a subsequent averaging provides an isotherm for each pore size range. The isotherms systematically point to an initial adsorption through the formation of water adlayers, followed by a capillary filling process at higher RH. The local isotherms correlate with (global) gravimetric determination of wetting. Our results point at the validation of a technique for the study of aging and stability of single-pore nanoscale devices.
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•Wetting studied by wetSTEM in size categorized silicon mesopores•Gray scale profile in pores changes as a function of relative humidity and chemistry•Isotherms constructed by averaging gray scale by pore size categories•Isotherms correlate with global wetting on hydrophilic-phobic mesopores
Physics; Materials science; Surface science
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