Search

Ferromagnetic films down to thicknesses of tens of nanometers and composed by polycrystalline Fe and Fe2O3 nanopillars are grown in large areas by glancing angle deposition with magnetron sputtering (MS-GLAD). The morphological features of these films strongly depend on the growth conditions. Vertical or tilted nanopillars have been fabricated depending on whether the substrate is kept rotating azimuthally during deposition or not, respectively. The magnetic properties of these nanopillars films, such as hysteresis loops squareness, adjustable switching fields, magnetic anisotropy and coercivity, can be tuned with the specific morphology. In particular, the growth performed through a collimator mask mounted onto a not rotating azimuthally substrate produces almost isolated well-defined tilted nanopillars that exhibit a magnetic hardening. The first-order reversal curves diagrams and micromagnetic simulations revealed that a growth-induced uniaxial anisotropy, associated with an anisotropic surface morphology produced by the glancing angle deposition in the direction perpendicular to the atomic flux, plays an important role in the observed magnetic signatures. These results demonstrate the potential of the MS-GLAD method to fabricate nanostructured films in large area with tailored structural and magnetic properties for technological applications.

Recent attempts to improve solar cell performance by increasing their spectral absorption interval incorporate up-converting fluorescent nanocrystals on the structure. These nanocrystals absorb low energy light and emit higher energy photons that can then be captured by the solar cell active layer. However, this process is very inefficient and it needs to be enhanced by different strategies. In this work, we have studied the effect of nanostructuration of perovskite thin films used in the fabrication of hybrid solar cells on their local optical properties. The perovskite surface was engraved with a focused ion beam to form gratings of one-dimensional grooves. We characterized the surfaces with a fluorescence scanning near-field optical microscope, and obtained maps showing a fringe pattern oriented in a direction parallel to the grooves. By scanning structures as a function of the groove depth, ranging from 100 nm to 200 nm, we observed that a 3-fold luminescence enhancement could be obtained for the deeper ones. Near-field luminescence was found to be enhanced between the grooves, not inside them, independent of the groove depth and the incident polarization direction. This indicates that the ideal position of the nanocrystals is between the grooves. In addition, we also studied the influence of the inhomogeneities of the perovskite layer and we observed that roughness tends to locally modify the intensity of the fringes and distort their alignment. All the experimental results are in good agreement with numerical simulations.

Herein, we investigate the chemical sensing by surface-enhanced Raman scattering regarding two templates of gold nanocolumns (vertical and tilted) manufactured by glancing angle deposition with magnetron sputtering. We selected this fabrication technique due to its advantages in terms of low-cost production and ease of implementation. These gold nanocolumnar structures allow producing a high density of strongly confined electric field spots within the nanogaps between the neighboring nanocolumns. Thiophenol molecules were used as model analytes since they have the principal property to adsorb well on gold surfaces. Regarding chemical sensing, the vertical (tilted) nanocolumnar templates showed a detection threshold limit of 10 nM (20 nM), an enhancement factor of 9.8 × 108 (4.8 × 108), and a high quality of adsorption with an adsorption constant Kads of 2.0 × 106 M−1 (1.8 × 106 M−1) for thiophenol molecules.

The use of metallic nanostructures in the fabrication of bioelectrodes (e.g., neural implants) is gaining attention nowadays. Nanostructures provide increased surface area that might benefit the performance of bioelectrodes. However, there is a need for comprehensive studies that assess electrochemical performance of nanostructured surfaces in physiological and relevant working conditions. Here, we introduce a versatile scalable fabrication method based on magnetron sputtering to develop analogous metallic nanocolumnar structures (NCs) and thin films (TFs) from Ti, Au, and Pt. We show that NCs contribute significantly to reduce the impedance of metallic surfaces. Charge storage capacity of Pt NCs is remarkably higher than that of Pt TFs and that of the other metals in both morphologies. Circuit simulations of the electrode/electrolyte interface show that the signal delivered in voltage-controlled systems is less filtered when nanocolumns are used. In a current-controlled system, simulation shows that NCs provide safer stimulation conditions compared to TFs. We have assessed the durability of NCs and TFs for potential use in vivo by reactive accelerated aging test, mimicking one-year in vivo implantation. Although each metal/morphology reveals a unique response to aging, NCs show overall more stable electrochemical properties compared to TFs in spite of their porous structure.

Nanostructured silver (Ag) and gold (Au) are widely known to be potent biocidal and cytotoxic agents as well as biocompatible nanomaterials. It has been recently reported that combining both metals in a specific chemical composition causes a significant enhancement in their antibacterial activity against antibiotic-resistant bacterial strains, as well as in their anticancer effects, while preserving cytocompatibility properties. In this work, Ag/Au bimetallic nanoparticles over a complete atomic chemical composition range were prepared at 10 at% through a green, highly reproducible, and simple approach using starch as a unique reducing and capping agent. The noble metal nanosystems were thoroughly characterized by different analytical techniques, including UV-visible and FT-IR spectroscopies, XRD, TEM/EDS, XPS and ICP-MS. Moreover, absorption spectra simulations for representative colloidal Ag/Au-NP samples were conducted using FDTD modelling. The antibacterial properties of the bimetallic nanoparticles were determined against multidrug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus, showing a clear dose-dependent inhibition even at the lowest concentration tested (5 µg/mL). Cytocompatibility assays showed a medium range of toxicity at low and intermediate concentrations (5 and 10 µg/mL), while triggering an anticancer behavior, even at the lowest concentration tested, in a process involving reactive oxygen species production per the nanoparticle Au:Ag ratio. In this manner, this study provides promising evidence that the presently fabricated Ag/Au-NPs should be further studied for a wide range of antibacterial and anticancer applications.

The green synthesis of nanomaterials offers advantages over traditional chemical methods, such as the production of biocompatible nanostructures in an environmentally friendly and cost-effective manner. Among all of the available green synthesis routes, the use of bacteria offers a high-throughput and versatile synthesis of nanoparticles that can be used in a wide range of biomedical approaches. In this article, we present a controllable and versatile synthesis of selenium nanoparticles (SeNPs) using bacterial isolates of both Gram negative and Gram positive bacteria. The SeNPs were characterized in terms of their physicochemical properties and tested in both antimicrobial and cytotoxicity assays, showing a selective dose-dependent antibacterial activity in a selected range of concentrations (especially when SeNPs synthesized by a particular bacterial isolate were exposed to that isolate) and a mild cytotoxicity when exposed to human dermal fibroblasts. Furthermore, the SeNPs were tested for their anticancer activity by exposure to melanoma cells (skin cancer) in in vitro models, showing a significant dose¿response cytotoxic behavior that was associated to the production of reactive oxygen species. Therefore, this work presents a robust and versatile method to produce SeNPs using selected bacterial isolates for numerous biomedical applications.

The production of nanoparticles for biomedical applications (namely with antimicrobial and anticancer properties) has been significantly hampered using traditional physicochemical approaches, which often produce nanostructures with poor biocompatibility properties requiring post-synthesis functionalization to implement features that such biomedical applications require. As an alternative, green nanotechnology and the synthesis of environmentally friendly nanomaterials have been gaining attention over the last few decades, using living organisms or biomolecules derived from them, as the main raw materials to produce cost-effective, environmentally friendly, and ready-to-be-used nanomaterials. In this article and building upon previous knowledge, we have designed and implemented the synthesis of selenium and tellurium nanoparticles using extracts from fresh jalapeño and habanero peppers. After characterization, in this study, the nanoparticles were tested for both their antimicrobial and anticancer features against isolates of antibiotic-resistant bacterial strains and skin cancer cell lines, respectively. The nanosystems produced nanoparticles via a fast, eco-friendly, and cost-effective method showing different antimicrobial profiles between elements. While selenium nanoparticles lacked an antimicrobial effect at the concentrations tested, those made of tellurium produced a significant antibacterial effect even at the lowest concentration tested. These effects were correlated when the nanoparticles were tested for their cytocompatibility and anticancer properties. While selenium nanoparticles were biocompatible and had a dose-dependent anticancer effect, tellurium-based nanoparticles lacked such biocompatibility while exerting a powerful anti-cancer effect. Further, this study demonstrated a suitable mechanism of action for killing bacteria and cancer cells involving reactive oxygen species (ROS) generation. In summary, this study introduces a new green nanomedicine

Organic-inorganic hybrid perovskite solar cells have attracted much attention due to their high power conversion efficiency (＞23%) and low-cost fabrication. Directions to further improve these solar cells include strategies to enhance their stability and their efficiency by modifying either the perovskite absorber layer or the electron/hole transport layer. For example, the transparent electron transport layer (ETL) can be an important tuning knob influencing the charge extraction, [1] light harvesting, [2] and stability [3] in these solar cells, or the use of up-conversion nanoparticles to get better performance in the near IR part of the visible spectrum. [4] Here we present two strategies based on nanostructuration, first a fundamental study of upconversion fluorescence enhancement effects near Au nanodisks by scanning near-field optical microscopy and second the effects of a nanocolumnar TiO2 layer on the performance and the stability of Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 perovskite solar cells. For the first case, the enhancement and localization of light near the metallic structures are directly visualized by using a single Er/Yb-codoped fluorescent nanocrystal glued at the end of a sharp scanning tip. [5] For the second we find that, compared to devices with planar TiO2 ETLs, the TiO2 nanocolumns can significantly enhance the power conversion efficiency of the perovskite solar cells by 17 % and prolong their shelf life. By analyzing the optical properties, solar cells characteristics, as well as transport/recombination properties by impedance spectroscopy, we observed light-trapping and reduced carrier recombination in solar cells associated with the use of TiO2 nanocolumn arrays. [6]

En la metodología SOLE (Self Organized Learning Environment) los estudiantes trabajan en comunidad para responder, con ayuda de Internet, a las preguntas planteadas, fomentando así el autodescubrimiento. Hemos aplicado SOLE para divulgar sobre biomateriales y nanotecnología en secundaria a partir de: "¿Cómo arreglarías un cráneo roto?" y “¿Cómo utilizarías nanopartículas para curar el cáncer?”. Discutimos los resultados y las reacciones obtenidas.

This publication contains the original data supporting our results concerning the application of biphasic pulsed electrical stimulation on MG-63 cells. We aim to discriminate between effects of the electric field and electrochemically conditioned medium. The dataset consists of the original output files, excel sheets to consolidate the information for the experiments as well as Readme.txt files with most important information concerning the data. For additional information on the material and methods as well as results see the corresponding research article.

We have developed a platform that combines nanostructured Pt electrodes with a microgrooved-compartmentalized cell culture module, for electrical stimulation of neural cells. We demonstrated that nanostructuration significantly improves electrochemical properties of the bioelectrodes, including charge storage capacity. Moreover, nanostructuration has positive effect on conserving the delivered signal. We also, established a methodology for simulating stimualtion conditions before experimental work. Future work will be focused on culturing neural cells in this platform, to expand their axonal compartment within the grooves, and testing the effect of electrical stimulation on growth and survival of the axons.

INTRODUCTION Electrical stimulations (ES), with various intensity, frequency, duration, signal shape, etc. are used to enhance tissue regeneration. However, it is not yet clear which combination of parameters is efficient in each application. A relevant approach to refine these sets of parameters is to reveal the significant electrochemical features linked to the biophysical responses [1,2]. Here, we characterized the electrochemical features of different in vitro ES systems and regimes in biologically relevant conditions. METHODS We characterized three different systems: miniaturized devices with electrode plates, coated with either Pt thin film (TF) or Pt nanocolumns (NC)[4]; and an 8-well plate with L-shaped Pt wires (W). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were measured using a potentiostat. Chronoamperometry was carried out for different ES regimes. RESULTS Impedance is significantly reduced when NC is used. The NC effective capacitance is larger than that of TF due to its increased electrochemically active area. The safe limits are between -0.7 V and 1.0 V for both NC and TF. Redox peaks were observed in the same potential ranges for both morphologies. Accumulated charge was considerably larger for both morphologies in the potential regions were oxidation of Pt and adsorption-desorption of H2 occur, showing its dependency on the applied potential ranges. Moreover, charge per pulse was around two orders of magnitude larger for NC than for TF in every region. DISCUSSION AND CONCLUSIONS The applied electrical signals are not equal to what cells sense due to the electric double layer at the interface and its characteristics are extractable from EIS. Chronoamperometry provides the accumulated charge in the system. The sum of charges passed to the extracellular fluid highly depends on electrode material, operation voltage range, and signal shape. Finally, even being in the safe operating voltage range, faradaic reactions [3], res

Glancing Angle Deposition (GLAD) with magnetron sputtering (MS) is an easy and versatile route to fabricate nanocolumnar films in large areas (several cm2 and above) in a single-step process, in clear contrast to other techniques in the nanoscale range such as e-beam lithography and ion-beam lithography. The morphology of the nanocolumns can be controlled depending on several parameters such as the gas pressure, the angle of inclination of the substrate and its possible rotation, the electromagnetic power, the deposition time, and the optional use of collimating masks [1-4]. Moreover, as GLAD with MS it is usually carried out at RT and does not involve chemical products (thus, without associated recycling issues), this technique is environmentally friendly. In this talk, I will start explaining the fundamentals of GLAD with MS and then I will present some recent examples of nanocolumnar films that are of interest in the field of energy and environment: Gold nanocolumnar templates for effective chemical sensing by surface-enhanced Raman scattering [5], Iron nanocolumnar films with tailored magnetic behavior [6], and Titanium oxide nanocolumnar films that exhibit photo‐induced self‐cleaning properties [7]. It will be finally shown that this latter effect can be enhanced when the nanocolumns are decorated with gold nanoparticles using a gas aggregation source that is also based on MS. References:[1] R. Alvarez et al., Nanotechnology 24, 045604 (2013). [2] R. Alvarez et al., J. Phys. D: Appl. Phys. 49, 045303 (2016). [3] A. Vitrey et al., Beilstein J. Nanotechnol. 8, 434 (2017).[4] G. Troncoso et al., Appl. Surf. Sci. 526, 146699 (2020).[5] G. Barbillon et al., Nanomaterials 12, 4157 (2022).[6] E. Navarro et al., Nanomaterials 12, 1186 (2022).[7] F. Fresno et al., Adv. Sustainable Syst. 5, 2100071 (2021).

Pulsed electrical stimulation at 25 mV/mm emerges as a potent physical approach for inducing neural differentiation in neuroblastoma cells, even in the absence of the critical growth factor BDNF. Our study demonstrates that the effectiveness of this method is dose-dependent, with the frequency and duty cycle significantly influencing the morphological expression of neurite outgrowth. Moreover, these parameters also exhibit a meaningful impact on the production yield of EVs and their protein cargo. In summary, our findings underscore the viability of fine-tuning of cell behavior and cell secretion through the regulation of electrical stimulation parameters.

Background Electrical stimulation is used for enhanced bone fracture healing. Electrochemical processes occur during the electrical stimulation at the electrodes and influence cellular reactions. Our approach aimed to distinguish between electrochemical and electric field effects on osteoblast-like MG-63 cells. We applied 20 Hz biphasic pulses via platinum electrodes for 2 h. The electrical stimulation of the cell culture medium and subsequent application to cells was compared to directly stimulated cells. The electric field distribution was predicted using a digital twin. Results Cyclic voltammetry and electrochemical impedance spectroscopy revealed partial electrolysis at the electrodes, which was confirmed by increased concentrations of hydrogen peroxide in the medium. While both direct stimulation and AC-conditioned medium decreased cell adhesion and spreading, only the direct stimulation enhanced the intracellular calcium ions and reactive oxygen species. Conclusion The electrochemical by-product hydrogen peroxide is not the main contributor to the cellular effects of electrical stimulation. However, undesired effects like decreased adhesion are mediated through electrochemical products in stimulated medium. Detailed characterisation and monitoring of the stimulation set up and electrochemical reactions are necessary to find safe electrical stimulation protocols.

Cancer and antimicrobial resistance to antibiotics are two of the most worrying healthcare concerns that humanity is facing nowadays. Some of the most promising solutions for these healthcare problems may come from nanomedicine. While the traditional synthesis of nanomaterials is often accompanied by drawbacks such as high cost or the production of toxic by-products, green nanotechnology has been presented as a suitable solution to overcome such challenges. In this work, an approach for the synthesis of tellurium (Te) nanostructures in aqueous media has been developed using aloe vera (AV) extracts as a unique reducing and capping agent. Te-based nanoparticles (AV-TeNPs), with sizes between 20 and 60 nm, were characterized in terms of physicochemical properties and tested for potential biomedical applications. A significant decay in bacterial growth after 24 h was achieved for both Methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli at a relative low concentration of 5 µg/mL, while there was no cytotoxicity towards human dermal fibroblasts after 3 days of treatment. AV-TeNPs also showed anticancer properties up to 72 h within a range of concentrations between 5 and 100 µg/mL. Consequently, here, we present a novel and green approach to produce Te-based nanostructures with potential biomedical applications, especially for antibacterial and anticancer applications.

Nanostructured noble metals are of great interest because of their tunable optical and electronic properties. However, the green synthesis of anisotropic nanostructures with a defined geometry by the systematic nanoassembly of particles into specific shape, size, and crystallographic facets still faces major challenges. The present work aimed to establish an environmentally friendly methodology for synthesizing gold-based anisotropic nanostructures using starch-capped bimetallic silver/gold nanoparticles as seeds and hydrogen peroxide as a reducing agent.

This protocol enables correlative light and electron microscopy (CLEM) imaging of cell surface features without using dedicated equipment. Cells are cultured and fixed on transparent substrates for confocal microscopy imaging. No conductive coating is employed in the scanning electron microscopy workflow, providing a clean cell surface observation, with fiducial markers assisting alignment of optical and topographical images. This protocol describes CLEM imaging for midbody remnants in MDCK cells but can also be applied to different cell types and surface features. For complete details on the use and execution of this protocol, please refer to Casares-Arias et al. (2020). https://doi.org/10.1016/j.isci.2020.101244

We present an analysis of the optical coupling between two gold nanodisks by near-field fluorescence microscopy. This is achieved by simultaneously scanning and measuring the light emitted by a single Er3þ/Yb3þ doped nanocrystal glued at the end of an atomic force microscope tip. The excitation of the nanocrystal was performed at k ¼ 975 nm via upconversion, and fluorescence was detected in the visible part of the spectrum at k ¼ 550 nm. For an isolated nanodisk, the near-field presents a two-lobe pattern oriented along the direction of the incident polarization. For two nanodisks with a sizable separation distance (385 nm) illuminated with the polarization along the interparticle axis, we observe a negative effect of the coupling with a slight decrease in fluorescence in the gap. For smaller gap values (195, 95, and 55 nm), a strong increase in fluorescence is observed as well as a reduced spatial localization of the field as the distance decreases. Finally, when the disks touch each other (0 nm), the dipolar–dipolar interaction between them disappears and no fluorescence enhancement occurs. A new plasmon mode is created at another wavelength. Our experimental results are in good agreement with numerical simulations of the nearfield intensity distribution at the excitation wavelength on the surface of the structures. Combining fluorescence mapping and far-field scattering spectroscopy should be of strong interest to develop bio-chemical sensors based on field enhancement effects.

Organic–inorganic hybrid perovskite solar cells have attracted much attention due to their high power conversion efficiency (>25%) and low-cost fabrication. Yet, improvements are still needed for more stable and higher-performing solar cells. In this work, a series of TiO2 nanocolumn photonic structures have been intentionally fabricated on half of the compact TiO2-coated fluorine-doped tin oxide substrate by glancing angle deposition with magnetron sputtering, a method particularly suitable for industrial applications due to its high reliability and reduced cost when coating large areas. These vertically aligned nanocolumn arrays were then applied as the electron transport layer into triple-cation lead halide perovskite solar cells based on Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3. By comparison to solar cells built onto the same substrate without nanocolumns, the use of TiO2 nanocolumns can significantly enhance the power conversion efficiency of the perovskite solar cells by 7% and prolong their shelf life. Here, detailed characterizations on the morphology and the spectroscopic aspects of the nanocolumns, their near-field and far-field optical properties, solar cells characteristics, as well as the charge transport properties provide mechanistic insights on how one-dimensional TiO2 nanocolumns affect the performance of perovskite halide solar cells in terms of charge transport, light harvesting, and stability, knowledge necessary for the future design of higher-performing and more stable perovskite solar cells.

Two different nanostructures are studied in this contribution: large-area nanopillar arrays fabricated by glancing angle deposition with magnetron sputtering (MS-GLAD) and magnetic thin films perforated with long-range order arrays of nanoholes prepared by focused ion beam (patterned antidots). MS-GLAD is an easy and versatile route to fabricate arrays of nanostructures in large areas in a single processing step. In our work, nanostructured films with vertical or tilted nanopillars composed by polycrystalline Fe and Fe2O3 have been fabricated depending on whether the substrate is kept rotating azimuthally during deposition or not, respectively [1]. The magnetic properties of these films can be tuned with the specific morphology. In particular, the growth performed through a collimator mask mounted onto a not rotating azimuthally substrate produces almost isolated well-defined tilted nanopillars that exhibit a magnetic hardening. The first-order reversal curves diagrams and micromagnetic simulations revealed that a growth-induced uniaxial anisotropy, associated with an anisotropic surface morphology produced by the GLAD in the direction perpendicular to the atomic flux, plays an important role in the observed magnetic signatures. Magnetic antidots are being studied for different applications, such as magnonic crystals for microwave devices, magnetically-active plasmonic media, magnetic biosensing, and magneto-resistance sensors. In our work, a top-down approach using focused ion beam has been employed to fabricate Co/Permalloy hard-soft bilayer antidot arrays [2]. The antidots have a 40 nm diameter and two symmetries are studied: square and hexagonal. A dependence of magnetic coercivity on the relative thicknesses of the magnetically hard (Co) and soft (Permalloy) layers is found; increasing Permalloy thickness results in lower magnetic coercivity. Furthermore, the long-range periodicity of these antidots results in higher magnetic coercivity and a stronger magnetic

Electrical stimulation (ES) has been employed in nume-rous biomedical applications such as neural stimulation, neural interfacing and tissue regeneration. The biological complexity of in vivo conditions encouraged many researchers to evaluate the role of ES via in vitro devices1. Among the several ES delivery methods, direct coupling is the one that fairly mimics implantable devices. The electrochemical properties of in vitro ES devices and the characteristics of the delivered electrical field remain broadly understudied. Electrode materials have a critical role in determining the impedance (Z) and charge injection capacity (CIC) of the system. A small CIC and high Z require larger potentials to inject a significant amount of charge, which may corrode the electrode or hydrolyse the electrolyte. In addition, electrochemical reactions result in by-products such as reactive oxygen species (ROS) or changes in the pH, which are harmful for the cells2. Nano-structuration is shown to improve the electrochemical properties of bioelectrodes. In this study, we defined biologically safe limits of ES delivered by both Pt thin films (TF) and nanostructured (NC) electrodes incorporated in an in vitro ES device. To this end, we performed comprehensive electrochemi-cal characterization in biologically relevant conditions.

It is demonstrated that, besides classical nanocolumnar arrays, the oblique angle geometry induces the growth of singular structures in the nanoscale when using wisely designed patterned substrates. Well-ordered array of crosses, cylindrical nanorods or hole structures arranged in square or hexagonal regular geometries are reported as examples, among others. The fundamental framework connecting substrate topography and film growth at oblique angles is presented, allowing the use of substrate patterning as a feasible thin film nanostructuring technique. A systematic analysis of the growth of TiO2 thin films on 4 different lithographic patterned substrates in 4 different scale lengths is also presented. A first conclusion is the existence of a height-based selective growth in the initial stages of the deposition, by which the film preferentially develops on top of the tallest substrate features. This behavior is maintained until the film reaches a critical thickness, the so-called Oblivion Thickness, above which the film topography becomes gradually independent of the substrate features. A general formula relating the spatial features of the pattern, the coarsening exponent and the Oblivion Thickness has been deduced.

[Background] Tradiditional physicochemical approaches for the synthesis of compounds, drugs, and nanostructures developed as potential solutions for antimicrobial resistance or against cancer treatment are, for the most part, facile and straightforward. Nevertheless, these approaches have several limitations, such as the use of toxic chemicals and production of toxic by-products with limited biocompatibility. Therefore, new methods are needed to address these limitations, and green chemistry offers a suitable and novel answer, with the safe and environmentally friendly design, manufacturing, and use of minimally toxic chemicals. Green chemistry approaches are especially useful for the generation of metallic nanoparticles or nanometric structures that can effectively and efficiently address health care concerns., [Objective] Here, tellurium (Te) nanowires were synthesized using a novel green chemistry approach, and their structures and cytocompatibility were evaluated., [Method] An easy and straightforward hydrothermal method was employed, and the Te nanowires were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and optical microscopy for morphology, size, and chemistry. Cytotoxicity tests were performed with human dermal fibroblasts and human melanoma cells (to assess anticancer properties). The results showed that a treatment with Te nanowires at concentrations between 5 and 100 µg/mL improved the proliferation of healthy cells and decreased cancerous cell growth over a 5-day period. Most importantly, the green chemistry -synthesized Te nanowires outperformed those produced by traditional synthetic chemical methods., [Conclusion] This study suggests that green chemistry approaches for producing Te nanostructures may not only reduce adverse environmental effects resulting from traditional synthetic chemistry methods, but also be more effective in numerous health care applications.

[ES] Electrodos nanoestructurados para la estimulación eléctrica de células en cultivo, dispositivos, sistemas y procedimientos asociados. La presente invención se refiere a un electrodo (1) de estimulación eléctrica celular, adaptado para su inserción en una placa (2) miniaturizada con mini-pocillos (3) de cultivo celular, que comprende al menos un material dispuesto como sustrato (4) y un material eléctricamente conductor dispuesto sobre dicho sustrato (4). Ventajosamente, el material eléctricamente conductor está formado por nanopilares (5) metálicos, depositados sobre el sustrato (4) a través de deposición con ángulo de incidencia (GLAD) con pulverización catódica por magnetrón. La invención se refiere, asimismo, a diferentes dispositivos, sistemas, usos y procedimientos asociados a dichos electrodos (1)., [EN] Nanostructured electrodes for the electrical stimulation of cells in culture, devices, systems and associated procedures. The present invention refers to an electrode (1) for cellular electrical stimulation, adapted for insertion in a miniaturized plate (2) with mini-wells (3) for cell culture, comprising at least one material arranged as substrate (4) and an electrically conductive material arranged on said substrate (4). Advantageously, the electrically conductive material is formed by metallic nanopillars (5), deposited on the substrate (4) through deposition with angle of incidence (GLAD) with magnetron sputtering. The invention also refers to different devices, systems, uses and procedures associated with said electrodes (1).

Neural implants are increasingly investigated to assist patients with defects or pathologies in nervous system. There is a growing research about developing new biomaterials to improve the effectiveness and biocompatibility of neural implants. For example, inflammatory responses to implantation of these devices, also called foreign body reactions (FBR), are still a challenge for their performance. During FBR, immune cells such as monocytes and macrophages are recruited and activated, leading to several consequences. One of those is the increased amount of reactive oxygen species (ROS) due to differentiation and phagocytosis of macrophages. ROS affects the performance of neural implants in the long-term by increasing corrosion and delamination. Reactive accelerated aging tests (RAAT) are used as a tool to test the durability of bioelectrodes and neural implants, mimicking the presence of ROS in vivo. In RAAT, an H2O2 solution with high temperature can mimic several years of implantation during a few weeks due to the increased reaction rate provided by temperature. A RAAT protocol for testing neural implants has been recently approved by FDA. In this work, we have built a RAAT setup based on this protocol. We have studied different parameters that affect the stability of the system and we have employed RAAT to analyse the durability of different flat and nanostructured metallic layers.

Bioelectricity facilitates sending and receiving information to/from the body to provide controlling and feedbacking ºystems to regulate, and monitor biological microenvironment. Also, numerous studies showed electrical stimulation (ES) promotes proliferation, migration and secretion of pro-regenerative factors in the cells and accelerates tissue regeneration, and wound healing. Moreover, ES has a great potential to be adapted as a digital medicine and/or smart therapeutic. Growing research on the use of ES in biological systems, promotes development of in vitro platforms to study the role and applications of ES in contact with cells and tissues. Up to now several in vitro ES devices has been established, such as: devices for measuring electrical impedance of cells that is used to evaluate specific biological activities; devices for inducing specific cell responses by means of low voltage ES (e.g., cell migration, differentiation); devices for stimulating and/or recording electrical activity of electroactive cells in CMOS-based multi-electrode arrays (MEAs) and/or multipurpose setups such as lab-on-the-chip. Nevertheless, quality of electrical signals, reproducibility of experiments, increasing of throughput and accuracy of performance of current in vitro platforms are yet to be improved. We believe, advances in biomaterials technology, computational modelling, microelectronics, microfabrication, and electrochemistry have opened new doors to meet these needs. Here we present the evolution of in vitro platforms for electrical stimulation and recording for different proposes and introduce our innovative device for low voltage direct electrical stimulation. We discussed design, fabrication and characterization of this platform and its benefits for conducting high throughput and controlled experiments within a standard cell culture vessel.

The use of electricity in interaction with biological systems for therapeutic and diagnostic purposes become a prominent research topic. Electrodes are key components of electrical stimulation and recording devices for in vivo and in vitro usages. Bioelectrodes should present excellent electroconductivity to be able to transfer the electrical current efficiently (charge mobility inside the device). Moreover, they need to provide excellent electroactivity to convert electronic current to ionic current at the electrode/extracellular fluid (ECF) interphase. The use of nanostructures in fabrication of bioelectrodes is beneficial, since nanostructures offer superior effective surface area that decreases impedance (Z) and increases charge storage capacity (CSC) of the electrodes. Low Z prevents irreversible faradic reactions that are harmful for biological systems (safe stimulation), and decreases thermal noises that interfere recording bioelectrical signals. Higher CSC ensures effective charge transfer (effective stimulation)1. Here we developed highly pure metallic nanostructured electrodes from Ti, Au and Pt and characterized their electrochemical properties. Electrical stimulation (ES) modes for both in vitro and in vivo applications were simulated. Finally, we present the design of an in vitro ES platform incorporating nanostructured electrodes.

In this work, the preparation of regular nanosized columnar structures of titanium dioxide by means of glancing angle deposition with magnetron sputtering (MS-GLAD) followed by thermal annealing is reported. MS-GLAD gives rise to metallic titanium columnar structures with regular width and length that after thermal treatment are fully oxidized to form TiO2 nanocolumns that maintain the morphological features of the original metallic ones. Further functionalization with gold by means of multiple ion cluster source results in well-dispersed Au nanoparticles across the nanocolumns’ surface with a narrow size distribution centered at ca. 8.5 nm. The obtained nanostructures show photocatalytic self-cleaning activity as shown by the elimination of an organic layer deposited on their surface and the detection of hydroxyl radicals. Photoelectrochemical measurements show a better charge separation at the Au/TiO2 interface. In addition, wettability studies show that the degree of hydrophobicity of the surface is increased by the presence of nanocolumns, both in the dark and under UV illumination. This behavior is not modified by the presence of Au nanoparticles on the surface. The obtained results open up interesting implications in the tunability of the properties of nanostructured thin films for this kind of photo-activated application.