Search

Spurred by outstanding optical properties, chemical stability, and facile bioconjugation, plasmonic metals have become the first-choice materials for optical signal transducers in biosensing. While the design rules for surface-based plasmonic sensors are well-established and commercialized, there is limited knowledge of the design of sensors based on nanoparticle aggregation. The reason is the lack of control over the interparticle distances, number of nanoparticles per cluster, or multiple mutual orientations during aggregation events, blurring the threshold between positive and negative readout. Here we identify the geometrical parameters (size, shape, and interparticle distance) that allow for maximizing the color difference upon nanoparticle clustering. Finding the optimal structural parameters will provide a fast and reliable means of readout, including unaided eye inspection or computer vision. J.L.M.-P., N.Z., and J.A. acknowledge financial support from Spanish MICIN/AE/DOI 10.13039/501100004837, Reg. No. PID2019-107432GB-I00 and from the Department of Education of the Basque Government under Project IT1526-22. M.G. acknowledges Euskampus Foundation for financial support (Resilience COVID19). This work received computational support from DIPC's HPC cluster ATLAS, operated by DIPC Supercomputing Center.

The ultrafast concentration of electromagnetic energy in nanoscale volumes is one of the key features of optical nanoantennas illuminated at their surface plasmon resonances. Here, we drive the insulator to metal phase transition in vanadium dioxide (VO2) using a laser-induced pumping effect obtained by positioning a single gold nanoantenna in proximity to a VO2 thermochromic material. We explore how the geometry of the single nanoantenna affects the size and permittivity of the nanometer-scale VO2 regions featuring phase transition under different pumping conditions. The results reveal that a higher VO2 phase transition effect is obtained for pumping of the longitudinal or transversal localized surface plasmon depending on the antenna length. This characterization is of paramount importance since the single nanoantennas are the building blocks of many plasmonic nanosystems. Finally, we demonstrate the picosecond dynamics of the VO2 phase transition characterizing this system, useful for the realization of fast nano-switches. Our work shows that it is possible to miniaturize the hybrid plasmonic-VO2 system down to the single-antenna level, still maintaining a controllable behavior, fast picosecond dynamics, and the features characterizing its optical and thermal response., LB, NZ, and JA acknowledge financial support from Spanish MICIN (DOI 10.13039/501100004837) through Project Ref. No. PID2019-107432GB-I00, from the Department of Education of the Basque Government under project IT1164-19 and the Department of Industry of the Basque Government under Elkartek project KK-2018/0000. OM and BC acknowledge support from EPSRC (DOI 10.13039/501100000266) through grants EP/J016918/1 and EP/M009122/1.

We show that the magnetic-modulation of the optical response induced by an external magnetic field in giant-magneto-resistance rod-slit arrays is more sensitive to the presence of a molecular vibration than the direct optical response.

We present experimental and theoretical results of the molecular sensing performance of a novel platform based on magnetic modulation of surface-enhanced infrared absorption spectroscopy. For this, we study the effect that molecular infrared vibrations of a PMMA layer have on the optical and magneto-refractive response of spintronic antennas. Specifically, a periodic array of rods is fabricated from giant-magneto-resistance Au/Ni81Fe19 metallic multilayers, and the effect of depositing a layer of PMMA on top of the array is investigated from both experimental and theoretical points of view. We find that the relative changes induced by the infrared vibrations of PMMA on the magneto-refractive signal are larger than the relative changes induced on the optical transmission. This result indicates that the magneto-refractive response is more sensitive to the excitation of molecular vibrations than the optical response and fosters the development of a novel type of an infrared sensing technique based on spintronic antennas: Magneto-Refractive Surface-Enhanced Infrared Absorption (SEIRA) Spectroscopy., We acknowledge financial support from MINECO through projects AMES (No. MAT 2014-58860-P), Quantum Spin Plasmonics (No. FIS2015-72035-EXP), and MIRRAS (No. MAT2017-84009-R) and Comunidad de Madrid (CM) through project SINOXPHOS-CM (No. S2018/BAA-4403). We acknowledge the service from the MiNa Laboratory at IMN and funding from MINECO under Project No. CSIC13-4E-1794 and from CM under Project No. S2013/ICE-2822 (Space-Tec), both with support from EU (FEDER, FSE). L.B., N.Z., and J.A. acknowledge support from the Department of Education, Research and Universities of the Basque Government through Project Ref. No. IT-1164-19, the Department of Industry of the Basque Government through Project No. KK-2018/00001, and the Spanish MICIN through Project Ref. No. PID2019-107432GB-I00.

"Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM", El objetivo principal de este documento internacional de consenso sobre apnea obstructiva del sue˜no esproporcionar unas directrices que permitan a los profesionales sanitarios tomar las mejores decisionesen la asistencia de los pacientes adultos con esta enfermedad según un resumen crítico de la literaturamás actualizada. El grupo de trabajo de expertos se ha constituido principalmente por 17 sociedadescientíficas y 56 especialistas con amplia representación geográfica (con la participación de 4 sociedadesinternacionales), además de un metodólogo experto y un documentalista del Centro Cochrane Iberoame-ricano. El documento consta de un manuscrito principal, con las novedades más relevantes, y una seriede manuscritos online que recogen las búsquedas bibliográficas sistemáticas de cada uno de los aparta-dos del documento internacional de consenso. Este documento no cubre la edad pediátrica ni el manejodel paciente en ventilación mecánica crónica no invasiva (que se publicarán en sendos documentos deconsenso aparte)., The main aim of this international consensus document on obstructive sleep apnea is to provide guidelines based on a critical analysis of the latest literature to help health professionals make the best decisions in the care of adult patients with this disease. The expert working group was formed primarily of 17 scientific societies and 56 specialists from a wide geographical area (including the participation of 4 international societies), an expert in methodology, and a documentalist from the Iberoamerican Cochrane Center. The document consists of a main section containing the most significant innovations and a series of online manuscripts that report the systematic literature searches performed for each section of the international consensus document. This document does not discuss pediatric patients or the management of patients receiving chronic non-invasive mechanical ventilation (these topics will be addressed in separate consensus documents).

Complementary metasurfaces composed of randomly-placed arrays of aligned rods or slits are fabricated out of giant magnetoresistance Ni81Fe19/Au multilayers (MLs), a material whose optical properties change under the application of an external static magnetic field. The two metasurfaces are studied from both the experimental and theoretical viewpoints. The induced magnetic modulation (MM) of both the far-field signal and the resonant near field, at the rod/slit localized surface plasmon frequency, are found to obey the Babinet’s principle. Furthermore, the near-field MM is found to be higher than the far-field counterpart. At resonance, both arrays show spots with high values of the magnetic modulated intensity of the electric near field (MM hot-spots). We show that this high magnetic modulation of the near-field intensity is very promising for the future development of high sensitivity molecular sensing platforms in the Mid- and Far-IR, using Magnetic-Modulation of Surface-Enhanced Infrared Absorption (MM-SEIRA) spectroscopy, Ministerio de Economía y Competitividad (AMES (MAT 2014-58860-P), CSIC13-4E-1794, MIRRAS(MAT2017-84009-R), PID2019-107432GB-I00, Quantum Spin Plasmonics (FIS2015-72035-EXP)); Ekonomiaren Garapen eta Lehiakortasun Saila, Eusko Jaurlaritza (KK-2018/00001); Hezkuntza, Hizkuntza Politika Eta Kultura Saila, Eusko Jaurlaritza (No. IT-1164-19); Comunidad de Madrid (S2013/ICE- 2822 (Space-Tec), SINOXPHOS-CM (S2018/BAA-4403)).

The dynamic restructuring of metal nanoparticle surfaces is known to greatly influence their catalytic, electronic transport, and chemical binding functionalities. Here we show for the first time that non-equilibrium atomic-scale lattice defects can be detected in nanoparticles by purely optical means. These fluctuating states determine interface electronic transport for molecular electronics but because such rearrangements are low energy, measuring their rapid dynamics on single nanostructures by X-rays, electron beams, or tunnelling microscopies, is invasive and damaging. We utilise nano-optics at the sub-5nm scale to reveal rapid (on the millisecond timescale) evolution of defect morphologies on facets of gold nanoparticles on a mirror. Besides dynamic structural information, this highlights fundamental questions about defining bulk plasma frequencies for metals probed at the nanoscale., Dynamic restructuring of metal nanoparticle surfaces greatly influences their catalytic, electronic transport, and chemical binding functionalities. Here, the authors show that non-equilibrium atomic-scale lattice defects can be detected in nanoparticles by using nano-optics at the sub-5nm scale.

In this work, we experimentally demonstrate magnetic modulation of mid-infrared (mid-IR) plasmon resonances in microantenna and hole-array metamaterial platforms made of Ni81Fe19/Au multilayers. The responsible mechanism is the magnetorefractive effect linked to the giant magnetoresistance (GMR) present in this system. Ni81Fe19/Au multilayers experience a modification in the electrical resistivity upon the application of a small magnetic field. This directly translates into a change in the optical constants of the multilayer, making it possible to magnetically modulate the plasmon resonances. Because GMR acts on conduction electrons, the optical modulation occurs in the low energy, mid-IR range, even being possible to extend it to the THz range. Electrodynamical calculations confirm the experimental observations. This approach improves by up to 2 orders of magnitude previous attempts for mid-IR magnetic modulation, is potentially ultrafast due to the characteristic spintronics dynamics, and establishes a roadmap for spintronically controlled devices in the whole mid-IR to THz band., We acknowledge financial support from MINECO through project AMES (MAT 2014-58860-P), Quantum Spin Plasmonics (FIS2015-72035-EXP), PlasmoQuanta (FIS2016-80174-P), and MIRRAS (MAT2017-84009-R). L.B., N.Z., and J.A. acknowledge support from the Basque Department of Education and the UPV-EHU (Grant IT-756-13). A.M. acknowledges support from the Spanish Ministry of Economy and Competiveness (MINECO) under grant TEC2014-51902-C2-1-R. We acknowledge the service from the MiNa Laboratory at IMN and funding from MINECO under project CSIC13-4E-1794 and from CM under project S2013/ICE-2822 (Space-Tec), both with support from EU (FEDER, FSE).

The non-physical effects on the transverse momentum transfer from fast electrons to gold nanoparticles associated to the use of non-causal dielectric functions are studied. A direct test of the causality based on the surface Kramers–Kronig relations is presented. This test is applied to the different dielectric function used to describe gold nanostructures in electron microscopy., A.R-C. acknowledges financial support from DGAPA/PAPIIT-UNAM project IA105917. R.E-S. acknowledges financial support from DGAPA/PAPIIT-UNAM project IN110916. N. Z. and A. R. acknowledge financial support from MINECO (FIS2016-80174-P) and Basque Government grant of UPV/EHU Grupos Consolidados IT-756-13.

The αv β3 integrin receptor plays an important role in tumor metastasis and tumor-induced angiogenesis. The inhibition of this receptor with diverse ligands, antibodies, or cyclic peptides is a promising research field for the treatment of a variety of tumors. The replacement of Phe-(Me)Val dipeptide by a β-lactam ring in Cilengitide has led to new products that show higher inhibitory activity than the parent cyclopeptide. In particular, substitution of a peptide bond β-lactam-NH-Asp linkage by a β-lactam-O-Asp ester linkage increases the activity of the new cyclodepsipeptide. In the same way it has been found that open-chain compounds of the form Asp-β-lactam-Arg can interact with the receptor and inhibit its activity moderately. The integrin inhibitory activity of the synthesized compounds has been established by using the CGH array, a method that appears to be a more reliable trial than the classical adhesion test.

We present magnetic field induced modulation of the optical response of slit plasmonic metasurfaces fabricated out of giant magnetoresistance/spintronic materials in the 2–17 μm spectral range of the spectrum. The modulation of the slit plasmonic modes is due to the modification of the electrical resistivity (and, in turn, of the optical constants) induced by the application of an external magnetic field. This modulation is found to continuously increase both with the slit concentration and with the slit resonance wavelength, with a prospective further increase for wavelengths of up to 60–80 μm. The direct fabrication and implementation of the modulation setup opens a competitive route for the development of active plasmonic metasurfaces in a wide spectral range., We acknowledge financial support from MINECO through projects AMES (MAT2014-58860-P), Quantum Spin Plasmonics (FIS2015-72035-EXP), PlasmoQuanta (FIS2016-80174-P), MIRRAS (MAT2017-84009-R), and Comunidad de Madrid through project SINOXPHOSCM (S2018/BAA-4403). LB, NZ, and JA acknowledge support from the Department of Education of the Basque Government under project IT1164-19, and the Department of Industry of the Basque Government under Elkartek project KK-2018/00001. We acknowledge the service from the MiNa Laboratory at IMN and funding from MINECO under project CSIC13-4E-1794 and from CM under project S2018/NMT-4291 TEC2SPACE, both with support from EU (FEDER, FSE).

This work is supported by Eusko Jaurlaritza under Grants No. IT-1005-16 and No. IT-756-13 and by Spanish Ministry of Economy and Competitiveness under Grant No. MAT2015- 65165-C2-R (MINECO/FEDER). I. Unzueta also wants to acknowledge Eusko Jaurlaritza for Grant No. PRE-2014-214.

Single-nanoantenna has intrigued vast interest due to its exceptional properties such as light harvesting and field enhancement, which provide the opportunities for strengthening light-matter interaction and efficient photon manipulation in nano-scale, as well as boosting nonlinear response. On the other hand, materials with structural or electronic phase transition have been employed to achieve large optical modulation contrast and order-unity switching, making them promising building blocks for high-performance optical circuits and devices with ultra-small footprint. In this context we demonstrate nano-scale all-optical modulation with single Au antennas fabricated on phase-transition material vanadium dioxide (VO2) substrate. VO2 films are deposited on boroaluminosilicate glass coated with a 30-nm layer of fluorine-doped tin oxide. The inclusion of this intermediate layer allows the production of VO2 films with low surface roughness and suitable thermochromic transition temperature. Then the nanoantennas are fabricated by e-beam lithography and subsequent 45-nm-thick gold deposition on the VO2 substrate. A 5-nm-thick Ti layer is used to improve the adhesion of the gold to the VO2. We use a pump-probe spectroscopy to characterize the modulation feature of the antenna/VO2. The pump beam at 1060 nm wavelength is used to introduce a local heating for VO2's phase transition and the probe beam from 1100 nm to 2000 nm wavelength is for readout of the modulated local transmission of antenna/VO2 hybrid owing to the dielectric environment change. A spatial modulation technique is also used to extract the differential transmission (ΔT/T) around the antennas. As a result, with pump pulse energy increasing to less than 1 nJ, the measured ΔT/T of single-antenna//VO2 hybrid exhibits substantial change that crossing the zero line and significant blue shift. As reported the ΔT/T obtained from spatial modulation spectroscopy is supposed to be proportional to the antenna’s extinction cross section. However, with the obtained negative values which lead to unphysical extinction cross sections less than 0, we believe the VO2 substrate beneath the antennas is highly involved as its optical property has been modified considerately. In addition, we observe that the pump-modulated differential transmission of the antenna/VO2 hybrid evidently depends on the polarisation of the pump when it is below a certain level. In this regime, the parallel pumping excites the longitudinal resonant mode while the perpendicular one only induces non-resonant absorption of antenna’s transverse mode. Going beyond this regime, the stronger pump transits the VO2 substrate from insulating phase into metallic phase completely, which dominates the dielectric environment change of the antenna, leading to nearly polarisation-independent modulation. The time for fully switch-on obtained from the pump-probe measurement is less than 50 ps. We also investigate the time response of the differential transmission dependent on the pulse repetition rate and substrate temperature, respectively. Less modulation depth with repetition rate over 2 MHz or base temperature higher than 40 °C suggest that the heat accumulation from adjacent pulses and thermal equilibrium time plays important roles in the achievable modulation speed. The single-antenna/VO2 structure may find applications in nano-scale optoelectronics for multiple functionalities including modulation, memory and so on.

We analyze the full relativistic force experienced by swift electrons moving close to planar films for the experimental conditions commonly used in electron energy loss spectroscopy in STEM. In metals the main effects derive from the dispersion of the surface plasmons, which are clearly observed in the EEL spectra. In insulators we explore the role played by the Cherenkov radiation (CR) emitted in the energy gap window. The focus is placed on the transverse force and different factors which may turn this force into repulsive, as reported in recent experimental and theoretical works., This project was supported by the ETORTEK project NANOIKER from the Basque Government (BG), project FIS2010-19609-C02-01 from the Spanish Ministry of Science and Innovation and Grant IT-75613 from BG-UPV/EHU.

Plasmonic gaps are known to produce nanoscale localization and enhancement of optical fields, providing small effective mode volumes of about a few hundred nm. Atomistic quantum calculations based on time-dependent density functional theory reveal the effect of subnanometric localization of electromagnetic fields due to the presence of atomic-scale features at the interfaces of plasmonic gaps. Using a classical model, we explain this as a nonresonant lightning rod effect at the atomic scale that produces an extra enhancement over that of the plasmonic background. The near-field distribution of atomic-scale hot spots around atomic features is robust against dynamical screening and spill-out effects and follows the potential landscape determined by the electron density around the atomic sites. A detailed comparison of the field distribution around atomic hot spots from full quantum atomistic calculations and from the local classical approach considering the geometrical profile of the atoms' electronic density validates the use of a classical framework to determine the effective mode volume in these extreme subnanometric optical cavities. This finding is of practical importance for the community of surface-enhanced molecular spectroscopy and quantum nanophotonics, as it provides an adequate description of the local electromagnetic fields around atomic-scale features with use of simplified classical methods., Financial support from Project No. FIS2016-80174-P and MAT2016-78293-C6-4-R of MINECO, grant of Consolidated Groups at UPV/EHU (IT-756-13) of the Basque Government, and project 70NANB15H32 from U.S. Department of Commerce, National Institute of Standards and Technology, is acknowledged. M.U. acknowledges support from the University of the Basque Country through a Ph.D. grant, as well as DIPC and CFM at the initial stages of this work. M.B. acknowledges support from the Departamento de Educacion of the Basque Government through a Ph.D. grant, as well as from Euskampus and the DIPC at the initial stages of this work. P.K. acknowledges financial support from the Fellows Gipuzkoa program of the Gipuzkoako Foru Aldundia through the FEDER funding scheme of the European Union, “Una manera de hacer Europa”.

The α

Angiogenesis, the sprouting of new blood vessels from pre-existing vessels, is a remarkable feature of tumours growth and metastasis. The in vivo inhibition of this receptor by cyclic peptides containing RGD sequence may be used to selectively suppress these disease1. Our research group has developed a new methodology2 for the evaluation of new antiangiogenic compounds, based in the genetic expression analysis using CGH array system. The RGD mimetics activity can be modified by the presence of ester-bond3, Therefore, we decided to prepare some depsipeptides analogous to the RGD-β-lactam compounds and evaluate their activity performing a genetic expression analysis. We also have evaluated the activity of open-chain compounds without RGD formal structure. The cyclic depsipeptides have demonstrated a very effective inhibitory activity. In the other hand the open-chain compounds have a surprising behavior, demonstrating a similar gene activation. This way, we call into question the essential need of RGD sequence to have an interaction between ligand and the receptor of the integrin4, 5. da Ressurreicao, A. S. M.; Vidu, A.; Civera M.; Belvisi L.; Potenza, D.; Manzoni, L.; Ongeri, S.; Gennari, C.; Piarulli, U.; Eur. 2009, 15, 12184. Aizpurua, J. M.; Ganboa, J. I.; Palomo, C.; Loinaz, I.; Oyarbide, J.; Fernandez, X.; Belentova, E.; Fratila, R. M.; Jimenez A.; Miranda, J. I.; Laso, A.; Avila, S.; Castrillo, J. L.; ChemBioChem, 2001, 11, 401. Cupido, T.; Spengler, J.; Ruiz-Rodriguez, J.; Adan, J.; Mitjans, F.; Puilats, J.; Albericio, F.; Chem. Int. Ed., 2010, 49, 2732. Xiong, J. P.; Stehle, T.; Zhang, R.; Joachimiak, A.; Frech, M.; Goodman, S. L.; Arnaout, M. A.; Science, 2002, 296, 151. Craig, D.; Gao, M.; Schulten, K.; Vogel, V.; Structure, 2004, 12, 2049.

Nanoscale devices in which the interaction with light can be configured using external control signals hold great interest for next-generation optoelectronic circuits. Materials exhibiting a structural or electronic phase transition offer a large modulation contrast with multi-level optical switching and memory functionalities. In addition, plasmonic nanoantennas can provide an efficient enhancement mechanism for both the optically induced excitation and the readout of materials strategically positioned in their local environment. Here, we demonstrate picosecond all-optical switching of the local phase transition in plasmonic antenna-vanadium dioxide (VO2) hybrids, exploiting strong resonant field enhancement and selective optical pumping in plasmonic hotspots. Polarization- and wavelength-dependent pump–probe spectroscopy of multifrequency crossed antenna arrays shows that nanoscale optical switching in plasmonic hotspots does not affect neighboring antennas placed within 100 nm of the excited antennas. The antenna-assisted pumping mechanism is confirmed by numerical model calculations of the resonant, antenna-mediated local heating on a picosecond time scale. The hybrid, nanoscale excitation mechanism results in 20 times reduced switching energies and 5 times faster recovery times than a VO2 film without antennas, enabling fully reversible switching at over two million cycles per second and at local switching energies in the picojoule range. The hybrid solution of antennas and VO2 provides a conceptual framework to merge the field localization and phase-transition response, enabling precise, nanoscale optical memory functionalities.

We demonstrate ultrafast all-optical switching of local phase-change in plasmonic gold antenna-VO 2 hybrids exploting the strong resonant Near-Field enhancement on localized nanoscale regions.

By synergically combining experiments and simulations, we show how the excitation of lattice surface modes in ordered arrays of magnetic and optically-anisotropic nanoantennas leads to a highly enhanced and tunable Fano-like modulation of the magnetoplasmonic response.

Following an adapted three-step seed-mediated method, we synthesize colloidal Au thin and long (L > 100 nm) nanorods (NRs) and characterize the metallic nanostructures evolving from the initial Au nanoparticle (NPs) seeds to thiolate-functionalized NRs, using HRTEM and ultraviolet, visible, and near-infrared absorption spectroscopy (UV-vis-NIR). For the long NRs we analyze the role of several solvents and rod concentration on the spectral features of the assembled products, which are further studied with simulated spectra. Superimposed to a broad resonance in the range 700-900 nm, which corresponds to short (L < 100 nm) interacting nanorods, the growth of long nanorods is clearly identified with the emergence of a robust resonance at 960 nm, linked to the three half-wavelength antenna plasmon mode. This mode is enhanced when the nanorod concentration decreases and splits into two peaks when the thiolate coverage chemically modifies the rod surface by a thin layer of nanometer size. This behavior is explained with a dielectric model based on ab initio calculations of thiolate-gold cluster surfaces., We gratefully acknowledge the support of the Basque Departamento de Educacion and the UPV/EHU (Grant No.IT-366-07) and Spanish Ministry of Economy and Competitiveness MINECO (FIS2013-48286-C2-1-P and FIS2013-41184-P) and the ETORTEK research program funded by the Basque Departamento de Industria and the Diputacion Foral de Guipuzcoa (nanoGUNE 2014). F.J. Recio thanks a Fondecyt 3130538 Postdoctoral Grant.