A Hydrophilic Channel Is Involved in Oxidative Inactivation of a [NiFeSe] Hydrogenase

International audienceHydrogenases are metalloenzymes that catalyze the redox conversion between H2 and protons. The so-called [NiFeSe] hydrogenases are highly active for both H2 production and oxidation, but like all hydrogenases, they are inhibited by O2. In the [NiFeSe] enzyme from Desulfovibrio vulgaris Hildenborough this inhibition results from the oxidation of an active site cysteine ligand. We designed mutations that constrict a hydrophilic channel which connects the protein surface to this active site cysteine. Two of the variants show markedly increased tolerance to O2 inactivation, while they retain high catalytic activities in both directions of the reaction, and structural studies confirm that these mutations prevent the oxidation of the cysteine. Our results indicate that the diffusion of O2 or ROS to the active site can occur through a hydrophilic water channel, in contrast to the widely held assumption that only hydrophobic channels are involved in active site inactivation. This provides an original strategy for optimizing the enzyme by protein engineering

Size and branching effects on the fluorescence of benzylic dendrimers possessing one apigenin fluorophore at the core

Different generations of dendrimers incorporating one fluorescent core of apigenin and three Fréchet benzylic dendrons have been prepared. The chief geometric features of these dendrimers have been obtained by Molecular Dynamics simulations. These computational data suggest that the asphericities of dendrimers belonging to the third and fourth generations are considerably larger than those associated with lower radii of gyration. Fluorescence spectra of high generation dendrimers evolve along time and quantum yields show an appreciable lowering for the fourth generation dendrimer. All these data suggest aggregation phenomena and lower quantum yields for nonspheric dendrimers in solution.Financial support by the Spanish Ministry of Economy and Competitiveness, with the participation of European Union (MINECO, projects CTQ2010-16959/BQU, CTQ2012- 35535 and Consolider-Ingenio CSD2007-00006), from the University of the Basque Country (UPV/EHU, UFI11/22 QOSYC), from the Basque Government (GV/EJ, grant IT-324-07), from the Donostia International Physics Center (DIPC), from the Ministry of Education, Youth and Sports of the Czech Republic (grant MSM6046137305), and Czech Science Foundation (projects 304/10/1951, P503/11/0616) is acknowledged. M. d. B. thanks the CSIC for the JAE-Pre contract funding for her PhD. The authors also thank the SGI/IZO-SGIker UPV/EHU and the DIPC for generous allocation of computational resources.Peer reviewe

FR2 5G Networks for Industrial Scenarios: An Experimental Characterization and Beam Management Procedures in Operational Conditions

Industrial environments constitute a challenge in terms of radio propagation due to the presence of machinery and the mobility of the different agents, especially at mmWave bands. This paper presents an experimental evaluation of a FR2 5G network deployed in an operational factory scenario at 26 GHz. The experimental characterization, performed with autonomous mobile robots that self-navigate the industrial lab, leads to the analysis of the received power along the factory and the evaluation of reference path gain models. The proposed assessment deeply analyzes the physical layer of the communication network under operational conditions. Thus, two different network configurations are assessed by measuring the power received in the entire factory, providing a comparison between deployments. Additionally, beam management procedures, such as beam recovery, beam sweeping or beam switching, are analyzed since they are crucial in environments where mobile agents are involved. They aim for a zero interruption approach based on reliable communications. The results analysis shows that beam recovery procedures can perform a beam switching to an alternative serving beam with power losses of less than 1.6 dB on average. Beam sweeping analysis demonstrates the prevalence of the direct component in Line-of-Sight conditions despite the strong scattering component and large-scale fading in the environment.Comment: 11 pages, 10 figure

Carbon nanodots modified-electrode for peroxide-free cholesterol biosensing and biofuel cell design

The determination of cholesterol is greatly important because high concentrations of this biomarker are associated to heart disease. Moreover, cholesterol can be used as a fuel in enzymatic fuel cells operating under physiological conditions. Here, we present a cholesterol biosensor and a peroxide-free biofuel cell based on the electrocatalytic oxidation of the NADH generated during the enzymatic reaction of cholesterol dehydrogenase (ChDH) as an alternative to the H2O2 biosensing strategies used with cholesterol oxidase-bioelectrodes. Azure A functionalized-carbon nanodots were used as NADH oxidation electrocatalysts and for ChDH covalent immobilization. The biosensor responded linearly to cholesterol concentrations up to 1.7 mM with good sensitivity (4.50 mA cm−2 M−1) and at a low potential. The ChDH bioelectrode was combined with an O2-reducing bilirubin oxidase cathode to produce electrical energy using cholesterol as fuel and O2 as oxidant. Furthermore, the resulting enzymatic fuel cell was tested in human serum naturally containing free cholesterolA.L.DL. and M.P. thank MCIU/AEI/FEDER, EU for funding project RTI2018–095090-B-I00. M.B. acknowledges funding from the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie grant agreement No. 713366. This work was also supported by Talent Attraction Project from CAM (SI3/PJI/ 2021–00341 and 2021–5A/BIO-20943), Spanish Ministerio de Ciencia e Innovacion (PID2020–116728RB-I00) and TRANSNANOAVANSENSCAM Program (S2018/NMT-4349

New data and genetic models of the Ba-Sr ore deposits related to the Jurassic-Cretaceous sequence of the Neuquén Basin, Neuquén Province

La cuenca Neuquina representa unos de los ejemplos más significativos en la Argentina de desarrollo de ciclos carbonático-evaporíticos marinos y de eventos de sedimentación clástica continental, sucedidos alternadamente durante el lapso Jurásico-Cretácico. Asociado a definidos horizontes estratigráficos de esos ciclos se encuentra un numeroso conjunto de depósitos barítico-celestínicos de carácter estratoligado vinculado a distintos procesos mineralizantes: depositación sedimentario-exhalativa en fondo marino, reemplazo preferencial de rocas carbonáticas y niveles yesíferos con procesos diagenéticos superpuestos y relleno de fracturas y oquedades. Las mineralizaciones de Ba-Sr, mayoritariamente epigenéticas, están vinculadas a la acción de fluidos hidrotermales en áreas con y sin afloramientos de rocas ígneas.The Neuquén Basin represents one of the more significant examples in Argentina where several marine carbonate-evaporite and continental cycles were developed during the Jurassic-Cretaceous. Numerous Ba-Sr stratabound deposits are closely associated with the carbonate and gypsum horizons of several stratigraphic units, as the result of different mineralizing processes: sedimentary-exhalative deposition onto the seafloor, selected replacements of carbonate rocks and gypsum beds with subsequent diagenetic processes and hydrothermal infilling of fractures, voids and vugs. The Ba-Sr mineralizations are mainly epigenetic, and they are related to hydrothermal fluids that occurred in areas with or without igneous rock outcrops.Facultad de Ciencias Naturales y Muse

Free PCR virus detection via few-layer bismuthene and tetrahedral DNA nanostructured assemblies

In this work we describe a highly sensitive method based on a biocatalyzed electrochemiluminescence approach. The system combines, for the first time, the use of few-layer bismuthene (FLB) as a platform for the oriented immobilization of tetrahedral DNA nanostructures (TDNs) specifically designed and synthetized to detect a specific SARS-CoV-2 gene sequence. In one of its vertices, these TDNs contain a DNA capture probe of the open reading frame 1 ab (ORF1ab) of the virus, available for the biorecognition of the target DNA/RNA. At the other three vertices, there are thiol groups that enable the stable anchoring/binding to the FLB surface. This novel geometry/approach enables not only the binding of the TDNs to surfaces, but also the orientation of the capture probe in a direction normal to the bismuthine surface so that it is readily accessible for binding/recognition of the specific SARS-CoV-2 sequence. The analytical signal is based on the anodic electrochemiluminescence (ECL) intensity of luminol which, in turn, arises as a result of the reaction with H2O2, generated by the enzymatic reaction of glucose oxidation, catalyzed by the biocatalytic label avidin-glucose oxidase conjugate (Av-GOx), which acts as co-reactant in the electrochemiluminescent reaction. The method exhibits a limit of detection (LOD) of 4.31 aM and a wide linear range from 14.4 aM to 1.00 μM, and its applicability was confirmed by detecting SARS-CoV-2 in nasopharyngeal samples from COVID-19 patients without the need of any amplification processPID2020-116728RB-I00, PID2020-116661RB-I00, PID2020-119352RB-I00, PDC2021-120782-C2, PID2022-138908NB-C31, CTQ2015-71955-REDT, S2018/NMT-434

Desarrollo de (nano)biosensores enzimáticos de fluorescencia dirigidos a la monitorización mínimamente invasiva de glucosa

Tesis llevada a cabo para conseguir el grado de doctor en la Universidad de ZaragozaEsta tesis doctoral consiste en el desarrollo de nuevas metodologías analíticas para la determinación de glucosa que puedan ser implementadas en sistemas de monitorización no invasivos. Una alternativa interesante es la determinación de glucosa en los fluidos intersticiales del tejido subcutáneo cuya concentración está relacionada con su valor en sangre La enzima glucosa oxidasa (GOx) posee propiedades ópticas que cambian reversiblemente durante la reacción enzimática (propiedades autoindicadoras) y, por tanto, su elección como biorreceptor permite cumplir los requisitos exigibles a estos sistemas de monitorización. Puesto que el sistema sensor requiere un soporte físico en el que se encuentre inmovilizado el elemento de reconocimiento, se estudiaron diferentes materiales o soportes para el diseño de biosensores implantables basados en GOx: - Nanopartículas magnéticas como base para el diseño de nanobiosensores ópticos - Nanobiosensores basados en las propiedades de fluorescencia upconversion de vidrios de fluorohafnato y nanopartículas (UCLNP) - Biosensores basados en hidrogeles de poliacrilamida Los mejores resultados se obtuvieron empleando GOx modificada con un derivado de fluoresceína (GOx-FS) y UCLNP. Se utilizaron láminas de poliacrilamida como soporte físico para la inmovilización de enzima y nanopartículas y un sistema FIA (análisis por inyección en flujo) para las medidas. Tras la optimización de los parámetros físicos y químicos que afectan a la señal analítica, el biosensor desarrollado responde linealmente a glucosa en el rango comprendido entre 3,3 y 16,6 mM y se mantiene estable al menos durante 9 días. Por otra parte, la GOx-FS, funcionalizada con grupos acrilato (para mejorar la estabilidad de la inmovilización), se incorporó a hidrogeles de poliacrilamida sintetizados con unas características físicas muy similares a los comerciales. Trabajando en modo FIA se obtuvieron señales estables durante una semana (dos medidas diarias). El rango lineal se extiende hasta 15,6 mM (DER=5%). Finalmente, se realizaron los primeros ensayos in vivo en ratones, a los que se inyectó subcutáneamente el hidrogel sintetizado.Peer reviewe

Enhancement of biosensors by implementing photoelectrochemical processes

Research on biosensors is growing in relevance, taking benefit from groundbreaking knowledge that allows for new biosensing strategies. Electrochemical biosensors can benefit from research on semiconducting materials for energy applications. This research seeks the optimization of the semiconductor-electrode interfaces including light-harvesting materials, among other improvements. Once that knowledge is acquired, it can be implemented with biological recognition elements, which are able to transfer a chemical signal to the photoelectrochemical system, yielding photo-biosensors. This has been a matter of research as it allows both a superior suppression of background electrochemical signals and the switching ON and OFF upon illumination. Effective electrode-semiconductor interfaces and their coupling with biorecognition units are reviewed in this work.European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 713366. G. Luna-López wishes to thank to “Comunidad de Madrid” and European Structural Funds for their financial support to FotoArt-CM project (S2018/NMT-4367). M. Pita thanks the Retos MCIU/AEI/FEDER, EU for funding project RTI2018-095090-B-I00

Metal-binding to Amyloid-β Peptide: Coordination, Aggregation and Reactive Oxygen Species Production

International audienceAmyloid-plaques are a hallmark of Alzheimer’s disease. They consist mainly of an aggregated peptide called amyloid-β. These plaques also accumulate high concentrations of metal ions, mainly Cu, Zn and Fe. Cu and Zn directly bind to amyloid-β in vivo. This triggered a strong researchactivity in order to understand the biology and chemistry of the interaction between metal ions and amyloid-β. This includes also the chemical and biophysical aspects of the metal-amyloid-β complexes. The present article describes the coordination chemistry of the Cu(II), Cu(I), Zn(II) andFe(II) complexes in terms of ligand spheres and affinities. Moreover, metal ions modulate the selfassembly of amyloid-β into amyloids, a central event in Alzheimer’s disease. Attention was paid on the catalytic role of Cu-bound to amyloid-β, in particular in terms of the production of reactive oxygen species, which have been proposed to be involved in the disease progression. Recent mechanistic insights are described