Gallium nanoparticles colloids synthesis for UV bio-optical sensors

F. Nucciarelli, I. Bravo, L. Vázquez, E. Lorenzo, J. L. Pau, "Gallium nanoparticles colloids synthesis for UV bio-optical sensors", SPIE Optics + Optoelectronics Proc. SPIE 10231 (16 May 2017) Copyright 2017 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Proceedings of the Optical Sensors Conference (Prague, Czech Republic) doi: https://doi.org/10.1117/12.2265883A new method for the synthesis of colloidal gallium nanoparticles (Ga NPs) based on the thermal evaporation of Ga on an expendable aluminum zinc oxide (AZO) layer is presented here. The growth of AZO layers was investigated on different substrates at room temperature and 300 °C. By means of physical evaporation process, nanoparticles were deposited with a distribution ranging from 10 nm to 80 nm in diameter. A study of their endurance in acidic environment was carried out in order to assure the NPs shape and size stability during the etching process. Smaller particles start to disappear between 1h and 2h immersion time in a pH=1 solution, while bigger particles reduce their dimension. The NPs were dispersed in tetrahydrofuran (THF) organic solvent and optically characterized, showing strong UV absorption with a band centered at 280 nm. The colloids size distribution of as-evaporated samples was compared with the distribution obtained in droplets of the solution after drop-casting. By Dipole Discrete Approximation simulations, a close relationship between the UV absorption and the NPs with diameter smaller than ∼40 nm was found. Because of the gallium oxide (Ga1-xOx) outer shell that surrounds the Ga NPs, an enhancement of their hydrophobicity occurs. Hence, the low agglomeration state between NPs in tetrahydrofuran allows to obtain narrow absorption band in the optical spectrumWe are also grateful to the international PROMIS project, framed in the Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 641899. This research is supported by the MINECO (CTQ2014-53334-C2-2-R and MAT2016-80394-R) and Comunidad de Madrid (NANOAVANSES ref. S2013/MIT-3029) Projec

Una experiencia sobre la construcción de listas en educación infantil

Una educación matemática de calidad constituye el fundamento para conseguir equipar a los estudiantes con las herramientas matemáticas necesarias para aprovechar las oportunidades que encontrarán en su futuro. En los primeros niveles de enseñanza se crea la base que los alumnos necesitarán para progresar en su aprendizaje posterior, de ahí la importancia de que los maestros planifiquen y gestionen situaciones matemáticas en contextos próximos a los alumnos, que los inciten a implicarse en su resolución. En el presente estudio se ha llevado a cabo una experiencia sobre una situación de aprendizaje basada en la construcción de listas como inventario de colecciones de objetos

La omnicanalidad como medio de homogeneización de la experiencia de compra

Una estrategia que adquiere cada vez más importancia entre las empresas es la omnicanalidad fruto de los cambios que tienen lugar en el entorno, convirtiéndose en un elemento imprescindible para las empresas que persiguen optimizar sus ventas por internet. De forma paralela a los cambios en las empresas, también se han producido cambios en los consumidores que tienen presente ambos canales a la hora de realizar el proceso de decisión de compra. Con este trabajo se pretende analizar esta estrategia en el sector de la moda y complementos en empresas españolas con el fin de dar a conocer las oportunidades que supone esta estrategia para las empresas. Para ello se ha desarrollado una investigación cualitativa mediante entrevistas en profundidad que ponen de manifiesto que es una de las estrategias más seguidas por parte de las empresas entrevistada

Digital Game-Based Heritage Education: Analyzing the Potential of Heritage-Based Video Games

Video games have emerged as a promising tool for enhancing engagement with cultural heritage. However, there is limited knowledge about how existing games can effectively fulfill this role. This study compiled and analyzed 100 video games based on cultural heritage by adapting an existing framework that includes 10 game attributes for a comparative statistical analysis of the games’ engagement features. These features include narrative-driven gameplay, information capsules, task-driven learning, ease of play, identity-driven content, open-world exploration, people-centered perspectives, meaningfulness, simulation, and verisimilitude. The analysis revealed that while the majority of games adhered to most of the recommended attributes, features such as task-driven learning, open-world exploration, and simulation were either uncommon or rare. These findings highlight a significant opportunity to develop games that incorporate these underrepresented features, thereby providing more immersive and engaging experiences in heritage education. Furthermore, the study offers a systematic overview of existing games that represent cultural heritage, serving as a valuable resource for developers, designers, and educators in this field.Predoctoral fellowship from the Spanish Ministry of Universities (FPU20/00281)Project “Influence of Video Game Addiction on the Adolescent Population of Andalusia in Educational and Family Contexts (PRY127/22)”, funded by the Andalusian Studies Centre Foundation (CENTRA

Sensitive glyphosate electrochemiluminescence immunosensor based on electrografted carbon nanodots

A novel electrochemiluminescence (ECL) immunosensor based on electrografted carbon nanodots (CND) is developed for the sensitive determination of glyphosate in soy milk and tea. Nitrogen rich CND were synthesized by microwave radiations using mild conditions and following the principles of green chemistry. L-Arginine and 3,3′-diamino-N-methyldipropylamine were selected as precursors. CND were exhaustively characterized as well as the resulting nanostructured electrodes after CND electrografting. The high stability of CND nanostructured electrode together with the high electrical conductivity and the improvement of the electrochemiluminescent properties from the luminophore [Ru(bpy)3]2+ makes it an excellent electrochemiluminescence detection platform for biosensing assays. The application to biosensors was assessed by combination with an immunoassay based on magnetic nanoparticles, in which anti-glyphosate-IgG coupled magnetic particles (MP-Ab) was used as recognition element of the analyte, glyphosate. The developed ECL immunosensor was successfully applied for the detection of glyphosate in a wide linear range from 28.9 to 200 pg/mL, a sensitivity of 3.38 × 10−3 mL/pg and a detection limit of 8.66 pg/mL. The immunosensor response is stable and reproducible and it has been applied to the determination of glyphosate in tea and soy milk, with results that agree with those provided by an ELISA kit involving the same immunoreagentsThis work has been supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (CTQ2017-84309-C2-1-R; RED2018-102412-T) and Comunidad Autónoma de Madrid (P2018/NMT-4349 TRANSNANOAVANSENS Program and 2017-T1/BIO-5435 Atracción de Talento Project

Insulin sensor based on nanoparticle-decorated multiwalled carbon nanotubes modified electrodes

Insulin sensors based on glassy carbon electrodes modified with nafion-multiwalled carbon nanotubes decorated with nickel hydroxide nanoparticles (Ni(OH)<inf>2</inf>NPs/Nafion-MWCNTs/GC), were prepared by electrochemical deposition of Ni(OH)<inf>2</inf>NPs from a dinuclear paddle-wheel Ni monothiocarboxylate complex on the MWCNTs/GC surface. The size and distribution of the Ni(OH)<inf>2</inf>NPs/Nafion-MWCNTs were characterized by transmission electron microscopy (TEM). The results show that Ni(OH)<inf>2</inf> nanoparticles were electrodeposited on the surface of carbon nanotubes. Moreover, the electrochemical behavior of the modified electrodes in aqueous alkaline solutions of insulin was studied by cyclic voltammetry and chronoamperometry. It was found that the as-prepared nanoparticles have excellent electrocatalytic activity towards insulin oxidation due to their special properties, reducing the overpotential and improving the electrochemical behavior, compared to the bare GC electrode. Amperometry was used to evaluate the analytical performance of modified electrode in the determination of insulin. Excellent analytical features, including high sensitivity (5.0 A mol cm<sup>-2</sup> μM<sup>-1</sup>), low detection limit (85 nM) and wide dynamic range (up to 10.00 μM), were achieved under optimum conditions. Moreover, these insulin sensors show good repeatability and a high stability after successive potential cycling. Common substances such as ascorbic acid, uric acid and acetaminophen do not interfere. Finally, the developed sensors have been applied to the determination of insulin in pharmaceuticals and in human plasma. Efficient recoveries for pharmaceuticals and human plasma demonstrate that the proposed methodology can be satisfactorily applied to these types of samplesThe authors acknowledge Ministerio de Economía y Competitividad (project No. CTQ2014-53334-C2-1-R and MAT2013-46753-C2-1-P) and Comunidad de Madrid (NANOAVANSENS Program) for financial support. E.M.P. gratefully acknowledges the FPU-2010 Grant from the Ministerio de Educació

Spectroelectrochemical operando method for monitoring a phenothiazine electrografting process on amide functionalized C-nanodots/Au hybrid electrodes

Phenothiazine derivatives are extensively explored dye molecules, which present interesting electrochemical and optical properties. In recent years, the possibility of transforming some phenothiazines in their aryl diazonium salt derivatives has been proved, what allows them to be electrochemically reduced and electrografted onto conductive surfaces. This is a smart way to modify these surfaces and enable them with specific functionalities. In order to better comprehend the electrografting process and consequently have a higher control of it, in this work we have carried out an exhaustive study by operando UV–Vis spectroelectrochemistry of the electrografting of a phenothiazine aryl diazonium salt onto amide carbon nanodots. As a model of phenothiazine dye we have chosen Azure A. The electrografting onto carbon nanodots has been stablished by comparison with the results obtained on bare gold electrodes in this novel study. The presence of carbon dots improves the reversibility of the electrochemical process as derived from the results obtained by operando UV–Vis spectroelectrochemistry. In addition, to asses that the electrochemical process studied corresponds to the electrografting, the results have been compared to those obtained for the simple Azure A adsorption. This study shows the advantages of obtaining simultaneously the electrochemical and the spectroscopic evolution of an electron-transfer process in a single experiment, in a particular electrochemical reaction. This work could be the starting point for the study of the electrografting on other nanomaterialsFunding from the Spanish Ministerio de Ciencia, Innovación y Universidades (project: CTQ2017-84309-C2-1-R) and Comunidad Autónoma de Madrid (NANOAVANSENS Program) is acknowledged. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (Ministerio de Ciencia, Innovación y Universidades, Grant SEV-2016-0686

Direct Covalent Immobilization of new Nitrogen-doped Carbon Nanodots by Electrografting for Sensing Applications

This paper reports a facile strategy to covalently immobilize nanosized carbon dots (CD) onto carbon conductive surfaces for sensing applications. The carbon nanodots designed with surface amine groups (N-CD) can be electrografted onto carbon electrodes and, thus, easily covalently immobilized on these conductive surfaces. They have been synthetized by a carbonization method microwave-assisted using preselected low cost and biocompatible precursors, such as D-fructose as primary carbon source and urea as N-donor reagent to obtain peripheral enriched nitrogen CD. The synthetized nanomaterial has been characterized by different techniques, that confirm the presence of size-regular amorphous structures with blue fluorescence when are irradiated with UV light. The highly stable immobilization of N-CD onto the electrode surfaces by electrografting provides hybrid electrodes with greater relative surface area and improved electron transfer properties, demonstrating to be a great promise for electrochemical sensing. Because of its good electrical conductivity, electrical properties, abundant edges sites and high catalytic activity, N-CD immobilized on carbon electrodes efficient amplify the electrochemiluminiscence (ECL) signal from the luminophore [Ru(bpy)3]2+ in a taurine sensor. A linear concentration range from 126 to 1000 μM, a sensitivity of 7.40ⅹ10-4 μM-1 and a detection limit of 37.8 μM were determined for the taurine sensorThis work has been supported by the Spanish Ministerio de Ciencia, Innovación y Universidades through projects CTQ2017-84309-C2-1-R and RED2018-102412-T, and Comunidad Autónoma de Madrid (S2018/NMT-4349 TRANSNANOAVANSENS-CM Program and 2017-T1/BIO-5435 Atracción de Talento Project). The authors thank Professor Hector Abruña the critical review of this wor

Bifunctional carbon nanodots for highly sensitive HER2 determination based on electrochemiluminescence

Early detection of breast cancer increases the chances of achieving adequate and successful treatment as soon as possible. In this work, a promising disposable electrochemiluminescent immunosensor has been developed for simple, efficient detection of the HER2 protein, a breast cancer biomarker. Nitrogen-rich carbon nanodots were synthesized with two functions: to provide functional groups for covalent immobilization of HER2 antibodies and to act as co-reactants in the electrochemiluminescent process. The proposed immunosensor responded linearly to HER2 concentration over a wide range, showing a detection limit of 20.4 pg mL−1. The reliability of this biosensor was confirmed by analyzing HER2 in the presence of another tumor biomarker (CEA), as well as various proteins and sugars. In addition, this proposed strategy presented good stability and applicability in the analysis of human serum samples, showing great potential for applications in the early diagnosis of breast cancerThis work has been supported by the Spanish Ministry of Science, Innovation and Universities (CTQ2017-84309-C2-1-R; RED2018- 102412-T) and by the Autonomous Community of Madrid (Talent Attraction Project 2017-T1/BIO-5435 and the P2018/NMT4349 TRANSNANOAVANSENS Program

Carbon nanodots based biosensors for gene mutation detection

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodAn electrochemical DNA biosensor based on a carbon nanodots (CDs) modified screen-printed gold electrode as a transducer is reported in this work. CDs were synthesized by thermal carbonization of ethyleneglycol bis-(2-aminoethylether)-N,N,N’,N’-tetraacetic acid (EGTA) and characterized by different techniques (DLS, TEM, FTIR, Raman). The electrode surface modification was accomplished by drop-casting a suspension of CDs. SEM analysis and cyclic voltammetry were used to characterize the resulting modified electrode. Synthetic 25-mer or 100-mer DNA capture probes, capable to hybridize with a specific sequence of the pathogen Helicobacter pylori or the cystic fibrosis transmembrane regulator (CFTR) gene were attached to the CDs-gold surface. A 25-bases synthetic fully complementary sequence or a single nucleotide polymorphism to the DNA capture probe and a 373-bases PCR amplicon of exon 11 of CFTR containing a sequence complementary to the capture probe, were employed as target. The hybridization event was electrochemically monitored by using safranine as redox indicator, which selectively binds to double stranded DNA (dsDNA). A detection limit of 0.16 nM was obtained for the 25-mer synthetic target DNA. The biosensor shows a very high reproducibility and selectivity, allowing to detect a single nucleotide polymorphism. It has been applied to the detection of F508del mutation in the CFTR geneThis work has been supported by the Comunidad Autónoma de Madrid NANOAVANSENS (project No. S2013/MIT-3029) and Spanish Ministerio de Economía, Industria y Competitividad through projects Nos. CTQ2015-71955-REDT (ELECTROBIONET) and CTQ2014-53334-C2-1-R. E. L. thanks the Fulbright scholarship-Salvador de Madariaga program from Spanish Ministerio de Economía, Industria y Competitividad. I. B. gratefully acknowledges the FPI-2012 Grant from Spanish Ministerio de Economía y Competitividad. R.W. gratefully acknowledges support by the European Union structural funds and the Comunidad de Madrid MAD2D-CM Program (S2013/MIT-3007), as well as by the Spanish Ministerio de Economía, Industria y Competitividad through project No. MAT2015-71879-