2,846 research outputs found

    Self-Assembled Peptide–Inorganic Nanoparticle Superstructures: From Component Design to Applications

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    [Abstract] Peptides have become excellent platforms for the design of peptide–nanoparticle hybrid superstructures, owing to their self-assembly and binding/recognition capabilities. Morover, peptide sequences can be encoded and modified to finely tune the structure of the hybrid systems and pursue functionalities that hold promise in an array of high-end applications. This feature article summarizes the different methodologies that have been developed to obtain self-assembled peptide–inorganic nanoparticle hybrid architectures, and discusses how the proper encoding of the peptide sequences can be used for tailoring the architecture and/or functionality of the final systems. We also describe the applications of these hybrid superstructures in different fields, with a brief look at future possibilities towards the development of new functional hybrid materials.We are thankful for the funding received from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 851179), the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (FEDER) (CTQ2016-75629-P), the Agencia Estatal de Investigación and FEDER (CTQ2017-89166-R) and the Consellería de Educación, Universidade e Formación Profesional, Xunta de Galicia (ED431C 2018/39). E. P. thanks the UDC-Inditex InTalent Programme for her research contract and funding and the Xunta de Galicia for the Oportunius ProgrammeXunta de Galicia; ED431C 2018/3

    Quantum authentication with unitary coding sets

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    A general class of authentication schemes for arbitrary quantum messages is proposed. The class is based on the use of sets of unitary quantum operations in both transmission and reception, and on appending a quantum tag to the quantum message used in transmission. The previous secret between partners required for any authentication is a classical key. We obtain the minimal requirements on the unitary operations that lead to a probability of failure of the scheme less than one. This failure may be caused by someone performing a unitary operation on the message in the channel between the communicating partners, or by a potential forger impersonating the transmitter.Comment: RevTeX4, 10 page

    Thinking Outside the Blue Box: Induced Fit within a Unique Self-Assembled Polycationic Cyclophane

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society.[Abstract] We present herein the development of a new polycationic molecular receptor, inspired by the ubiquitous cyclobis(paraquat-p-phenylene)cyclophane (“blue box”). Our analogue, the “white box”, has been easily self-assembled on a preparative scale in water, using a template-assisted process by acyl hydrazone bonding of complementary bis(pyridinium)xylylene tweezers, followed by kinetic trapping of the empty receptor. The obtained macrocycle was found to display a marked pH responsiveness in water, because of an abnormal acidity of the amide protons within its structure. Consequently, and because of the concurrence of rotational isomerism under acidic conditions (fixed at higher pH values), the compound was found to display a dual behavior as a conformationally locked/flexible molecular host, being able to recognize appropriate aromatic substrates, in a lock and key or induced fit fashion, by a conjunction of π–π, C–H···π, and, crucially, the hydrophobic effect.This research was supported by the Ministerio de Economía y Competitividad (MINECO FEDER, Grant CTQ2016-75629-P

    A convenient synthesis of new 6-substituted purinylcarbanucleosides on cyclopenta[b]thiophene

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    The 12th International Electronic Conference on Synthetic Organic Chemistry session Bioorganic Chemistry and Natural ProductsThe first members of a new family of heterocarbobicyclic nucleoside analogues have been synthesized from the cis/trans mixture of (4-amino-5,6-dihydro-4H-cyclopenta[b]thiophen-6-yl)methanols cis/trans-7. The separation of cis and trans intermediates during preparation of the 6-chloropurine derivatives allowed separate preparation of the purine heterocarbanucleosides cis-10 and trans-11, from which cis-(12-14) and trans-(16-18) were obtained by replacement of the 6-chloro substituent with amino, hydroxy and cyclopropylamino groups. Additionally, the 6-phenyl-purinyl analogues cis-15 and trans-19 were prepared from cis-10 and trans-11 using Suzuki-Miyaura methodologyThe authors thank the Xunta de Galicia for financial support under project PGIDIT02BTF20305P

    Aplicación para la gestión personalizada de pacientes con diabetes

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    El término "diabetes mellitus" se emplea para describir un grupo de trastornos metabólicos caracterizados por la hiperglucemia debido a la deficiencia en la secreción de insulina, acción deteriorada de la insulina o ambas condiciones. Además, se erige como una de las enfermedades no contagiosas más comunes en el mundo. Los individuos con diabetes requieren un monitoreo constante de sus niveles de glucosa y otros factores que afectan la enfermedad, lo que genera una carga importante en los centros de salud que se centran en tareas de control y seguimiento. Con el avance de las tecnologías, han surgido aplicaciones móviles orientadas a mejorar la vida de las personas afectadas por esta enfermedad. Este estudio presenta una aplicación diseñada para la gestión personalizada e integral de la diabetes, abordando las limitaciones que tienen otras aplicaciones existentes en el mercado. La aplicación captura, monitorea y analiza todos los factores relevantes que contribuyen a la enfermedad, al tiempo que evalúa el cumplimiento del paciente de los objetivos establecidos. Esta contribución aspira a mejorar la calidad de vida y las capacidades de autocuidado de las personas que padecen diabetes, ofreciendo un enfoque global de su condición

    Biodegradable PEG–dendritic block copolymers: synthesis and biofunctionality assessment as vectors of siRNA

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    One important drawback of most of the currently used dendrimers for biomedical applications is their high stability under physiological conditions that can result in cytotoxicity or complications induced by the accumulation of non-degradable synthetic materials in the organism. Particularly in the gene therapy field, vector stability can further hinder the intracellular release of the nucleic acid from the dendriplex, consequently leading to low transfection efficiencies. Therefore, biodegradable cationic dendritic structures have been eagerly awaited. However, the development of these dendritic nanocarriers is challenging because of the undesired and/or premature degradation observed during their synthesis and/or application. Here, we report new hybrid-biodegradable, biocompatible, non-toxic, and water-soluble azide-terminated PEG–GATGE dendritic block copolymers, based on a gallic acid (GA) core and triethylene glycol (TG) butanoate arms, incorporating ester bonds (E) at the dendritic arms/shell. Their successful functionalization by “click” chemistry with unprotected alkynated amines allowed complexation and delivery of siRNA. The hydrophobic character of the GATGE building unit confers to these hydrolyzable dendritic bionanomaterials a great ability to complex, protect and mediate the cellular internalization of siRNA. Moreover, the localization of the degradation points at the dendritic periphery, close to the complexed siRNA, was found to be important for nucleic acid release from the nanoparticles, rendering a significant improvement of the transfection efficiency compared to their hydrolytically stable PEG–GATG copolymer counterparts. The present study puts forward these biodegradable PEG–dendritic block copolymers not only as suitable vectors for nucleic acids, but also as new avenues for further developments exploring their use in theranosticsThe authors would like to acknowledge the FEDER funds through the Programa Operacional Factores de Competitividade – COMPETE and the Portuguese funds through FCT – Fundação para a Ciência e a Tecnologia (PTDC/CTM-NAN/112428/2009 and PTDC/CTM-NAN/3547/2014) that supported this work and the FCT / MEC through National Funds and, when applicable, co-financed by the FEDER via the PT2020 Partnership Agreement under the 4293 Unit I&D. V. Leiro acknowledges the support by FCT (SFRH/BPD/69110/2010) and by the project NORTE-01-0145-FEDER-000012, financed by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). P.M.D. Moreno acknowledges the support from the Marie Curie Actions of the European Community’s Seventh Framework Program (PIEF-GA-2011-300485) and FCT fellowship (SFRH/BPD/108738/2015). This work was also financially supported by the Spanish Government (MINECO: CTQ2012-34790, CTQ2012-33436) and the Xunta de Galicia (CN2011/037)S

    Identificación de fuentes de ruido en los sectores automovilístico y de la construcción

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    La identificación de fuentes de ruido es uno de los temas de actualidad en el campo de la acústica, ya que nos permite conocer las causas de la generación de ruido y atajar el problema en su raíz, actuando sobre aquellas zonas en las que la emisión de ruido es mayor. En el presente artículo se muestra la investigación sobre identificación de fuentes de ruido llevada a cabo en dos sectores distintos: el sector automovilístico y el sector de la construcción. En el sector automovilístico se han llevado a cabo dos investigaciones diferenciadas. En primer lugar, se ha evaluado la forma en que las distintas fuentes de ruido del vehículo parado (motor y tubo de escape) influyen en el ruido percibido por el conductor y los viandantes, identificando las fuentes más molestas y cuyo nivel de ruido debería reducirse. Por otro lado, se han identificado las fuentes que mayor nivel de ruido generan cuando el vehículo circula a velocidad constante, observándose que la mayor radiación se produce en la interacción de las ruedas con el asfalto, siendo el siguiente paso el diseño de neumáticos y pavimentos que, cumpliendo las exigencias de seguridad, contribuyan a una menor generación de ruido, que redunde en un mayor confort acústico en nuestras ciudades. Dentro del sector de la construcción, se han utilizado distintas técnicas que nos permiten identificar aquellas partes de los paramentos que poseen un menor aislamiento acústico, localizando las partes de los mismos (juntas, ventanas, puertas…) sobre las que deberíamos actuar si queremos mejorar el aislamiento acústico en los edificios

    An immersed boundary hierarchical B-spline method for flexoelectricity

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    This paper develops a computational framework with unfitted meshes to solve linear piezoelectricity and flexoelectricity electromechanical boundary value problems including strain gradient elasticity at infinitesimal strains. The high-order nature of the coupled PDE system is addressed by a sufficiently smooth hierarchical B-spline approximation on a background Cartesian mesh. The domain of interest is embedded into the background mesh and discretized in an unfitted fashion. The immersed boundary approach allows us to use B-splines on arbitrary domain shapes, regardless of their geometrical complexity, and could be directly extended, for instance, to shape and topology optimization. The domain boundary is represented by NURBS, and exactly integrated by means of the NEFEM mapping. Local adaptivity is achieved by hierarchical refinement of B-spline basis, which are efficiently evaluated and integrated thanks to their piecewise polynomial definition. Nitsche’s formulation is derived to weakly enforce essential boundary conditions, accounting also for the non-local conditions on the non-smooth portions of the domain boundary (i.e. edges in 3D or corners in 2D) arising from Mindlin’s strain gradient elasticity theory. Boundary conditions modeling sensing electrodes are formulated and enforced following the same approach. Optimal error convergence rates are reported using high-order B-spline approximations. The method is verified against available analytical solutions and well-known benchmarks from the literature

    Aqueous Three-Component Self-Assembly of a Pseudo[1]rotaxane Using Hydrazone Bonds

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    [Abstract] We present herein the synthesis of a new polycationic pseudo[1]rotaxane, self-assembled in excellent yield through hydrazone bonds in aqueous media of three different aldehyde and hydrazine building blocks. A thermodynamically controlled process has been studied sequentially by analyzing the [1 + 1] reaction of a bisaldehyde and a trishydrazine leading to the macrocyclic part of the system, the ability of this species to act as a molecular receptor, the conversion of a hydrazine-pending cyclophane into the pseudo[1]rotaxane and, lastly, the one-pot [1 + 1 + 1] condensation process. The latter was found to smoothly produce the target molecule through an integrative social self-sorting process, a species that was found to behave in water as a discrete self-inclusion complex below 2.5 mM concentration and to form supramolecular aggregates in the 2.5–70 mM range. Furthermore, we demonstrate how the abnormal kinetic stability of the hydrazone bonds on the macrocycle annulus can be advantageously used for the conversion of the obtained pseudo[1]rotaxane into other exo-functionalized macrocyclic species.The authors are thankful for the funding received from the MCIN/AEI/10.13039/501100011033 and ERDF “A way of making Europe” (CTQ2016-75629-P, CTQ2017-89166-R and PID2019-105272GB-I00), the Consellería de Cultura, Educación e Universidade, Xunta de Galicia (ED431C 2018/39, ED431C 2022/39 and 508/2020), and the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant Agreement No. 851179). P.C. and A.B.-G. thank the Consellería de Cultura, Educación e Universidade, Xunta de Galicia for their PhD and postdoctoral fellowships (ED481A-2020/019 and ED481B-2021-099, respectively). M.D.-A. thanks the Fundación Gil Dávila and the Ministerio de Universidades (FPU21/06302) for his PhD fellowships. E.P. thanks the MCIN/AEI/10.13039/501100011033 and ESF “Investing in your future” for her Ramón y Cajal contract (RYC2019-027199-I)Xunta de Galicia; ED431C 2018/39Xunta de Galicia; ED431C 2022/39Xunta de Galicia; 508/2020Xunta de Galicia; ED481A-2020/019Xunta de Galicia; ED481B-2021-09
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