Suchergebnisse

Radiotherapy is one of the most commonly used cancer treatments, with an estimate of 40% success that could be improved further if more efficient targeting and retention of radiation at the tumor site were achieved. This review focuses on the use of dendrimers in radionanotherapy, an emerging technology aimed to improve the efficiency of radiotherapy by implementing nanovectorization, an already established praxis in drug delivery and diagnosis. The labeling of dendrimers with radionuclides also aims to reduce the dose of radiolabeled materials and, hence, their toxicity and tumor resistance. Examples of radiolabeled dendrimers with alpha, beta, and Auger electron emitters are commented, along with the use of dendrimers in boron neutron capture therapy (BNCT). The conjugation of radiolabeled dendrimers to monoclonal antibodies for a more efficient targeting and the application of dendrimers in gene delivery radiotherapy are also covered ; This work was financially supported by the Spanish Government (CTQ2015-69021-R, CTQ2012-34790) and the Xunta de Galicia (GRC2014/040) and by the "Institut National de la Santé et de la Recherche Médicale" (INSERM), by the "Axe Vectorisation and Radiothérapies" and the "Réseau Gliome Grand Ouest" (ReGGO) of the"Cancéropôle Grand-Ouest". The coauthors of this manuscript are also members of the LabEx IRON "Innovative Radiopharmaceuticals in Oncologyand Neurology" as part of the french government program "Investissements d'Avenir". F.L. thanks the European Commission, Education, Audiovisual and Cultural Executive Agency (EACEA) for an Erasmus Mundus Grant under the NanoFar Joint Doctoral Program ; SI

The characteristic distribution of transverse relaxation times (T2) within dendrimers (shorter values at the core than the periphery) can be exploited in T2-edited 1D and 2D NMR experiments for the stepwise filtering of internal nuclei according to their topology within the dendritic structure. The resulting filtered spectra, which can be conceived as corresponding to virtual hollow dendrimers, benefit from reduced signal overlap, thus facilitating signal assignment and characterization. The generality of the method as a powerful tool in structural and end-group analysis has been confirmed with various dendritic families and nuclei (1H, 13C, 31P) ; This work was financially supported by the Spanish Government (CTQ2009-10963, CTQ2012-34790, CTQ2009-14146-C02-02, CTQ2012-33436) and the Xunta de Galicia (10CSA209021PR and CN2011/037). L.F.P. thanks the Portuguese Foundation for Science and Technology (FCT MCTES) for a Ph.D. grant (SFRH/BD/37341/2007) ; SI

An unexpected 1H NMR invisible fraction (IF) for chitosan (CS) and CS-g-PEG is reported. The presence of this IF is remarkable considering that solution NMR is recognized as the method of choice for studying structural modifications in CS, including the degrees of acetylation (DA) and substitution (DS). In spite of IF figures as high as 50%, this IF does not interfere in the correct determination of the DA by 1H NMR, pointing to a homogeneous distribution of acetyl groups along the visible and invisible fractions. Quite in contrast, the IF negatively biases the determination of the DS in CS-g-PEG, with relative errors as high as 150% in a broad range of temperatures, pH values, and concentrations. This fact raises concerns about the accuracy of previously reported DS data for CS-g-PEG and many other CS copolymers. Efficient user-friendly conditions have been developed for the correct determination of the DS of CS-g-PEG by depolymerization by nitrous acid ; This work was financially supported by the Spanish Government (CTQ2009-10963, CTQ2012-34790, CTQ2009-14146-C02-02, and CTQ2012-33436) and the Xunta de Galicia (10CSA209021PR and CN2011/037) ; SI

The aggregation of chitosan (CS) has been studied as a function of concentration, degree of acetylation (DA), and degree of polymerization (DP) by means of pyrene fluorescence and rheology. Fluorescence experiments show that aggregation of CS involves hydrophobic domains (HD) which are more favoured as lower the DA and DP. Consistent with these results, the viscosity of CS solutions decreases continuously on increasing DA, in the whole range of DP. These results, which rule out the participation of the acetyl groups in the HD, have been interpreted by the theory of hydrophobic polyelectrolytes in terms of the electrostatic energy of the aggregates ; This work was financially supported by the Spanish Government (CTQ2009-10963 and CTQ2009-14146-C02-02) and the Xunta de Galicia (10CSA209021PR and CN2011/037) ; SI

The paramagnetic spin relaxation (PSR) filter allows the suppression of the NMR resonances of individual components in mixtures according to their Gd3+-complexing ability. The difficulty in predicting this property hampers, however, the widespread application of this filter. Herein we describe that the PSR filter is dominated by the transverse relaxation enhancement (R2p) experienced by nuclei in the presence of Gd3+, so that R2p represents a reliable predictive tool of suppression in the 1D and 2D PSR filter of complex mixtures. The robustness of R2p as a predictive tool in PSR filters has been demonstrated at different magnetic fields and for the 1H, 13C, COSY, and HMQC filtering of commercial multicomponent compositions, including beverages and drugs ; This work was financially supported by the Spanish Government (CTQ2012-34790, CTQ2012-33436) and the Xunta de Galicia (CN2011/037). L.F.P. thanks the Portuguese Foundation for Science and Technology (FCT MCTES) for a Ph.D. grant (SFRH/BD/37341/2007) ; SI

Multivalency is a key, ubiquitous phenomenon in nature characterized by a complex combination of binding mechanisms, with special relevance in carbohydrate–lectin recognition. Herein we introduce an original surface plasmon resonance kinetic approach to analyze multivalent interactions that has been validated with dendrimers as monodisperse multivalent analytes binding to lectin clusters. The method, based on the analysis of early association and late dissociation phases of the sensorgrams provides robust information of the glycoconjugate binding efficiency and real-time structural data of the binding events under the complex scenario of the glyco-cluster effect. Notably, it reveals the dynamic nature of the interaction and offers experimental evidence on the contribution of binding mechanisms ; This work was financially supported by the Spanish Government (CTQ2009-10963, CTQ2012-34790, CTQ2009-14146-C02-02) and the Xunta de Galicia (10CSA209021PR and CN2011/037). E.M.M. thanks the Xunta de Galicia for a "Parga Pondal" research contract ; SI

This is a post-peer-review, pre-copyedit version of an article published in The AAPS Journal. The final authenticated version is available online at: https://doi.org/10.1208/s12248-014-9642-3 ; Dendrimers are synthetic macromolecules composed of repetitive layers of branching units that emerge from a central core. They are characterized by a tunable size and precise number of peripheral groups which determine their physicochemical properties and function. Their high multivalency, functional surface, and globular architecture with diameters in the nanometer scale makes them ideal candidates for a wide range of applications. Gallic acid-triethylene glycol (GATG) dendrimers have attracted our attention as a promising platform in the biomedical field because of their high tunability and versatility. The presence of terminal azides in GATG dendrimers and poly(ethylene glycol) (PEG)-dendritic block copolymers allows their efficient functionalization with a variety of ligands of biomedical relevance including anionic and cationic groups, carbohydrates, peptides, or imaging agents. The resulting functionalized dendrimers have found application in drug and gene delivery, as antiviral agents and for the treatment of neurodegenerative diseases, in diagnosis and as tools to study multivalent carbohydrate recognition and dendrimer dynamics. Herein, we present an account on the preparation and recent applications of GATG dendrimers in these fields ; The authors wish to acknowledge past and present lab members who have contributed to the development of dendrimers in our group. This work was financially supported by the Spanish Government (CTQ2009-10963, CTQ2012-34790, CTQ2009-14146-C02-02, CTQ2012-33436) and the Xunta de Galicia (10CSA209021PR and CN2011/037) ; SI

The paramagnetic spin relaxation filter is described for the rapid NMR screening of intermolecular interactions between ligands and macromolecular anionic receptors with large transverse relaxation enhancements (R2p). The addition of micromolar concentrations of Gd3+ to the mixture produces the immediate broadening/suppression of the NMR signals of interacting species while leaving unaffected those of noncompetitive binders (one-dimensional and two-dimensional experiments). The method is highly sensitive, unveiling interactions that are too weak to generate changes in chemical shifts or relaxation times. It is operationally very simple and hence, it is amenable to ready implementation by nonspecialists. Examples of application such as detecting the formation of interpolymer complexes, cyclodextrin host–guest interactions, and the screening of DNA ligands are included that demonstrate the reliability and broad applicability of the method ; This work was financially supported by the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO)(CTQ2015-69021-R), the Xunta de Galicia (GRC2014/040 and Centro Singular de Investigacion de Galicia Accreditation 2016-2019, ED431G/09), and the European Union (European Regional Development Fund-ERDF) ; SI

NMR is a powerful tool to study the dynamics of dendrimers. By analogy to linear polymers, shorter T1 relaxation times have been traditionally associated to less mobile nuclei and hence, dendrimers described with reduced local motions at either the core or the periphery. Herein we report a NMR relaxation study [1H and 13C T1, T2; 13C{1H}NOE; various fields and temperatures] which reveals profound differences between the relaxation behavior of dendrimers and linear polymers. Dendrimers show slower dynamics at internal layers and on increasing generation and may display internal nuclei in the slow motional regime with larger T1 values than the periphery. In contrast to the relaxation properties of linear polymers, these T1 increments should not be interpreted as resulting from faster dynamics. Only the recording of T1 data at various temperatures (alternatively, T2 or NOE at one temperature) ensures the correct interpretation of dendrimer dynamics ; This work was financially supported by the Spanish Government (CTQ2009-10963 and CTQ2009-14146-C02-02) and the Xunta de Galicia (10CSA209021PR and CN2011/037). L.F.P. thanks the Portuguese Foundation for Science and Technology (FCT MCTES) for a Ph.D. grant (SFRH/BD/37341/2007) ; SI

An in situ template fabrication of inorganic nanoparticles using carboxylated PEG-dendritic block copolymers of the GATG family is described as a function of the dendritic block generation, the metal (Au, CdSe) and metal molar ratio. The biocompatibility of the generated nanoparticles analysed in terms of their aggregation in physiological media, cytotoxicity and uptake by macrophages relates to the PEG density of the surface of the hybrids ; C.S.E. and A.G.-F. thank to the European Commission BIOCAPS (316265, FP7/REGPOT-2012-2013.1) and Xunta de Galicia (Agrupamento INBIOMED and Grupo con potencial crecimiento). A.S.-H. and E.F.-M. thank the Spanish Government (CTQ2012-34790) and the Xunta de Galicia (CN2011/037) ; SI

Here, we evaluate how cationic gallic acid-triethylene glycol (GATG) dendrimers interact with bacteria and their potential to develop new antimicrobials. We demonstrate that GATG dendrimers functionalised with primary amines in their periphery can induce the formation of clusters in Vibrio harveyi, an opportunistic marine pathogen, in a generation dependent manner. Moreover, these cationic GATG dendrimers demonstrate an improved ability to induce cluster formation when compared to poly(N-[3-(dimethylamino)propyl]methacrylamide) [p(DMAPMAm)], a cationic linear polymer previously shown to cluster bacteria. Viability of the bacteria within the formed clusters and evaluation of quorum sensing controlled phenotypes (i.e. light production in V. harveyi) suggest that GATG dendrimers may be activating microbial responses by maintaining a high concentration of quorum sensing signals inside the clusters while increasing permeability of the microbial outer membranes. Thus, the reported GATG dendrimers constitute a valuable platform for the development of novel antimicrobial materials that can target microbial viability and/or virulence ; This work was financially supported by the Spanish Government (CTQ2012-34790) and the Xunta de Galicia (GRC2014/040). E.L. thanks the European Commission, Education, Audiovisual and Cultural Executive Agency (EACEA) for an Erasmus Mundus grant under the NanoFar Joint Doctoral Program. F. F-T. thanks the University of Birmingham for the John Evans Fellowship. C. A. thanks the Engineering and Physical Sciences Research Council for a Leadership Fellowship (EP/H005625/1) and the research grant EP/G042462/1. I. L. has been supported by the EPSRC grant EP/K005138/11 ; SI

This is the peer-reviewed version of the following article: Fernandez-Villamarin, M., Sousa-Herves, A., Correa, J., Munoz, E., Taboada, P., Riguera, R., & Fernandez-Megia, E. (2016). The Effect of PEGylation on Multivalent Binding: A Surface Plasmon Resonance and Isothermal Titration Calorimetry Study with Structurally Diverse PEG-Dendritic GATG Copolymers. Chemnanomat, 2(5), 437-446, which has been published in final form at https://doi.org/10.1002/cnma.201600008. This article may be used for non-commercial purposes in accordance with Wiley-VCH Terms and Conditions for Self-Archiving ; A general synthetic strategy to polyethylene glycol (PEG)‐dendritic block copolymers of the GATG (gallic acid–triethylene glycol) family is described from commercially available PEG of different molecular weights and architectures. Glycosylation of the resulting azide‐terminated copolymers with fucose by copper‐catalyzed azide–alkyne cycloaddition (CuAAC) afforded a toolbox to study the effect of PEG on the multivalent binding with the lectin UEA‐I by surface plasmon resonance (SPR, on surface) and isothermal titration calorimetry (ITC, in solution). Our results indicate that PEG reduces the affinity of glycodendrimers towards lectins by steric hindrance in a molecular‐weight‐dependent fashion. Great differences were observed as a function of the PEG architecture, with diblock PEG‐dendritic copolymers benefiting from a positive entropic contribution (PEG folding), not seen in the dendritic‐PEG‐dendritic systems. The self‐inflicted steric stabilization of the PEGylated copolymers onto lectin clusters reveals the necessity of additional competitive experiments to fully assess the antiadhesive properties of PEG in biological environments ; Spanish Government. Grant Numbers: CTQ2015-69021-R, CTQ2012-34790, CTQ2014-61470-EXP Xunta de Galicia. Grant Number: GRC2014/040 ; SI

This work was financially supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) (CTQ2015‐ 69021‐R), the Consellería de Cultura, Educación e Ordenación Universitaria (GRC2014/040 and Centro Singular de Investigación de Galicia Accreditation 2016‐2019, ED431G/09), and the European Regional Development Fund (ERDF). M.F.‐V. thanks the Spanish Government for a FPU Fellowship ; Polyion complex (PIC) micelles incorporating PEG-dendritic copolymers display an unprecedented stability towards ionic strength that is amplified via hydrophobic interactions. The tridimensional orientation of peripheral hydrophobic linkers between charged groups and the globular/rigid dendritic scaffold maximizes this stabilization compared to PIC micelles from linear polymers. As a result, micelles stable at concentrations higher than 3 M NaCl are obtained, which represents the highest saline concentration attained with PIC micelles. Advantages of this stabilizing dendritic effect have been taken for the design of a robust, pH-sensitive micelle for the controlled intracellular release of the anticancer drug doxorubicin. This micelle displays a slightly higher toxicity, and distinctive mechanisms of cell uptake and intracellular trafficking relative to the free drug. The preparation of mixed PIC micelles by combining differently functionalized PEG-dendritic block copolymers has allowed the fine-tuning of their stability, paving the way towards the facile modulation of properties like biodegradability, drug loading, or the response to external stimuli ; SI

The synthesis of a new family of amino-functionalized gallic acid-triethylene glycol (GATG) dendrimers and their block copolymers with polyethylene glycol (PEG) has recently being disclosed. In addition, these dendrimers have shown potential for gene delivery applications, as they efficiently complex nucleic acids and form small and homogeneous dendriplexes. On this basis, the present study aimed to explore the interaction of the engineered dendriplexes with blood components, as well as their stability, cytotoxicity and ability to enter and transfect mammalian cells. Results show that GATG dendrimers can form stable dendriplexes, protect the associated pDNA from degradation, and are biocompatible with HEK-293T cells and erythrocytes. More importantly, dendriplexes are effectively internalized by HEK-293T cells, which are successfully transfected. Besides, PEGylation has a marked influence on the properties of the resulting dendriplexes. While PEGylated GATG dendrimers have improved biocompatibility, the long PEG chains limit their uptake by HEK-293T cells, and thus, their ability to transfect them. As a consequence, the degree of PEGylation in dendriplexes containing dendrimer/block copolymer mixtures emerges as an important parameter to be modulated in order to obtain an optimized stealth formulation able to effectively induce the expression of the encoded protein ; The authors gratefully acknowledge support from the Spanish Ministry of Science and Innovation (SAF2004‐09230‐004‐01, CTQ2006‐12222/BQU, and CTQ2009‐10963) and the Xunta de Galicia (10CSA209021PR). M. Raviña and A. Sousa‐Herves also acknowledge fellowships from the Spanish Government (FPI and FPU, respectively) ; SI

The progressive accumulation of amyloid-beta (Aβ) in specific areas of the brain is a common prelude to late-onset of Alzheimer's disease (AD). Although activation of liver X receptors (LXR) with agonists decreases Aβ levels and ameliorates contextual memory deficit, concomitant hypercholesterolemia/hypertriglyceridemia limits their clinical application. DMHCA (N,N-dimethyl-3β-hydroxycholenamide) is an LXR partial agonist that, despite inducing the expression of apolipoprotein E (main responsible of Aβ drainage from the brain) without increasing cholesterol/triglyceride levels, shows nil activity in vivo because of a low solubility and inability to cross the blood brain barrier. Herein, we describe a polymer therapeutic for the delivery of DMHCA. The covalent incorporation of DMHCA into a PEG-dendritic scaffold via carboxylate esters produces an amphiphilic copolymer that efficiently self-assembles into nanometric micelles that exert a biological effect in primary cultures of the central nervous system (CNS) and experimental animals using the intranasal route. After CNS biodistribution and effective doses of DMHCA micelles were determined in nontransgenic mice, a transgenic AD-like mouse model of cerebral amyloidosis was treated with the micelles for 21 days. The benefits of the treatment included prevention of memory deterioration and a significant reduction of hippocampal Aβ oligomers without affecting plasma lipid levels. These results represent a proof of principle for further clinical developments of DMHCA delivery systems ; This work was supported by PICT-2013-2840 (PI: M.A. B.), the Spanish Ministry of Science and Innovation (RTI2018-102212–B-I00), the Xunta de Galicia (ED431C 2018/30, and Centro singular de investigación de Galicia accreditation 2019–2022, ED431G2019/03), Axencia Galega de Innovación (IN845D 2020/09), and the European Union (European Regional Development Fund-ERDF) ; SI