Suchergebnisse

Ionic liquids (ILs) have shown advantages in organic synthesis and catalysis, energy storage and conversion, and a variety of pharmaceutical applications. Understanding the miscibility behavior of IL/monomer, IL/polymer, and IL/polymer nanoparticle mixtures is critical for the use of ILs as green solvents in polymerization processes as well as to rationalize recent observations concerning the superior solubility of some proteins in ILs when compared to standard solvents. In this work, the most relevant results obtained in terms of extended three-component Flory–Huggins theory concerning the extra solvent power (ESP) of ILs when compared to traditional nonionic solvents for monomeric solutes (Case I), linear polymers (Case II), dry (i.e., without IL inside) globular single-chain polymer nanoparticles (SCNPs) (Case III), and wet (i.e., with IL inside) globular SCNPs (Case IV) are presented. Moreover, useful ESP maps are drawn for the first time for IL mixtures corresponding to Cases I, II, III, and IV at a constant temperature and pressure. Finally, a potential pathway to improve the miscibility of nonionic polymers in ILs is proposed. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015-63704-P (MINECO/FEDER, UE), the Basque Government, IT-654-13, and the Gipuzkoako Foru Aldundia, RED 101/17, is acknowledged. M.G.-B. is grateful to the University of the Basque Country for her UPV/EHU predoctoral grant. ; Peer reviewed

This is an open access article distributed under the Creative Commons Attribution License. ; Single-chain technology (SCT) allows the transformation of individual polymer chains to folded/collapsed unimolecular soft nanoparticles. In this work we contribute to the enlargement of the SCT toolbox by demonstrating the efficient synthesis of single-chain polymer nanoparticles (SCNPs) via intrachain amide formation. In particular, we exploit cross-linking between active methylene groups and isocyanate moieties as powerful >click> chemistry driving force for SCNP construction. By employing poly(methyl methacrylate)- (PMMA-) based copolymers bearing β-ketoester units distributed randomly along the copolymer chains and bifunctional isocyanate cross-linkers, SCNPs were successfully synthesized at r.t. under appropriate reaction conditions. Characterization of the resulting SCNPs was carried out by means of a combination of techniques including size exclusion chromatography (SEC), infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, dynamic light scattering (DLS), and elemental analysis (EA). ; Financial support from Projects MAT2012-31088 (MINECO), T-654-13 (GV), and S-PE13UN034 (GV) is acknowledged. Ana Sanchez-Sanchez thanks the Ph.D. grant support of Basque Government. ; Peer Reviewed

Resumen de la comunicación presentada al 14th Congress of the European Polymer Federation celebrado en Pisa (Italia) del 16 al 21 de Junio de 2013. ; A. S.-S. thanks the PhD grant support of Basque Government. ; Peer reviewed

Single-chain nanoparticles (SCNPs) are ultrasmall soft nanomaterials constructed via intrachain cross-linking of individual precursor polymer chains, with promising prospects for nanomedicine, catalysis, and sensing, among other different fields. SCNPs are versatile building blocks for the construction of new fluorescent probes with ultrasmall size, higher brightness, and better photostability than previous particle-based systems. Herein, we report on a new, fast, and efficient method to produce SCNPs with intense fluorescence emission in solution which is based on the photoactivation of appropriate aggregation-induced emission (AIE) cross-linking molecules containing azide functional groups. Remarkably, the presence of the azide moiety—that can be transformed to highly reactive nitrene species upon UV irradiation—was found to be essential for the SCNPs to display intense fluorescence emission. We attribute the fluorescence properties of the SCNPs to the immobilization of the initially nonfluorescent AIE molecules via intrachain cross-linking upon photoactivation. Such cross-linking-induced immobilization process activates the AIE mechanism and, hence, leads to fluorescent SCNPs in both solution and solid state. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015-63704-P (MINECO/FEDER, UE), the Basque Government, IT-654-13, and the Gipuzkoako Foru Aldundia, Programa Red Gipuzkoana de Ciencia, Tecnología e Innovación 2017 (RED 101/17), is acknowledged. J.D.L.C. is grateful to MINECO for his predoctoral grant. ; Peer reviewed

In this study the superior stability against degradation induced by ultrasound irradiation of water‐soluble single‐chain polymer nanoparticles when compared to their parent precursor polymers is reported, and a loop scission mechanism in support of such behavior is suggested. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015‐63704‐P (MINECO/FEDER, UE), the Basque Government, IT‐654‐13, and the Gipuzkoako Foru Aldundia, RED 101/17, is acknowledged. M.G.‐B. is grateful to the University of the Basque Country for her UPV/EHU predoctoral grant. E.G. received funding from the "Fellows Gipuzkoa" fellowship of the Gipuzkoako Foru Aldundia. ; Peer reviewed

Enzymes are the most efficient catalysts known for working in an aqueous environment near room temperature. The folding of individual polymer chains to functional single-chain nanoparticles (SCNPs) offers many opportunities for the development of artificial enzyme-mimic catalysts showing both high catalytic activity and specificity. In this review, we highlight recent results obtained in the use of SCNPs as bioinspired, highly-efficient nanoreactors (3–30 nm) for the synthesis of a variety of nanomaterials (inorganic nanoparticles, quantum dots, carbon nanodots), polymers, and chemical compounds, as well as nanocontainers for CO capture and release. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015-63704-P (MINECO/FEDER, UE), the Basque Government, IT-654-13, and the Gipuzkoako Foru Aldundia, Programa Red Gipuzkoana de Ciencia, Tecnología e Innovación 2017, is acknowledged. Jon Rubio-Cervilla is grateful to the Materials Physics Center-MPC for his predoctoral grant. Edurne González received funding from the "Fellows Gipuzkoa" fellowship of the Gipuzkoako Foru Aldundia. ; Peer Reviewed

Structurally dynamic single-chain polymer nanoparticles that can reversibly undergo a coil to particle transition via formation and cleavage of intramolecular dynamic enamine cross-links are reported. © 2014 The Royal Society of Chemistry. ; Financial support from EPSRC and Projects MAT2012-31088 (MINECO) and IT-654-13 (GV) is acknowledged. A.S.-S. thanks the Basque Government for support (Mobility and PhD grants). ; Peer Reviewed

Clean use of photons from light to activate chemical reactions offers many possibilities in different fields, from chemistry and biology to materials science and medicine. This review article describes the advances carried out in last decades toward the phototriggered synthesis of single-chain polymer nanoparticles (SCNPs) as soft nanomaterials with promising applications in enzyme-mimicking catalysis and nanomedicine, among other different uses. First, wesummarize some different strategies developed to synthesize SCNPs based on photoactivated intrachain homocoupling, phototriggered intrachain heterocoupling and photogenerated collapse induced by an external cross-linker. Next, we comprehensively review the emergent topic of photoactivated multifolding applied to SCNP construction. Finally, we conclude by summarizing recent strategies towards phototriggered disassembly of SCNPs. ; This research was funded by Gipuzkoako Foru Aldundia -Programa Red Gipuzkoana de Ciencia, Tecnología e Innovación 2019-, grant number 2019-CIEN-000050-01; Basque Government, grant number IT-1175-19; and MCIU/AEI/FEDER, UE, grant number PGC2018-094548-B-I00.

Fluorophore molecules can be monitored by fluorescence spectroscopy and microscopy, which are highly useful and widely used techniques in cell biology, biochemistry, and medicine (e.g., biomarker analysis, immunoassays, cancer diagnosis). Several fluorescent micro- and nanoparticle systems based on block copolymer micelles and cross-linked polymer networks, quantum dots, π-conjugated polymers, and dendrimers have been evaluated as optical imaging systems. In this review, we highlight recent advances in the construction of fluorescent single-chain nanoparticles (SCNPs), which are valuable artificial soft nano-objects with a small tunable size (as small as 3 nm). In particular, the main methods currently available to endow SCNPs with fluorescent properties are discussed in detail, showing illustrative examples. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015-63704-P (MINECO/FEDER, UE), the Basque Government, IT-654-13, and the Gipuzkoako Foru Aldundia, Programa Red Gipuzkoana de Ciencia, Tecnología e Innovación 2017, is acknowledged. J.D.-L.-C. is grateful to MINECO for his predoctoral grant. E. G. received funding from the "Fellows Gipuzkoa" fellowship of the Gipuzkoako Foru Aldundia. ; Peer Reviewed

This is an open access article distributed under the Creative Commons Attribution License. ; Single-chain polymeric nanoparticles are artificial folded soft nano-objects of ultra-small size which have recently gained prominence in nanoscience and nanotechnology due to their exceptional and sometimes unique properties. This review focuses on the current state of the investigations of click chemistry techniques for highly-efficient single-chain nanoparticle construction. Additionally, recent progress achieved for the use of well-defined single-chain nanoparticles in some promising fields, such as nanomedicine and catalysis, is highlighted. ; Financial support from the projects MAT2012-31088 (MINECO) and IT-654-13 (GV) is acknowledged. A. S.-S. thanks the PhD grant support of the Basque Government. I. P.-B. acknowledges CSIC for her JAE-PREDOC grant. ; Peer Reviewed

Trabajo presentado al European Symposium on Polymer Blends celebrado en San Sebastian (España) del 25 al 28 de Marzo de 2012. ; We report for the first time the synthesis of unimolecular polystyrene-based nanoparticles (PS-NPs) under normal air atmosphere by direct carbon-carbon "click" chemistry (i.e., "self-click" chemistry). First, statistical poly(styrene-co-4-vinylbenzyl chloride) copolymers synthesized by RAFT polymerization were decorated in a facile manner with alkyne groups by reaction with potassium propiolate, providing well-defined nanoparticle precursors (PS-Prec). Next, individual PS-Prec chains were collapsed irreversibly to unimolecular nanoparticles of ca. 12 nm in size by intrachain Cu(II)-catalyzed alkyne dimerization under high-dilution conditions, as revealed by SEC, H1-NMR, DLS and TEM measurements. Based on predictions from a recent compressible thermodynamic model, the resulting nanoparticles could be promising materials for the development of homogeneous, miscible PS-NPs / polycarbonate all-polymer nanocomposites ; This work was supported by Gipuzkoako Foru Aldundia (project 2011-CIEN-000085-01) and Basque Government (Project S-PE11UN009). I. P.-B. thanks CSIC for her JAE-PREDOC grant. L. B. acknowledges financial support by Basque Excellence Research Center-Materials Physics Center (BERC-MPC). ; Peer reviewed

Cyclotides are small cyclic polypeptides found in a variety of organisms, ranging from bacteria to plants. Their ring structure endows those polypeptides with specific properties, such as improved stability against enzymatic degradation. Optimal cyclotide activity is often observed only in the presence of intra-ring disulfide bonds. Synthesis of soft nano-objects mimicking the conformation of natural cyclotides remains challenging. Here, a new class of natural cyclotide mimics synthesized by a stepwise folding-activation-collapse process at high dilution starting from simple synthetic precursor polymers is established. The initial folding step is carried out by a photoactivated hetero Diels-Alder (HDA) ring-closing reaction, which is accompanied by chain compaction of the individual precursor polymer chains as determined by size exclusion chromatography (SEC). The subsequent activation step comprises a simple azidation procedure, whereas the final collapse step is driven by CuAAC in the presence of an external cross-linker, providing additional compaction to the final single-ring nanoparticles (SRNPs). The unique structure and compaction degree of the SRNPs is established via a detailed comparison with conventional single-chain nanoparticles (SCNPs) prepared exclusively by chain collapse from the exact same precursor polymer (without the prefolding step). The stepwise folding-activation-collapse approach opens new avenues for the preparation of artificial cyclotide mimetics. ; Financial support by the Spanish Ministry "Ministerio de Economia y Competitividad", MAT2015-63704-P (MINECO/ FEDER, UE), the Basque Government, IT-654-13, and the Gipuzkoako Foru Aldundia, RED 101/17, is acknowledged. J.R.-C. thanks the Materials Physics Center – MPC for support (mobility and Ph.D. grants). C.B.-K. acknowledges the Australian Research Council (ARC) in the context of a Laureate Fellowship, enabling his photochemical research program. H.F. acknowledges generous funding from the German National Academy of Science, Leopoldina. ; Peer reviewed

Protection of acetylenic monomers is a common practice to avoid parasitic side reactions during polymerization. Herein, we report that redox-initiated RAFT polymerization allows the direct, room temperature synthesis of a variety of single-chain nanoparticle precursors (displaying narrow molecular weight dispersity, M̄ wM̄ n = 1.12 -1.37 up to M̄ w = 100 kDa) containing well-defined amounts of naked, unprotected acetylenic functional groups available for rapid and quantitative intrachain cross-linking via metal-catalyzed carbon-carbon coupling (i.e., C-C click chemistry). To illustrate the useful self-clickable character of the new unprotected acetylenic precursors, single-chain nanoparticles have been prepared for the first time in a facile and highly efficient manner by copper-catalyzed alkyne homocoupling (i.e., Glaser-Hay coupling) at room temperature under normal air atmosphere. ; This work was supported by Gipuzkoako Foru Aldundia (project 2011-CIEN-000085-01) and Basque Government (Project S-PE11UN009). A.S.-S. thanks the PhD grant support of Basque Government . L.B. acknowledges financial support by Basque Excellence Research Center-Materials Physics Center (BERC-MPC). ; Peer Reviewed

The fabrication of antibacterial films based on renewable materials (e.g., chitosan) has attracted significant interest in fields such as food packaging, health care and medicine. However, exploiting the antibacterial properties of cinchona alkaloids to design active nanostructured films able to release quinine-based antimicrobial compounds has not been considered previously. Herein, we develop two different routes to produce active quinine-based nanostructured cross-linked films by exploiting the multiple reactive sites of quinine and, specifically, both the nitrogen atom and the vinyl group of the quinuclidine portion of the molecule, as well as their corresponding orthogonal quaternization and thiol-ene coupling reactions. The first synthetic strategy produces stiff and brittle nanostructured quinine-based films of limited utility for practical applications. Conversely, the second approach produces active, flexible and nanostructured quinine-based films (T = -14 °C, Young's modulus = 1.3 GPa), which are able to release antimicrobial compounds against E. coli that, remarkably, are noncytotoxic against mouse macrophage and human dermal fibroblast cells. These kinds of active cinchona alkaloid-based coatings are easy to prepare by means of simple, solvent-free, melt quaternization/spreading procedures at a relatively low temperature (120 °C), making this second approach one of the most facile reported procedures to date to produce active nanostructured bio-based films. ; Financial support by the Spanish Ministry ''Ministerio de Economia y Competitividad'', MAT2015-63704-P (MINECO/FEDER, UE) and the Basque Government, IT-654-13 is acknowledged. A. L.-S. is grateful to the University of the Basque Country for his UPV/EHU pre-doctoral grant, and to both MPC and Gipuzkoako Foru Aldundia for financial support during his stay at KTH. ; Peer Reviewed

Mimicking the substrate specificity and catalytic activity of enzymes is of great interest for different fields (e.g., chemistry, biology, nanomedicine). Enhanced reaction rates using artificial, enzyme-mimic catalysts based on a variety of molecular structures and nanoentities (e.g., macrocyclic compounds, star and helical polymers, dendrimers) have been previously reported. However, examples of enzyme-sized soft entities displaying substrate specificity are certainly scarce. Herein, we report the synthesis and characterization of single-chain nanoparticles based on metallo-folded polymer chains containing complexed Cu(II) ions showing catalytic specificity during the oxidative coupling of mixtures of chemically related terminal acetylene substrates. This work paves the way for the easy and efficient construction of other Pd-, Ni-, Co-, Fe-, Mn-, or Mo-containing soft nanoentities approaching the substrate specificity of natural enzymes for a variety of organic reactions. © 2014 American Chemical Society. ; Financial support from the Projects MAT2012-31088 (MINECO), T-654-13 (GV) and S-PE13UN034 (GV) is acknowledged. A. S.-S. thanks the Ph.D. grant support of Basque Government. This work has been supported by the European Commission under the 7th Framework Programme through the "Research Infra-structures" action of the "Capacities" Programme, NMI3-II Grant Number 283883. ; Peer Reviewed