Showing papers by "Daniel Maspoch published in 2013"

A spray-drying strategy for synthesis of nanoscale metal–organic frameworks and their assembly into hollow superstructures

Abstract: Metal-organic frameworks (MOFs) are among the most attractive porous materials known today. Their miniaturization to the nanoscale--into nanoMOFs--is expected to serve myriad applications from drug delivery to membranes, to open up novel avenues to more traditional storage and catalysis applications, and to enable the creation of sophisticated superstructures. Here, we report the use of spray-drying as a versatile methodology to assemble nanoMOFs, yielding spherical hollow superstructures with diameters smaller than 5 µm. This strategy conceptually mimics the emulsions used by chemists to confine the synthesis of materials, but does not require secondary immiscible solvents or surfactants. We demonstrate that the resulting spherical, hollow superstructures can be processed into stable colloids, whose disassembly by sonication affords discrete, homogeneous nanoMOFs. This spray-drying strategy enables the construction of multicomponent MOF superstructures, and the encapsulation of guest species within these superstructures. We anticipate that this will provide new routes to capsules, reactors and composite materials.

Relaxometry studies of a highly stable nanoscale metal-organic framework made of Cu(II), Gd(III), and the macrocyclic DOTP.

Abstract: The macrocyclic ligand DOTP is used to assemble a porous, heterometallic metal-organic framework (MOF). This MOF is miniaturizable down to the nanoscale to form stable colloids, is stable in physiological saline solution and cell culture media, and is not cytotoxic. It shows interesting relaxometric properties with r1 at high field (500 MHz) of 5 mM(-1)·s(-1) and a maximum r1 = 15 mM(-1)·s(-1) at 40 MHz, which remains constant over a wide pH range and increases with temperature.

A Novel Liposome-Based Nanocarrier Loaded with an LPS-dsRNA Cocktail for Fish Innate Immune System Stimulation

Abstract: Development of novel systems of vaccine delivery is a growing demand of the aquaculture industry. Nano- and micro- encapsulation systems are promising tools to achieve efficient vaccines against orphan vaccine fish diseases. In this context, the use of liposomal based-nanocarriers has been poorly explored in fish; although liposomal nanocarriers have successfully been used in other species. Here, we report a new ∼125 nm-in-diameter unilamellar liposome-encapsulated immunostimulant cocktail containing crude lipopolysaccharide (LPS) from E. coli and polyinosinic:polycytidylic acid [poly (I:C)], a synthetic analog of dsRNA virus, aiming to be used as a non-specific vaccine nanocarrier in different fish species. This liposomal carrier showed high encapsulation efficiencies and low toxicity not only in vitro using three different cellular models but also in vivo using zebrafish embryos and larvae. We showed that such liposomal LPS-dsRNA cocktail is able to enter into contact with zebrafish hepatocytes (ZFL cell line) and trout macrophage plasma membranes, being preferentially internalized through caveolae-dependent endocytosis, although clathrin-mediated endocytosis in ZFL cells and macropinocytocis in macrophages also contribute to liposome uptake. Importantly, we also demonstrated that this liposomal LPS-dsRNA cocktail elicits a specific pro-inflammatory and anti-viral response in both zebrafish hepatocytes and trout macrophages. The design of a unique delivery system with the ability to stimulate two potent innate immunity pathways virtually present in all fish species represents a completely new approach in fish health.

Femtolitre chemistry assisted by microfluidic pen lithography

Abstract: Chemical reactions at ultrasmall volumes are becoming increasingly necessary to study biological processes, to synthesize homogenous nanostructures and to perform high-throughput assays and combinatorial screening. Here we show that a femtolitre reaction can be realized on a surface by handling and mixing femtolitre volumes of reagents using a microfluidic stylus. This method, named microfluidic pen lithography, allows mixing reagents in isolated femtolitre droplets that can be used as reactors to conduct independent reactions and crystallization processes. This strategy overcomes the high-throughput limitations of vesicles and micelles and obviates the usually costly step of fabricating microdevices and wells. We anticipate that this process enables performing distinct reactions (acid-base, enzymatic recognition and metal-organic framework synthesis), creating multiplexed nanoscale metal-organic framework arrays, and screening combinatorial reactions to evaluate the crystallization of novel peptide-based materials.

Self-assembled tetragonal prismatic molecular cage highly selective for anionic π guests.

Abstract: We are grateful for financial support from the MICINN of Spain (CTQ2009-08464/BQU to M. C., CTQ2011-25086/BQU, CTQ2011-23156/BQU, PhD grant AP2010-2517 to M. G. B, INNPLANTA- INP-2011-0059PCT-420000-ACT1 and Consolider-Ingenio CSD2010-00065), the FEDER fund (European Fund for Regional Development) for the grant UNGI08-4E-003, the European Research Council for Project ERC-2011StG-277801 to X. R. and ERC-2008-StG-29910 to M. C., and the Generalitat de Catalunya (2009SGR637, 2009SGR528, and a Ph.D. grant to C. G. S.). X. R. and M. C. thank ICREA-Academia awards. I. I. thanks MINECO for a Ramon y Cajal contract. We thank Dr. Teodor Parella for fruitful discussions. We thank STR's from UdG for technical support, and we also acknowledge the computer resources, technical expertise, and assistance provided by the Barcelona Supercomputing Center Centro Nacional de Supercomputacion, and Centre de Serveis Cientifics i Academics de Catalunya (CESCA) for partial funding of computer time

“Dual-Template” Synthesis of One-Dimensional Conductive Nanoparticle Superstructures from Coordination Metal–Peptide Polymer Crystals

Abstract: Bottom-up fabrication of self-assembled structures made of nanoparticles may lead to new materials, arrays and devices with great promise for myriad applications. Here a new class of metal-peptide scaffolds is reported: coordination polymer Ag(I)-DLL belt-like crystals, which enable the dual-template synthesis of more sophisticated nanoparticle superstructures. In these biorelated scaffolds, the self-assembly and recognition capacities of peptides and the selective reduction of Ag(I) ions to Ag are simultaneously exploited to control the growth and assembly of inorganic nanoparticles: first on their surfaces, and then inside the structures themselves. The templated internal Ag nanoparticles are well confined and closely packed, conditions that favour electrical conductivity in the superstructures. It is anticipated that these Ag(I)-DLL belts could be applied to create long (>100 μm) conductive Ag@Ag nanoparticle superstructures and polymetallic, multifunctional Fe3 O4 @Ag nanoparticle composites that marry the magnetic and conductive properties of the two nanoparticle types.