Fibula de plata de pie vuelto con prótomo zoomorfo. Detalle del cuerpo - VDJ_210704_0275

Proyectos del Plan Nacional I+D+I con referencias PB94-0129, PB97-1132, BHA 2002-00138, HUM 2006-06250/HISTProyectos de la CAM con referencias 06/0020/1997, 06/0094/1998, 06/0090/2000, 06/0043/2001Programa Consolider-Ingenio 2010 con sigla CSD2007-00058NoInstituto Valencia de Don JuanSin procedenciaFibula de plata de pie vuelto con prótomo zoomorfo. Detalle del cuerp

Light-Responsive Micelles of Spiropyran Initiated Hyperbranched Polyglycerol for Smart Drug Delivery

Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-<i>hb</i>-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-<i>hb</i>-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-<i>hb</i>-PG_<i>n</i> (<i>n</i> = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-<i>hb</i>-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems

Double Hydrophilic Block Copolymer Templated Au Nanoparticles with Enhanced Catalytic Activity toward Nitroarene Reduction

We present a facile method for synthesizing water-dispersible gold nanoparticles (Au NPs) using a double hydrophilic block copolymer (DHBC), poly­(ethylene oxide)-<i>block</i>-poly­(acrylic acid) (PEO-<i>b</i>-PAA), as a template and demonstrate their application in the reduction of nitroarenes. Selective coordinative interactions between a gold precursor and the PAA block of the DHBC lead to the formation of micelles, which are subsequently transformed into Au NPs with an average diameter of 10 nm using a reducing agent. The DHBC-templated Au NPs (Au@DHBC NPs) remain stable in water for several months without any noticeable aggregation. Furthermore, Au@DHBC NPs are found to be highly effective in catalyzing the reduction of a series of nitroarenes. Remarkably, the turnover frequency in the case of 4-nitrophenol using Au@DHBP NPs reaches 800 h^–1, outperforming previously reported Au NP-based catalytic systems. We believe the enhanced catalytic activity is due to the DHBC shell around Au NPs, which templates the formation of spherical Au NPs and, more importantly, provides the confined interior for the enhanced catalytic activity in nitroarene reduction. Considering the wide potential application of DHBC as a template for the synthesis of novel metal NPs, we anticipate that the approach presented in this study will offer a new means to create a variety of water-stable catalytic nanomaterials in various fields of green chemistry

Highly Efficient Layer-by-Layer-Assisted Infiltration for High-Performance and Cost-Effective Fabrication of Nanoelectrodes

We present a novel cathode fabrication technique for improved performance and production efficiency of SOFCs based on an infiltration method assisted by layer-by-layer (LbL) assembly of polyelectrolytes. Preparation of the electrode with LbL-assisted infiltration leads to a 6.5-fold reduction in the electrode fabrication time while providing uniform and small formation of Pr_0.7Sr_0.3CoO_3‑δ (PSC) particles on the electrode. The increased surface area by 24.5% and number of active sites of the prepared electrode exhibits superior electrochemical performance up to 36.1% while preserving the electrical properties of the electrode. Because of its versatility and tenability, the LbL-assisted infiltration process may become a new route for fabrication of composite electrodes for other energy storage and conversion devices

Bioinspired Catecholic Primers for Rigid and Ductile Dental Resin Composites

In the construction of dental restorative polymer composite materials, surface priming on mineral fillers is essential to improve the mechanical performance of the composites. Here we present bioinspired catechol-functionalized primers for a tougher dental resin composite containing glass fillers. The catecholic primers with different polymerizable end groups were designed and then coated on glass surfaces using a simple drop-casting or dip-coating process. The surface binding ability and possible cross-linking (coupling or chemical bridging between the glass substrate and the dental resin) of the catecholic bifunctional primers were evaluated using atomic force microscopy, contact angle measurements, and the knife shear bonding test and compared to a state-of-the-art silane-based coupling agent. Various mechanical tests including shrinkage and compression tests of the dental resin composites were also conducted. Compression tests of the composites containing the catecholic primed fillers exhibited enhanced mechanical properties, owing to the bidentate hydrogen bonding of catechol moieties to the oxide mineral surface. Furthermore, the superior biocompatibility of the primed surface was confirmed via cell attachment assay, thus providing applicability of catecholic primers for practical dental and biomedical applications

Hyperbranched Double Hydrophilic Block Copolymer Micelles of Poly(ethylene oxide) and Polyglycerol for pH-Responsive Drug Delivery

We report the synthesis of a well-defined hyperbranched double hydrophilic block copolymer of poly­(ethylene oxide)-<i>hyperbranched</i>-polyglycerol (PEO-<i>hb</i>-PG) to develop an efficient drug delivery system. In specific, we demonstrate the hyperbranched PEO-<i>hb</i>-PG can form a self-assembled micellar structure on conjugation with the hydrophobic anticancer agent doxorubicin, which is linked to the polymer by pH-sensitive hydrazone bonds, resulting in a pH-responsive controlled release of doxorubicin. Dynamic light scattering, atomic force microscopy, and transmission electron microscopy demonstrated successful formation of the spherical core–shell type micelles with an average size of about 200 nm. Moreover, the pH-responsive release of doxorubicin and in vitro cytotoxicity studies revealed the controlled stimuli-responsive drug delivery system desirable for enhanced efficiency. Benefiting from many desirable features of hyperbranched double hydrophilic block copolymers such as enhanced biocompatibility, increased water solubility, and drug loading efficiency as well as improved clearance of the polymer after drug release, we believe that double hydrophilic block copolymer will provide a versatile platform to develop excellent drug delivery systems for effective treatment of cancer

Beauty of Lotus is More than Skin Deep: Highly Buoyant Superhydrophobic Films

We develop highly buoyant superhydrophobic films that mimic the three-dimensional structure of lotus leaves. The high buoyancy of these structure stems from mechanically robust bubbles that significantly reduce the density of the superhydrophobic films. These highly buoyant superhydrophobic films stay afloat on water surface while carrying a load that is more than 200 times their own weight. In addition to imparting high buoyancy, the incorporation of robust hydrophilic bubbles enables the formation of free-standing structures that mimic the water-collection properties of Namib Desert beetle. We believe the incorporation of robust bubbles is a general method that opens up numerous possibilities in imparting high buoyancy to different structures that needs to stay afloat on water surfaces and can potentially be used for the fabrication of lightweight materials. (Image on the upper left reproduced with permission from Yong, J.; Yang, Q.; Chen, F.; Zhang, D.; Du, G.; Si, J.; Yun, F.; Hou, X. A Bioinspired Planar Superhydrophobic Microboat. <i>J. Micromech. Microeng.</i> 2014, 24, 035006. Copyright 2014 IOP Publishing.

Highly Tunable Charge Transport in Layer-by-Layer Assembled Graphene Transistors

We demonstrate a controlled, systematic method to tune the charge transport in graphene field-effect transistors based on alternating layer-by-layer assembly of positively and negatively charged graphene oxide followed by thermal reduction. Surprisingly, tuning the number of bilayers of thermally reduced graphene oxide multilayer films allowed achieving either ambipolar or unipolar (both n- and p-type) transport in graphene transistors. On the basis of X-ray photoemission spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry, and temperature-dependent charge transport measurements, we found that nitrogen atoms from the functional groups of positively charged graphene oxide are incorporated into the reduced graphene oxide films and substitute carbon atoms during the thermal reduction. This nitrogen-doping process occurs in different degrees for graphene multilayers with varying numbers of bilayers and thereby results in the interesting transition in the electrical behavior in graphene multilayer transistors. We believe that such a versatile method to control the charge transport in graphene multilayers will further promote their applications in solution-processable electronic devices based on graphene

One-Pot Synthesis of Linear-Hyperbranched Amphiphilic Block Copolymers Based on Polyglycerol Derivatives and Their Micelles

This paper describes the one-pot synthesis of a polyglycidol (PG)-based polymer, poly­(ethoxyethyl glycidyl ether) (PEEGE)-<i>b</i>-[<i>hyperbranched</i> polyglycerol (<i>hb</i>PG)-<i>co</i>-PEEGE]_{<i>x</i>/<i>y</i>}, its micelle formulation, and the ability to encapsulate a model therapeutic molecule. Amphiphilic block copolymers were prepared by the sequential addition of ethoxyethyl glycidyl ether (EEGE) to glycidol. The composition of the block copolymers varied from 62:38 to 92:8. Block copolymers with composition <i>x</i>:<i>y</i> ≥ 66:34 were soluble only in organic solvents. Micelles were formulated by injection of deionized water into a tetrahydrofuran block copolymer solution with or without pyrene as a model hydrophobic molecule. The critical micelle concentration was 18.2–30.9 mg/L, and the micelle size was 100–250 nm. The pyrene-containing micelle rapidly collapsed on acidic exposure, allowing conversion of hydrophobic PEEGE to hydrophilic PG, thus, facilitating the release of the encapsulated pyrene. Cytotoxicity data showed high biocompatibility of PG-based block copolymers, suggesting their potential as a drug delivery carrier

Interface-Controlled Synthesis of Heterodimeric Silver–Carbon Nanoparticles Derived from Polysaccharides

Hybrid nanoparticles composed of multiple components can offer unique opportunities for understanding the nanoscale mechanism and advanced material applications. Here, we report the synthesis of heterodimeric silver–carbon dot nanoparticles (Ag-CD NPs) where the Ag NP is grown on the surface of CDs derived from polysaccharides, such as chitosan and alginate, through the photoelectron transfer reaction between CD and Ag⁺ ions. The nanoscale interface between the Ag NPs and the CDs is highly tunable depending on the precursor of the CDs and the amount of additives, resulting in fine modification of photoluminescence of the CDs as well as the related surface plasmon resonance of the Ag NPs. This result demonstrates the critical role of the interface between the hybrid nanoparticles in governing the electrical and optical properties of respective nanoparticles