Supramolecular Nested Microbeads as Building Blocks for Macroscopic Self‐Healing Scaffolds

The ability to construct self‐healing scaffolds that are injectable and capable of forming a designed morphology offers the possibility to engineer sustainable materials. Herein, we introduce supramolecular nested microbeads that can be used as building blocks to construct macroscopic self‐healing scaffolds. The core–shell microbeads remain in an “inert” state owing to the isolation of a pair of complementary polymers in a form that can be stored as an aqueous suspension. An annealing process after injection effectively induces the re‐construction of the microbead units, leading to supramolecular gelation in a preconfigured shape. The resulting macroscopic scaffold is dynamically stable, displaying self‐recovery in a self‐healing electronic conductor. This strategy of using the supramolecular assembled nested microbeads as building blocks represents an alternative to injectable hydrogel systems, and shows promise in the field of structural biomaterials and flexible electronics.     

Diastereoselective diaza-Cope rearrangement reaction

Steric effect is used to obtain a highly diastereoselective rearrangement reaction.     

Solid-phase synthesis of graphitic carbon nanostructures from iron and cobalt gluconates and their utilization as electrocatalyst supports

We present a novel and facile synthesis methodology for obtaining graphitic carbon structures from Fe(II) and Co(II) gluconates. The formation of graphitic carbon can be carried out in only one step by means of heat treatment of these organic salts at a temperature of 900 degrees C or 1000 degrees C under inert atmosphere. This process consists of the following steps: (a) pyrolysis of the organic gluconate and its transformation to amorphous carbon, (b) conversion of Fe(2+) and Co(2+) ions to Fe(2)O(3) and CoO and their subsequent reduction to metallic nanoparticles by the carbon and (c) conversion of a fraction of formed amorphous carbon to graphitic structures by Fe and Co nanoparticles that act as catalysts in the graphitization process. The removal of the amorphous carbon and metallic nanoparticles by means of oxidative treatment (KMnO(4) in an acid solution) allows graphitic carbon nanostructures (GCNs) to be selectively recovered. The GCNs thus obtained (i.e. nanocapsules and nanopipes) have a high crystallinity as evidenced by TEM/SAED, XRD and Raman analysis. In addition, we used these GCNs as supports for platinum nanoparticles, which were well dispersed (mean Pt size approximately 2.5-3.2 nm). Most electrocatalysts prepared in this way have a high electrocatalytical surface area, up to 90 m(2) g(-1) Pt, and exhibit high catalytic activities toward methanol electrooxidation.     

Protein extraction from Phoenix dactylifera L. leaves, a recalcitrant material, for two-dimensional electrophoresis

This work was aimed at optimizing a protein extraction procedure for date palm (Phoenix dactylifera L.) leaves, a highly recalcitrant plant tissue for 2-DE. Five protein extraction protocols based on different protein precipitation agents (TCA/acetone vs. phenol (Ph) methods) and protein resolubilization methods (physical treatments, e.g., sonication, shaking and/or heating) were tested. Ph/SDS extraction with methanol/ammonium acetate precipitation, followed by DOC preincubation and TCA/acetone precipitation and, finally, solubilization by shaking in rehydration solution was found to be the best protein extraction method. We conclude that DOC with TCA/acetone precipitation step eliminates interfering compounds, thus allowing efficient resolubilization of date palm leaf proteins. This method could be appropriate for proteomic studies such as date palm colonization by entomopathogenic fungi.     

A Look at BMOϕ(ω) through Carleson Measures

As Fefferman and Stein showed, there is a tight connection between Carleson measures and BMO functions. In this work we extend this type of results to the more general scope of the BMO_ϕ(ω) spaces. As a byproduct a weighted version of the Triebel-Lizorkin space is introduced, which turns out to be isomorphic to BMO(ω) as in the unweighted case.     

Determination of fluoroquinolones in urine and serum by using high performance liquid chromatography and multiemission scan fluorimetric detection

A high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of four fluoroquinolones. The studied compounds have been enoxacin (ENO), norfloxacin (NOR), ofloxacin (OFLO) and enrofloxacin (ENRO). An isocratic elution method, using a mixture of tetrahydrofuran (8%) and phosphate buffer (pH 3.00, 30.0 mM, 92%) as mobile phase, has been developed. Fluorimetric detection, exciting at 277 nm, and multiemission scan (407 nm for ENO, 444 nm for both NOR and ENRO and 490 nm for OFLO) has been used. Detection limits of 500, 14.7, 25.2 and 15.0 ng mL⁻¹ for ENO, NOR, OFLO and ENRO, respectively, have been obtained. The proposed method has been satisfactorily applied to analyze NOR, OFLO and ENRO in human urine and serum samples.     

Enzymatic rotating biosensor for cysteine and glutathione determination in a FIA system

The high sensitivity that can be attained using an enzymatic system and mediated by catechols has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP, [EC 1.11.1.7], immobilized on a rotating disk, in presence of hydrogen peroxide catalyzed the oxidation of catechols, whose back electrochemical reduction was detected on glassy carbon electrode surface at −150 mV. Thus, when l-cysteine (Cys) or glutathione (GSH) was added to the solution, these thiol-containing compounds participate in Michael addition reactions with catechols to form the corresponding thioquinone derivatives, decreasing the peak current obtained proportionally to the increase of its concentration. Cys was used as the model thiol-containing compound for the study. The highest response for Cys was obtained around pH 7. This method could be used to determine Cys concentration in the range 0.05-90 μM (r = 0.998) and GSH concentration in the range 0.04-90 μM (r = 0.999). The determination of Cys and GSH were possible with a limit of detection of 0.7 and 0.3 nM, respectively, in the processing of as many as 25 samples per hour. Current response of the HRP-rotating biosensor is not affected by the oxidized form of GSH and Cys (glutathione disulfide, GSSG, and l-cystine, respectively), by sulfur-containing and alkyl-amino compounds such as methionine and lysine, respectively. The interferences from easily oxidizable species such as ascorbic acid and uric acid are lowest.