Three‐Dimensional Branched and Faceted Gold–Ruthenium Nanoparticles: Using Nanostructure to Improve Stability in Oxygen Evolution Electrocatalysis

Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low‐index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close‐packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low‐index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts.     

Combined Short-Term Glucose Starvation and Chemotherapy in 3D Colorectal Cancer Cell Culture Decreases 14-3-3 Family Protein Expression and Phenotypic Response to Therapy

Short-term glucose starvation prior to chemotherapy has the potential to preferentially weaken cancer cells, making them more likely to succumb to treatment, while protecting normal cells. In this study, we used 3D cell cultures of colorectal cancer and assessed the effects of short-term glucose starvation and chemotherapy compared to treatment of either individually. We evaluated both phenotypic changes and protein expression levels. Our findings indicate that the combined treatment results in more significant phenotypic responses, including decreased cell viability and clonogenicity. These phenotypic responses can be explained by the decreased expression of LDHA and 14-3-3 family proteins, which were found only in the combined treatment groups. This study indicates that short-term glucose starvation has the potential to increase the efficacy of current cancer treatment regimes.

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Vicinal functionalization of propiolate esters via a tandem catalytic carbocupration-Mukaiyama aldol reaction sequence

The vicinal functionalization of propiolate esters via a tandem catalytic carbocupration-Mukaiyama aldol reaction sequence has been investigated. It has been shown that catalyst loadings as low as 8 mol % readily allow for good yields and excellent diastereoselectivities (>20:1) for a series of Grignard reagents and aldehydes.     

Structural and functional changes in the membrane and membrane skeleton of red blood cells induced by peroxynitrite

The changes in passive ion permeability of the red blood cell membrane after peroxynitrite action (3 microM-3 mM) have been studied by biophysical (using radioisotopes of rubidium, sodium and sulphur (sulphate)) and electrophysiological methods. The enhancement of passive membrane permeability to cations (potassium and sodium ions) and the inhibition of anion flux through the anion exchanger in peroxynitrite-treated red blood cells were revealed. In patch-clamp experiments the whole-cell conductance after peroxynitrite (80 muM) treatment of red blood cells increased 3-3.5-fold with a shift in the reversal potential from -7.0+/-1.5 mV to -4.3+/-0.9 mV (n=7, p=0.005). The addition of cobalt and nickel ions to red blood cell suspensions before peroxynitrite treatment had no effect on the peroxynitrite-induced cation flux but zinc ions in the same condition decreased cation flux about 2-fold. Using atomic force microscopy methods we revealed an increase in red blood cell membrane stiffness and the membrane skeleton complexity after peroxynitrite action. We conclude that the peroxynitrite-induced water and ion imbalance and reorganization in membrane structure lead to crenation of red blood cells.     

Cross-conjugated poly(p-phenylene) aided supramolecular self-organization of fullerene nanocrystallites

Formation and characterization of nanocrystallite spheres from a hybrid of functionalized cross-conjugated poly(p-phenylene) and C(60) are reported.     

Components of the ubiquitin-proteasome pathway compete for surfaces on Rad23 family proteins

Background  

The delivery of ubiquitinated proteins to the proteasome for degradation is a key step in the regulation of the ubiquitin-proteasome pathway, yet the mechanisms underlying this step are not understood in detail. The Rad23 family of proteins is known to bind ubiquitinated proteins through its two ubiquitin-associated (UBA) domains, and may participate in the delivery of ubiquitinated proteins to the proteasome through docking via the Rad23 ubiquitin-like (UBL) domain.     

Intramolecular direct arylation in the synthesis of fluorinated carbazoles

The amination of 2-chloroanilines with aryl bromides and subsequent intramolecular direct arylation can be exploited in the synthesis of a range of fluorinated carbazoles, where the fluorine substituent can be introduced via the aniline, the aryl bromide or both substrates. Depending on substitution patterns, the two steps can either be performed in tandem in one-pot under microwave heating conditions or else require a two pot approach.     

Uniform antibacterial cylindrical nanoparticles for enhancing the strength of nanocomposite hydrogels

Crystallization-driven self-assembly (CDSA) was employed for the preparation of monodisperse cationic cylindrical nanoparticles with controllable sizes, which were subsequently explored for their effect on antibacterial activity and the mechanical properties of nanocomposite hydrogels. Poly(ɛ-caprolactone)-block-poly(methyl methacrylate)-block-poly[2-(tert-butylamino) ethyl methacrylate] (PCL-b-PMMA-b-PTA) triblock copolymers were synthesized using combined ring-opening and RAFT polymerizations, and then self-assembled into polycationic cylindrical micelles with controllable lengths by epitaxial growth. The polycationic cylinders exhibited intrinsic cell-type-dependent antibacterial capabilities against gram-positive and gram-negative bacteria under physiological conditions, without quaternization or loading of any additional antibiotics. Furthermore, when the cylinders were combined into anionic alginate hydrogel networks, the mechanical response of the hydrogel composite was tunable and enhanced up to 51%, suggesting that cationic polymer fibers with controlled lengths are promising mimics of the fibrous structures in natural extracellular matrix to support scaffolds. Overall, this polymer fiber/hydrogel nanocomposite shows potential as an injectable antibacterial biomaterial, with possible application in implant materials as bacteriostatic agents or bactericides against various infections.     

Structure-activity relationship studies of the two-component lantibiotic haloduracin

The lantibiotic haloduracin consists of two posttranslationally processed peptides, Halalpha and Halbeta, which act in synergy to provide bactericidal activity. An in vitro haloduracin production system was used to examine the biological impact of disrupting individual thioether rings in each peptide. Surprisingly, the Halalpha B ring, which contains a highly conserved CTLTXEC motif, was expendable. This motif has been proposed to interact with haloduracin's predicted target, lipid II. Exchange of the glutamate residue in this motif for alanine or glutamine completely abolished antibacterial activity. This study also established that Halalpha-Ser26 and Halbeta-Ser22 escape dehydration, requiring revision of the Halbeta structure previously proposed. Extracellular proteases secreted by the producer strain can remove the leader peptide, and the Halalpha cystine that is dispensable for bioactivity protects Halalpha from further proteolytic degradation.