Thiol–Yne Click Reactions on Alkynyl–Dopamine‐Modified Reduced Graphene Oxide

The large‐scale preparation of graphene is of great importance due to its potential applications in various fields. We report herein a simple method for the simultaneous exfoliation and reduction of graphene oxide (GO) to reduced GO (rGO) by using alkynyl‐terminated dopamine as the reducing agent. The reaction was performed under mild conditions to yield rGO functionalized with the dopamine derivative. The chemical reactivity of the alkynyl function was demonstrated by post‐functionalization with two thiolated precursors, namely 6‐(ferrocenyl)hexanethiol and 1H,1H,2H,2H‐perfluorodecanethiol. X‐ray photoelectron spectroscopy, UV/Vis spectrophotometry, Raman spectroscopy, conductivity measurements, and cyclic voltammetry were used to characterize the resulting surfaces.     

Synthesis and Properties of Partially Saturated Fluorenyl-Derived [n]Helicenes Featuring an Overcrowded Alkene

The straightforward, multigram-scale synthesis of the partially saturated H₆-fluoreno[n]helicenes (n=5 or 7) featuring a central, overcrowded alkene is described. The key cyclization step was based on an intramolecular McMurry reaction from the corresponding 1,5-diketones. Chiral stationary phase HPLC analysis and isomer separation indicate that each helicenic compound is constituted of three diastereoisomers at room temperature, i. e. the configurationally stable (R,R,P)/(S,S,M) pair of enantiomers and an apparently achiral compound resulting from the rapid interconversion between the (R,S,P) and (S,R,M) enantiomers. The partially saturated H₆-fluoreno[n]helicenes are oxidatively aromatized to give an efficient access to the corresponding fluoreno[n]helicenes. The chiroptical properties (vibrational and electronic circular dichroism) of the chiral, enantiopure compounds have been measured and analyzed by quantum-chemical calculations, confirming their helicoidal nature.     

SECM for Studying the Immobilization and Repartition of a Redox Anti-tetracycline Aptamer on Screen-printed Carbon Electrodes

Scanning electrochemical microscopy (SECM) is discussed as a versatile tool to provide a unique approach of localized electrochemical information in the context of biosensing research. The step-by-step immobilization of DNA aptamer with intrinsic redox activity on screen-printed carbon electrode (SPCE) was successfully monitored using SECM imaging tool. Control experiments were performed with a non-electroactive aptamer. After immobilization of these aptamers, SECM images showed the repartition of the electroactive anti-tetracycline aptamer when comparing with images produced for control and for all modification steps of SPCE. The possibility of tetracycline detection was also proved by causing a decrease in recorded current.     

Characterization of New Specific Copper Chelators as Potential Drugs for the Treatment of Alzheimer’s Disease

The non‐controlled redox‐active metal ions, especially copper, in the brain of patients with Alzheimer disease (AD) should be considered at the origin of the intense oxidative damage in the AD brain. Several bis(8‐aminoquinoline) ligands, such as 1 and PA1637, are able to chelate Cu²⁺ with high affinity, and are specific chelators of copper with respect to iron and zinc. They are able to efficiently extract Cu²⁺ from a metal‐loaded amyloid. In addition, these tetradentate ligands are specific for the chelation of Cu²⁺ compared with Cu⁺. Consequently, the copper ion is easily released from the bis(8‐aminoquinoline) ligand under reductive conditions, and can be trapped again by a protein having some affinity for copper such as human serum albumin (HSA) proteins. In addition, the copper is not efficiently released from [Cu(CQ)₂] in reductive conditions. The catalytic production of H₂O₂ by [Cu²⁺‐Aβ_1?28]/ascorbate is inhibited in vitro by the bis(8‐aminoquinoline) 1 , suggesting that 1 should be able to play a protective role against oxidative damages induced by copper‐loaded amyloids.     

Sequestration of Proteins by Fatty Acid Coacervates for Their Encapsulation within Vesicles

Encapsulating biological materials in lipid vesicles is of interest for mimicking cells; however, except in some particular cases, such processes do not occur spontaneously. Herein, we developed a simple and robust method for encapsulating proteins in fatty acid vesicles in high yields. Fatty acid based, membrane‐free coacervates spontaneously sequester proteins and can reversibly form membranous vesicles upon varying the pH value, the precrowding feature in coacervates allowing for protein encapsulation within vesicles. We then produced enzyme‐enriched vesicles and show that enzymatic reactions can occur in these micrometric capsules. This work could be of interest in the field of synthetic biology for building microreactors.