Versatile Near-Infrared Super-Resolution Imaging of Amyloid Fibrils with the Fluorogenic Probe CRANAD-2

CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo.     

Thermal stability of the PBAT biofilms with cellulose nanostructures/essential oils for active packaging

The primary objective of this study is to evaluate the thermal stability of the active films with the cellulose nanostructure (CNS, 5?mass%) treated with encapsulated essential oils (EOs), eugenol and linalool. CNS untreated and treated were incorporated in the poly(butylene adipate-co-terephthalate) (PBAT) polymer matrix prepared by casting. In this study, all samples were characterized by FTIR, DRX, TG, DSC and SEM, elucidating the contribution of each component in the final films. CNS untreated and treated with EOs were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA), confirming the interaction between these components. The active biofilms were analyzed by TGA and DSC analyses (differential scanning calorimetry), confirming that their thermal stability was maintained similar to the neat PBAT film, without loss of properties. The CI (crystallinity index, %) of the polymeric films was calculated from heat fusion (ΔH) values, indicating that the incorporation of the nanostructures into the PBAT matrix increases the crystallinity of the biofilms, from 11.5 (neat PBAT) to 13.8% (PBAT/CNS-E), acting as a nucleating agent in the polymeric matrix. The presence of the EOs did not decrease the CNS stability, as well of the biocomposite films. Moreover, the thermal analysis confirmed that the EO was well involved by the CNS, before and after the incorporation in the PBAT polymer, as observed in the SEM images.

     

Mechanistic Insights into C(sp2)−C(sp)N Reductive Elimination from Gold(III) Cyanide Complexes

A new family of phosphine-ligated dicyanoarylgold(III) complexes has been prepared and their reactivity towards reductive elimination has been studied in detail. Both, a highly positive entropy of activation and a primary ^12/13C KIE suggest a late concerted transition state while Hammett analysis and DFT calculations indicate that the process is asynchronous. As a result, a distinct mechanism involving an asynchronous concerted reductive elimination for the overall C(sp²)−C(sp)N bond forming reaction is characterized herein, for the first time, complementing previous studies reported for C(sp³)−C(sp³), C(sp²)−C(sp²), and C(sp³)−C(sp²) bond formation processes taking place on gold(III) species.     

The Lewis acidities of gold(I) and gold(III) derivatives: a theoretical study of complexes of AuCl and AuCl3

Chloride complexes of gold(I) (seventeen) and gold(III) (seventeen) with different ligands (including H, C, N, O, P, S as interacting atoms) have been studied at the CCSD(T)/CBS level. The computed geometries were compared with those found in the Cambridge Structural Database and the dissociation energies related with those previously reported in the literature by Yamamoto et al. Some special processes catalysed by these gold complexes such as bond-breaking (dihydrogen, cyclopropane) and arenes reactivity were studied in detail.

     

Amphiphilic pentablock copolymers and their blends with PDMS for antibiofouling coatings

Well‐defined amphiphilic pentablock copolymers Siy‐(EGx‐FAz)₂ composed of polysiloxane (Si), polyethylene glycol (EG), and perfluorohexylethyl polyacrylate (FA) blocks are synthesized by ATRP of FA monomer starting from a difunctional bromo‐terminated macroinitiator. Diblock copolymers EGx‐FAz are also synthesized as model systems. The block copolymers are used, either alone or blended with a PDMS matrix in varied loadings, to prepare antibiofouling coatings. Angle‐resolved XPS and contact angle measurements show that the coating surface is highly enriched in fluorine content but undergoes reconstruction after contact with water. Protein adsorption experiments with human serum albumin and calf serum highlight that diblock copolymers resist protein adhesion better than do pentablock copolymers. Blending of the pentablock copolymer with PDMS results in increased protein adsorption. By contrast, the PDMS‐matrix coatings show high removal percentages of sporelings of the green fouling alga Ulva linza. © 2015 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 2015 , 53, 1213–1225     

Synthesis of partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions

Partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions (ps‐PES‐FPES), with ionic exchange capacity (IEC) ranging between 0.9 and 1.5 meq H⁺/g, are synthesized by regioselective bromination of partially fluorinated poly(arylene ether sulfone) multiblock copolymers (PES‐FPES), followed by Ullman coupling reaction with lithium 1,1,2,2‐tetrafluoro‐2‐(1,1,2,2‐tetrafluoro‐2‐iodoethoxy)ethanesulfonate. The PES‐FPES are prepared by aromatic nucleophilic substitution reaction by an original approach, that is, “one pot two reactions synthesis.” The chemical structures of polymers are analyzed by ¹H and ¹⁹F NMR spectroscopy. The resulted ionomers present two distinct glass transitions and α relaxations revealing phase separation between the hydrophilic and the hydrophobic domains. The phase separation is observed at much lower block lengths of ps‐PES‐FPES as compared with the literature. AFM and SANS observations supported the phase separation, the hydrophilic domains are well dispersed but the connectivity to each other depends on the ps‐PES block lengths. The thermomechanical behavior, the water up‐take, and the conductivity of the ps‐PES‐FPES membranes are compared with those of Nafion 117^® and randomly functionalized polysulfone (ps‐PES). Conductivities close or higher to those of Nafion 117^® are obtained. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1941–1956