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Chiral transcription and enantioselective separation have garnered significant research interests and showed potential for a broad range of practical applications. Here, we present a novel and facile strategy for chiral templating and enantiomers resolution by coating metal-ion-mediated l -phenylalanine derivatives (LPF/M) with graphene oxide (GO) via simply mixing. The LPF/M hydrogels precipitate from the liquid by encapsulation of GO through coordination interactions and hydrogen bonds, making heterogeneous transfer and separation possible. The chirality inversion of the internal LPF/M nanostructure could be triggered by different addition of metal ions, which further provides means for controlled chiral transfer of guest molecules on the outer GO surfaces as demonstrated in the transcription of thioflavin T (ThT) and 3-aminopyridine (AP) at the supramolecular level. Changing the metal ions also provides control over enantiomer selectivity with outstanding efficiency and reproducibility, as revealed by the separation of racemic mixtures of phenylanine (>98%), lysine (>96%), and histidine (>97%). In addition, the resultant hybrid materials exhibit excellent environmental stability and reusability (more than 20 times) with significant separation efficiency. More importantly, the GO-coated LPF/M could determine the enantiomeric composition of various chiral substrates. The proposed strategy opens up a promising avenue for practical chiral separation application. Image 1 [ABSTRACT FROM AUTHOR]

The layered nanocomposite hydrogel films containing chitosan (CS) and graphene oxide (GO) have been prepared by water evaporation induced self-assembly and subsequent physical cross-linking in alkaline solution. The layered CS/GO hydrogel films obtained have a nacre-like brick-and-mortar microstructure, which contributes to their excellent mechanical properties. The tensile strength and elongation at break of the hydrogel films with 5 wt% GO are 5.35 MPa and 193.5%, respectively, which are comparable to natural costal cartilage. Furthermore, the CS/GO hydrogel films exhibited pH-driven shape memory effect, and this unique phenomenon is mainly attributed to the reversible transition of partial physically cross-linking corresponding to hydrogen bondings and hydrophobic interactions between CS polymer chains due to pH changing. [ABSTRACT FROM AUTHOR]

In this paper, we are presenting a facile, green and in situ synthesis strategy for the convenient preparation of well-dispersed gold nanoparticles (AuNPs)-decorated reduced graphene oxide (RGO) without the use of any template molecules and poisonous reductant. The as-synthesized nanocomposite has been detailedly characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis as well as electrochemical technologies. The morphological and structural characterizations illustrate that AuNPs can be efficiently decorated on RGO with the Au content of 20.33 wt% in the matrix and the size of the embedded AuNPs vary between 25 and 40 nm. The electrochemical investigations confirm that the small-sized AuNPs on the RGO film can remarkably boost the electrocatalytic activity for the oxidation of Sudan I, which can be used as an enhanced electrochemical sensing platform for the sensitively detection of the toxicant Sudan I. Moreover, the kinetic parameter studies demonstrate that the Sudan I electro-oxidation at the AuNPs/RGO electrode is a diffusion-controlled process which involves two-electron and two-proton transfer. Under the optimal conditions, a wide linear range of Sudan I detection from 0.01 to 70 μmol L −1 with good linearity ( R 2 = 0.9965, 0.9942) and a low detection limit (1.0 nmol L −1 , S/N = 3) were obtained. In comparison with the existing analogues ever reported, the AuNPs/RGO eletrode exhibits overwhelmingly superior comprehensive properties for the sensitive detection of Sudan I. Finally, the newly developed sensor was applied to quantitative determination of Sudan I in food samples such as chilli powder and ketchup sauce with satisfactory sensitivity, selectivity and reversibility. [ABSTRACT FROM AUTHOR]

A copper nanostructures-graphene oxide (Cu/GO) hybrid as a new electrocatalyst for highly sensitive detection of 2-naphthol (2-NAP) was successfully synthesized by a one-pot and in situ chemical reduction approach. The characterization results reveal that the cubic Cu nanostructures are tightly attached onto the GO sheets in the resulting hybrid. A lower oxidation potential and a larger peak current were observed for the 2-NAP oxidation at the Cu/GO modified electrode, demonstrating the synergistic electrocatalysis from Cu nanostructures and GO sheets. Consequently, the Cu/GO hybrid exhibits a low detection limit (5.0 nM) and wide linear ranges (0.1–4.0 μM and 4.0–130.0 μM) when used as a sensing material for the sensitive detection of 2-NAP. Finally, the fabricated sensor was successfully applied in the detection of 2-NAP in real samples and satisfactory recoveries in the range of 99.3%–104.0% were achieved. [ABSTRACT FROM AUTHOR]